A novel surface plasmon resonance biosensor based on graphene oxide decorated with gold nanorod-antibody conjugates for determination of transferrin.

A surface plasmon resonance (SPR) biosensor based on graphene oxide (GO) decorated with gold nanorod (AuNR)-antibody conjugates was developed. Compared with traditional SPR biosensor, GO sheets were assembled on the amino-modified Au film via electrostatic interaction, and then AuNR-antibody conjugates were immobilized via carbodiimide-assisted amidation reaction. The abundant oxygen-containing functional groups, large specific surface area and friendly biocompatibility of GO sheets are beneficial to the immobilization of AuNR-antibody conjugates. Meanwhile, AuNRs are anchored to the GO surface through antibody and function as enhancers for the transferrin determination, which greatly enhance the sensitivity of the detection. As a result, the present biosensor shows a satisfactory response to transferrin in the concentration range of 0.0375-40.00 μg mL(-1). The lowest concentration of transferrin that can be determined by this method is about 32-fold lower than that obtained with the sensor based on Au film. This design affords a facile method of controlling the assembly of AuNRs on the GO sheets and can be easily extended to other protein detection by preparing corresponding AuNR-antibody conjugates.