The fabrication of highly monodisperse silica coated Au NPs by the microemulsion approach and the selection of the nanostructure morphology have been described. Several experimental conditions, synthetic parameters and post-preparative strategies such as reaction time, precursor concentration, size selection techniques and NP surface treatments have been suitably investigated in order to fabricate Au and Au@SiO2 NPs with peculiar and tuneable plasmonic properties that strongly depend on the specific size distribution and nanostructure morphology. In particular, size selected precipitation of oleylaminecapped Au NPs by antisolvent titration has successfully offered a strategy to discriminate and collect monodisperse fractions with different average size and narrow size distribution. Moreover, for the first time, a deep insight into the microemulsion mechanism for the silica shell growth has been provided, highlighting the critical role played by the density of oleylamine at the Au NP surface. Specifically the capping agent has been demonstrated to strongly determine the multiplicity of the core in the final Au@SiO2 nanostructures. Density gradient centrifugation has been finally performed to sort the achieved Au@SiO2 NPs with different morphologies, which was ultimately able to recover a significant fraction formed of two Au NPs in one silica shell. A systematic characterization of the Au and Au@SiO2 NPs has been carried out by complementary morphological and spectroscopic techniques. These deeply investigated materials, with tuneable plasmonic properties, have been proposed as versatile building blocks useful for the design and fabrication of plasmonic and photonic structures as well as metamaterials for device applications.

In this paper, industrial dyes, Disperse Red and Disperse Orange, were studied as model pollutants to show the excellent performance of olive pomace (OP) in sequestering and recovering these dangerous dyes from wastewater. The nature of interactions involved between dyes and OP were inferred by changing several parameters: contact time, pomace dosage, pH and temperature values. Visible spectroscopy was mainly used to obtain the percentage of the removed dyes, while SEM (scanning electron microscopy), FTIR-ATR (Fourier transform infra-red spectroscopy in total attenuated reflectance), TG (thermo gravimetric) and XPS (X-ray photoelectron spectroscopy) analyses were used to carefully investigate the systems. The recovery of dyes was also obtained using glacial acetic acid, the auxiliary solvent used during the dyeing processes, enabling the recycling of both of the adsorbent material and dyes presenting a green and a wide-ranging strategic approach.

Asymmetric binary nanocrystals (BNCs) formed by a spherical gamma-Fe(2)O(3) magnetic domain epitaxially grown onto a lateral facet of a rodlike anatase TiO(2) nanorod have been functionalized with PEG-terminated phospholipids, resulting in a micellar system that enables the BNC dispersion in aqueous solution. The further processability of the obtained water-soluble BNC including PEG lipid micelles and their use in bioconjugation experiments has been successfully demonstrated by covalently binding to bovine serum albumin (BSA). The whole process has also been preliminarily performed on spherical iron oxide nanocrystals (NCs) and TiO(2) nanorods (NRs), which form single structural units in the heterostructures. Each step has been thoroughly monitored by using optical, structural, and electrophoretic techniques. In addition, an investigation of the magnetic behavior of the iron oxide NCs and BNCs, before and after incorporation into PEG lipid micelles and subsequently bioconjugation, has been carried out, revealing that the magnetic characteristics are mostly retained. The proposed approach to achieving water-soluble anisotropic BNCs and their bioconjugates has a large potential in catalysis and biomedicine and offers key functional building blocks for biosensor applications.

In this study, ultrathin film multilayers of Photosystem II-enriched photosynthetic membranes (BBY) were prepared and immobilized on quartz substrates by means of a Layer by Layer procedure exploiting electrostatic interactions with poly(ethylenimine) as polyelectrolyte. The biomaterials thus obtained were characterized by means of optical techniques and Atomic Force Microscopy, highlighting the fact that the Layer by Layer approach allowed the BBYs to be immobilized with satisfactory results. The activity of these hybrid materials was evaluated by means of optical assays based on the Hill Reaction, indicating that the biosamples, which preserved about 65% of their original activity even ten weeks after preparation, were both stable and active. Furthermore, an investigation of the biochips’ sensitivity to the herbicide terbutryn, as a model analyte, gave interesting results: inhibition of photosynthetic activity was observed at terbutryn concentrations higher than 10-7 M, thus evidencing the potential of such biomaterials in the environmental biosensor field.

Nanoparticles (NPs) emitting in the second biological near infrared (NIR) window of the electromagnetic spectrum have been successfully synthesized by growing a silica shell on the hydrophobic surface of OLEA/TOP PbS nanocrystals (NCs), by means of a reverse microemulsion approach, and subsequently decorated with biotin molecules. The fabrication of very uniform and monodisperse NPs, formed of SiO2 shell coated single core PbS NCs, has been demonstrated by means of a set of complementary optical and structural techniques (Vis-NIR absorption and photoluminescence spectroscopy, transmission electron microscopy) that have highlighted how experimental parameters, such as PbS NC and silica precursor concentration, are crucial to direct the morphology and optical properties of silica coated PbS NPs. Subsequently, the silica surface of the core-shell NPs has been grafted with amino groups, in order to achieve covalent binding of biotin to NIR emitting silica coated NPs. Finally the successful reaction with a green-fluorescent labelled streptavidin has verified the molecular recognition response of the biotin molecules decorating the PbS@SiO2 NP surface. Dynamic light scattering (DLS) and zeta-potential techniques have been used to monitor the hydrodynamic diameter and colloidal stability of both PbS@SiO2 and biotin decorated NPs, showing their high colloidal stability in physiological media, as needed for biomedical applications. Remarkably the obtained biotinylated PbS@SiO2 NPs have been found to retain emission properties in the 'second optical window' of the NIR region of the electromagnetic spectrum, thus representing attractive receptor-targeted NIR fluorescent probes for in vivo tumour imaging.

The covalent functionalization of photosynthetic proteins with properly tailored organic molecular antennas represents a powerful approach to build a new generation of hybrid systems capable of exploiting solar energy. In this paper the strategy for the synthesis of the tailored aryleneethynylene organic fluorophore (AE) properly designed to act as light harvesting antenna is presented along with its successful bioconjugation to the photosynthetic reaction center RC from the bacterium Rhodobacter sphaeroides .

The response of the carotenoidless Rhodobacter sphaeroides mutant R26 to chromate stress under photosynthetic conditions is investigated by biochemical and spectroscopic measurements, proteomic analysis and cell imaging. Cell cultures were found able to reduce chromate within 3-4 days. Chromate induces marked changes in the cellular dimension and morphology, as revealed by atomic force microscopy, along with compositional changes in the cell wall revealed by infrared spectroscopy. These effects are accompanied by significant changes in the level of several proteins: 15 proteins were found up-regulated and 15 down-regulated. The protein content found in chromate exposed cells is in good agreement with the biochemical, spectroscopic and microscopic results. Moreover at the present stage no specific chromate-reductase could be found in the soluble proteome, indicating that detoxification of the pollutant proceeds via aspecific reductants.

The goal of this study is the chemical-physical characterization of a drug delivery system for Photodynamic Therapy (PDT) [1]: Chlorophyll a (Chl a) entrapped in a water-soluble matrix made of Ca2+ cross-linked alginic acid [2]. Chl a, a lipophilic natural pigments, is a molecule with characteristic photosensitising properties usable in PDT. In PDT the photosensitizer, selectively accumulated in malignant tissues, produces, upon light irradiation, reactive oxygen species (ROS) which are responsible for cytotoxicity of neoplastic cells and tumor regression since induce cellular damage via apoptosis, necrosis, or both. The Chl a/alginate microspheres produced were characterized by means of different techniques as UV-Vis absorption and emission spectroscopy, FT-IR spectroscopy, Atomic Force Microscopy, Dynamic Light Scattering and Differential Scanning Calorimetry. Moreover, it was estimated the ROS production, mainly singlet oxygen (1O2) by means of a selective luminescent probe, Singlet Oxygen Sensor Green [3] and in vitro tests were carried out on human adenocarcinoma cells (HT29). [1] R.M. Szeimies, S. Karrer, S. Radakovic-Fijan. J. Am. Acad. Dermatol., 2002, 47, 259-262. [2] G.T. Grant, E.R. Morris, D.A. Rees, P.J.C. Smith, D. Thom. FEBS letters, 1973, 32,195-198. [3] A. Gollmer, J. Arnbjerg, H. Frances, F.H. Blaikie, B.Wett Pedersen, T. Breitenbach, K. Daasbjerg, P.R. Ogilby. Photochemistry and Photobiology, 2011, 87, 671–679.

