In this work, a novel composite sorbent material for water remediation from oily contaminants, based on a cellulose three-dimensional fibrous scaffold treated with stearic acid and expanded graphite flakes, is presented. The pristine cellulose foams are inherently omniphilic, absorbing indiscriminately both water and oils. However, after being modified with stearic acid and graphite via drop casting, they become superhydrophobic (still preserving their superoleophilic characteristics). As a result, the foams start exhibiting a highly selective behaviour which permits to absorb different kinds of oils and organic solvents, while repelling water completely. Thermal and chemical characterizations reveal that the modification treatment is successfully performed, while the performed mechanical tests demonstrate a good recovery of elasticity after repeated deformations and confirm that the elasticity of the foam is preserved after the treatment. Although based on natural materials, the fabricated foams exhibit oil absorption rate, saturation time and capacity values comparable to those of some synthetic materials with the same aim, exhibiting a very important added value, as it is based on low cost, green and biodegradable materials, requiring, at the same time, low processing costs and providing excellent reusability properties.

Physical foaming combined with microwave-induced curing was used in this study to develop an innovative device for bone tissue regeneration. In the first step of the process, a stable physical foaming was induced using a surfactant (i.e. pluronic) as blowing agent of a homogeneous blend of Sodium salt of carboxymethylcellulose (CMCNa) and polyethylene glycol diacrylate (PEGDA700) solution. In the second step, the porous structure of the scaffold was chemically stabilized by radical polymerization induced by a homogeneous rapid heating of the sample in a microwave reactor. In this step 2,2-Azobis[2-(2-imidazolin-2 yl)propane]Dihydrochloride was used as thermoinitiator (TI). CMCNa and PEGDA were mixed with different blends to correlate the properties of final product with the composition. The chemical properties of each sample were evaluated by spectroscopy analysis ATR-IR (before and after curing) in order to maximize reaction yield, and optimize kinetic parameters (i.e. time curing, microwave power). The stability of the materials was evaluated in vitro by degradation test in Phosphate Buffered Saline (PBS). Biological analyses were performed to evaluate the effect of scaffold materials on cellular behaviour in terms of proliferation and early osteogenic differentiation of human Mesenchymal Stem Cells (hMSC). This article is protected by copyright. All rights reserved.

In the last decade cellulose-based hydrogels have been receiving increasing attention for a number of applications, due to their smart swelling behaviour, biodegradability and biocompatibility. Given the dramatic spreading of obesity and overweight in the industrialized countries and the lack of scientific consensus over currently available dietary supplements, it was recently proposed that such hydrogels might be used as orally administered bulking agents in hypocaloric diets, since the hydrogel swelling in the stomach may greatly reduce the space available for food intake, thus giving a sense of fullness. This study focused on the synthesis of cellulose-based hydrogels, starting from pharmaceutical and food grade cellulose derivatives, and showed that such hydrogels possess good swelling properties in water solutions mimicking the environmental conditions of the stomach and the intestine, as well as a good biocompatibility. The crosslinking agent used was a ‘zero-length’ crosslinker, i.e. a water soluble carbodiimide, which is washed out from the gel after the synthesis and does not affect the gel compatibility, as shown by preliminary biocompatibility assays. The experimental results confirmed that cellulosebased hydrogels might be a scientifically valid dietary adjuvant in the treatment of obesity and overweight, and provide further scientific evidence for future experiments on humans.

Purpose: The objective of this work was to develop composite hydrogels based on poly(ethylene glycol) diacrylate (PEGDA) and collagen (Coll), potentially useful for biomedical applications. Methods: Semi-interpenetrating polymer networks (semi-IPNs) were obtained by photo-stabilizing aqueous solutions of PEGDA and acrylic acid (AA), in the presence of collagen. Further grafting of the collagen macromolecules to the PEGDA/poly(AA) network was achieved by means of a carbodiimide-mediated crosslinking reaction. The resulting hydrogels were characterized in terms of swelling capability, collagen content and mechanical properties. Results and conclusions: The grafting procedure was found to significantly improve the mechanical stability of the IPN hydrogels, due to the establishment of covalent bonding between the PEGDA/poly(AA) and the collagen networks. The suitability of the composite hydrogels to be processed by means of stereolithography (SLA) was also investigated, toward creating biomimetic constructs with complex shapes, which might be useful either as platforms for tissue engineering applications or as tissue mimicking phantoms.

