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Only recently polymers with intrinsic conductive properties have been studied in relation to their incorporation into bioactive scaffolds for use in tissue engineering. The reason for this interest is that such scaffolds could electrically stimulate cells and thus regulate specific cellular activities, and by this means influence the process of regeneration of those tissues that respond to electrical impulses. In our work, macroporous hydrogels are developed with controlled pore morphology and conductive properties to enable sufficient cell signaling to supply events inherent to nerve regeneration. A hybrid material has been prepared by in situ precipitation of polyaniline (PANi) in polyethyleneglycol diacrylate (PEGDA) solution, followed by crosslinking via UV irradiation. A porous architecture, characterized by macropores from 136 μm to 158 μm in size, has been achieved by sodium chloride particle leaching. In this work, we demonstrate that PANi synthesis and hydrogel crosslinking combine to enable the design of materials with suitable conductive behaviour. The presence of PANi evidently increased the electrical conductivity of the hybrid material from (1.1 ± 0.5) × 10(-3) mS/cm with a PANi content of 3wt%. The hydrophilic nature of PANi also enhanced water retention/proton conductivity by more than one order of magnitude. In vitro studies confirmed that 3 wt% PANi also improve the biological response of PC12 and hMSC cells. Hybrid PANi/PEGDA macroporous hydrogels supplement new functionalities in terms of morphological and conductive properties, both of which are essential prerequisites to drive nerve cells in regenerative processes.

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.

The design of functionalized polymers that can elicit specific biological responses and the development of methods to fabricate new devices that incorporate biological cues are of great interest to the biomedical community. The realization of nanostructured matrices that exhibit biological properties and that comprise fibers with diameters of similar scale to those of the natural extracellular matrix (ECM) would enable the provision of tailored materials for tissue engineering. Accordingly, the goal of this work is to create a biologically active functionalized electrospun matrix capable of guiding neurite growth for the regeneration of nerve tissue. In this study, nanoscale electrospun membranes made of poly ε-caprolactone enhanced with gelatin from calf skin were investigated to validate their biological response under in vitro culture of PC-12 nerve cells. Preliminary observations from SEM studies supported by image analysis highlighted the nanoscale texture of the scaffold with fiber diameters equal to 0.548 ± 0.140 μm. In addition, contact angle measurements confirmed the hydrophilic behavior of the membranes, ascribable to the gelatin content. We demonstrate that the balance of morphological and biochemical properties improves all the fundamental biological events of nerve regeneration, enhancing cell adhesion, proliferation, and differentiation in comparison with PCL nanofibrous scaffolds, as well as supporting the neurite outgrowth.

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