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Biological activities of cells such as survival and differentiation processes are mainly maintained by a specific extracellular matrix (ECM). Hydrogels have recently been employed successfully in tissue engineering applications. In particular, scaffolds made of gelatin methacrylate-based hydrogels (GelMA) showed great potential due to their biocompatibility, biofunctionality, and low mechanical strength. The development of a hydrogel having tunable and appropriate mechanical properties as well as chemical and biological cues was the aim of this work. A synthetic and biological hybrid hydrogel was developed to mimic the biological and mechanical properties of native ECM. A combination of gelatin methacrylate and acrylamide (GelMA-AAm)-based hydrogels was studied, and it showed tunable mechanical properties upon changing the polymer concentrations. Different GelMA-AAm samples were prepared and studied by varying the concentrations of GelMA and AAm (AAm2.5% + GelMA3%, AAm5% + GelMA3%, and AAm5% + GelMA5%). The swelling behavior, biodegradability, physicochemical and mechanical properties of GelMA-AAm were also characterized. The results showed a variation of swelling capability and a tunable elasticity ranging from 4.03 to 24.98 kPa depending on polymer concentrations. Moreover, the podocyte cell morphology, cytoskeleton reorganization and differentiation were evaluated as a function of GelMA-AAm mechanical properties. We concluded that the AAm2.5% + GelMA3% hydrogel sample having an elasticity of 4.03 kPa can mimic the native kidney glomerular basement membrane (GBM) elasticity and allow podocyte cell attachment without the functionalization of the gel surface with adhesion proteins compared to synthetic hydrogels (PAAm). This work will further enhance the knowledge of the behavior of podocyte cells to understand their biological properties in both healthy and diseased states.

International audience; Synthetic polymers are widely employed for bone tissue engineering due to their tunable physical properties and biocompatibility. Inherently, most of these polymers display poor antimicrobial properties. Infection at the site of implantation is a major cause for failure or delay in bone healing process and the development of anti-microbial polymers is highly desired. In this study, silver nanoparticles (AgNps) were synthesized in poly-caprolactone (PCL) solution by in-situ reduction and further extruded into PCL/AgNps filaments. Customized 3D structures were fabricated using the PCL/AgNps filaments through 3D printing technique. As demonstrated by scanning electron microscopy, the 3D printed scaffolds exhibited interconnected porous structures. Furthermore, X-ray photoelectron spectroscopy analysis revealed the reduction of silver ions. Transmission electron micro-scopy along with energy-dispersive X-ray spectroscopy analysis confirmed the formation of silver nanoparticles throughout the PCL matrix. In vitro enzymatic degradation studies showed that the PCL/AgNps scaffolds dis-played 80% degradation in 20 days. The scaffolds were cytocompatible, as assessed using hFOB cells and their antibacterial activity was demonstrated on Escherichia coli. Due to their interconnected porous structure, me-chanical and antibacterial properties, these cytocompatible multifunctional 3D printed PCL/AgNps scaffolds appear highly suitable for bone tissue engineering.

International audience; The aim of this work was to develop a bioresorbable, biodegradable and biocompatible synthetic polymer with good mechanical properties for bone tissue engineering applications. Polylactic acid (PLA) scaffolds were generated by 3D printing using the fused deposition modelling method, and reinforced by incorporation of graphene oxide (GO). Morphological analysis by scanning electron microscopy indicated that the scaffold average pore size was between 400 and 500 μm. Topography imaging revealed a rougher surface upon GO incorporation (Sa = 5.8 μm for PLA scaffolds, and of 9.9 μm for PLA scaffolds with 0.2% GO), and contact angle measurements showed a transition from a hydrophobic surface (pure PLA scaffolds) to a hydrophilic surface after GO incorporation. PLA thermomechanical properties were enhanced by GO incorporation, as shown by the 70 °C increase of the degradation peak (thermal gravimetric analysis). However, GO incorporation did not change significantly the melting point assessed by differential scanning calorimetry. Physicochemical analyses by X-ray diffraction and Raman spectroscopy confirmed the filler presence. Tensile testing demonstrated that the mechanical properties were improved upon GO incorporation (30% increase of the Young's modulus with 0.3% GO). Cell viability, attachment, proliferation and differentiation assays using MG-63 osteosarcoma cells showed that PLA/GO scaffolds were biocompatible and that they promoted cell proliferation and mineralization more efficiently than pure PLA scaffolds. In conclusion, this new 3D printed nanocomposite is a promising scaffold with adequate mechanical properties and cytocompatibility which may allow bone formation.

