Researchers at Zhengzhou University, China, have recently reported a simple immersion plating route for preparing a patterned silver structure on a silicon nanoporous pillar array (Si-NPA). As shown in the image, two kinds of silver structures were grown on Si-NPA. The first is a continuous film covering the Si-NPA substrate and composed of silver nanocrystallites, and the second is a quasi-regular, interconnected network of loop-chains of sub-micron silver crystallites.

To test the silver/Si-NPA design, the team used the active substrate to detect low concentrations of adenine solution and noted significantly enhanced Raman signals. Based on these spectra, the adsorption mode of adenine molecules on silver/Si-NPA was deduced. The strong SERS enhancement was attributed to the active spacing sites formed between the silver particles and the silver nanocrystallites, which were ideal for realizing a SERS effect.

Currently the team is using the silver/Si-NPA active substrate to study the SERS detection of Rhodamine 6G (R6G), an important biological colouring agent and adsorption indicator. The set-up is capable of detecting R6G solution concentrations lower than 10–15 M . In addition, the team plans to investigate the detection of different kinds of viruses or bacteria, for applications such as disease diagnosis.

The researchers reported their work in Nanotechnology.