Superparamagnetic iron oxide nanoparticles are well known for biomedical applications. The particle size, morphology, surface area, and functionalization are the key parameters that affect their bioactivity properties. Inline to this, the superparamagnetic Fe3O4 nanoparticles were prepared via chemical coprecipitation method with an average particle size of 6 ± 3 nm. The particles were surface-functionalized with chitosan and in-house prepared reduced graphene oxide (rGO) to obtain chitosan-coated Fe3O4 nanoparticles (C-Fe3O4) and rGO-Fe3O4 nanocomposites (G-Fe3O4), respectively. Upon functionalization, the physicochemical properties of the materials were characterized thoroughly using X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer, Raman Spectroscopy, and thermal gravimetric analysis. Furthermore, they have subjected to cytotoxicity assay, agar two-fold broth dilution test, and disc diffusion assay experiments for the determination of cytotoxicity and antibacterial activities. The effect of surface functionalization on their bioactivity was investigated thoroughly. The surface functionalization with chitosan and rGO has enhanced the bioactivity of the Fe3O4 nanoparticles.

The drive to replace scarce and expensive Pt-based electrocatalysts for oxygen reduction reaction (ORR) has led to the development of a group of electrocatalysts composed of transition-metal ion centers coordinated with four nitrogen groups (M-N4). Among these, metal phthalocyanines (MPcs), due to low cost of preparation, highly conjugated structure as well as high thermal and chemical stability, have received a great interest. The catalytic activity of MPcs can be improved by employing conducting supports. Here, in this report, we have solvothermally synthesized graphene-supported zinc phthalocyanine nanostructures, and their ORR kinetics and mechanism have been investigated in neutral solution (pH = 7) by using the rotating disk electrode technique. The as-synthesized nanocomposite followed a 4e− reduction pathway. The onset potential (−0.04 V versus Ag/AgCl) found in this work can be comparable with other state-of-the-art material, demonstrating good performance in neutral solution. The fascinating performance leads the nanocomposite material toward future energy applications.