Effect of electrical discharge plasma on cytotoxicity against cancer cells of N,O-carboxymethyl chitosan-stabilized gold nanoparticles

[Display omitted] •N,O-carboxymethyl chitosan effectively stabilized gold nanoparticles (CMC-AuNPs).•CMC-AuNPs were treated by electrical discharge plasma (plasma-treated CMC-AuNPs).•Plasma-treated CMC-AuNPs had smaller hydrodynamic sizes and less aggregation of AuNPs.•Plasma-treated CMC-AuNPs had cytotoxic effect on MCF-7, HeLa, and H460 cancer cells.•Plasma-treated CMC-AuNPs caused apoptotic cell death of cancer cells. Electrical discharge plasma in a liquid phase can generate reactive species, e.g. hydroxyl radical, leading to rapid reactions including degradation of biopolymers. In this study, the effect of plasma treatment time on physical properties and cytotoxicity against cancer cells of N,O-carboxymethyl chitosan-stabilized gold nanoparticles (CMC-AuNPs) was investigated. AuNPs were synthesized by chemical reduction of HAuCl4 in 2 % CMC solution to obtain CMC-AuNPs, before being subjected to the plasma treatment. Results showed that the plasma treatment not only led to the reduction of hydrodynamic diameters of CMC-AuNPs from 400 nm to less than 100 nm by the plasma-induced degradation of CMC but also provided the narrow size distribution of AuNPs having diameters in the range of 2–50 nm, that were existing in CMC-AuNPs. In addition, the plasma-treated CMC-AuNPs could significantly reduce the percentage of cell viability of breast cancer cells by approximately 80 % compared to the original CMC and CMC-AuNPs.