Effective composite partnering of green synthesized rGO with SnO2:Ce: An eco-friendly approach using Cassia fistula fruit pulp for photocatalytic and biomedical applications

Abstract

Reduced graphene oxide (rGO) - green synthesized using Cassia fistula fruit pulp extract - was selected as the composite partner to cerium doped tin oxide (SnO2:Ce) to prepare SnO2:Ce/rGO nanocomposite and its photocatalytic ability was determined by degrading a cationic (Methylene Blue (MB)) and an anionic dye (Rose Bengal (RB)). Its biomedical application potential was analyzed through the antioxidant assays 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and superoxide, and anti-diabetic assay α-glucosidase. The nanocomposite exhibits superior dye degrading efficiency of 98% and 97% for MB and RB, respectively. The long hetero-junction formed between the composite partners as observed from the Transmission Electron Microscope (TEM) images facilitates charge recombination delay and desirable carrier transport. The rGO partnering makes the nanocomposite material visible light responsive photocatalyst by reducing the band gap. In the DPPH and super oxide free radical scavenging assays, the percentage inhibition of the free radicals for the nanocomposite was 89.38±0.14% with half-maximal inhibitory concentration (IC50) of 79.68±1.39 μg/mL) and 86.93±0.11% with an IC50 of 107.23±1.17 μg/mL, respectively. Similarly, the nanocomposite exhibited highest inhibition of 83.62 ± 0.73% (IC50 of 186.40 ± 1.40 μg/mL) against the α-glucosidase enzyme. Thus the bio-friendly SnO2:Ce/rGO nanocomposite synthesized using Cassia fistula fruit pulp extract is promising for photocatalytic and many biomedical applications.