Enhancement of polyvinylpyrrolidone on antimicrobial activity and mechanism of Copper(II)-β-cyclodextrin

Abstract

Copper-based materials are a cheap and efficient antibacterial agent that has received much attention for centuries. Copper(II)-β-cyclodextrin (Cu2-β-CD) can be applied at pH values in the range of 5.0–9.0, and its antibacterial effect remains unchanged. Herein, the antimicrobial activity of Cu2-β-CD were evaluated including the inhibition zone diameter, the minimum inhibitory concentration and the minimum bactericide concentration towards Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans). Interestingly, the antimicrobial activity of Cu2-β-CD was remarkably improved by adding polyvinylpyrrolidone (PVP), and the antimicrobial rates were increased from 96%, 62%, and 29% with single Cu2-β-CD to 100%, 100%, and 84% with Cu2-β-CD incorporated with 0.1 wt% PVP against E. coli, S. aureus, and C. albicans, respectively, whereas PVP had almost no antimicrobial effect. In addition, cell membrane integrity and cell wall integrity were severely destroyed by Cu2-β-CD/PVP according to the results of the permeability assay of cell membrane, the leakage assay of nucleic acids, protein and alkaline phosphatase, and scanning electron microscopy. Hence, this work presented a novel prospective and broad-spectrum antimicrobial system consisting of Cu2-β-CD and PVP.