Enhancing sensitivity of surface plasmon resonance biosensor by Ag nanocubes/chitosan composite for the detection of...

A novel surface plasmon resonance (SPR) biosensor based on Ag nanocubes/chitosan composite was fabricated for mouse IgG detection. Ag nanocubes (AgNCs) were successfully synthesized with sulfide-mediated protocol. They were characterized with transmission electron microscopy (TEM) and UV-vis adsorption spectrum. AgNCs were etched by 3-Mercaptopropinic acid (MPA) and simply mixed with chitosan and glutaraldehyde. The Ag nanocubes/chitosan composite was deposited on Au film by the spin-coating. The electronic coupling between the AgNCs and the surface plasmon wave leads to the amplification of the SPR response, which results in the sensitivity enhancement of SPR biosensor. Moreover, antibody can be immobilized on Au film with aldehyde groups via Schiff alkali reaction. The traditional SPR biosensor based on MPA shows a response for mouse IgG in the concentration range of 2.50-40.00 μg mL(-1). The SPR biosensor based on AgNCs/chitosan composite shows a good response for mouse IgG in the concentration range of 0.60-40.00 μg mL(-1). The limit of quantification by the biosensor based on AgNCs/chitosan composite substrate is about 4 times lower than traditional biosensor, which has proved the SPR biosensor here proposed with more sensitivity and better performance than traditional SPR biosensor.