We report the synthesis of various iron oxide nanocontainers and Pt-iron oxide nanoparticles based on a cast-mold approach, starting from nanoparticles having a metal core (either Au or AuPt) and an iron oxide shell. Upon annealing, the particles evolve to asymmetric core-shells and then to heterodimers. If iodine is used to leach Au out of these structures, asymmetric core-shells evolve into "nanocontainers", that is, iron oxide nanoparticles enclosing a cavity accessible through nanometer-sized pores, while heterodimers evolve into particles with a concave region. When starting from a metal domain made of AuPt, selective leaching of the Au atoms yields the same iron oxide nanoparticle morphologies but now encasing Pt domains (in their concave region or in their cavity). We found that the concave nanoparticles are capable of destabilizing Au nanocrystals of sizes matching that of the concave region. In addition, for the nanocontainers, we propose two different applications: (i) we demonstrate loading of the cavity region of the nanocontainers with the antitumoral drug cis-platin; and (ii) we show that nanocontainers encasing Pt domains can act as recoverable photocatalysts for the reduction of a model dye.

Smart materials able to sense environmental stimuli can be exploited as intelligent carrier systems. Acidic pHresponsive polymers, for instance, exhibit a variation in the ionization state upon lowering the pH, which leads to their swelling. The different permeability of these polymers as a function of the pH could be exploited for the incorporation and subsequent release of previously trapped payload molecules/nanoparticles. We provide here a proof of concept of a novel use of pH-responsive polymer nanostructures based on 2-vinylpyridine and divinylbenzene, having an overall size below 200 nm, as cargo system for magnetic nanoparticles, for oligonucleotide sequences, as well as for their simultaneous loading and controlled release mediated by the pH. © 2010 American Chemical Society.

Aim of this work was to investigate the automatic echographic detection of an experimentaldrug delivery agent, halloysite clay nanotubes (HNTs), by employing an innovative methodbased on advanced spectral analysis of the corresponding "raw" radiofrequency backscattersignals. Different HNT concentrations in a low range (5.5-66  1010 part/mL, equivalent to0.25-3.00 mg/mL) were dispersed in custom-designed tissue-mimicking phantoms and imagedthrough a clinically-available echographic device at a conventional ultrasound diagnostic frequency(10 MHz). The most effective response (sensitivity = 60%, specificity = 95%), was found ata concentration of 33  1010 part/mL (1.5 mg/mL), representing a kind of best compromisebetween the need of enough particles to introduce detectable spectral modifications in thebackscattered signal and the necessity to avoid the losses of spectral peculiarity associated tohigher HNT concentrations. Based on theoretical considerations and quantitative comparisonswith literature-available results, this concentration could also represent an optimal concentrationlevel for the automatic echographic detection of different solid nanoparticles when employinga similar ultrasound frequency. Future dedicated studies will assess the actual clinical usefulness ofthe proposed approach and the potential of HNTs for effective theranostic applications.

Immunofluorescence techniques on formalin fixedparaffin-embedded sections allow for the evaluation of the expressionand spatial distribution of specific markers in patient tissuespecimens or for monitoring the fate of labeled cells after in vivoinjection. This technique suffers however from the auto-fluorescencebackground signal of the embedded tissue that eventuallyconfounds the analysis. Here we show that rod-like semiconductornanocrystals (QRs), intramuscularly injected in living mice, couldbe clearly detected by confocal microscopy in formalin fixedparaffin-embedded tissue sections. Despite the low amount ofQRs amount injected (25 picomoles), these were clearly visibleafter 24 h in the muscle sections and their fluorescence signal wasstronger than that of CdSe/ZnS quantum dots (QDs) similarlyfunctionalized and in the case of QRs only, the signal lasted evenafter 21 days after the injection.

Early detection and diagnosis of diseases is a critical issue. A colorimetric "point-of-care" device - based on the principle of electrochromism - is proposed here for the precocious diagnosis of cystic fibrosis, especially in resource-limited environments, developing countries and ambulatory contests. We designed a complete device architecture to detect sodium chloride in a small amount of human sweat (3 ?L), conceived in order to complete the steps of sample preparation and disease diagnosis. The device, as an alternative route for conductivimetric analysis, measures the amount of sodium chloride in a sample of sweat exploiting the electrochromic properties of tungsten oxide. In our case, sodium sweat promotes an oxide blue coloration depending on the cation concentration. Indeed the device shows an effective transmittance modulation when sodium cations exceed the physiological threshold. optical modulations of 48%, 35%, 15%, 7% were observed, at 555 nm, for sodium concentrations of 120 mmol/L, 90 mmol/L, 60 mmol/L, and 30 mmol/L, respectively. In the reported experimental investigations, both human and artificial sweat were employed, with strictly comparable results.