Heterostructures formed of films of organic-capped ZnO and TiO2 nanocrystals (both with the size of ca. 6 nm) and photosynthetic pigments were prepared and characterized. The surface of optically transparent electrodes (Indium Tin Oxide) was modified with nanocrystals and prepared by colloidal synthetic routes. The nanostructured electrodes were sensitized by a mixture of chlorophyll a and carotenoids. The characterization of the hybrid structures, carried out by means of steady-state optical measurements, demonstrated such class of dyes able to extend the photoresponse of the large band-gap semiconductors. The charge-transfer processes between the components of the heterojunction were investigated, and photoelectrochemical measurements taken on the sensitized ZnO and TiO2 nanocrystals electrodes elucidated the photoactivity of the heterojunctions as a function of the dyes and of the red-ox mediator used in solution. The effect of methyl viologen as different red-ox mediator was also evaluated in order to show its effect on the heterojunction photoactivity. The overall results contributed to describe the photoelectrochemical potential of the investigated heterojunctions, highlighting a higher response of the dye-sensitized ZnO nanocrystals, and then provided the TiO2-modified counterparts.

A new analytical method for the determination of ochratoxin A (OTA) in red wine has been developed by using a double-extract cleanup and a fluorometric measurement after spectral deconvolution. Wine samples were diluted with a solution containing 1% polyethylene glycol and 5% sodium hydrogencarbonate, filtered, and purified by immunoaffinity and aminopropyl solid-phase column. OTA contents in the purified extract were determined by a spectrofluorometer (excitation wavelength, 330 nm; emission wavelength, 470 nm) after deconvolution of fluorescence spectra. Average recoveries from wine samples spiked with OTA at levels ranging from 0.5 to 3.0 ng/mL were 94.5–105.4% with relative standard deviations (RSD) of <15% (n = 4). The limit of detection (LOD) was 0.2 ng/mL, and the total time of analysis was 30 min. The developed method was tested on 18 red wine samples (naturally contaminated and spiked with OTA at levels ranging from 0.4 to 3.0 ng/mL) and compared with AOAC Official Method 2001.01, based on immunoaffinity column cleanup and HPLC with fluorescence detector. A good correlation (r2 = 0.9765) was observed between OTA levels obtained with the two methods, highlighting the reliability of the proposed method, the main advantage of which is the simple OTA determination by a benchtop fluorometer with evident reductions of cost and time of analysis.

Ultrasounds are used in many industrial, medical and research applications. Properties and function of proteins are strongly influenced by the interaction with the ultrasonic waves and their bioactivity can be lost because of alteration of protein structure. Surprisingly, to the best of our knowledge no study was carried out on Integral Membrane Proteins (IMPs), which are responsible for a variety of fundamental biological functions. In this work, the photosynthetic Reaction Center (RC) of the bacterium Rhodobacter sphaeroides has been used as a model for the study of the ultrasound-induced IMP denaturation. Purified RCs were suspended in i) detergent micelles, in ii) detergent-free buffer and iii) reconstituted in liposomes, and then treated with ultrasound at 30 W and 20 kHz at increasing times. The optical absorption spectra showed a progressive and irreversible denaturation in all cases, resulting from the perturbation of the protein scaffold structure, as confirmed by circular dichroism spectra that showed progressive alterations of the RC secondary structure. Charge recombination kinetics were studied to assess the protein photoactivity. The lifetime for the loss of RC photoactivity was 32 min in detergent micelles, ranged from 3.8 to 6.5 min in the different proteoliposomes formulations, and 5.5 min in detergent-free buffer. Atomic force microscopy revealed the formation of large RC aggregates related to, the sonication-induced denaturation, in agreement with the scattering increase observed in solution. (C) 2016 Elsevier B.V. All rights reserved.

In order to investigate the effects of cryomaceration and reductive vinification on chemical and physical indices and on antioxidant compounds of Sauvignon blanc wines, four wine-making procedures were applied: traditional white vinification, skin cryomaceration, vinification in a reductive environment, and a combination of the last two procedures. Significant differences were highlighted by both conventional analyses and NMR spectroscopy. The strongest changes were for organic acid concentrations (tartaric, in particular) and phenolic content. Cryomaceration caused a strong precipitation of tartaric acid, which may be desired if grapes have high acidity values. Cryomaceration protected those fiavans reactive with vanillin from the action of oxidative enzymes. Vinification in a reductive environment, alone or combined with a cryomaceration step, gave wines with the highest solids content and caused a greater extraction of phenolic compounds from skins compared to traditional winemaking or cryomaceration alone, due to SO2 solubilisation. Grape oenological expression can be strongly affected by the application of the investigated wine-making procedures. (C) 2012 Elsevier Ltd. All rights reserved.

Nanostructured films based on Au nanorods (NRs) have been obtained by layer-by-layer (LbL) assembly driven by electrostatic interaction between metal nanoparticles and polyelectrolytes. Multilayer films have been fabricated by using LbL assembly of poly(sodium styrenesulfonate) (PSS) and positively charged Au NRs on a polyelectrolyte-modified substrate. The effect of fabrication parameters, including the nature of the substrate, the polyelectrolyte initial anchoring layer, and the number of layers has been investigated by means of UV vis absorbance spectroscopy and atomic force microscopy (AFM). The results demonstrated the dependence of morphology and plasmonic features in the multilayered nanostructured architectures from the nature of the anchoring polyelectrolyte on the substrate, the number of layers, and the kind of NR mutual assembly. In addition, a study of the electrochemical activity at the solid/liquid interface has been carried out in order to assess charge transport through the NR multilayer by using two molecular probes in solution, namely, potassium ferricyanide, a common and well-established redox mediator with reversible behavior, and cytochrome C, a robust model redox protein. The presented systematic study of the immobilization of Au NRs opens the venue to several application areas, such as (bio)chemical sensing.

Sweet cherries from two Italian regions, Apulia and Emilia Romagna, were analysed using electronic nose (EN) and isotope ratio mass spectrometry (IRMS), with the aim of distinguishing them according to their geographic origin. The data were elaborated by statistical techniques, examining the EN and IRMS datasets both separately and in combination. Preliminary exploratory overviews were performed and then linear discriminant analyses (LDA) were used for classification. Regarding EN, different approaches for variable selection were tested, and the most suitable strategies were highlighted. The LDA classification results were expressed in terms of recognition and prediction abilities and it was found that both EN and IRMS performed well, with IRMS showing better cross-validated prediction ability (91.0%); the EN–IRMS combination gave slightly better results (92.3%). In order to validate the final results, the models were tested using an external set of samples with excellent results.

Light machine: The simplest photosynthetic protein able to convert sunlight in other energy forms is covalently functionalized with a tailored organic dye to obtain a fully functional hybrid complex that outperforms the natural system in light harvesting and conversion ability.

The relaxation dynamics of charge carriers of organic capped TiO2 nanorods dispersed in chloroform was investigated by femtosecond transient absorption in a weak-excitation regime. Anisotropic TiO2 nanocrystals were excited in the UVvis range, using different pump wavelengths, namely above (300 nm), close to (350 nm), and below (430 nm) the direct band gap of anatase TiO2. We show that the ultrafast dynamics strongly depends on excitation wavelength and determine the time constants of all the processes entering the relaxation. Moreover, we demonstrate that two transient absorption bands at 500 and 700 nm, typically attributed to trapped h(+) and e, respectively, are accessible only when TiO2 is photoexcited well above the band gap, while there is no evidence of such bands when TiO2 is photoexcited close to or below its band gap. In such cases the observed dynamics are attributed to trapped excitons.

In this work a genuine combination of a bottom-up approach, which is based on synthesis and functionalization of emitting nanocrystals (NCs), with a top-down strategy, which relies on a flexible and versatile cold plasma process, is shown. Luminescent semiconducting colloidal NCs consisting of a CdSe core coated with a ZnS shell (CdSe@ZnS) are directly assembled onto micro-patterned substrates previously functionalized by means of glow discharges performed through physical masks. The NC assembly is driven by electrostatic interactions that led to their successful organization into spatially resolved domains. Two distinct protocols are tested, the former using a plasma deposition process combined with an electrostatic layer-by-layer procedure, the latter based on a two-step plasma deposition/treatment process. The procedures are thoroughly monitored with fluorescence microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The two-step plasma protocol is demonstrated to be more efficient in directing a uniform and specific assembly of luminescent NCs with respect to the hybrid procedure. The presented 'mix and match' approach offers great potential for integrating NCs, with their unique size-dependent properties, into microstructures, providing a universal platform for the fabrication of sensors, biochips, displays and switches.

In this work a genuine combination of a bottom-up approach, which is based on synthesis and functionalization of emitting nanocrystals (NCs), with a top-down strategy, which relies on a flexible and versatile cold plasma process, is shown. Luminescent semiconducting colloidal NCs consisting of a CdSe core coated with a ZnS shell (CdSe@ZnS) are directly assembled onto micro-patterned substrates previously functionalized by means of glow discharges performed through physical masks. The NC assembly is driven by electrostatic interactions that led to their successful organization into spatially resolved domains. Two distinct protocols are tested, the former using a plasma deposition process combined with an electrostatic layer-by-layer procedure, the latter based on a two-step plasma deposition/treatment process. The procedures are thoroughly monitored with fluorescence microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The two-step plasma protocol is demonstrated to be more efficient in directing a uniform and specific assembly of luminescent NCs with respect to the hybrid procedure. The presented ‘mix and match’ approach offers great potential for integrating NCs, with their unique size-dependent properties, into microstructures, providing a universal platform for the fabrication of sensors, biochips, displays and switches.

