Structural and optical sensing properties of nonthermal atmospheric plasma‐synthesized polyethylene glycol‐functionalized gold nanoparticles

Abstract

Polyethylene glycol‐functionalized gold nanoparticles (Au@PEG NPs) were prepared by a simple plasma‐assisted method without additional reducing chemicals. After irradiating tetra-chloroauric acid (HAuCl4) and polyethylene glycol (PEG) in aqueous medium with an argon plasma jet, the gold precursor transformed into an Au@PEG NP colloid that exhibited surface plasma resonance at 530 nm. When the plasma jet entered the water, additional reactive species were induced through interactions between plasma‐generated reactive species and aqueous media. Interaction of the gold precursor with the plasma‐activated medium allowed the synthesis of gold nanoparticles (AuNPs) without reductants. The plasma‐synthesized Au@PEG NPs had a quasi‐spherical shape with an average particle diameter of 32.5 nm. The addition of PEG not only helped to stabilize the AuNPs but also increased the number of AuNPs. Au@PEG NP‐loaded paper (AuNP‐paper) was able to detect the degradation of rhodamine B, therefore, indicating that AuNP‐paper can act as a surface‐enhanced Raman scattering platform. Dye degradation by plasma treatment was investi-gated by optical absorption and Raman spectroscopy. The method proposed for the fabrication of Au@PEG NPs is rapid, low‐cost, and environment‐friendly and will facilitate the application of plasma‐synthesized nanomaterials in sensors.