Detection of DNA molecules by SERS spectroscopy with silvered porous silicon as an active substrate

Here we report the SERS spectroscopy study of the herring sperm DNA adsorbed on the silvered porous silicon. Porous silicon has been fabricated by an electrochemical anodic etching of a highly doped n-type silicon wafer. It has been shown that the following silver immersion deposition on porous silicon lead to the formation of a layer of silver nano-and microparticles assembled in a quasi-ordered array. Reflectance spectroscopy has revealed that the silver layer demonstrates the surface plasmon resonance band expanded to near-IR range. Preliminary SERS measurements with rhodamine 6G have showed that the silvered porous silicon is characterized by a very good reproducibility of the SERS signal and one-year shelf life. It has been found that the silvered porous silicon is SERS-active in relation to the herring sperm DNA under the excitation at 473, 633 and 785 nm. Collection of the SERS spectra of the DNA molecules in the random points of the silvered porous silicon has resulted in their weak reproducibility typical for the solid SERS substrates. However, the SERS mapping has helped to find the classical DNA spectra. In addition, the herring sperm DNA at an extremely low concentration of 1 mg mL(-1) has been detected with the SERS substrate based on the silvered porous silicon. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim