Synthesis and characterization of bovine serum albumin–copper nanocomposites for antibacterial applications

A method for the synthesis of bovine serum albumin (BSA) and copper (Cu0) nanocomposites is described. The synthesis is achieved by adding [100 mM] hydrazine hydrate ((N2H4·H2O) to [10 mM] copper sulfate (CuSO4·5H2O) solution in the presence of 0.02% bovine serum albumin at pH-10.0 and then heating the reaction mixture at 50 °C for 3 h. The process resulted into the formation of well-dispersed hexagonal Cu-BSA composite particles (size 5 ±2.5) μm consisting of embedded copper nanoparticles (Cu NPs). The nanoparticles embedded in composite were of average diameters of 28 ± 12 nm. Phase analysis, purity and morphology of the product have been studied by various physical techniques. Effect of various reaction parameters have been investigated on the morphology of synthesized nanocomposite. Efforts have been made to investigate the possible mechanism of Cu-BSA composite synthesis which gave it unique hexagonal morphology. The important characteristic of the reported method is that the highly stable Cu NPs present in composite were synthesized without any inert atmosphere which could be dried under vacuum and stored for long term use. The synthesized Cu NPs containing BSA composite material exhibited good antibacterial potential against both Gram positive and Gram negative bacterial strains. The minimum inhibitory concentration (MIC) of Cu NPs in the form Cu-BSA composite on Escherichia coli was calculated to be 50 μg mL−1. Transmission electron microscopic and cytoplasmic leakage analysis revealed that Cu-BSA composite attached to the bacteria causing irreversible membrane damage leading to leakage of intracellular metabolites and eventually death of the organism.