To evaluate the diagnostic performance of gold nanorod (GNR)-enhanced optoacoustic imaging employing a conventional echographic device and to determine the most effective operative configuration in order to assure optoacoustic effectiveness, nanoparticle stability, and imaging procedure safety. The most suitable laser parameters were experimentally determined in order to assure nanoparticle stability during the optoacoustic imaging procedures. The selected configuration was then applied to a novel tissue-mimicking phantom, in which GNR solutions covering a wide range of low concentrations (25-200 pM) and different sample volumes (50-200 μL) were exposed to pulsed laser irradiation. GNR-emitted optoacoustic signals were acquired either by a couple of single-element ultrasound probes or by an echographic transducer. Off-line analysis included: (a) quantitative evaluation of the relationships between GNR concentration, sample volume, phantom geometry, and amplitude of optoacoustic signals propagating along different directions; (b) echographic detection of "optoacoustic spots," analyzing their intensity, spatial distribution, and clinical exploitability. MTT measurements performed on two different cell lines were also used to quantify biocompatibility of the synthesized GNRs in the adopted doses. Laser irradiation at 30 mJ/cm(2) for 20 seconds resulted in the best compromise among the requirements of effectiveness, safety, and nanoparticle stability. Amplitude of GNR-emitted optoacoustic pulses was proportional to both sample volume and concentration along each considered propagation direction for all the tested boundary conditions, providing an experimental confirmation of isotropic optoacoustic emission. Average intensity of echographically detected spots showed similar behavior, emphasizing the presence of an "ideal" GNR concentration (100 pM) that optimized optoacoustic effectiveness. The tested GNRs also exhibited high biocompatibility over the entire considered concentration range. An optimal configuration for GNR-enhanced optoacoustic imaging was experimentally determined, demonstrating in particular its feasibility with a conventional echographic device. The proposed approach can be easily extended to quantitative performance evaluation of different contrast agents for optoacoustic imaging.

Understanding the relationships between material surface properties and cellular responses is essential to designing optimal material surfaces for implantation and tissue engineering. In this study, cellulose hydrogels were crosslinked using a non-toxic and natural component namely citric acid. The chemical treatment induces -COOH functional groups that improve the hydrophilicity, roughness, and materials rheological properties. The physiochemical, morphological, and mechanical analyses were performed to analyze the material surface before and after crosslinking. This approach would help determine if the effect of chemical treatment on cellulose hydrogel improves the hydrophilicity, roughness, and rheological properties of the scaffold. In this study, it was demonstrated that the biological responses of human mesenchymal stem cell with regard to cell adhesion, proliferation, and differentiation were influenced in vitro by changing the surface chemistry and roughness.

Alginate micro beads containing Lactobacillus kefiri (the principal bacteria present in the kefir probiotic drink) were produced by a novel technique based on dual aerosols spaying of alginate based solution and CaCl2 as cross linking agent. Carboxymethylcellulose (CMC) has been also added to the alginate in order to change the physic-chemical properties (viscosity and permeability) of the microbeads. Calcium alginate and CMC are biopolymers that can be used for developing oral drug-delivery systems. These biopolymers have been reported to show a pH-dependent swelling behaviour. Calcium alginate and CMC have also been known to possess an excellent mucoadhesive property. The loaded microbeads have been characterized in terms of morphology, chemical composition and stability in different conditions mimicking the gastric environment. In this study, we demonstrate the feasibility of a continuous fabrication of alginate microbeads in a range of 50–70 μm size, encapsulating L. kefiri as active ingredient. The technique involves the use of a double aerosols of alginate based solution and CaCl2 as crosslinking agent. Moreover, the encapsulation process was proved to be effective and not detrimental to bacteria viability. At the same time, it was verified the protective efficacy of the microcapsules against the gastric environment using both SGF pH 1.2 (fasted state) and pH 2.2 (feed state).