International audience; Here, we produced a synthetic polymer having adequate biocompatibility, biodegradability, and bioresorbability, as well as mechanical properties for applications in bone tissue engineering. We used the fused deposition modeling (FDM) based 3D printing approach in order to produce biomimetic biodegradable scaffolds made of polylactic acid (PLA). We strengthened these scaffolds by addition of exfoliated boron nitride (EBN) as filler. We demonstrated the presence of EBN by physicochemical analysis using Raman spectroscopy and X-ray diffraction (XRD). Using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), we found that EBN incorporation did not influence the transition temperature, but reduced the polymer crystallinity. Scanning electron microscopy for morphology evaluation showed a mean scaffold pore size of 500 μm. EBN incorporation did not affect the scaffold mechanical properties (tensile test), but modified the surface roughness. Moreover, contact angle quantification indicated that the surface of PLA/EBN scaffolds was hydrophilic and that of PLA scaffolds hydrophobic. Finally, the results of the cytotoxicity, cell attachment, and proliferation experiments using MG-63 and MC3T3 cells indicated that PLA scaffolds filled with EBN were nontoxic and compatible with osteoblastic cells and also promoted the scaffold mineralization by MG-63 cells. Altogether, our results suggest that this 3D printed nanocomposite scaffold is suitable for tissue engineering.

International audience; Gelatin is a fascinating biomaterial due to its biocompatibility, biodegradability and chemical composition. The engineering of gelatin scaffolds with the most appropriate architecture is crucial for tissue engineering applications. Currently available porogen assisted scaffold fabrication technique are limited for the fabrication of repeatable and customized scaffolds. Three dimensional printing is an appropriate technique to prepare customized structure. In this report, customized gelatin scaffolds were fabricated using 3D printed polyvinyl alcohol (PVA) sacrificial molds. Gelatin was stabilized through crosslinking and the PVA was solubilized to obtain 3D customized gelatin scaffolds. The gelatin scaffolds displayed tunable pore size from 350 to 1200 ​μm. The influence of PVA infill density on the gelatin scaffold porous structure and interconnectivity was also analyzed. Furthermore, the gelatin scaffold stability in phosphate buffered saline solution and their swelling capacity demonstrated that they were effectively crosslinked. The scaffold cytocompatibility and the good cell attachment and proliferation on these scaffolds showed that the sacrificial mold-assisted 3D printing is suitable for producing customizable gelatin scaffolds for biomedical applications.

International audience; Gelatin is a biodegradable biopolymer obtained by collagen denaturation, which shows poor mechanical properties. Hence, improving its mechanical properties is very essential towards the fabrication of efficient nontoxic material for biomedical applications. For this aim, various methods are employed using external fillers such as ceramics or bioglass. In this report, we introduce boron nitride (BN) reinforced gelatin as a new class of two dimensional biocompatible nanomaterials. The effect of the nanofiller on the mechanical behavior isanalyzed. BN is efficiently exfoliated using the biopolymer gelatin as shown through Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The exfoliated BN reinforces gelatin electrospun fibers, which results in an increase in the Young’s modulus. The ESM are stable after the glutaraldehyde cross-linking and the fibrous morphology is preserved. The cross-linked gelatin/BN ESM is highly bioactive in forming bone like hydroxyapatite as shown by scanning electron microscopy. Due to their enhanced mineralization ability, the cross-linked ESM have been tested on human bone cells (HOS osteosarcoma cell line). The cell attachment, proliferation and biocompatibility results show that the ESM are nontoxic and biodegradable. The analysis of osteoblast gene expression and the measurement of alkaline phosphatase activity confirm that these materials are suitable for bone tissue engineering

The objective of this study was to implement electrochemical advanced oxidation processes (EAOPs) for mineralization and biodegradability enhancement of nanofiltration (NF) concentrate from landfill leachate initially pre-treated in a membrane bioreactor (MBR). Raw carbon felt (CF) or Fe II Fe III layered double hydroxides-modified CF were used for comparing the efficiency of homogeneous and heterogeneous electro-Fenton (EF), respectively. The highest mineralization rate was obtained by heterogeneous EF: 96% removal of dissolved organic carbon (DOC) was achieved after 8 h of electrolysis at circumneutral initial pH (pH 0 = 7.9) and at 8.3 mA cm −2 . However, the most efficient treatment strategy appeared to be heterogeneous EF at 4.2 mA cm −2 combined with anodic oxidation using Ti 4 O 7 anode (energy consumption = 0.11 kWh g −1 of DOC removed). Respirometric analyses under similar conditions than in the real MBR emphasized the possibility to recirculate the NF retentate towards the MBR after partial mineralization by EAOPs in order to remove the residual biodegradable by-products and improve the global cost effectiveness of the process. Further analyses were also performed in order to better understand the fate of organic and inorganic species during the treatment, including acute toxicity tests (Microtox ® ), characterization of dissolved organic matter by three-dimensional fluorescence spectroscopy, evolution of inorganic ions (ClO 3 − , NH 4 + and NO 3 − ) and identification/quantification of degradation by-products such as carboxylic acids. The obtained results emphasized the interdependence between the MBR process and EAOPs in a combined treatment strategy. Improving the retention in the MBR of colloidal proteins would improve the effectiveness of EAOPs because such compounds were identified as the most refractory. Enhanced nitrification would be also required in the MBR because of the release of NH 4 + from mineralization of refractory organic nitrogen during EAOPs.

