Improved antimicrobial and anticancer potential of eco-friendly synthesized Co-doped Bi2O3/RGO nanocomposites

Bismuth oxide nanoparticles (Bi2O3 NPs) is now getting vast attention for biomedical research because of its tailorable physicochemical properties. There is limited information on the biological activity of green synthe-sized Bi2O3-based nanocomposites (NCs). Here, we explored the antimicrobial and anticancer efficacy of green synthesized cobalt-doped Bi2O3/reduced graphene oxide (Co-Bi2O3/RGO) NCs applying an extract of garlic (Allium sativum L.). Several active phytochemicals present in garlic extract acted as reducing and capping agents for the synthesis of NCs of Co-Bi2O3/RGO. Our objective was to limit the usage of environmentally hazardous substances and augment the antimicrobial and anticancer efficacy of Co-Bi2O3/RGO NCs without causing side effects in non-cancerous normal cells. Green synthesized pure Bi2O3 NPs and Co-Bi2O3/RGO NCs were char-acterized by XRD, TEM, SEM, EDS, PL, DLS, and zeta potential. Prepared pure Bi2O3 NPs and Co-Bi2O3/RGO NCs exhibited strong antimicrobial activity for several bacterial strains (e.g. Bacillus subtilis, Staphylococcus epi-dermidis, Escherichia coli, and Pseudomonas aeruginosa), and fungal pathogens (e.g. Candida albicans and Candida krusei). Moreover, Co-Bi2O3/RGO NCs showed significantly enhanced microbicidal activity than Bi2O3 NPs. It was further observed that the anticancer efficacy of Co-Bi2O3/RGO NCs in human hepatocellular carcinoma (HepG2) and lung adenocarcinoma (A549) was about 2.5 times higher than that of Bi2O3 NPs. Mechanistic data suggested that oxidative stress and caspase-3 were plausible pathways of Co-Bi2O3/RGO NCs-mediated cancer cell death. Co-Bi2O3/RGO NCs displayed better biocompatibility toward primary rat hepatocytes and normal lung fibroblasts (IMR90) than pure Bi2O3 NPs. Improved antimicrobial and anticancer efficacy along with excellent biocompatibility indicate garlic constituents mediated excellent synergism of Bi2O3, Co, and RGO in Co-Bi2O3/RGO NCs. This study underlines the importance of facile and cost-effective medicinal plant-based synthesis of novel nanocomposites for biomedical applications.