SERS performance of cubic-shaped gold nanoparticles for environmental monitoring

초록

A subtle change in the geometry of nanoparticles affects the local electromagnetic field distribution and intensity of the analytes under optical excitation, which leads to distinguished enhancement effects on Raman signals. We report covalently modified gold-aryl nanocubes (AuNCs) for surface-enhanced Raman scattering (SERS). We performed transmission electron microscopy studies to investigate the morphology of AuNCs and UV-visible and Raman spectroscopy studies to understand their optical properties. Dynamic light scattering measurements, zeta-potential analyses, and contact angle measurements were performed to understand particle size distribution, surface charge, and wettability of the substrate. We obtained a high SERS enhancement (10(8)) for AuNCs using 10(-6) M rhodamine 6G (R6G, organic dye pollutant) as an analyte. AuNCs interact with the incoming electromagnetic wave, and due to the presence of multiple sharp corners ( "hot spots "), there is a large enhancement of the electromagnetic field allowing the detection of 10(-11) M R6G. The relative standard deviations were obtained within 5.8% for 10(-6) M R6G, indicating excellent uniformity. Moreover, a wide linear range of 10(-3)-10(-6) M was obtained for the detection of 4-nitrophenol (4-NPh, a high-priority toxic pollutant). These results indicate that highly SERS-active AuNCs could be successfully used for monitoring environmental contamination.

키워드