Dual Functions of Highly Potent Graphene Derivative–Poly‑l‑Lysine Composites To Inhibit Bacteria and Support Human Cells

Dual-function poly(l-lysine) (PLL) composites that function as antibacterial agents and promote the growth of human cell culture have been sought by researchers for a long period. In this paper, we report the preparation of new graphene derivative–PLL composites via electrostatic interactions and covalent bonding between graphene derivatives and PLL. The resulting composites were characterized by infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The novel dual function of PLL composites, specifically antibacterial activity and biocompatibility with human cells [human adipose-derived stem cells and non-small-cell lung carcinoma cells (A549)], was carefully investigated. Graphene–DS–PLL composites composed of 4-carboxylic acid benzene diazonium salt (DS) generated more anionic carboxylic acid groups to bind to cationic PLLs, forming the most potent antibacterial agent among PLL and PLL composites with high biocompatibility with human cell culture. This dual functionality can be used to inhibit bacterial growth while enhancing human cell growth.