Three-dimensional inverted-cone PDA-Ag nanoparticles array with highly-sensitive SERS performance

Abstract

Surface-enhanced Raman scattering (SERS) technology can realize ultra-sensitive quantitative analysis and detection of analytes, but how to simply prepare SERS active substrates with high sensitivity and high uniformity is still a huge challenge. Herein, we take advantage of the characteristic that dopamine can form polydopamine (PDA) coating on the surface of complex shape, the uniform and ordered V-shaped AAO template was modified by PDA. Then, the modified AAO template was immersed in AgNO3 solution, and the reduction of Ag+ by PDA and the uniformity of AAO template were utilized to make the Ag nanoparticles (AgNPs) uniformly reduced and grow into the V-shaped AAO template holes. In addition, the reduction growth of AgNPs on AAO template was accelerated by irradiation with 365 nm UV light, and the size and gap of AgNPs could be regulated by illumination time, thus obtaining a highly efficient, uniform and ordered 3D inverted-cone nano-cascade structure that could be regulated. The R6G molecule was selected to measure its sensitivity and homogeneity, relative standard deviation (RSD) value of Raman intensity at 1354 cm−1 mode of R6G molecules (with concentration of 10−6 M) was 3.85%, indicating homogeneity and good near-field enhancement of AAO-PDA-Ag substrate. This paper provides a simple, low-cost, popular and stable preparation method of SERS substrate, which provides a practical example for further improving the sensitivity of SERS technology.