Abstract
Polyethylene glycol-functionalized gold nanoparticles (Au@PEG NPs) were prepared by a simple plasma-assisted method without additional reducing chemicals. After irradiating tetrachloroauric 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 investigated 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.
Highlights
Published: 25 June 2021Metal nanoparticles are used in various applications, such as optical sensing, bioimaging, drug delivery, and photothermal therapy
200–1000 nm; strong emission lines indicate the presence of plasma-generated reactive species
To study the optical sensing activity ofRhodamine plasma-synthesized gold nanoparticles, we investigated theoptical effect sensing of plasma treatment on rhodamine B (RhB)
Summary
Metal nanoparticles are used in various applications, such as optical sensing, bioimaging, drug delivery, and photothermal therapy. Nanomaterials 2021, 11, 1678 substances contain large amounts of hydroxyl and phenol groups that reduce Au ions [12] These non-hazardous substances are weak reducing agents, resulting in longer processing times compared with that of chemical synthesis [13]. The non-thermal plasma synthesis of metal nanostructures is an alternative green synthesis approach that has substantial advantages compared to chemical synthesis [14,15,16,17] This method uses non-thermal atmospheric pressure plasmas under ambient conditions and produces large amounts of reactive oxygen and nitrogen species, excited metastable species, free electrons, and charged particles [18]. For Raman spectroscopic measurements of plasma-treated RhB, AuNP-loaded paper was used as a SERS platform (Figure 1)
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