Sensitivity enhancement and application of surface plasmon resonance biosensors using nanostructures and nanoparticles

Abstract

Surface plasmon resonance (SPR) has been applied to biosensing applications due to its intriguing characteristics arising from surface-selective detection of optical indices. Among researches in this field, enhancing sensitivity has received much interest in terms of application of SPR biosensors to molecular detection of DNAs and proteins. Conventional SPR biosensor can detect 1 pg/mm 2 of typical biochemical molecules, which corresponds to 6 × 10 7 molecules per square millimeter, assuming small molecules with 10 kDa. Thus, enhancing sensitivity and subsequently improving the detection limit is the key to achieving inexpensive and efficient molecular detection apparatus.This study suggests a hybrid mode for sensitivity enhancement scheme combining plasmonic enhancement via nanoparticles and localized surface plasmon effect obtained with surface relief nanostructure. Namely, use of gold nanoparticles (GNPs) and gold@silica core-shell nanoparticles (CSNPs) served as index contrast, while employment of localized surface plasmon (LSP) nanograting contributed to boost signal per unit index change. The hybrid sensing scheme demonstrated 18 to 36 times enhanced detection sensitivity for DNA hybridization monitoring, respectively for GNPs and CSNP conjugation.Enhanced sensitivity suggests capability of femto-scale measurements of biomolecular interactions on LSP nanostructures, and potential application to high throughput screening in drug discovery and medical researches promises retrenchment of vast cost.