Monodisperse cubic spinel iron oxide magnetic nanoparticles with variablesizes were prepared following a multi-injection seeded-growth approach. As expectedfrom such a well-known synthetic route, all samples were characterized by narrow sizedistributions, and showed excellent stability in both organic and aqueous media withoutthe presence of aggregates, thus becoming ideal candidates for the study of theirhyperthermia performance. Specific Loss Power measurements indicated low heatingpowers for all samples without a maximum for any specific size, contrary to what theorypredicts. The magnetic study showed the formation of size-dependent nonsaturatedmagnetic regions, which enlarged with the particle size, evidencing a clear discrepancybetween the crystal size and the effective magnetic volume. Strain map analysis of highresolution transmission electron micrographs indicated the presence of highly strainedcrystal areas even if nanoparticles were monocrystalline. The origin of the crystal strainwas found to be strictly correlated with the seeded-growth synthetic procedure used forthe preparation of the nanoparticles, which turned out to alter their magnetic structure by creating antiphase boundaries.Considering the calculated effective magnetic volumes and their magnetic dispersions in each sample, a reasonable agreementbetween hyperthermia experiments and theory was obtained.

Among the various nanosized particles developed forinnovative biomedical applications, like selective molecularimaging and targeted drug delivery, silica nanoparticles (SiNPs)seem to be particularly attractive since of their low cost, lowtoxicity, ease of functionalization and acoustic properties. In fact,SiNPs have been demonstrated to effectively enhance ultrasoundcontrast at clinical diagnostic frequencies and, therefore, theymight be potentially employed in non-ionizing echographicmolecular imaging. Aim of this work was the development of asilica nanoparticle based system for in vitro molecular imaging ofhepatocellular carcinoma, using both ultrasound and laserscanningconfocal microscopy, by exploiting the particularfeature of these tumor cells to express on their surface high levelsof Glypican-3 protein (GPC-3). At this regard, we have designedand characterized novel GPC-3 ligand peptide-functionalizedfluorescent silica nanoparticles and tested them on GPC-3positive HepG2 cells, a human hepatocarcinoma cell line. Laserscanning confocal microscopy analysis showed that GPC-3-targeted fuorescent SiNP, in the concentration range used forexperimental ultrasound detection, did not exert significantcytotoxic effects and were effectively bound and taken up byHepG2 cells. These results suggest that silica nanoparticles mightbe a very promising contrast agents for non-ionizing ultrasoundmolecular imaging since of their high biocompatibility, targetingeffectiveness and ultrasound enhancement power.

Medical nanoplatforms based on clusters of superparamagnetic nanoparticles decorated with a PNIPAM thermo-responsive shell have been synthesized and used as drug carriers for doxorubicin (DOXO), a common chemotherapeutic agent. The nanosystem here developed has a total diameter below 200 nm and exploits the temperature responsive behaviour of the PNIPAM polymeric shell for the controlled loading and release of DOXO. The system has been tested in vitro on tumour cells and it clearly demonstrates the effectiveness of drug polymer encapsulation and time-dependent cell death induced by the doxorubicin release. Comparative cellular studies of the DOXO loaded nanoplatform in the presence or absence of an external magnet (0.3 T) showed the synergic effect of accumulation and enhanced toxicity of the system, when magnetically guided, resulting in the enhanced efficacy of the system.

In this work we investigate the magnetic properties of iron oxide nanoparticles obtained by two-step synthesis (seeded-growth route) with sizes that range from 6 to 18 nm. The initial seeds result monocrystalline and exhibit ferromagnetic behavior with low saturation field. The subsequent growth of a shell enhances the anisotropy inducing magnetic frustration, and, consequently, reducing its magnetization. This increase in anisotropy occurs suddenly at a certain size (similar to 10 nm). Electronic and structural analysis with X-ray absorption spectroscopy indicates a step reduction in the oxidation state as the particle reaches 10 nm size while keeping its overall structure in spite of the magnetic polydispersity. The formation of antiphase magnetic boundaries due to island percolation in the growing shells is hypothesized to be the mechanism responsible of the magnetic behavior, as a direct consequence of the two-step synthesis route of the nanoparticles.

We report about the realization of a negative-tone photoresist for two-photon lithography containing superparamagnetic iron-oxide nanoparticles at 0.1 wt.% concentration. The material was characterized in terms of optical transparence in the visible spectral range and the microfabrication process engineered in order to minimize particles agglomeration. The versatility of two-photon direct laser writing allowed us to fabricate three-dimensional structures with sub-micrometer resolution, letting us envision possible applications of this nanocomposite blend for the realization of complex magnetically actuated MEMS.

