Immunoassays Based on Surface-Enhanced Infrared Absorption Spectroscopy

摘要

A new type of biosensor for pathogens has been developed. The sensor produces spectral fingerprints of biological systems by using surface-enhanced infrared absorption (SEIRA) spectroscopy. Antibodies were immobilized onto a lO-nm-thick Aim of gold which had been previously deposited on a Si wafer. SEIRA spectra of the antibodies measured in the external reflection mode exhibited two new bands at 1085 and 990 cm↑-1. These new bands were observed with p-polarized radiation but were absent with s-polarized radiation. The spectrum of water on the surface *of the sensor was observed under both directions of polarization, The sensor was first tested with a model system consisting of glucose oxidase (GOX) and the antibodies for glucose oxidase (anti-GOX). In addition to the bands due to the anti-GOX at 1085 and 990cm↑-1, new bands were observed at 1397, 1275, and 930 cm↑-1 when the GOX antigens were present. The same type of sensor wins prepared for Salmonella (SAL) by immobilizing antibodies for Salmonella (anti-SAL)on a gold-surfaced Si wafer. The SEIRA spectra for anti-SAL antibodies were very similar to those for anti-GOX, with bands at 1085 and 990 cm↑-l; however, a sharp new band was observed at 1045 cm↑-1 alter the sensor was exposed to the SAL antigens. In addition to specific new bands due to antigens, both GOX and SAL sensors exhibited changes in the regions of water absorptions at ~3500 and 850 cm↑-1 when the antigens were present.