A facile, cost-effective, and general solution-based "bottom-up" method for nanopatterning dense arrays of colloidal Au nanoparticles (NPs) has been developed. The organization of the NPs has been successfully achieved onto a microphase-separated poly(styrene-block-ethylene oxide) (PS-b-PEO) block copolymer (BCP) thin film which acts as structural template. The NP assembly process occurs by incubating the BCP films in dispersions of the ex situ synthesized Au NPs, not requiring any chemical pre-treatment or activation step of the copolymer surface, and has demonstrated to be distinctively controlled by multiple, cooperative, and selective hydrogen bonding interactions between hydroxyl functionalities of the capping molecules coating the Au NP surface and the hydrophilic PEO block. The effect of incubation time and concentration of NPs on the selectivity of the assembly has been investigated by atomic force and scanning electron microscopy. The results show that the BCP pattern is preserved after decoration with the Au NPs. The fabricated nanopatterns are good candidates for nanostructure integration in sensing and optoelectronic applications, as well as in memory devices and photonic systems. Moreover, the proposed immobilization protocol represents a model system that can be extended to other NPs having different compositions and surface chemistries.

In this work, studies on the effects produced by atrazine, terbutryn or diuron onto spinach photosynthetic materials were performed by observing changes in fluorescence emission and in electron transfer activities of the bio-samples in the presence of such herbicides; chloroplasts, thylakoids, Photosystem II-enriched thylakoids (BBYs) and isolated Photosystem II (PSII) were employed. This approach evidenced differences in the herbicide-photosynthetic material interactions going up-down from chloroplasts to proteins. Rapid emission increments were detected for chloroplasts and thylakoids, in particular in the presence of terbutryn; no remarkable emission increment was recorded when BBYs or PSII were used for this assay. The dependences of the chloroplast and thylakoid emission intensities upon herbicide concentration were investigated with responses even at concentrations below 10-7 M. The influence of lowering the temperature was also tested, and stabilizing effects on the resistances of the bio-samples against herbicides were recorded. Furthermore, Hill Reaction-based colorimetric assays were performed to monitor the electron transfer activities of the bio-samples in the presence of herbicides, after brief incubations. As results, chloroplasts and thylakoids resulted to be sensitive tools in responding to concentrations even lower than 10-7 M of most herbicides; nevertheless, an interesting sensitivity to herbicides was also observed for PSII.

Here a luminescent hybrid nanostructure based on functionalized quantum dots (QDs) is used as a fluorescent imaging agent able to target selectively mitochondria thanks to the molecular recognition of the translocator protein (TSPO). The selective targeting of such an 18 kDa protein mainly located in the outer mitochondrial membrane and overexpressed in several pathological states including neurodegenerative diseases and cancers may provide valuable information for the early diagnosis and therapy of human disorders. In particular, the rational design of amino functionalized luminescent silica coated QD nanoparticles (QD@SiO2 NPs) provides a versatile nanoplatform to anchor a potent and selective TSPO ligand, characterized by a 2-phenyl-imidazo[1,2-a] pyridine acetamide structure along with a derivatizable carboxylic end group, useful to conjugate the TSPO ligand and achieve TSPO-QD@SiO2 NPs by means of a covalent amide bond. The colloidal stability and optical properties of the proposed nanomaterials are comprehensively investigated and their potential as mitochondrial imaging agents is fully assessed. Subcellular fractionation, together with confocal laser scanning fluorescence microscopy and co-localization analysis of targeted TSPO-QD@SiO2 NPs in C6 glioma cells overexpressing the TSPO, proves the great potential of these multifunctional nanosystems as in vitro selective mitochondrial imaging agents.

Because of the growing potential of nanoparticles in biological and medical applications, tuning and directing their properties toward a high compatibility with the aqueous biological milieu is of remarkable relevance. Moreover, the capability to combine nanocrystals (NCs) with biomolecules, such as proteins, offers great opportunities to design hybrid systems for both nanobiotechnology and biomedical technology. Here we report on the application of the micelle-to-vesicle transition (MVT) method for incorporation of hydrophobic, red-emitting CdSe@ZnS NCs into the bilayer of liposomes. This method enabled the construction of a novel hybrid proteo-NC-liposome containing, as model membrane protein, the photosynthetic reaction center (RC) of Rhodobacter sphaeroides. Electron microscopy confirmed the insertion of NCs within the lipid bilayer without significantly altering the structure of the unilamellar vesicles. The resulting aqueous NC-liposome suspensions showed low turbidity and kept unaltered the wavelengths of absorbance and emission peaks of the native NCs. A relative NC fluorescence quantum yield up to 8% was preserved after their incorporation in liposomes. Interestingly, in proteo-NC-liposomes, RC is not denatured by Cd-based NCs, retaining its structural and functional integrity as shown by absorption spectra and flash-induced charge recombination kinetics. The outlined strategy can be extended in principle to any suitably sized hydrophobic NC with similar surface chemistry and to any integral protein complex. Furthermore, the proposed approach could be used in nanomedicine for the realization of theranostic systems and provides new, interesting perspectives for understanding the interactions between integral membrane proteins and nanoparticles, i.e., in nanotoxicology studies.

SWNTs have been functionalized with an archaeal glycolipid which wraps around the nano-objects in a single layer or bilayer, as a function of the nanotube diameter. Hydrogen bonds between the lipid glucose rings and the aromatic SWNT walls are involved in the formation of hybrid complexes resulting in electron transfer from the glycolipid to the nanotubes

Photodynamic therapy (PDT) is a way of treating malignant tumors and hyperproliferative diseases. It is based on the use of photosensitizer, herein the chlorophyll a (chl a), and a light of an appropriate wavelength. The interaction of the photosensitizer (PS) with the light produces reactive oxygen species (ROS), powerful oxidizing agents, which cause critical damage to the tissue. To solubilize chl a in aqueous solution and to obtain it as monomer, we have used cyclodextrins, carriers which are able to interact with the pigment and form the inclusion complex. The aim of this study is to examine which types of ROS are formed by Chl a/cyclodextrin complexes in phosphate buffered solution and cell culture medium, using specific molecules, called primary acceptors, which react selectively with the reactive species. In fact the changes of the absorption and the emission spectra of these molecules after the illumination of the PS provide information on the specific ROS formation. The 1O2 formation has been tested using chemical methods based on the use of Uric Acid (UA), 9,10-diphenilanthracene (DPA) and Singlet oxygen sensor green (SOSG) and by direct detection of Singlet Oxygen (1O2) luminescence decay at 1270nm. Moreover, 2,7-dichlorofluorescin and ferricytochrome c (Cyt Fe3+) have been used to detect the formation of hydrogen peroxide and superoxide radical anion, which reduces Fe3+ of the ferricytochrome to Fe2+, respectively.

In this paper, virgin olive oils (VOOs) coming from three different geographic origins of Apulia, were analysed for free acidity, peroxide value. spectrophotometric indexes, chlorophyll content. sterol, fatty acid, and triacylglycerol compositions. In order to predict the geographical origin of VOOs, different multivariate approaches were applied. By performing principal component analysis (PCA) a modest natural grouping of the VOOs was observed on the basis of their origin, and consequently three supervised techniques, i.e., general discriminant analysis (GDA), partial least squares-discriminant analysis (PLS-DA) and soft independent modelling of class analogy (SIMCA) were used and the results were compared. In particular, the best prediction ability was produced by applying GDA (average prediction ability of 82.5%), even if interesting results were obtained also by applying the other two classification techniques, i.e., 77.2% and 75.5% for PLS-DA and SIMCA, respectively. (C) 2012 Elsevier Ltd. All rights reserved.

Binary asymmetric nanocrystals (BNCs), composed of a photoactive TiO2 nanorod joined with a superparamagnetic gamma-Fe2O3 spherical domain, were embedded in polyethylene glycol modified phospholipid micelle and successfully bioconjugated to a suitably designed peptide containing an RGD motif. BNCs represent a relevant multifunctional nanomaterial, owing to the coexistence of two distinct domains in one particle, characterized by high photoactivity and magnetic properties, that is particularly suited for use as a phototherapy and hyperthermia agent as well as a magnetic probe in biological imaging. We selected the RGD motif in order to target integrin expressed on activated endothelial cells and several types of cancer cells. The prepared RGD-peptide/BNC conjugates, comprehensively monitored by using complementary optical and structural techniques, demonstrated a high stability and uniform dispersibility in biological media. The cytotoxicity of the RGD-peptide/BNC conjugates was studied in vitro. The cellular uptake of RGD-peptide conjugates in the cells, assessed by means of two distinct approaches, namely confocal microscopy analysis and emission spectroscopy determination in cell lysates, displayed selectivity of the RGD-peptide-BNC conjugate for the alpha v beta 3 integrin. These RGD-peptide-BNC conjugates have a high potential for theranostic treatment of cancer.

