Honey-mediated synthesis of Cr2O3 nanoparticles and their potent anti-bacterial, anti-oxidant and anti-inflammatory activities

Abstract

Green synthesis of nanoparticles has gained tremendous attention in recent era which is pertinent to their unique properties and broad applications. This approach is cost-effective, environment-friendly as well as highly biocompatible. In this research, chromium oxide nanoparticles (Cr2O3-NPs) were synthesized by using Apis mellifera honey as a reducing and capping agent and their anti-bacterial, anti-biofilm, anti-oxidant and anti-inflammatory abilities were explored. Ultra Violet-visible double beam spectroscopy revealed that chromium underwent d-d transition during synthesis of nanoparticles. X-ray diffraction (XRD) analysis verified that Cr2O3-NPs were crystalline in nature and average crystal size was 24 nm. Energy-dispersive X-ray (EDX) analysis confirmed that chromium and oxygen formed nano-composites in solution which possessed a stable form. Scanning electron microscopy (SEM) provided morphological characteristics of nanoparticles and proved that their average size was 20 nm. Cr2O3-NPs displayed excellent anti-bacterial activity (minimum inhibition zone, 20 mm; maximum inhibition zone, 26 mm) against 30 selected clinical isolates of Klebsiella pneumoniae as determined by agar well-diffusion method. Their antibacterial activity was considerably superior to that of three selected antibiotics including Gentamicin, Ciprofloxacin and Cefepime. However, no synergism was observed between nanoparticles and these antibiotics as calculated from fractional inhibitory concentration index (FICI) values all of which were > 1. The synthesized nanoparticles possessed good biofilm inhibition potential (60 % to 73 %) at all concentrations (20 µg/ml to 50 µg/ml) tested. Cr2O3-NPs exhibited excellent anti-oxidant activity (IC50 = 128 µg/ml) which was nearly equivalent to that of ascorbic acid. Anti-inflammatory effect of Cr2O3-NPs was also significant (IC50 = 549 µg/ml) and comparable to that of standard. Both anti-oxidant and anti-inflammatory capacities were found to increase with an increase in the concentration of Cr2O3-NPs. In conclusion, this work revealed that Apis mellifera honey-mediated synthesis of Cr2O3-NPs could be investigated for future biomedical applications.