High-sensitivity biosensors fabricated by tailoring the localized surface plasmon resonance property of core-shell gold nanorods.

An enhanced sensitive biosensor has been developed to detect biological targets by tailoring the localized surface plasmon resonance property of core-shell gold nanorods. In this new concept, a shell layer is produced on gold nanorods by generating a layer of chalcogenide on the gold nanorod surface after attachment of the recognition reagent, namely, goat IgG and antigen of schistosomiasis japonica. The bioactivity of these attached biomolecules is retained and the sensitivity of this biosensor is thus enhanced significantly. The plasmonic properties of the gold nanorods attached with the biomolecules can be adjusted and the plasmon resonance wavelength can be red-shifted up to several hundred nanometers in the visible or near infrared (NIR) region, which is extremely important to biosensing applications. This leads to a lager red-shift in the localized surface plasmon resonance absorption compared to the original gold nanorod-based sensor and hence offers greatly enhanced sensitivity in the detection of schistosomiasis japonica. The human serum infected with schistosomiasis japonica diluted to 1:50,000 (volume ratio, serum/buffer solution) can be detected readily. The technique offers enhanced sensitivity and can be easily extended to other sensing applications based on not only immuno-recognition but also other types of specific reactions.