Rapid urbanization proportionally increases the waste products which force humankind to find a suitable waste management system. This study aims at identifying the possibility of using toner waste powder (TWP) as a filler for fabricating polymer composites for enhanced electrical conductivity of polymer blends. TWP was successfully incorporated into a polymer blend of low-density polyethylene/high impact polystyrene (LDPE/HIPS) at a high loading percentage of up to 20 wt %. Elemental analysis (SEM-EDS and XRF) showed that the main constituents of TWP are carbon and iron with traces of other metals such as Ca, Cs, Ti, Mn, Si. The electrical conductivity of LDPE/HIPS is significantly enhanced by loading the TWP into the polymer blend. The addition of TWP to LDPE/HIPS blend decreases the electrical resistivity of the LDPE/HIPS/TWP composite to ~2.9 &times, 107 Ohm.cm at 10 wt % of TWP, which is several orders of magnitude lower than that of the neat blend with maintaining the thermal stability of the polymer composite. The prepared polymer composite is lightweight and shows electrical conductivity, thus it can have potential applications in electronic materials and automotive industries.

In the search for biomaterials that exhibit both versatility and compatibility with human-tissues, considerable interest has been shown in collagen-based biomaterial for the repair and replacement of the body tissues such as tendons, skin, vascular grafts, heart valves, dental and bones. Some of the general properties of collagen which makes it an interesting biomaterial are the high mechanical strength of the fibers, low antigenicity, its suitability as a substrate for cell growth, and its tunable stability by chemical or physical cross-linking. Collagen based composites are used in various biomedical applications as collagen shields in ophthalmology, sponges for burns and wounds, mini-pellets and tablets for protein delivery, gel formulation in combination with liposome for sustained drug delivery, as controlling material for transdermal delivery, basic matrices for cell culture systems, coating material of metal implant for bone replacement and 3-D printed matrix for various tissue engineering applications. For an adequate biomedical application of collagen, basic knowledge about collagen structure, hierarchical structural organisation and the processing technology in combination with understanding of the physico-chemical properties is of vital importance.

International audience; Biopolymers are playing a vital role in biomedical applications. Among them, protein-based biopolymers are utilized for the fabrication of tissue-engineering constructs, therapeutic molecule delivery carriers, emulsifiers, and food packaging materials. Wide ranges of proteins are extracted from animal or plant sources and are being utilized for the fabrication of scaffolds for regenerative tissue-engineering application. Here, an overview about the protein structure, extraction procedure, solubility, and various formulation-based proteins found in the literature are discussed. Biopolymers display several advantages such as biocompatibility and degradability by enzymes. Methods to overcome the disadvantages of these proteins such as immunogenicity, antigenicity, and solubility are reported. Various crosslinking reagents specific to protein chemistry are discussed as well.

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Inherent physical properties such as high surface area and extracellular matrix mimicking structure of electrospun fibers are advantageous for loading the drug/biomolecule. Also, controlling the release of therapeutic molecule is crucial to achieve high therapeutic effect. Carefully engineering the experimental conditions allows fabrication of drug delivery carriers that display prolonged release of drugs/biomolecules for long-term application. Feasibility of loading lipophilic and hydrophilic drugs/biomolecules together in single three-dimensional (3D) fibrous construct is reviewed. Effects of polymer wettability, sheath thickness, and polymer degradability on therapeutic molecule delivery are also discussed. This chapter also discuss the different electrospinning techniques used to prepare 3D construct that bears multinutrients or growth factor or drugs that are essential for enhanced cell proliferation adhesion and differentiation. Influence of polymer hydrophobicity, hydrophilicity, and polymer degradation on release of drugs and biomolecules are reviewed. Importance of various stimuli on the drug/biomolecule delivery is focused on in this chapter. Delivery of biomolecules such as growth factors and nucleic acid using electrospinning provides a favorable environment and supporting matrix to the cells, hence, application of electrospun fibers on regenerative tissue engineering is also reviewed.