T-2 and HT-2 toxins are mycotoxins produced by several Fusarium species that are commonly found in various cereal grains, including oats, barley, wheat and maize. Intake estimates indicate that the presence of these mycotoxins in the diet can be of concern for public health. In this work, the inclusion processes occurring between fluorescent anthracene-derivatives of T-2 and HT-2 toxins and different cyclodextrin (CD) molecules were investigated in aqueous solutions by means of UV–Vis absorption, fluorescence emission and dynamic light scattering. Binding constant values and chemico-physical parameters were calculated. It was found that b-CDs give stronger inclusion reactions with both T-2 and HT-2 derivatives, as stated by important emission intensity increments. Such interactions were found to be fundamentally enthalpy-driven. Among b-CDs, the effect of the methylation at hydroxyl groups was tested: as a result, the di-methyl form of b-CD was found to induce the best fluorescence intensity enhancements.

Squarebop I bacteriorhodopsin is a light-activated proton pump present in the membranes of the archeon Haloquadratum walsbyi, a square-shaped organism representing 50-60% of microbial population in the crystallizer ponds of the coastal salterns. Here we describe: (1) the operating mode of a bioreactor designed to concentrate the saltern biomass through a microfiltration process based on polyethersulfone hollow fibers; (2) the isolation of Squarebop I bacteriorhodopsin from solubilized biomass by means of a single chromatographic step; (3) tightly bound lipids to the isolated and purified protein as revealed by MALDI-TOF/MS analysis; (4) the photoactivity of Squarebop I bacteriorhodopsin isolated from environmental samples by flash spectroscopy. Yield of the isolation process is 150 μg of Squarebop I bacteriorhodopsin from 1l of 25-fold concentrated biomass. The possibility of using the concentrated biomass of salterns, as renewable resource for the isolation of functional bacteriorhodopsin and possibly other valuable bioproducts, is briefly discussed.

The life cycle of the bacterium Rhodobacter sphaeroides was investigated by isothermal microcalorimetry using two different procedures based on the use of a static ampoule and a flow cell, respectively. In the static ampoule method it is possible to follow the growth phase and also the death phase which cannot be revealed by total biomass based techniques like turbidimetry. However, different cellular metabolisms, possibly due do the oxygen limitation occurring during the bacterial life cycle, produce complex behavior in the experimental curves. In the stop-flow cell mode this limitation is overcome as the bacteria are grown outside the calorimeter under well-defined aerobic conditions and aliquots of cell suspension are transferred in the calorimeter at different time intervals. The complex behavior shown in the static ampoule mode was successfully analyzed by a population evolution model based on a Fujikawa modified logistic equation which provides a quantitative description of the process.

Photosynthetic reaction center (RC) is the minimal nanoscopic photoconverter in the photosynthetic membrane that catalyzes the conversion of solar light to energy readily usable for the metabolism of the living organisms. After electronic excitation the energy of light is converted into chemical potential by the generation of a charge separated state accompanied by intraprotein and ultimately transmembrane proton movements. We designed a system which fulfills the minimum structural and functional requirements to investigate the physico/chemical conditions of the processes: RCs were reconstituted in closed lipid vesicles made of selected lipids entrapping a pH sensitive indicator, and electron donors (cytochrome c(2) and K-4[Fe(CN)(6)]) and acceptors (decylubiquinone) were added to sustain the photocycle. Thanks to the low proton permeability of our preparations, we could show the formation of a transmembrane proton gradient under illumination and low buffering conditions directly by measuring proton-related signals simultaneously inside and outside the vesicles. The effect of selected ionophores such as gramicidin, nigericin and valinomycin was used to gain more information on the transmembrane proton gradient driven by the RC photochemistry.

The fabrication of hierarchical architectures of colloidal nanoparticles (NPs) represents an increasingly relevant approach to obtain innovative mesoscale materials, thanks to the original size-dependent characteristics of the nanosized building blocks, as well as, the collective properties arising from their organization. Here, an unconventional patterning method, based on formation of "breath figures" (BF), has been used to fabricate highly ordered honeycomb structures in nanocomposite materials, obtained by blending pre-synthesized colloidal gold NPs (Au NPs) in a polymeric matrix. The cast nanocomposite solutions have successfully allowed the fabrication of highly regular microporous self standing films. Large scale iridescent and ordered micropatterns with an hexagonal symmetry have been prepared and the fundamental role of NPs in stabilizing the templating water droplets in BF formation has been demonstrated. The resulting structured arrays of NP decorated pores can have a great potential as efficient catalysts for chemical reactions, as well as, templates for fabrication of photonic and optoelectronic devices, sensors and membranes for separation and purification purposes.

The photosynthetic reaction center (RC) is an integral membrane protein that, upon absorption of photons, generates a hole-electron couple with a yield close to one. This energetic state has numerous possible applications in several biotechnological fields given that its lifetime is long enough to allow non-metabolic ancillary redox chemistry to take place. Here we focus on RCs reconstituted in liposomes, formed with sole phospholipids or in blends with other lipids, and show that the electrical charge sitting on the polar head of such hydrophobic molecules does play an important role on the stability of the hole-electron couple. More specifically this study shows that the presence of negative charges in the surrounding of the protein stabilizes the charge-separated state while positive charges have a strong opposite effect.

In this work nanocomposites based on organic-capped semiconductor nanocrystals formed of a core of CdSe coated with a shell of ZnS (CdSe@ZnS), with different sizes, and a semiconducting conjugated polymer, namely poly[(9,9-dihexylfluoren-2,7-diyl)-alt- (2,5-dimethyl-1,4-phenylene)] (PF-DMB) have been investigated. The nanocomposites are prepared by mixing the pre-synthesized components in organic solvents, thereby assisting the dispersion of the organic-coated nano-objects in the polymer host. UV–vis steady state and time-resolved spectroscopy along with (photo)electrochemical techniques have been performed to characterize the obtained materials. The study shows that the embedded nanocrystals increase the PF-DMB stability against oxidation and, at the same time, extend the light harvesting capability to the visible spectral region, thus resulting in detectable photocurrent signals. The nanocomposites have been dispensed by means of a piezo-actuated inkjet system. Such inks present viscosity and surface tension properties well suited for stable and reliable drop-on-demand printing using an inkjet printer. The fabrication of arrays of single-color pixels made of the nanocomposites and micrometers in size has been performed. Confocal and atomic force microscopy have confirmed that inkjet-printed microstructures present the intrinsic emission properties of both the embedded nanocrystals and PF-DMB, resulting in a combined luminescence. Finally, the morphology of the printed pixels is influenced by the embedded nanofillers.

Photo-oxidation processes assisted by nanosized semiconductors are receiving increasing attention due to their potential application in environmental field. The ability to exploit the strong potential of photoactive nanomaterials and access their properties relies on the ability to integrate them in photo-reactors and to effectively deposit them on large surfaces. Such a strategy can bridge the gap between the nanoscopic and mesoscopic scale and avoiding nanoparticle release in the environment. In order to integrate nanopartides in functional structures and, finally, devices, their incorporation in suitable host matrices is crucial to achieve processable nanocomposite materials. Here, a comprehensive overview on the preparation of photocatalytic nanocomposite materials and their application for pollutants degradation will be provided. In particular, we will focus on modern synthetic approaches to synthetize UV and visible light active nanocatalysts, on their post-synthesis surface functionalization and on their incorporation in suitable host matrices toward nanocomposite preparation. Finally, some examples from recent literature on their application in environmental remediation and as bactericidal and self-cleaning coatings will be reported. (C) 2016 Elsevier B.V. All rights reserved.

In this work nanocomposites based on organic-capped semiconductor nanocrystals formed of a core of CdSe coated with a shell of ZnS (CdSe@ZnS), with different sizes, and a semiconducting conjugated polymer, namely poly[(9,9-dihexylfluoren-2,7-diyl)-alt-(2,5-dimethyl-1,4-phenylene)] (PF-DMB) have been investigated. The nanocomposites are prepared by mixing the pre-synthesized components in organic solvents, thereby assisting the dispersion of the organic-coated nano-objects in the polymer host. UV-vis steady state and time-resolved spectroscopy along with (photo) electrochemical techniques have been performed to characterize the obtained materials. The study shows that the embedded nanocrystals increase the PF-DMB stability against oxidation and, at the same time, extend the light harvesting capability to the visible spectral region, thus resulting in detectable photocurrent signals. The nanocomposites have been dispensed by means of a piezo-actuated inkjet system. Such inks present viscosity and surface tension properties well suited for stable and reliable drop-on-demand printing using an inkjet printer. The fabrication of arrays of single-color pixels made of the nanocomposites and micrometers in size has been performed. Confocal and atomic force microscopy have confirmed that inkjet-printed microstructures present the intrinsic emission properties of both the embedded nanocrystals and PF-DMB, resulting in a combined luminescence. Finally, the morphology of the printed pixels is influenced by the embedded nanofillers.

