Biologically synthesized copper and zinc oxide nanoparticles for important biomolecules detection and antimicrobial applications

In the present study, we report CuO and ZnO nanoparticles (NPs) synthesized through biological route using Camellia japonica plant leaf extract and their efficiency detection of cysteine and dihydronicotinamide adenine dinucleotide (NADH) in addition to their antimicrobial properties. Changes in absorption peak intensity in the presence of cysteine or NADH was assessed by UV–vis spectrophotometry. The spectrometric detection limit for the cysteine and NADH was found to be 5 and 10 μM, respectively, for both CuO and ZnO NPs. Good linear relationships with R 2  = 0.9727 for CuO and 0.9862 for ZnO NPs were obtained when plotting the absorbance as a function of cysteine and NADH concentrations at 290 and 301 nm, respectively. The present metal oxide (CuO and ZnO) NPs sensors were found to be useful for the detection of two biomolecules; namely cysteine and NADH. Furthermore, the CuO and ZnO NPs were found to be highly effective against gram positive ( Streptococcus pneumoniae , Bacillus subtilis ) and gram negative ( Escherichia coli , Salmonella typhimurium ) bacterial pathogens as well as fungal strains of Aspergillus flavus, Aspergillus fumigates, Aspergillus niger and Candida albicans . A minimum inhibition concentration of 100 μg/mL was observed for both NPs against bacterial and fungal pathogens. Consequently, the present investigation offers an environmentally friendly approach to synthesize CuO and ZnO NPs for biomolecule detection as well as antimicrobial and antifungal applications.