In this work, an innovative cellulose-based superabsorbent polymer (SAP) was experimentally assessed as an environmentally friendly alternative to acrylate-based SAPs, for the optimization of water consumption in agriculture. The cellulose-based SAP was synthesized and tested for its swelling capability in different aqueous media. The effectiveness of the SAP in agricultural applications was then evaluated by analyzing its performance after several absorption/desorption cycles, over a period of approximately 80 days, upon addition to different types of soil, i.e., white and red soil, for the cultivation of two varieties of plants typical of the Mediterranean area (tomatoes and chicory). The results confirmed that SAP-amended soil can store a considerable amount of water and can release it gradually to the plant roots when needed. The adoption of the proposed SAP in cultivations could thus represent a promising solution for the rationalization of water resources, especially in desert areas.

Poly(ethylene glycol) diacrylate (PEGDA) cryogels, particularly useful for biotechnological applications, are currently fabricated exploiting crosslinking systems that require long freezing/crosslinking times (20 h or longer). The aim of this work was to assess whether fast UV irradiation (up to 60 s) of frozen PEGDA solutions could be an advantageous alternative for cryogel production. By using different polymer concentrations and UV times, cryogels with highly interconnected macropores (about 50–90 μm) were produced. A gelation yield in the range 60–80% was recorded, with higher values obtained for low PEGDA concentrations (5 and 10% w/v). Interestingly, while decreasing the swelling and increasing the stiffness of the cryogels, a higher polymer concentration was also found to reduce the pore size. Furthermore, increasing the UV time resulted in significantly higher swelling and larger pores for 10% PEGDA samples, while having negligible effect on other cryogel types and/or features. Although deserving further exploration, fast UV irradiation is an effective method to produce PEGDA cryogels with tunable properties.

Rationale and Objectives: The aim of this study was to identify the optimal parameter configuration of a new algorithm for fully automatic segmentation of hepatic vessels, evaluating its accuracy in view of its use in a computer system for three-dimensional (3D) planning of liver surgery. Materials and Methods: A phantom reproduction of a human liver with vessels up to the fourth subsegment order, corresponding to a minimum diameter of 0.2 mm, was realized through stereolithography, exploiting a 3D model derived from a real human computed tomographic data set. Algorithm parameter configuration was experimentally optimized, and the maximum achievable segmentation accuracy was quantified for both single two-dimensional slices and 3D reconstruction of the vessel network, through an analytic comparison of the automatic segmentation performed on contrast-enhanced computed tomographic phantom images with actual model features. Results: The optimal algorithm configuration resulted in a vessel detection sensitivity of 100% for vessels > 1 mm in diameter, 50% in the range 0.5 to 1 mm, and 14% in the range 0.2 to 0.5 mm. An average area overlap of 94.9% was obtained between automatically and manually segmented vessel sections, with an average difference of 0.06 mm2. The average values of corresponding false-positive and false-negative ratios were 7.7% and 2.3%, respectively. Conclusions: A robust and accurate algorithm for automatic extraction of the hepatic vessel tree from contrast-enhanced computed tomographic volume images was proposed and experimentally assessed on a liver model, showing unprecedented sensitivity in vessel delineation. This automatic segmentation algorithm is promising for supporting liver surgery planning and for guiding intraoperative resections.

