Rapid and sensitive detection of Candida mannan related to the immune system with a plasmonic sensor chip

Abstract

To establish a rapid evaluation method for Candida mannan in the saliva, which is a marker molecule of immunity, we develop a fluorescent immunosensor enhanced with grating-coupled surface plasmon resonance using a plasmonic chip i.e., a metal-coated substrate with a wavelength-sized periodic structure. A two-dimensional hole-array chip with two kinds of pitches of 495 nm × 475 nm is used for fluorescence enhancement. The capture antibody is immobilized to the aminated chip surface via a crosslinker with succinimide at both ends, and a stable capture interface is constructed by covalent bonding. Finally, Candida mannan in the standard solution is measured up to 0.1 ng ml−1. Furthermore, in saliva samples, Candida mannan is quantitatively detected between 0.05 and 0.25 ng ml−1, and the highly sensitive detection with the Candida mannan assay system is indicated.