[EN] Neural tissue engineering aims at producing a simulated environment using a matrix that is suitable to grow specialized neurons/glial cells pertaining to CNS/PNS which replace damaged or lost tissues. The primary goal of this study is to design a compatible scaffold that supports the development of neural-lineage cells which aids in neural regeneration. The fabricated, freeze-dried scaffolds consisted of biocompatible, natural and synthetic polymers: gelatin and polyvinyl pyrrolidone. Physiochemical characterization was carried out using Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) imaging. The 3D construct retains good swelling proficiency and holds the integrated structure that supports cell adhesion and proliferation. The composite of PVP-gelatin is blended in such a way that it matches the mechanical strength of the brain tissue. The cytocompatibility analysis shows that the scaffolds are compatible and permissible for the growth of both stem cells as well as differentiated neurons. A change in the ratios of the scaffold components resulted in varied sizes of pores giving diverse surface morphology, greatly influencing the properties of the neurons. However, there is no change in stem cell properties. Different types of neurons are characterized by the type of gene associated with the neurotransmitter secreted by them. The change in the neuron properties could be attributed to neuroplasticity. The plasticity of the neurons was analyzed using quantitative gene expression studies. It has been observed that the gelatin-rich construct supports the prolonged proliferation of stem cells and multiple neurons along with their plasticity., Dr SNK is grateful to the Department of Biotechnology (DBT) BCIL/NER-BPMC/2014-1094 and SVAGATA for the financial support rendered. JMMD and JLGR are grateful for the fi nancial support of the Spanish Ministry of Economy and Competitiveness through the MINECO MAT2016-76039-C4-1-R project (including Feder funds). CIBER-BBN is an initiative funded by the VI National R&D & I Plan 2008-2011, "IniciativaIngenio 2010", Consolider Program. CIBER actions are financed by the "Instituto de Salud Carlos III" with assistance from the European Regional Development Fund. The authors also thank Department of Science and Technology (DST) - SR/WOS-A/LS-193/2012, for the financial support rendered for the cell culture experiments. The authors also thank Dr Jayanthi V., Mr Baskar S. S. and Dr Vishnuvardhanan M., for their contribution in this work.

Gelatin is a biodegradable, nontoxic and biocompatible biopolymer. The biomedical application of un-crosslinked gelatin is limited, due to poor mechanical strength and high solubility. Hence, 2D graphene oxide (GO) nanosheets are used as reinforcing agents to enhance the mechanical properties. The GO exfoliation in gelatin is confirmed using X-ray diffraction (XRD) analysis. The GO reinforcement enhances Young modulus (E) by 70% and tensile stress is also significantly improved. Moreover, the fibrous cross-linked electrospun mats are stable in phosphate buffered saline solution. The cell attachment and proliferation of the ESM are evaluated with human osteosarcoma cells (HOS) and the ESM is found to be biocompatible. However, the expression of osteoblast genes decreases with increasing GO incorporation. This report demonstrates that GO with high degree of oxidation, effectively reinforces and enhances the mechanical properties of the gelatin fibers. Also, increasing the concentration of GO does not show any significant influence on cell viability and cell attachment even though the expression of osteoblast gene is affected.

This work aimed to the development of chitosan and protein isolate composite hydrogels, for carotenoids-controlled delivery and wound healing. By increasing the concentration of the protein isolate, chitosan hydrogels were more elastic at a protein isolate concentration not exceeding 15% (w/w). Chitosan-protein isolate composite hydrogels revealed low cytotoxicity towards MG-63 osteosarcoma cells. Thanks to its appropriate structural, swelling and mechanical resistance properties, chitosan hydrogel (3%; w/v), reinforced with 15% (w/w) of protein isolate, was selected for the carotenoids in vitro release study. Release profiles, show delivery patterns, where carotenoids were more barely released at a pH 7.4 medium (p .05), compared to more acidic microenvironments (pH 4.0 and pH 2.0). Thus, developed hydrogels could be applied as pH-sensitive intelligent carriers, for drugs-controlled release, with interesting antioxidant abilities. The in vivo healing potential of hydrogels in rats' models was further studied. Topical application of hydrogel-based patches allowed the acceleration of wound healing and the complete healing, for composite hydrogel enriched with carotenoids.

