Surface plasmon resonance biosensor based on water-soluble ZnO–Au nanocomposites

A wavelength modulation surface plasmon resonance biosensor based on ZnO–Au nanocomposites for the detection of human IgM was developed. Self-assembly technique has the advantages of flexibility, simplicity and the precise control of film component and was applied to the building of the sensor. The ZnO–Au nanocomposites are in a dumbbell-like shape and can be immobilized on the Au film through 1,6-hexanedithiol by covalent attachment. Meanwhile the activated ZnO nanocrystals can be used to connect protein. The biosensor based on ZnO–Au nanocomposites was used to detect human IgM. Some experimental conditions were examined and optimized. In the selected conditions, the modified biosensor exhibits a satisfactory response for human IgM in the concentration range of 0.30–20.00 μg mL−1. However, the biosensor without ZnO–Au nanocomposites shows a response for human IgM in the concentration range of 1.25–20.00 μg mL−1. Compared with the biosensor based on Au film, when the biosensor based on the ZnO–Au nanocomposites was applied, the sensitivity for determination of human IgM is significantly enhanced.