Bioinspired gold nanoparticles decorated reduced graphene oxide nanocomposite using Syzygium cumini seed extract: Evaluation of its biological applications.

The development of novel functionalized reduced graphene oxide nanocomposite materials keeping in mind environmental and health perspectives via green approaches is currently gaining enormous research interest in the field of nanoscience and nanotechnology. Herein, we report a bio-inspired green synthesis approach for gold nanoparticles decorated reduced graphene oxide nanocomposite in which Syzygium cumini seed extract (SCSE) is applied as natural reducing and stabilizing agent for the simultaneous reduction of chloroauric acid and graphene oxide (GO). The obtained nanocomposite was thoroughly investigated using UV-visible and FT-IR spectroscopy, XRD, SEM-EDX, TEM-SAED, Raman spectroscopy and XPS analysis. These characterization techniques clearly confirmed the successful synthesis of gold nanoparticles decorated reduced graphene oxide nanocomposite. In addition, this study evaluated the systematic and detailed analysis of AuNPs-rGO-NC and its efficacy towards cellular and antibacterial toxicological behavior. A detailed in-vitro cytotoxicity study was performed by analysing the percentage inhibition of cell viability, generation of reactive oxygen species (ROS) in cell lines using 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide (MTT) assay on human colorectal (HCT116) and lung (A549) cancer cell lines. Further, antibacterial toxicological evaluation was performed by analysing diameter of inhibition Zone (DIZ), activity index (AI), minimum bactericidal concentration (MBC), minimum inhibitory concentration (MIC), growth kinetics (GrK) and death kinetics (DeK) against Gram-negative bacterial strain Escherichia coli and Gram-positive bacterial strains Staphylococcus aureus and Bacillus subtilis. The cytotoxicity and antibacterial toxicological assays revealed that the synthesized nanocomposite showed significant anti-cancer activity towards A549 cell line and Gram-negative bacterial strain Escherichia coli compared to the rest.