International audience; Human exposure to air pollution and especially to nanoparticles is increasing due to the combustion of carbon-based energy vectors. Fibrous filters are among the various types of equipment potentially able to remove particles from the air. Nanofibers are highly effective in this area; however, their utilization is still a challenge due to the lack of studies taking into account both nanoparticle collection efficiency and antibacterial effect. The aim of this work is to produce and evaluate novel silver/polyacrylonitrile (Ag/PAN) electrospun fibers deposited on a nonwoven substrate to be used as air filters to remove nanoparticles from the air and also showing antibacterial activity. In order to determine the optimum manufacturing conditions, the effects of several electrospinning process parameters were analyzed such as solution concentration, collector to needle distance, flow rate, voltage, and duration. Ag/PAN nanofibers were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier Transform Infra-Red spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and Scanning Electron Microscopy (SEM). In addition, filtration performances were determined by measuring the pressure drop and collection efficiency of sodium chloride (NaCl) aerosol particles (9 to 300 nm diameters) using Scanning Mobility Particle Sizers (SMPS). Filters with high filtration efficiency (≈100%) and high-quality factor (≈0.05 Pa-1) were obtained even adding different concentrations of Ag nanoparticles (AgNPs) to PAN nanofibers. The resultant Ag/PAN nanofibers showed excellent antibacterial activity against 10 4 CFU/ml E.coli bacteria.

This article presents a novel procedure for preparing porous membranes from water-soluble polymers involving the formation of a Pickering emulsion. Gelatin is a biodegradable biopolymer obtained by the partial hydrolysis of collagen. A biopolymer such as gelatin is capable of adsorbing at an oil/water interface, resulting in decreased interfacial energy. Hence, gelatin is widely employed as an alternate for synthetic surfactants to stabilize emulsions in the food industry. However, high-molecular-weight gelatin leads to large emulsion droplets and poor emulsion stability. The amphoteric nature of graphene oxide (GO) nanosheets was helpful in stabilizing the oil/water interface and allows for the preparation of a stable gelatin/GO emulsion. Membranes fabricated using gelatin/GO have a uniformly distributed porous structure. However, prepared membranes are highly hydrosoluble, so the membranes were cross-linked without affecting their morphology. XRD results evidenced that gelatin effectively exfoliated the graphite oxide which is essential to stabilizing the emulsion. Fabricated gelatin/GO membranes possess uniformly distributed pores and are highly stable in aqueous solution. Pure water filtration tests were conducted on the membranes. The permeability results proved that the membranes fabricated by a Pickering emulsion are promising materials for filtration.

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Electrospinning is a versatile technique to produce micron or nano sized fibers using synthetic or bio polymers. The unique structural characteristic of the electrospun mats (ESM) which mimics extracellular matrix (ECM) found influential in regenerative tissue engineering application. ESM with different morphologies or ESM functionalizing with specific growth factors creates a favorable microenvironment for the stem cell attachment, proliferation and differentiation. Fiber size, alignment and mechanical properties affect also the cell adhesion and gene expression. Hence, the effect of ESM physical properties on stem cell differentiation for neural, bone, cartilage, ocular and heart tissue regeneration will be reviewed and summarized. Electrospun fibers having high surface area to volume ratio present several advantages for drug/biomolecule delivery. Indeed, controlling the release of drugs/biomolecules is essential for sustained delivery application. Various possibilities to control the release of hydrophilic or hydrophobic drug from the ESM and different electrospinning methods such as emulsion electrospinning and coaxial electrospinning for drug/biomolecule loading are summarized in this review.

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The aim of this study was to synthesize stable gelatin electrospun mats (ESMs) (cross-linked by glutaraldehyde (GTA) vapors) with tunable drug release properties using pH as a stimulus. Gelatin ESMs loaded with rhodamine as a model drug were first synthesized. The in vitro release of rhodamine was characterized to understand the mechanisms of drug release and the effects of both cross-linker concentration and pH on drug release. An optimal cross-linker concentration of 5% was evidenced to provide ESMs allowing both sustainable release of drugs at pH 7 and burst release at pH 2. The release profiles were then fitted with a power law model to describe the release kinetics. The chlorhexidine antibiotic drug was finally loaded into the optimal electrospun mat and its bactericidal activity was demonstrated against Gram-negative (E. coli) and Gram-positive (S. epidermidis) bacteria by agar diffusion tests. This biocompatible material was shown to efficiently destroy bacterial biofilms and prevent bacterial growth within a short time (3 h), while maintaining its antibacterial activity up to at least 72 h. This study provides a promising material, which could treat infected sites and prevent infections, with tunable drug releasing properties using pH as a stimulus.