PbS colloidal nanocrystal (NC) assemblies with monomodal and bimodal size distribution have been fabricated by slow evaporation of solvent on silicon substrates. The interparticle distances of the assembled structures have been carefully defined, both in the plane and in the z direction, perpendicular to the substrate, thanks to the combination of small and wide-angle X-ray diffraction and TEM measurements. The spectroscopic characteristics of PbS NCs, both in solution and organized in a superlattice, have been investigated by steady-state and time-resolved photoluminescence measurements. The optical results reveal the occurrence of a Forster resonant energy transfer (FRET) mechanism between closed-packed neighboring PbS NCs. The occurrence of FRET is dependent on NC assembly geometry, and thus on their interparticle distance, suggesting that only when NCs are close enough, as in the close-packed arrangement of the monomodal assembly, the energy transfer can be promoted. In bimodal assemblies, the energy transfer between large and small NCs is negligible, due to the low spectral overlap between the emission and absorption bands of the different sized nanoparticles and to the large interparticle distance. Moreover, recombination lifetimes on the microsecond time scale have been observed and explained in terms of dielectric screening effect, in agreement with previous findings on lead chalcogenide NC optical properties.

In this study, non-targeted 1H NMR fingerprinting was used in combination with multivariate statistical techniques for the classification of Italian sweet cherries based on their different geographical origins (Emilia Romagna and Puglia). As classification techniques, Soft Independent Modelling of Class Analogy (SIMCA), Partial Least Squares Discriminant Analysis (PLS-DA), and Linear Discriminant Analysis (LDA) were carried out and the results were compared. For LDA, before performing a refined selection of the number/combination of variables, two different strategies for a preliminary reduction of the variable number were tested. The best average recognition and CV prediction abilities (both 100.0%) were obtained for all the LDA models, although PLS-DA also showed remarkable performances (94.6%). All the statistical models were validated by observing the prediction abilities with respect to an external set of cherry samples. The best result (94.9%) was obtained with LDA by performing a best subset selection procedure on a set of 30 principal components previously selected by a stepwise decorrelation. The metabolites that mostly contributed to the classification performances of such LDA model, were found to be malate, glucose, fructose, glutamine and succinate.

We report on the synthesis, characterization and application of a novel nanocomposite made of a negative tone epoxy based photoresist modified with organic-capped Fe(2)O(3) nanocrystals (NCs). The mechanical properties of the nanocomposite drastically improve upon incorporation of a suitable concentration of NCs in the polymer, without deteriorating its photolithography performance. High aspect ratio 3D microstructures made of the nanocomposite have been fabricated with a uniform surface morphology and with a resolution down to few micrometres. The embedded organic-capped Fe(2)O(3) NCs drastically increase the stiffness and hardness of the epoxy based photoresist matrix, making the final material extremely interesting for manufacturing miniaturized polymer based mechanical devices and systems. In particular, the nanocomposite has been used as structural material for fabricating photoplastic Atomic Force Microscopy (AFM) probes with integrated tips showing outstanding mechanical response and high resolution imaging performance. The fabricated probes consist of straight cantilevers with low stress-gradient and high quality factors, incorporating sharp polymeric tips. They present considerably improved performance compared to pure epoxy based photoresist AFM probes, and to commercial silicon AFM probes.

Osmotic shock was used as a tool to obtain cardiolipin (CL) enriched chromatophores of Rhodobacter sphaeroides. After incubation of cells in iso- and hyper-osmotic buffers both chromatophores with a physiological lipid profile (Control) and with an almost doubled amount of CL (CL enriched) were isolated. Spectroscopic properties, reaction centre (RC) and reducible cytochrome (cyt) contents in Control and CL enriched chromatophores were the same. The oxidoreductase activity was found higher for CL enriched than for Control chromatophores, raising from 60±2 to 93±3 mol cyt c s−1 (mol total cyt c)−1. Antymicin and myxothiazol were tested to prove that oxidoreductase activity thus measured was mainly attributable to the cyt bc1 complex. The enzyme was then purified from BH6 strain yielding a partially delipidated and almost inactive cyt bc1 complex, although the protein was found to maintain its structural integrity in terms of subunit composition. The ability of CL in restoring the activity of the partially delipidated cyt bc1 complex was proved in micellar systems by addition of exogenous CL. Results here reported indicate that CL affects oxidoreductase activity in the bacterium Rhodobacter sphaeroides both in chromatophore and in purified cyt bc1 complex.

A fundamental and systematic study on the fabrication of a supramolecularly assembled nanostructure of an organic ligand-capped CdS nanocrystal (NC) and multiple heptamine beta-cyclodextrin ((NH2)(7)beta CD) molecules in aqueous solution has been here reported. The functionalization process of presynthesized hydrophobic CdS NCs by means of (NH2)(7)beta CD has been extensively investigated by using different spectroscopic and structural techniques, as a function of different experimental parameters, such as the composition and the concentration of CD, the concentration of CdS NCs, the nature of the NC surface capping ligand (oleic acid and octylamine), and the organic solvent. The formation of a complex based on the direct coordination of the (NH2)(7)beta CD amine groups at the NC surface has been demonstrated and found responsible for the CdS NC phase transfer process. The amine functional group in (NH2)(7)beta CD and the appropriate combination of pristine capping agent coordinating the NC surface and a suitable solvent have been found decisive for the success of the CdS NC phase transfer process. Furthermore, a layer-by-layer assembly experiment has indicated that the obtained (NH2)(7)beta CD functionalized CdS NCs are still able to perform the host guest chemistry. Thus, they offer a model of a nanoparticle-based material with molecular receptors, useful for bio applications.

The photocatalytic properties of anatase TiO(2) nanorods (NRs) and noble metal-semiconductor nanocomposites (TiO(2) NRs/Ag) prepared by colloidal chemistry routes and immobilized onto suitable substrates were investigated. Photocatalytic experiments were performed under UV irradiation in order to test the degradation of a target compound (the azo dye, methyl red) in aqueous solution using TiO(2) P25 Degussa as a reference material. Absorbance spectroscopy and liquid chromatography/mass spectrometry (LC/MS) measurements pointed out that, according to pH conditions, TiO(2) NRs and TiO(2) NRs/Ag presented a photoactivity up to 1.3 and 2 times higher than TiO(2) P25 Degussa, respectively. Notably, the TiO(2) NRs/Ag-based catalysts demonstrated a photocatalytic activity 2-fold higher than bare TiO(2) NRs. Remarkably, only a negligible dependence on pH conditions was detected for the nanocomposite catalyst, whereas both TiO(2) NRs and TiO(2) P25 Degussa showed much higher photoactivity at acidic pH. In all the investigated cases, the identified byproducts pointed out the occurrence of the same reaction mechanism, basically relying on the hydroxyl radical attaching on the benzene ring and on the homolytic rupture of the nitrogen-carbon bond of the dimethyl-amino moiety.

Two different nanosized TiO2-based catalysts supported onto glass with tailored photocatalytic properties upon irradiation by UV light were successfully employed for the degradation of nalidixid acid, a widely diffused antibacterial agent of environmental relevance known to be non-biodegradable. Anatase rod-like TiO2 nanocrystals (TiO(2)NRs) and a semiconductor oxide-noble metal nanocomposite TiO2 NRs/Ag nanoparticles (NPs), synthesized by colloidal chemistry routes, were cast onto glass slide and employed as photocatalysts. A commercially available catalyst (TiO2 P25), also immobilized onto a glass slide, was used as a reference material. It was found that both TiO2 NRs/Ag NPs composite and TiO2 NRs demonstrated a photocatalytic efficiency significantly higher than the reference TiO2 P25. Specifically, TiO2 NRs/Ag NPs showed a photoactivity in nalidixic acid degradation 14 times higher than TiO2 P25 and 4 times higher than bare TiO2 NRs in the first 60 min of reaction. Several by-products were identified by HPLC-MS along the nalidixic acid degradation, thus getting useful insight on the degradation pathway. All the identified by-products resulted completely removed after 6 h of reaction. (C) 2013 Elsevier Ltd. All rights reserved.

