Bio-capped multifunctional CuO nanoparticles via Knautia arvensis for dye removal, antibacterial and antifungal efficiency, and molecular docking

Abstract

Copper oxide nanoparticles (CuONPs) synthesized using Knautia arvensis flower extract in an environmentally friendly and one-step procedure were characterized by UV–vis, FT-IR, SEM and DLS. The in vitro antibacterial and antifungal activities of CuONPs were determined using E. coli, S. aureus and A. niger. In silico antibacterial and antifungal evaluation of CuONPs were performed by molecular docking analysis using chitin deacetylase of A. niger, topoisomerase IV of E. coli and tyrosyl-tRNA synthetase of S. aureus. The best binding energy was determined using these microbial targets in molecular docking analyses and the antimicrobial mechanisms between the microorganism and the CuONP were elucidated. The degradation potential of Remazol brilliant blue R (RBBR) and Napthol blue black (NBB) dyes in the presence of CuONPs were investigated. The peak obtained at 289 nm as a result of UV–vis analysis revealed the presence of CuONPs. The spherical morphology of CuONPs and the particle size varying between 88–289 nm were visualized by SEM. DLS analysis pointed out the mean diameter of CuONPs was 189 nm along with the PDI value of 0.324. The 600 and 595 cm−1 vibrations attained in the FT-IR spectroscopy showed the presence of CuONPs. In addition, the presence of phenolic compounds found in the plant extract responsible for bio-capping of copper ions into CuONPs were enlightened by the FT-IR analysis. Dye degradation activity of CuONPs was found as 69% and 71% using NBB and RBBR at 50 °C in 90 min, respectively. Antifungal and antibacterial interactions of CuONPs with chitin deacetylase of A. niger, topoisomerase IV of E. coli and tyrosyl-tRNA synthetase of S. aureus were analyzed in order to reveal the antimicrobial mechanisms of CuONPs and it was found that CuONPs demonstrate significant interactions with those proteins with binding energies −7.25, −7.14 and −7.89 kcal mol−1, respectively.