Graphene, with its unique physico-chemical properties, has found widespread biomedical application. It is used as a carrier for drug or gene delivery, photothermal therapy, bioimaging, in antibacterial agents and for the development of biosensors. Besides this, graphene has the scope to be used for wound healing, tissue engineering and regenerative medicine. In the present study, polyethylene-glycol-(PEG)ylated reduced graphene oxide (PrGO) was synthesized, characterized, and its interaction with mouse bone marrow mesenchymal stem cells (MSCs) was studied. in vitro cytotoxicity and differentiation study showed PrGO neither induced toxicity nor impaired the differentiation potential of the stem cells. PrGO was effectively internalized by MSCs and distributed throughout the cytoplasm. None of the PrGO was seen in the nucleus. Although it seems to induce increased reactive oxygen species (ROS) production inside the cell, no change in cell proliferation or cellular function was observed. Hence it is recommended that the synthesized PrGO is applicable for tissue engineering, and can also be used as a substrate platform for stem cell culture and differentiation.

Electrochemical oxygen reduction reaction (ORR) via nonprecious catalysts has the potential for significant cost reduction in fuel cells. Dense, multi-layered poly(vinyl) alcohol (PVA) nanofibers dispersed with catalytically active carbon nitride (CN x ) nanoparticles were synthesized using electrospinning process. Size, morphology, elemental composition, bond structure of the CN x /PVA nanofibers were analysed using TEM, SEM, FTIR, XPS and Raman spectroscopic studies. Significant improvement in the electrocatalytic activity of CN x nanoparticles dispersed in the nanofibers as compared to its native form was observed towards ORR by voltammetry coupled with FTIR studies. Onset potential and peak current density observed for CN x /PVA nanofibers using cyclic voltammetry was comparable to conventional Pt/C (40:60 % by weight) catalyst. ORR mechanism was further analysed using RRDE and in-situ FTIR with linear sweep voltammetry studies. RRDE analysis confirmed that ORR takes place primarily via 4-electron pathway. The catalytic activity of CN x /PVA nanofibers for ORR was stable over 5000 repetitions of voltammetric studies coupled with FTIR.

Conventional synthesis of silver nanoparticles employs a reducing agent and a capping agent. Surfactants are effec-tive capping agents as they prevent the aggregation of nanoparticles during storage and use. However, the biocompatibility of several of the surfactants is questionable. In this report, the use of thiosalicylic acid as both reducing and capping agent is reported. Compared to conventional synthesis, this methodology requires higher temperature for synthesis, which then is expected to result in aggregates of larger size. The ability of three different synthesis methodologies – direct heating, photochemical and microwave dielectric treatment were evaluated and assessed on the basis of the size, size distribution and stability of the particles. Microwave irradiation was found to be most suitable for achieving particles with a hydrodynamic diameter of 10 nm. Our studies indicate that -COO- group is involved in the reduction of Ag+ and –SH group of TSA is involved in the capping of the nanoparticles

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