This paper reports a study on the photoelectrochemical processes occurring at the interface of ZnO nanocrystals/MEH-PPV composites. Colloidal chemical routes were used to obtain size controlled non-hydrolytic ZnO nanocrystals (NCs) dispersible in organic solvents, while a low molecular weight poly[2-methoxy-5-(2'-ethylhexyloxy)phenylene vinylene] (MEH-PPV), characterized by high degree of structural order, was synthesized via an organometallic method. The optical properties of the nanocomposite material were comprehensively investigated on solution and on films deposited by spin coating. Remarkably, a significant fluorescence quenching of the polymer at the MEH-PPV/ZnO junction was observed. Photoelectrochemical measurements demonstrated that the photoactivity of the composite material was significantly improved in the case of non-hydrolytic NCs with respect to hydrolytic route prepared ZnO. Moreover, the effective role of the organic/inorganic blend to improve the charge transfer with respect to the double layer hetero-junction was confirmed, thanks to the extended interfaces which enable an effective electron transfer between the hetero-junction components. The system was also studied at different film thicknesses and electrolyte compositions. The results indicated that film photoactivity increased with film thickness up to 300 nm due to the presence of a large number of interfaces, while the change of cation size influenced the ionic conductivity through the nanocomposite film. It was shown that efficient photoconductivity requires not only efficient charge separation, but also efficient transport of the carriers to the electrodes without recombination. (C) 2015 Elsevier B.V. All rights reserved.

Photosystem II (PSII) proteins from spinach leaves were immobilized onto quartz substrates according to the Layer-by-Layer (LbL) procedure, alternating protein to polyethylenimine (PEI) layers by exploiting electrostatic interactions. The effects of several factors, such as storage conditions, ageing of the PSII-modified substrates, as well as PSII concentration in buffer, on the quality of the prepared multilayers, were investigated by UV-vis Absorption Spectroscopy and Atomic Force Microscopy (AFM). A number of 13 layers was found to be optimal to guarantee intense PSII optical signals with homogeneous morphological distributions of proteins. The multilayers resulted stable if stored in contact with air at 4 degrees C, as observed by UV-vis Absorption spectra recorded after 48 h. The best results in terms of AFM images and electron transfer efficiency (measured by Hill Reaction assays) were gained by using 5.6 x 10(-7) M chlorophyll concentration, obtaining multilayers with the most ordered protein distributions and the highest electron transfer efficiency, i.e. 85 % of an iso-absorbing PSII suspension. The results highlight the possibility to successfully immobilize PSII proteins, without considerable loss of bioactivity, thanks to the mild nature of the electrostatic LbL technique, opening up possibilities of applications in the bioelectrochemical energy conversion and biosensoristic fields.

The pH-related characteristics of 4-thiothymidine and its stability during prolonged exposure, at room temperature, to a neon lamp emitting in the 400–700 nm wavelength range were investigated by different spectroscopic techniques (UV-Vis, FTIR-ATR, 1H-NMR) and by ElectroSpray Ionization Mass Spectrometry (ESI-MS). The evaluation of the nucleoside photostability was performed as a control, with the perspective of studying its reactivity under the same conditions but in the presence of visible lightabsorbing photosensitizers, able to generate reactive oxygen species. The comparison between UV-Vis spectra recorded at different pH values in the 7–12 range suggested the presence of an equilibrium related to the deprotonation of the N3–H group of 4-thiothymidine, with a pKa estimated to be close to 9. Some effects of the deprotonation occurring at alkaline pH were observed also in FTIR-ATR spectra, the main feature being the appearance of a band related to C]N stretching, interpreted with the assumption of a partial double bond character by C2–N3, N3–C4 and C2–O bonds, as a consequence of negative charge delocalization on the pyrimidine ring. As for photostability, UV-Vis, FTIR-ATR and NMR measurements suggested the generation of thymidine as a by-product but only after a prolonged (48 hours) irradiation time, whereas no significant alteration occurred in a shorter time range (1–2 hours), i.e. the one that will be considered in future studies involving the presence of photosensitizers. The nucleoside stability up to 2 hours of irradiation was confirmed by ESI-MS analyses; furthermore, on the other hand, the latter indicated the presence of three additional by-products, besides thymidine, after 48 hours of irradiation. In particular, an hydroxylated form of 4-thiothymidine and two dimeric species, characterized by S–S and S–O covalent bridges between two 4-thiothymidine and a 4-thiothymidine and a thymidine molecule, respectively, were detected.

Nanocomposite materials have been obtained by dispersing organic capped TiO2 nanocrystals (NCs) with different shape and surface chemistry in poly(methyl methacrylate) (PMMA) as a host medium. Films of the prepared nanocomposites based on TiO2 NCs have been fabricated by spin coating and morphologically characterized as a function of the preparative conditions. The organic vapor absorption ability of the PMMA/TiO2 NC based nanocomposites has been then investigated both for spherical and rod-like NCs, and the chemical nature of the coordinating organic molecules has been also varied. The results of the investigation have demonstrated that NC geometry and surface chemistry can modulate the specific absorption characteristics of the modified PMMA in order to absorb different solvent molecules (i.e. acetone, ethanol, propan-2-ol and water). Such features, due to specific interactions between the potential analyte vapors and the functionalized surface of NCs, can effectively be addressed in a controlled and reproducible way, thus offering original opportunities for designing innovative chemical sensors. (C) 2011 Elsevier B.V. All rights reserved.

The fabrication of uniform and patterned nanocrystal (NC) assemblies has been investigated by exploiting the possibility of carefully tailoring colloidal NC surface chemistry and the ability of polyelectrolyte (PE) to functionalize substrates through an electrostatic layer-by-layer (LbL) strategy. Appropriate deposition conditions, substrate functionalization, and post-preparative treatments were selected to tailor the substrate surface chemistry to effectively direct the homogeneous electrostatic-induced assembly of NCs. Water-dispersible luminescent NCs, namely, (CdSe)ZnS and CdS, were differently functionalized by (1) ligand-exchange reaction, (2) growth of a hydrophilic silica shell, and (3) formation of a hydrophilic inclusion complex, thus providing functional NCs stable in a defined pH range. The electrostatically charged functional NCs represent a comprehensive selection of examples of surface-functionalized NCs, which enables the systematic investigation of experimental parameters in NC assembly processes carried out by combining LbL procedures with microcontact printing and also exploiting NC emission, relevant for potential applications, as a prompt and effective probe for evaluating assembly quality. Thus, an ample showcase of combinations has been investigated, and the spectroscopic and morphological features of the resulting NC-based structures have been discussed.

A reliable strategy is presented to combine the preparation of functional building blocks based on polymer beads decorated with luminescent nanocrystals (NCs) and their precise positioning onto suitable patterns by capillary assembly technique. In particular, a layer-by-layer (LbL) polyelectrolyte (PE) deposition procedure has been implemented to provide uniform NC coverage on PS beads, thus conveying the optical properties of luminescent nanocrystals to highly processable PS beads. The latter have then been integrated into patterned stamps by means of template-driven capillary assembly. Their selective positioning has been directed by means of pattern geometry. The use of luminescent (CdSe)ZnS NCs offers a direct optical probe to evaluate the efficiency of the positioning procedure on the substrate, enabling the extension of the method to a wide range of materials, i.e., NCs with different compositions and specific geometry-dependent properties. Moreover, the precise control over the pattern geometry and the micrometer accuracy in positioning achieved by capillary assembly make such functional patterned structures excellent candidates for integration into devices exploiting specific size-dependent NC properties.

Ornithine lipids (OLs), a sub-group of the large (and of emerging interest) family of lipoamino acids of bacterial origin, contain a 3-hydroxy fatty acyl chain linked via an amide bond to the alpha -amino group of ornithine and via an ester bond to a second fatty acyl chain. OLs in extracts of Rhodobacter sphaeroides (R. sphaeroides) were investigated by high-performance reversed phase liquid chromatography (RPLC) with electrospray ionization mass spectrometry (ESI-MS) in negative ion mode using a linear ion trap (LIT). The presence of OLs bearing both saturated (i.e, 16:0, 17:0, 18:0, 19:0 and 20:0) and unsaturated chains (i.e., 18:1, 19:1, 19:2 and 20:1) was ascertained and their identification, even for isomeric, low abundance and partially co-eluting species, was achieved by low-energy collision induced dissociation (CID) multistage mass spectrometry (MSn, n = 2-4). OLs signatures found in two R. sphaeroides strains, i.e., wild type 2.4.1 and mutant R26, were examined and up to 16 and 17 different OL species were successfully identified, respectively. OLs in both bacterial strains were characterized by several combinations of fatty chains on ester-linked and amide-linked 3-OH fatty acids. Multistage MS spectra of monoenoic amide-linked 3-OH acyl chains, allowed the identification of positional isomer of OL containing 18:1 (i.e. 9-octadecenoic) and 20:1 (i.e. 11-eicosenoic) fatty acids. The most abundant OL ([M-H](-) at m/z 717.5) in R. sphaeroides R26 was identified as OL 3-OH 20:1/19:1 (i.e., 3-OH-eicosenoic acid amide-linked to ornithine and esterified to a nonadecenoic chain containing a cyclopropane ring). An unusual OL (m/z 689.5 for the [M-H](-) ion), most likely containing a cyclopropene ester-linked acyl chain (i.e., OL 3-OH 18:0/19:2), was retrieved only in the carotenoidless mutant strain R26. Based on the biosynthetic pathways already known for cyclopropa(e)ne ring-including acyl chains, a plausible explanation was invoked for the enzymatic generation of this ester-linked chain in R. sphaeroides. (C) 2015 Elsevier B.V. All rights reserved.

