Enhanced wavelength modulation SPR biosensor based on gold nanorods for immunoglobulin detection.

In this study, gold nanorods (GNRs) and graphene oxide (GO) were used to enhance the sensitivity of wavelength modulation surface plasmon resonance (SPR) biosensor to detect bovine IgG. GNRs were prepared by a method of seed-mediated growth and immobilized on the Au film through 1,6-hexanedithiol by covalent attachment. GO was prepared by a modified Hummers and Offeman's method and can be assembled on the sensor surface through electrostatic interaction with GNRs. Meanwhile, GO was used as a support to immobilize antibody directly. The biosensor based on GNRs/GO sensing membrane exhibits a satisfactory response for bovine IgG in the concentration range of 0.075-40.00 µg mL(-1). For comparison, the biosensor based on 3-mercaptopropinic acid (MPA) and the biosensor based on GNRs/MPA sensing membrane were also studied for the detection of bovine IgG. The biosensor based on MPA shows a response for bovine IgG in the concentration range of 2.50-40.00 µg mL(-1). The biosensor based on GNRs/MPA sensing membrane shows a response for bovine IgG in the concentration range of 0.30-40.00 µg mL(-1). As a result, the biosensor based on GNRs/GO sensing membrane was found to be the most sensitive of the three types of biosensors.