SERS detection of protein biochip fabricated by etching polystyrene template

In this study, a nanoscale protein chip is prepared by using an etched polystyrene (PS) template. This protein chip can be directly used for immunoassay, with the help of Surface Enhanced Raman Scattering (SERS) spectra. Some glass slides submerged in aldehyde is initially prepared, modified with antibodies, human immunoglobulin G (IgG). Then PS arrays are self-assembled on these slides with the Langmuir-Blodgett method. The PS template pattern is transferred to the human IgG substrate using an etching process-slides are exposed to O(2) plasma for 90s. The PS nanoparticles are then washed away using phosphate buffered saline solution. Next, the slides are dipped into bovine serum albumin solution to ensure that the anti IgG would bond only to the human IgG. At this moment, a patterned protein chip is obtained. When used for protein detection, the protein chip could be immersed into labeled specificity antigen solution. Here we chose fluorescein isothiocyanate anti-human IgG. After washing, only bonded antigens remain. Fluorescence microscopy and SERS is used to characterize the samples. The SERS spectra intensity shows liner correlation with the concentration of anti-human IgG. All the experiments are conducted in a phosphate buffered saline solution at 37°C for 2 h.