Strontium titanate (SrTiO3, STO) is a prototypical perovskite oxide, widely exploited in many technological applications, from catalysis to energy conversion devices. In the context of solid-oxide fuel cells, STO has been recently applied as an epitaxial substrate for nano-sized layers of mixed ion-electron conductive catalysts with enhanced electrochemical performances. To extend the applications of such heterogeneous nano-cathodes in real devices, also the STO support should be active for both electron transport and oxide diffusion. To this end, we explored using first-principles calculations the strategy of doping of STO at the Sr site with sodium and potassium. These two ions fit in the perovskite structure and induce holes in the STO valence band, so as to obtain the desired p-type electronic conduction. At the same time, the doping with alkali ions also promotes the formation of oxygen vacancies in STO, a prerequisite for effective oxide diffusion. Analysis of electron density rearrangements upon defect formation allows relating the favorable vacancy formation energies to an improved electronic delocalization over the oxide sub-lattice, as observed in closely related materials (e.g. Sr2Fe1.5Mo0.5O6). Overall, our results suggest the alkali-doped STO as a new potential substrate material in nanoscale heterogeneous electrodes for solid oxide electrochemical cells.

Fluorescent polystyrene microspheres are prepared by the incorporation of fluorescent CdSe/CdS core/shell semiconductor nanocrystals (quantum dots, QDs) using the emulsification/solvent evaporation method. The radiative exciton recombination dynamics is investigated by nanosecond time-resolved fluorescence spectroscopy at ambient conditions. The time constants of fast and slow fluorescence decay in QDs, dispersed in toluene, were 3.5 and 17.8 ns, respectively. For the QD-tagged microspheres, the time constants of fast and slow processes were similar to 2-3 and similar to 11-12 ns, respectively, and did not depend significantly on the QD-content of the microspheres. The fast decay component could be attributed to the recombination of delocalized exciton in the internal core states, and the slow component was attributed to the localized exciton in the surface states. It was found that the ratio of amplitudes of the fast and slow processes also changed after incorporation of QDs in microspheres. The observed differences in fluorescence decay between non-entrapped QDs and QD-tagged microspheres were probably due to energy transfer between the nanocrystals, which were in close proximity inside the microspheres. The obtained fluorescent QD-tagged microspheres are characterized by the other methods as well, which makes them of value for various applications as optical materials.

The ability of microorganisms to adhere to abiotic surfaces and the potentialities of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy have been exploited to study protonation and heavy metal binding events onto bacterial surfaces. This work represents the first attempt to apply on bacteria the recently developed method known as perfusion-induced ATR-FTIR difference spectroscopy.(1,2) Such a technique allows measurement of even slight changes in the infrared spectrum of the sample, deposited as a thin layer on an ATR crystal, while an aqueous solution is perfused over its surface. Solutions at different pH have been used for inducing protonation/deprotonation of functional groups lying on the surface of Rhodobacter sphaeroides cells, chosen as a model system. The interaction of Ni2+ with surface protonable groups of this microorganism has been investigated with a double-difference approach exploiting competition between nickel cations and protons. Protonation-induced difference spectra of simple model compounds have been acquired to guide band assignment in bacterial spectra, thus allowing identification of major components involved in proton uptake and metal binding. The data collected reveal that carboxylate moieties on the bacterial surface of R. sphaeroides play a role in extracellular biosorption of Ni2+, establishing with this ion relatively weak coordinative bonds.

Amphiphilic polystyrene-block-polyethylene oxide (PS-b-PEO) block copolymers (BCPs) have been demonstrated to be effective in directing organization of colloidal Au nanoparticles (NPs). Au NPs have been incorporated into the polymer and the different chemical affinity between the NP surface and the two blocks of the BCP has been used as a driving force of the assembling procedure. The morphology of the nanocomposites, prepared and fabricated as thin films, has been investigated by means of atomic force and scanning electron microscopies as a function of the NP content and BCP molecular weight. NPs have been effectively dispersed in PS-b-PEO hosts at any investigated content (up to 17 wt%) and a clear effect of the BCP properties on the final nanocomposite morphology has been highlighted. Finally, electrostatic force microscopy has demonstrated the conductive properties of the nanocomposite films, showing that the embedded Au NPs effectively convey their conductive properties to the film. The overall investigation has confirmed the selective confinement of the as-prepared surfactant-coated metal NPs in the PS block of PS-b-PEO, thus proposing a very simple and prompt assembling tool for nanopatterning, potentially suitable for optoelectronic, sensing and catalysis applications.

Here the synthesis of distinct monomodal and bimodal PbS nanocrystal (NC) populations, with narrow size-distribution, is reported. The ability to achieve careful control of NC size and size distribution allowed the preparation, in one single synthetic step, of two distinct populations of PbS NCs, with tuneable size ratio. The NC growth was carefully studied in order to gain insight into the mechanism underlying the formation of the mono and bimodal PbS NC families. The synthesized PbS NCs were structurally and chemically characterized, and subsequently used as building blocks for fabricating solid crystal assemblies by solvent evaporation. In particular the role played by different parameters, namely NC size and concentration, dispersing solvent and substrate, on crystallinity, geometry and structure of the obtained solids was systematically investigated. Interestingly the assembly of bimodal PbS NC samples leads to the formation of diverse superlattice structures, with a final geometry dependent on the NC size and the size ratio in the bimodal population. The synthetic procedure was then ultimately responsible of the superlattice structures, through the control of the PbS NC size and size ratio in the bimodal population.

A growing interest is devoted to the study of imidazolium-based ionic liquids as innovative materials to combine with functional elements for advanced technological applications. Materials based on semiconductor and oxide nanocrystals in ionic liquids can be promising for their integration in lithium batteries, as well as in innovative solar cells. Although the physical chemical properties and the solvation dynamics of bare ionic liquids have been extensively studied, their combination with colloidal nanocrystals still remains almost unexplored. Here, the optical properties of organic-capped luminescent cadmium selenide nanocrystals coated by a shell of zinc sulfide (CdSe(ZnS)) dispersed in 1,3-dialkyl imidazolium ionic liquids have been investigated, also in dependence of the alkyl chain length on the imidazolium ring and of the anion nature, by using both time-integrated and time-resolved optical spectroscopy. The observed variations in decay profiles of the ionic liquid in presence of colloidal nanocrystals suggest that the dispersion of the nanostructures induces modifications in the ionic liquid structural order. Finally, atomic force microscopy analysis has provided insight into the topography of the investigated dispersions deposited as film, confirming the organization of the ionic liquids in super-structures, also upon nanocrystal incorporation.

The amplification of Raman signals of the heteroaromatic cation 1-(N-methylpyrid-4-yl)-2-(N-methylpyrrol-2-yl)ethylene (PEP+)) bound to Au nanorods (NRs) was investigated at different excitation wavelengths to study the effect of the laser resonance with the absorption band of the PEP+ moiety and with the two plasmon oscillation modes of the NR. Two different PEP+ derivatives, differing in the length of the alkyl chain bearing the anchoring group, were used as target molecules. Raman spectra obtained exciting at 514 or at 785 nm (i.e., exciting the transverse or the longitudinal plasmon band) present a higher intensity than that at 488 nm suggesting a higher Raman amplification when the laser excitation wavelength is resonant with one of the two plasmon modes. Moreover, considering results of Discrete Dipole Approximation (DDA) calculations of the local field generated at the NR surface when either the transverse or the longitudinal plasmon modes are excited, we deduced that the resonance condition of the 514-nm laser excitation with the absorption band of the dye strongly contributes to the amplification of the Raman signal.

Colloidal white emitting nanostructures were successfully fabricated by covalently binding a blue emitting oligofluorene at the surface of silica beads, that incorporate orange luminescent colloidal CdSe@ZnS quantum dots (QDs). White light was achieved by carefully tuning the size of the QDs to complementarily match the emission color of the blue fluorophore and taking into account the delicate balance between the emission of the QDs in the core of the silica beads and the amount of the organic dye bound to the silica surface. The proposed approach is highly versatile as it can be extended to the fabrication of a variety of luminescent hybrid nano-objects, playing with the complementarity of the emission color of the inorganic and organic fluorophores at the nanoscale.

Room temperature ionic liquids are currently used as functional materials in several application and their optical investigation can provide a better understanding of their physical and chemical behavior. Absorption and emission properties of imidazolium-based ILs have been attributed to the imidazolium moiety and related to the presence of energetically different aggregates. Here, time-integrated and time-resolved investigation has been carried out on 1-alkyl-3-methylimidazolium tetrafluoroborate and hexafluorophosphate ionic liquids with different chain lengths in order to probe the occurrence of energy transfer processes, and hence to disclose the presence of various states with different energy. Such a study contributes to provide relevant insight on the effect of alkyl chain and anion type on the emission characteristics, and, hence, on the presence of associated structures.

