Zinc oxide-coated plasmonic chip modified with a bispecific antibody for sensitive detection of a fluorescent labeled-antigen

A plasmonic biosensor chip of silver-coated PMMA grating with a zinc oxide (ZnO) overlayer is fabricated for surface plasmon field-enhanced fluorescence (SPF) detection of Cy5-labeled green fluorescent protein (GFP). A bispecific antibody (anti-GFP x anti-ZnO antibody) prepared in our lab is densely immobilized on the sensor chip for GFP detection. The sensitivity of the plasmonic biosensors is improved due to densely packed antibodies and ZnO-coating that suppresses nonspecific protein adsorption and fluorescent quenching. With the ZnO-coated plasmonic chip, Cy5-labeled GFP of 10 pM can be detected through SPF. This sensitivity is 100 higher compared with the normal fluorescent detection on a ZnO-coated glass slide.