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

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 × 10 5 . 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.