In this Letter, a solution-based approach has been used for chemically immobilising oleic acid (OLEA)-capped TiO2 nanocrystals (NCs) on the surface of microcantilevers formed of SU-8, a negative tone epoxy photoresist. The immobilisation has been carried out at room temperature, under visible light, in ambient atmosphere and without applying any external driving force or chemical activation of the epoxy photoresist surface. Atomic force microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy investigation demonstrate the spontaneous chemical anchoring of the organic-coated TiO2 NCs on the microcantilevers, which resulted in a highly interconnected nanoporous multilayer structure. The chemical and morphological characterisation shows that the immobilised NCs do not change either their pristine morphology or the chemical structure after binding. Spectroscopic investigation infers that the TiO2 NCs chemically bind through the free and highly reactive epoxy groups located on the epoxy photoresist surface by means of the OLEA capping molecules. Finally, the results show that the fabrication procedure of the microcantilevers has not been affected by the immobilisation protocol. The capability of the immobilised TiO2 NCs to generate surface-reactive hydroxyl radicals under UV-light irradiation has a good potential for detecting families of organic compounds when integrating the modified microcantilevers in electronic noses.

In this paper the functionalization of single walled carbon nanotubes (SWNTs) with the site-specific single aminoacid mutant D96N of Bacteriorhodopsin (PM- D96N) in its native purple membrane (PM) patches has been investigated in view of the possible application of such nanocomposites as active materials in FET or impedance sensors. The procedure of functionalization has been performed without using any chemical, including surfactants which can delipidate the PM. Absorption spectroscopy investigations provide evidence of the occurrence of hydrophobic interactions between the SWNT walls and the PM - D96N. The PM - D96N biosystem seems to undergoes conformation changes due to assembling on the nanotube walls. The chemical interactions among the components can effectively combine the sensitivity of PM-D96N with the ballistic charge transport properties of the SWNTs to exploit in electronic sensor devices for analyte detection.

In this work, single walled carbon nanotubes (SWNTs) have been chemically functionalized at their walls with a membrane protein, namely the mutated bacteriorhodopsin D96N, integrated in its native archaeal lipid membrane. The modification of the SWNT walls with the mutant has been carried out in different buffer solutions, at pH 5, 7.5 and 9, to investigate the anchoring process, the typical chemical and physical properties of the component materials being dependent on the pH. The SWNTs modified by interactions with bacteriorhodopsin membrane patches have been characterized by UV-vis steady state, Raman and attenuated total reflection Fourier transform infrared spectroscopy and by atomic force and transmission electron microscopy. The investigation shows that the membrane protein patches wrap the carbon walls by tight chemical interactions undergoing a conformational change; such chemical interactions increase the mechanical strength of the SWNTs and promote charge transfers which p-dope the nano-objects. The functionalization, as well as the SWNT doping, is favoured in acid and basic buffer conditions; such buffers make the nanotube walls more reactive, thus catalysing the anchoring of the membrane protein. The direct electron communication among the materials can be exploited for effectively interfacing the transport properties of carbon nanotubes with both molecular recognition capability and photoactivity of the cell membrane for sensing and photoconversion applications upon integration of the achieved hybrid materials in sensors or photovoltaic devices.

A functionalization procedure is integrated in the fabrication of micromechanical SU-8 cantilevers in order to chemically bind organic-capped Fe(2)O(3) NCs at the photoresist surface, under visible light, ambient atmosp here and room temperature. The achieved highly interconnected NC multilayer network is demonstrated an active layer for real-time detection of acetone vapor molecules.

Liposomes represent a versatile biomimetic environment for studying the interaction between integral membrane proteins and hydrophobic ligands. In this paper, the quinone binding to the Q(B)-site of the photosynthetic reaction centers (RC) from Rhodobacter sphaeroides has been investigated in liposomes prepared with either the zwitterionic phosphatidylcholine (PC) or the negatively charged phosphatidylglycerol (PG) to highlight the role of the different phospholipid polar heads. Quinone binding (K (Q)) and interquinone electron transfer (L (AB)) equilibrium constants in the two type of liposomes were obtained by charge recombination reaction of Q(B)-depleted RC in the presence of increasing amounts of ubiquinone-10 over the temperature interval 6-35 A degrees C. The kinetic of the charge recombination reactions has been fitted by numerically solving the ordinary differential equations set associated with a detailed kinetic scheme involving electron transfer reactions coupled with quinone release and uptake. The entire set of traces at each temperature was accurately fitted using the sole quinone release constants (both in a neutral and a charge separated state) as adjustable parameters. The temperature dependence of the quinone exchange rate at the Q(B)-site was, hence, obtained. It was found that the quinone exchange regime was always fast for PC while it switched from slow to fast in PG as the temperature rose above 20 A degrees C. A new method was introduced in this paper for the evaluation of constant K (Q) using the area underneath the charge recombination traces as the indicator of the amount of quinone bound to the Q(B)-site.

In this work, we report on 4% power conversion efficiency (PCE) depleted bulk heterojunction (DBH) solar cells based on a high-quality electrode with a three-dimensional nanoscale architecture purposely designed so as to maximize light absorption and charge collection. The newly conceived architecture comprises a mesoporous electron-collecting film made of networked anisotropic metal-oxide nanostructures, which accommodates visible-to-infrared light harvesting quantum dots within the recessed regions of its volume. The three-dimensional electrodes were self-assembled by spin-coating a solution of colloidal branched anatase TiO2 NCs (BNC), followed by photocatalytic removal of the native organic capping from their surface by a mild UV-light treatment and filling with small PbS NCs via infiltration. The PCE 4% of our TiO2 BNC/PbS QD DBH solar cell features an enhancement of 84% over the performance obtained for a planar device fabricated under the same conditions. Overall, the DBH device fabrication procedure is entirely carried out under mild processing conditions at room temperature, thus holding promise for low-cost and large-scale manufacturing.

Au nanoparticles (NPs) self-assembled by means of a simple solvent evaporation strategy in a two-dimensional (2D) superlattice with a highly controlled geometry and extending over micrometers squared when drop cast onto a suitably functionalized silicon substrate. The assembly procedure was defined by carefully monitoring experimental parameters, namely, dispersing solvent, deposition temperature, Au NP concentration, and chemistry of supporting substrate. The investigated parameters were demonstrated to play a significant role on the delicate energetic balance of the mutual NPs as well as NP-substrate interactions, ultimately directing the NP assembly. Remarkably, substrate surface chemistry revealed to be decisive to control the extent of the organization. Scanning electron microscopy demonstrated that the 2D superlattice extends uniformly over hundreds of square micrometers. Grazing-incidence small-angle X-ray scattering investigation validated the Au NP organization in crystalline domains and confirmed the role played by the surface chemistry of the substrate onto the 2D lattice assembly. Finally, preliminary spectroscopic ellipsometry investigation allowed extraction of optical constants of NP assemblies. The localized surface plasmon resonance modes of the NP assemblies were studied through a combined analysis of reflection, transmission, and ellipsometric data that demonstrated that the plasmonic properties of the Au NP assemblies strongly depend on the substrate, which was found to influence NP ordering and near-field interactions between NPs.

Anew photocatalyst based on nano-sized TiO2 supported on single wall carbon nanotubes (SWCNTs) with tailored photocatalytic properties upon irradiation by both UV and solar simulated light was successfully employed for the degradation of a mixture of 22 organic pollutants in both ultrapure water and real secondary wastewater effluent. First-order degradation rates showed that under UV irradiation nanosized TiO2 supported on SWCNTs is much more effective than conventional Degussa P25 for degradation of iopamidol, iopromide, diatrizoic acid, diclofenac, triclosan and sulfamethoxazole in ultrapure water. For the remaining organics the degradation rates were comparable being in most of the cases Degussa P25 slightly more effective than nano-sized TiO2 supported on SWCNTs. Reactions performed in real secondary wastewater effluent showed a general reduction of degradation rates. Specifically, such a reduction was in the range 9-87% and 9-96% for the Degussa P25 and the nano-sized TiO2 supported on SWCNTs, respectively. Overall, the nano-sized TiO2 supported on SWCNTs under UV irradiation displayed comparable degradation rates with respect to convention Degussa P25. Under simulated solar irradiation the new prepared photocatalyst showed lower efficiency than Degussa P25 in ultrapure water. Such a gap was greatly reduced when the reactions were carried out in real secondary wastewater effluent. The nano-sized TiO2 supported on SWCNTs demonstrated to have the addition benefit to be easily removed from the aqueous solution by a mild centrifugation or a filtration step and, consequently, can be reused for a further photocatalytic treatment batch. Therefore, the obtained results showed that new photocatalyst based on nano-sized TiO2 supported on SWCNTs has proved to be a promising candidate to be used in a photocatalytic based-AOP and to be integrated with a biological step for the effective removal of emerging organic pollutants.