Cannabis sativa-Mediated Synthesis of Copper-Doped Zinc Oxide Nanoparticles (Cu2O-ZnONPs), Characterisation and Biomedical Activity Assessment

Abstract

The escalating emergence of antibacterial resistance to most organic drugs by common pathogenic microbes necessitates the search for alternatives. Inorganic metal oxide nanoparticles have displayed in many studies their suitability as substitute treatments for organic antibiotic-resistant pathogens. The aim of this study was to biosynthesise Copper-doped ZnO nanocomposites (Cu2O-ZnONPs) mediated by the polyphenolic extracts of “wild’ Cannabis sativa. Upon legalization in many countries, cultivars of C. sativa L have gained interest and attention due to their uses in traditional medicinal practices. Their purported richness in polyphenolic compounds also make them good candidates to mediate in the bio reduction capping and stabilisation of biosynthesised nanocomposites. In this study we utilised wildly growing C. sativa as a mediator because wild plant species are reported to naturally possess more protective secondary metabolites due to increased environmental stresses and threats.  The C. sativa was qualitatively and quantitatively investigated for its secondary metabolites and compared to commercial cultivars prior to the biosynthesis. The biosynthesised nanoalloys were structurally characterised and the anti-inflammatory, antioxidant and antibacterial activity was investigated. Our results confirm the increased abundance of numerous secondary metabolites in hydroethanolic extracts of the aerial parts of the wild C. sativa compared to the artificially propagated cultivar. The lyophilised extracts of the wild C. sativa and the Cu2O-ZnONPs demonstrated high efficacy against microbes with zones of inhibition between 19 and 27mm at all tested concentrations. UV-Vis spectra identified the fabricated nanostructures as Cu2O-ZnONPs, Transmission electron microscopy confirmed the formation of both spherical and cubic nanostructures.  Dynamic light scattering estimated the average particle size to be 44nm. Our studies confirm that the wildly growing variety is medicinally superior to the domestic C. sativa specimen. We also concluded that highly potent, anti-bacterial, anti-inflammatory and antioxidant platforms combining synergistic Cu2O-ZnONPs and polyphenols can be biosynthesised using        C. sativa.