The Variety of Substrates for Surface-enhanced Raman Spectroscopy

Abstract

Surface-enhanced Raman spectroscopy (SERS) is a widespread and powerful technique for analytic detection in various fields (pharmaceuticals, forensics, agronomy, biomedicine...). Therefore, today there is an increased demand for the development of stable, sensitive, reproducible and portable SERS-active substrates. Some of the most broadly used SERS substrates are noble metal colloids. During the preparation of colloidal suspensions, the size and shape of the particles can be well controlled. However, the use of colloids for SERS has some disadvantages, like problems with reproducibility and stability. Other popular types of substrates are rough or nanoporous surfaces, such as the substrates obtained by coating the porous silicon with noble metals. Porous silicon (PSi) is a semiconducting material fabricated by electrochemical etching in hydrofluoric acid (HF). Porous materials have high surface-to-volume ratios and are therefore interesting materials for photonic and sensing devices, drug delivery systems and for use in SERS. The third type of substrates to discuss in this article are noble metal films evaporated on the monolayer of polystyrene spheres (PS). The polystyrene spheres are drop-coated on hydrophilic glass substrates in order to form a self-assembled 2D monolayer. In this paper, we present the SERS substrates produced by different synthesis methods. It was possible to detect low concentration of SERS probe molecules on thus prepared substrates.