An on-chip localized surface plasmon resonance-based biosensor for label-free monitoring of antigen–antibody reaction

The unique localized surface plasmon resonance (LSPR) property of gold nanoparticles has been used to design a label-free biosensor in a chip format. In this research, a sensitive and low-cost microfluidic integrated LSPR-based biosensor is developed. The gold nanoparticles were synthesized in solution and immobilized on quartz substrates by a silane layer as molecular glue. The gold nanoparticle-coated substrate was further integrated with a microfluidic chip. An automated sample introduction system was developed to perform a variety of processes including sample loading, chip washing and sample change. A refractive index resolution of 1 × 10−4 RIU (refractive index unit) was demonstrated by using the on-chip biosensor combined with the automated sampling system. This developed microfluidic integrated system is capable of transporting a specific amount of bio-samples into the sensing chambers to achieve sensitive and specific biosensing with decreased reaction time and less reagent consuming. Proof-of-concept detection of antigen/antibody (biotin/anti-biotin) binding was performed and was quantitatively detected.