Biogenic fabrication of CuNPs,Cu bioconjugates and in vitro assessment of antimicrobial and antioxidant activity

In the present study, the authors synthesised copper nanoparticles (CuNPs) by using extract of Zingiber officinale (ginger) and later the NPs were bioconjugated with nisin, which shows antimicrobial activity against food spoilage microorganisms. CuNPs and its bioconjugate were characterised by ultraviolet–vis spectroscopy, NP tracking analysis, Zetasizer, transmission electron microscopy analysis, X‐ray diffraction and Fourier transform infra‐red (FTIR) spectroscopy. Zeta potential of CuNPs and its bioconjugate were found to be very stable. They evaluated in vitro efficacy of CuNPs and its bioconjugate against selected food spoilage bacteria: namely, Staphylococcus aureus, Pseudomonas fluorescens, Listeria monocytogenes and fungi including Fusarium moniliforme and Aspergillus niger. Antimicrobial activity of CuNPs was found to be maximum against F. moniliforme (18 mm) and the least activity was noted against L. monocytogenes (13 mm). Antioxidant activity of CuNPs and ginger extract was performed by various methods such as total antioxidant capacity reducing power assay, 1‐1‐diphenyl‐2‐picryl‐hydrazyl free radical scavenging assay and hydrogen peroxide assay. Antioxidant activity of CuNPs was higher as compared with ginger extract. Hence, CuNPs and its bioconjugate can be used against food spoilage microorganisms.Inspec keywords: antibacterial activity, biomedical materials, copper, nanoparticles, nanofabrication, nanomedicine, microorganisms, ultraviolet spectra, visible spectra, electrokinetic effects, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectra, free radical reactions, food technologyOther keywords: biogenic fabrication, Cu bioconjugates, in vitro assessment, antimicrobial activity, antioxidant activity, copper nanoparticles, Zingiber officinale, ultraviolet‐visible spectroscopy, NP tracking analysis, Zetasizer, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, FTIR, zeta‐potential, food spoilage bacteria, Staphylococcus aureus, Pseudomonas fluorescens, Listeria monocytogenes, fungi, Fusarium moniliforme, Aspergillus niger, F. moniliforme, L. monocytogenes, ginger extract, total antioxidant capacity, power assay, 1‐1‐diphenyl‐2‐picryl‐hydrazyl free radical scavenging assay, hydrogen peroxide assay, food spoilage microorganisms, Cu