In this study, a new foaming method, based on physical foaming combined with microwave-induced curing, is proposed in combination with a surface bioactivation to develop scaffold for bone tissue regeneration. In the first step of the process, a stable physical foaming was induced using a surfactant (Pluronic) as blowing agent of a homogeneous blend of Chitosan and polyethylene glycol diacrylate (PEGDA700) solutions. In the second step, the porous structure of the foaming was chemically stabilized by radical polymerization induced by homogeneous heating of the sample in a microwave reactor. In this step, 2,2-azobis[2-(2-imidazolin-2yl)propane]dihydrochloride was used as thermoinitiator (TI). Chitosan and PEGDA were mixed in different blends to investigate the influence of the composition on the final properties of the material. The chemical properties of each sample were evaluated by infrared attenuated total reflectance analysis, before and after curing in order to maximize reaction yield and optimize kinetic parameters (i.e. time curing, microwave power). Absorption capacity, elastic modulus, porosity and morphology of the porous structure were measured for each sample. The stability of materials was evaluated in vitro by degradation test in phosphate-buffered saline. To improve the bioactivity and biological properties of chitosan scaffold, a biomineralization process was used. Biological characterization was carried out with the aim to prove the effect of biomineralization scaffold on human mesenchymal stem cells behaviour. Copyright © 2016 John Wiley & Sons, Ltd.

Bioactive food-preserving materials are based on the use of a natural antimicrobial compound loaded in a carrier material, which is able to trigger its release when requested and to modulate the rate of release, thus using either toxic or inhibitory properties against pathogens or bacteria due to food decomposition. In this study, the Schiff base formation for chitosan functionalization was achieved by the reaction of chitosan with cinnamaldehyde at different concentrations. Cinnamaldehyde is an aromatic α,β-unsaturated aldehyde, and the major component in essential oils from some cinnamon species. It has been shown to exert antimicrobial action against a large number of microorganisms including bacteria, yeasts, and mould. The formation of the Schiff base is reversible under suitable conditions, and this might allow the release of the active cinnamaldehyde from chitosan, used as the carrier. The reaction kinetics was investigated by means of rheological measurements, while infrared spectroscopy was used to assess the efficacy of the functionalization. The addition of nanometric graphene stacks to the cinnamaldehyde-functionalized chitosan films was evaluated with the aim to increase the mechanical properties of the film. Finally, the films were tested for antifungal properties with bread slices against a selected mould line.

Wound closure represents a primary goal in the treatment of very deep and/or large wounds, for which the mortality rate is particularly high. However, the spontaneous healing of adult skin eventually results in the formation of epithelialized scar and scar contracture (repair), which might distort the tissues and cause lifelong deformities and disabilities. This clinical evidence suggests that wound closure attained by means of skin regeneration, instead of repair, should be the true goal of burn wound management. The traditional concept of temporary wound dressings, able to stimulate skin healing by repair, is thus being increasingly replaced by the idea of temporary scaffolds, or regenerative templates, able to promote healing by regeneration. As wound dressings, polymeric hydrogels provide an ideal moisture environment for healing while protecting the wound, with the additional advantage of being comfortable to the patient, due to their cooling effect and non-adhesiveness to the wound tissue. More importantly, recent advances in regenerative medicine demonstrate that bioactive hydrogels can be properly designed to induce at least partial skin regeneration in vivo. The aim of this review is to provide a concise insight on the key properties of hydrogels for skin healing and regeneration, particularly highlighting the emerging role of hydrogels as next generation skin substitutes for the treatment of full-thickness burns.

The present work deals with the development of a biodegradable superabsorbent hydrogel, based on cellulose derivatives, for the optimization of water resources in agriculture, horticulture and, more in general, for instilling a wiser and savvier approach to water consumption. The sorption capability of the proposed hydrogel was firstly assessed, with specific regard to two variables that might play a key role in the soil environment, that is, ionic strength and pH. Moreover, a preliminary evaluation of the hydrogel potential as water reservoir in agriculture was performed by using the hydrogel in experimental greenhouses, for the cultivation of tomatoes. The soil-water retention curve, in the presence of different hydrogel amounts, was also analysed. The preliminary results showed that the material allowed an efficient storage and sustained release of water to the soil and the plant roots. Although further investigations should be performed to completely characterize the interaction between the hydrogel and the soil, such findings suggest that the envisaged use of the hydrogel on a large scale might have a revolutionary impact on the optimization of water resources management in agriculture.

