Label-free nanobiosensor to detect infectious bacterica based on SERS.

Bacteria detection has been important in food, water and air industry to detect contamination or infection. However, conversational bacteria detection method such as culture collection is time-consuming and complicated. In this study, Surface Enhanced Raman Scattering (SERS), one of the most convenient and reliable biosensing techniques, was applied to detect bacteria such as e. coli. First, gold nanoparticles were deposited on Indium Tin Oxide (ITO) substrate by using electrochemical method and confirmed by Scanning Electron Microscope and Ultraviolet-Visible spectroscopy. After antibody against e. coli was immobilized on the gold nanoparticles fabricated on ITO substrate, e. coli samples with different concentrations were applied to the system by antibody-antigen interaction. Then, e. coli was detected by using SERS spectroscopy, demonstrating that the SERS peak intensity at certain raman shift were good relationship with the concentration. In conclusion, this technique could be applied to the biosensor or biochip such as raw milk chip.