A systematic and thorough quantitative analysis of the in vivo effects of inorganic nanoparticles isextremely important for the design of functional nanomaterials for diagnostic and therapeutic applications,better understanding of their non-specificity toward tissues and cell types, and for assessments oftheir toxicity. This study was undertaken to examine the impact of CdTe quantum dots (QDs) on aninvertebrate freshwater model organism, Hydra vulgaris, for assessment of long term toxicity effects. Thecontinuous exposure of living polyps to sub-lethal doses of QDs caused time and dose dependentmorphological damages more severe than Cd2þ ions at the same concentrations, impaired both reproductiveand regenerative capability, activated biochemical and molecular responses. Of remarkableinterest, low QD doses, apparently not effective, caused early changes in the expression of general stressresponsive and apoptotic genes. The occurrence of subtle genetic variations, in the absence ofmorphological damages, indicates the importance of genotoxicity studies for nanoparticle risk assessment.The versatility in morphological, cellular, biochemical and molecular responses renders Hydraa perfect model system for high-throughput screening of toxicological and ecotoxicological impact ofnanomaterials on human and environmental health.

New amphiphilic block copolymers are easily synthesised by post-polymerisation modifications of poly(glycidyl methacrylate) chain derivatives. The obtained material, upon dispersion in water, is capable of self-assembling into robust micelles. These nanoparticles, which are also characterised by adaptable stability, were loaded with different thiophene based fluorophores. The photoluminescent micelles were administered to cultured cells revealing a high and rapid internalisation of structurally different fluorescent molecules by the same internalisation pathway. Appropriate pairs of chromophores were selected and loaded into the micelles to induce Förster resonance energy transfer (FRET). The disappearing of the FRET phenomenon, after cell uptaking, demonstrated the intracellular release of the nanoparticle contents. The studied nanomaterial and the loaded chromophores have also shown to be biocompatible and non toxic towards the tested cells.

Synthetic carriers that mimic "natural lipid-based vesicles" (such as micro/nanovesicles, exosomes) have found broad applications in biomedicine for the delivery of biomolecules and drugs. Remarkable advantages of using synthetic carriers include control over the lipid composition, structure and size, together with the possibility to add tracer molecules to monitor their in situ distribution via fluorescence microscopy. Over the past few years, new methods of vesicles production have been developed and optimized, such as those based on microfluidic techniques. These innovative approaches allow us to overcome the limitations faced in conventional methods of liposome preparation, such as size distribution and polydispersity. Herein, a Microfluidic Hydrodynamic Focusing (MHF) device has been used for the production of lipid-based vesicles with different lipid combinations that resemble natural exosomes, such as phosphatidylcholines (PC), cholesterol (Chol), dicetyl phosphate (DCP) and ceramide (Cer). Thanks to a fine control on fluid manipulation, the MHF device allows preparation of vesicles with controlled size, a relevant feature in the emerging field of carrier-assisted cell-delivery. Interestingly, PC/Chol/Cer vesicles exhibit low polydispersity and high stability up to 45 days. Later, quantum dots (QDs) were successfully embedded in these vesicles through the same preparation process. The development of QD-embedded lipid nanovesicles by MHF devices has never been described previously.

The use of inorganic nanoparticles in biomedicine, in particular in the field of diagnosis andtherapy of human diseases, has rapidly grown in the last decades. Water solubilisation of thenanoparticles, especially for particles synthesized in non-polar solvents, is an essential prerequisitefor their biological exploitation. The encapsulation of surfactant coated nanoparticlesinto polymer shells represents one of the most suitable and most popular methods to make themwater soluble. Herein we provide an overview of the amphiphilic polymer molecules used andthe efforts undertaken to further tailor the surface of polymer coated nanoparticles withfluorescent dyes, chemical sensor molecules and small or large biomolecules for the preparationof bio-functional nanoprobes. Their biological implications, highlighting limitations andchallenges, are also discussed.

Efficient targeting in tumor therapies is still an open issue: systemic biodistribution and poor specific accumulation of drugs weaken efficacy of treatments. Engineered nanoparticles are expected to bring benefits by allowing specific delivery of drug to the tumor or acting themselves as localized therapeutic agents. In this study we have targeted epithelial ovarian cancer with inorganic nanoparticles conjugated to a human antibody fragment against the folate receptor over-expressed on cancer cells. The conjugation approach is generally applicable. Indeed several types of nanoparticles (either magnetic or fluorescent) were engineered with the fragment, and their biological activity was preserved as demonstrated by biochemical methods in vitro. In vivo studies with mice bearing orthotopic and subcutaneous tumors were performed. Elemental and histological analyses showed that the conjugated magnetic nanoparticles accumulated specifically and were retained at tumor sites longer than the non-conjugated nanoparticles.