Development of label-free optical diagnosis for sensitive detection of influenza virus with genetically engineered fusion protein

An active immobilization method utilizing the metal-binding property was developed and examined for its ability to facilitate the biosensing of avian influenza virus. The special biosensing performance with optical plasmonic analysis, including surface plasmon resonance (SPR) was evaluated on gold substrate and also by SPR imaging (SPRi) and localized SPR (LSPR) system where antigen–antibody interaction occurs. A complete optical analytical system was developed by integrating microarray and fabricating nanoparticles onto a single glass chip, thus allowing specific and sensitive diagnosis with subsequent binding. Reaction condition for the maximum reactivity was optimized by SPR analysis and more sensitive interaction was performed by SPRi analysis. Furthermore, ultra-sensitive detection was successfully developed up to the target molecules of 1 pg mL−1 by LSPR analysis. The advanced phase-in of enhanced plasmonic sensing system allows more efficient and sensitive detection by switching fabrication processes, which were prepared on the gold surface using the nanoparticles. This inflow contains the gold binding polypeptide (GBP)–fusion protein, which was expressed in recombinant Escherichia coli cells, was bound onto the gold substrates by means of specific interaction. The GBP–fusion method allows immobilization of proteins in bioactive forms onto the gold surface without surface modification suitable for studying antigen–antibody interaction. It was used for the detection of influenza virus, an infectious viral disease, as an example case.