Utilizing pillararenes as capping agents to stabilize copper nanoparticles for cost-effective and high-performance...

Gold, silver, and copper nanoparticles (CuNPs) exhibit strong localized surface plasmon resonance (LSPR) effects at specific sizes, which can amplify the Raman signals of adsorbed molecules. However, despite the cost-effectiveness of CuNPs, their applications in surface-enhanced Raman spectroscopy (SERS) are limited due to their susceptibility to surface oxidation and particle aggregation. In this study, three distinct capping agents-pillararenes, polyvinylpyrrolidone, and sodium citrate-were employed to enhance particle dispersion, improve stability, and protect the CuNPs from oxidation and degradation. The synthesized CuNPs were thoroughly characterized using UV-Vis absorption spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and Raman spectroscopy. Results revealed that CuNPs capped with pillararenes demonstrated superior SERS enhancement effects when using 4-aminothiophenol as the probe molecule, achieving an enhancement factor of 3.7 × 10⁵. Furthermore, pillararene-capped CuNPs exhibited a broader linear range in SERS quantitative detection applications. This proposed method offers a versatile and cost-effective SERS substrate compared to commercial gold and silver nanocolloids, positioning it as a promising candidate for a wide range of SERS applications.