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Tissue engineering is a highly interdisciplinary field of medicine aiming at regenerating damaged tissues by combining cells with porous scaffolds materials. Scaffolds are templates for tissue regeneration and should ensure suitable cell adhesion and mechanical stability throughout the application period. Chitosan (CS) is a biocompatible polymer highly investigated for scaffold preparation but suffers from poor mechanical strength. In this study, graphene oxide (GO) was conjugated to chitosan at two weight ratios 0.3% and 1%, and the resulting conjugates were used to prepare composite scaffolds with improved mechanical strength. To study the effect of GO oxidation degree on scaffold mechanical and biological properties, GO samples at two different oxygen contents were employed. The obtained GO/CS scaffolds were highly porous and showed good swelling in water, though to a lesser extent than pure CS scaffold. In contrast, GO increased scaffold thermal stability and mechanical strength with respect to pure CS, especially when the GO at low oxygen content was used. The scaffold in vitro cytocompatibility using human primary dermal fibroblasts was also affected by the type of used GO. Specifically, the GO with less content of oxygen provided the scaffold with the best biocompatibility. [ABSTRACT FROM AUTHOR]

In the path of direct energy conversion and wastewater disposal through microbial fuel cells (MFCs), the oxygen reduction reaction (ORR) plays a pivotal role. However, kinetic limitations hinders the spread of such technology requiring the use of a catalyst to develop efficient and cost effective devices. Herein we report a facile method for the preparation of iron-based catalyst supported on graphene oxide (GO) obtained by electrochemical exfoliation of graphite in aqueous solution of ammonium sulfate. Two different strategies to include nitrogen functionalities on/in GO matrix have been used, such as one-step nitrogen-doping in solution and post treatments based on annealing with ammonia gas. Iron (II) phthalocyanine (FePc) was used as iron source and deposited on GO by pyrolysis-free impregnation. Tuning the adjustable parameters governing the materials preparation allowed producing GO nanosheets with unique morphology and surface properties for enhancing the interaction with FePc. By combining the use of microscopy, electrochemical and spectroscopic techniques, a correlation between structure and surface chemistry of the prepared materials with catalytic activity towards ORR was established. The applicability of iron-based materials as ORR cathodes was evaluated by assembling single chamber air-cathodes MFCs, which power and voltage generation over time were acquired. The obtained results demonstrated that FePc/GO-based electrocatalysts can be used for electricity generation and waste treatment at the cathode side of MFCs. [ABSTRACT FROM AUTHOR]