The aim of this study was to investigate the synthesis of chitosan nanoparticles for growth factor delivery in bone tissue engineering. Chitosan nanoparticles were synthesized via a modified precipitation process and their morphology and dimensions characterized by means of scanning electron microscopy (SEM) and dynamic light scattering (DLS), respectively. In particular, both chitosan molecular weight and concentration were varied during the synthesis to assess the effect of those variables on the particle size and morphology. The stability of the nanoparticles in aqueous media was also assessed, by measuring the average increase of the particle size with time. A specific particle formulation was then selected and loaded with a model molecule, i.e. an oligopeptide derived from the bone morphogenetic protein BMP2. The effect of the nanoparticles on the viability of osteoblast-like MG63 cells was finally assessed in a cytotoxicity assay. The encouraging results obtained in this study, although preliminary, suggested the possible use of chitosan nanoparticles for bone tissue engineering.

In this work, a mixture of a sodium salt of carboxymethylcellulose (CMCNa) and polyethylene glycol diacrylate (PEGDA700) was used for the prepara- tion of a microporous structure by using the combination of two different procedures. First, physical foaming was induced using Pluronic as a blowing agent, followed by a chemical stabilization. This second step was carried out by means of an azobis(2-methylpropionamidine)dihydrochloride as the thermoinitiator (TI). This reaction was activated by heating the sample homo- geneously using a microwave generator. Finally, the influence of different CMCNa and PEGDA700 ratios on the final properties of the foams was inves- tigated. The viscosity, water absorption capacity, elastic modulus and porous structure were evaluated for each sample. In addition, preliminary biological characterization was carried out with the aim to prove the biocompatibility of the resulting material. The foam, including 20% of PEGDA700 in the mixture, demonstrated higher viscosity and stability before thermo-polymerization. In addition, increased water absorption capacity, mechanical resistance and a more uniform microporous structure were obtained for this sample. In particu- lar, foam with 3% of CMCNa shows a hierarchical structure with open pores of different sizes. This morphology increased the properties of the foams. The full set of samples demonstrated an excellent biocompatibility profile with a good cell proliferation rate of more than 7 days.

In this study, free-standing expanded graphite chitosan (EG-chitosan) nanocomposite films have been prepared using a novel green and simple preparation method, starting from a commercial expandable graphite (GIC). The in situ exfoliation of GIC by a solvent-free sonication method was monitored as a function of the process parameters using X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) and UV-visible transmittance (UV-VIS) analyses. The optimal process parameters were selected in order to obtain an efficient dispersion of EG in chitosan solutions. The effective EG amount after the in situ exfoliation was also determined by thermogravimetric analyses.

The aim of this project was to study the proliferation and differentiation of human Mesenchymal Stem Cells (hMSCs) onto a cellulose-based hydrogel for bone tissue engineering. Methods: Modified-cellulose hydrogel was prepared via double esterification crosslinking using citric acid. The response of hMSCs in terms of cell proliferation and differentiation into osteoblastic phenotype was evaluated by using Alamar blue™ assay and alkaline phosphatase (ALP) activity. Results: The results showed that CMCNa and CMCNa_CA have no negative effect on hMSC, adhesion and proliferation. Moreover, the increase of the ALP expression for CMCNa_CA confirms the ability of the hydrogels to support the osteoblastic differentiation. Conclusions: The cellulose-based hydrogels have a potential application as filler in bone tissue regeneration.

