Non-thermal plasma-enabled one-step synthesis of polyethylene glycol-functionalized gold nanoparticles for antimicrobial biointerface applications.

This study presents a rapid, single-step synthesis of polyethylene glycol functionalized gold nanoparticles (PEG-AuNPs) using an atmospheric-pressure non-thermal plasma jet (NTPJ), without conventional chemical reducing agents or post-synthetic modification. Extensive plasma diagnostics through electrical, optical, and thermal characterizations revealed a strongly non-equilibrium environment with high electron density, moderate electron temperature, and rich in reactive oxygen and nitrogen species, which enabled simultaneous Au3 + reduction and PEG-assisted stabilization. Controlled NTPJ exposures and precursor conditions produce spherical PEG-AuNPs with an average diameter 25 ± 10 nm and good colloidal stability. Plasma treatment generates a chemical complex, acidic, and oxidative medium that regulates nanoparticle growth and surface chemistry. The resulting PEG-AuNPs exhibit enhanced antibacterial activity against Staphylococcus aureus, Shigella flexneri, and Hafnia alvei, likely due to their colloidal stability, PEG-surface-association, and effective interaction with bacterial membranes. PEG-surface-association further improves nanoparticle stability, reduces cytotoxicity and suppress biofilm formation. This energy-efficient plasma strategy enables precise structure-property control and provides a scalable pathway for the rational design of antibacterial nanomaterials.