In this study, graphene oxide (GO) nanoflakes (0.5 and 1 wt%) were incorporated into a gelatin-hydroxyapatite (GHA) matrix through a freeze drying technique and its effect to enhance mechanical strength and osteogenic differentiation was studied. The GHA matrix with GO demonstrated less brittleness in comparison to GHA scaffolds. There was no significant difference in mechanical strength between GOGHA0.5 and GOGHA1.0 scaffolds. When the scaffolds were immersed in phosphate buffered saline (to mimic physiologic condition) for 60 days, around 50-60% of GO was released in sustained and linear manner and the concentration was within the toxicity limit as reported earlier. Further, GOGHA0.5 scaffolds were continued for cell culture experiments, wherein the scaffold induced osteogenic differentiation of human adipose derived mesenchymal stem cells without providing supplements like dexamethasone, L-ascorbic acid and β glycerophosphate in the medium. The level of osteogenic differentiation of stem cells was comparable to those cultured on GHA scaffolds with osteogenic supplements. Thus biocompatible, biodegradable and porous GO reinforced gelatin-HA 3D scaffolds may serve as a suitable candidate in promoting bone regeneration in orthopaedics.

The study shows the development of a biodegradable bi-functional composite scaffold that can reduce bacterial infection, while promotes bone regeneration in osteomyelitis, without the need for revision surgery.

Recent trends in titanium implants are towards the development of nanoscale topographies that mimic the nanoscale properties of bone tissue. Although the nanosurface promotes the integration of osteoblast cells, infection related problems can also occur, leading to implant failure. Therefore it is imperative to reduce bacterial adhesion on an implant surface, either with or without the use of drugs/antibacterial agents. Herein, we have investigated two different aspects of Ti surfaces in inhibiting bacterial adhesion and concurrently promoting mammalian cell adhesion. These include (i) the type of nanoscale topography (Titania nanotube (TNT) and Titania nanoleaf (TNL)) and (ii) the presence of an antibacterial agent like zinc oxide nanoparticles (ZnOnp) on Ti nanosurfaces. To address this, periodically arranged TNT (80-120 nm) and non-periodically arranged TNL surfaces were generated by the anodization and hydrothermal techniques respectively, and incorporated with ZnOnp of different concentrations (375 μM, 750 μM, 1.125 mM and 1.5 mM). Interestingly, TNL surfaces decreased the adherence of staphylococcus aureus while increasing the adhesion and viability of human osteosarcoma MG63 cell line and human mesenchymal stem cells, even in the absence of ZnOnp. In contrast, TNT surfaces exhibited an increased bacterial and mammalian cell adhesion. The influence of ZnOnp on these surfaces in altering the bacterial and cell adhesion was found to be concentration dependent, with an optimal range of 375-750 μM. Above 750 μM, although bacterial adhesion was reduced, cellular viability was considerably affected. Thus our study helps us to infer that nanoscale topography by itself or its combination with an optimal concentration of antibacterial ZnOnp would provide a differential cell behavior and thereby a desirable biological response, facilitating the long term success of an implant.

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