Rapid prototyping techniques have been investigated for the production of biomedical devices that perfectly fit the patient's tissue defect (e.g. for bone and dental applications) and/or reproduce the microstructure of the tissue or organ of interest. The possibility to create patient-specific devices has been recently exploited for the creation of tissue engineer-ing scaffolds, i.e. porous, resorbable matrices, which stimulate cell functions and induce tissue regenera-tion by providing cells with appropriate physical, mechanical and biochemical cues. Poly(ethylene glycol) (PEG)-based hydrogels, although intrinsically non-biodegradable and non-bioactive, show great promise as tissue engineering scaffolds, due to their ability to be covalently linked to bioactive and/or degradable moieties, that elicit specific cell responses, and to their fast and biocompatible formation under ultra-violet (UV) exposure. In this work, poly(ethylene glycol)-based hydrogels, containing bioactive moieties, were photopolymerized and characterized in terms of mechanical, swelling and degradation properties. The production of hydrogels possessing a complex shape was finally investigated by means of stereolithography, a rapid prototyping technique which is able to build a three-dimensional object, starting from the CAD model, by guiding an ultravio-let laser beam on the surface of a photosensitive solution. The results demonstrated that the developed hydrogel formulations allow the creation of biomimetic constructs with complex shapes, which might be useful as platforms for tissue engineering or as tissue mimicking phantoms.

In the present work, we measured the degradation rate of different chitosan slurries. Several parameters were monitored such as temperature (25 °C, 37 °C, 50 °C); chitosan concentration (1% and 2% (w/V)); and polymer molecular weight. The samples were tested in dynamic sweep test mode. This test is able to provide a reliable estimation of viscosity variations of the slurries; in turn, these variations could be related to degradation rate of the system in the considered conditions. The resulting information is particularly important especially in applications in which there is a close relationship between physical properties and molecular structure.

Due to its intrinsic biocompatibility, degradability, and antibacterial properties, chitosan is widely explored for biomedical and pharmaceutical applications, especially for the development of tissue engineering scaffolds and controlled drug delivery systems. In this work, physically crosslinked chitosan-based particles with submicrometric size were synthesized by means of a modified coacervation process, starting from aqueous solutions differing for the chitosan molecular weight and concentration. Scanning electron microscopy (SEM) and dynamic light scattering (DLS) were used to analyse the particle morphology and the mean diameter yielded by the different synthesis parameters. Daily DLS measurements were also performed to monitor the expected swelling of the particles in a buffer solution, up to four days of storage. The experimental findings showed that submicrometric chitosan particles, with an average diameter in the range 150–400 nm, could be successfully produced, with both chitosan molecular weight and concentration affecting the particle size. Moreover, the smallest particles, among those synthesized, were found to be stable in water solutions up to three days. This seems to suggest the potential of the investigated particles for short-term biomedical applications, e.g., controlled drug delivery over time windows ranging from hours to days.

The aim of this work is to develop a novel approach to control the growth of food-borne and food-spoilage microorganisms while reducing the use of synthetic preservatives. Bioactive food-preserving systems are based on the use of a natural antimicrobial agent loaded in a carrier material, which is able to trigger its release once necessary and to control the rate of release, thereby exerting either lethal or inhibitory effects against food pathogens or spoilage microorganisms. In this study the Schiff base of chitosan was synthesized by the reaction with cinnamaldehyde at different concentrations (0,1%, 0,25%, 0,5% w/w of dry polymer). Cinnamaldehyde is an aromatic α,β-unsaturated aldehyde, and the major component in essential oils from some cinnamon species. It has been shown to exert antimicrobial activity against a wide range of microorganisms including bacteria, yeasts, and mould. The formation of the Schiff base is reversible under suitable conditions, and this might allow the release of the active cinnamaldehyde from chitosan, used as the carrier. The reaction kinetics was investigated by means of rheological analyses, while Fourier transform infrared spectroscopy (FTIR) was used to assess the efficacy of the functionalization. The results from FT-IR spectra highlighted the presence of the absorption peak of the Schiff base, which confirmed the reactivity of the nitrogen from amino group of chitosan and carbonyl carbon of the aldehyde to form imine. Moreover, the reaction rate was found to increase as higher percentages of cinnamaldehyde were used. Cinnamaldehyde-functionalized chitosan films were then prepared and tested for contact angle and antifungal properties in vitro. The envisaged application of the films for food packaging was also tested, by placing the films in direct contact with slices of bread. It was demonstrated that the cinnamaldehyde-functionalized chitosan films increased the shelf life of the product.