Fig. 1. Specialized applications for metal nanoplasmonic sensors.

a Real-time label-free plasmonic detection of single-molecule binding events. Wide-field imaging of hundreds of single gold nanorods enables multiplex single-molecule sensing. Reprinted from ref. ¹⁷ with permission. b Plasmonic gold nanorods coupled to a whispering gallery mode resonator were used to monitor DNA/polymerase interactions. Reprinted from ref. ¹⁸ with permission. c Lipid nanovesicles localized inside gold nanohole plasmonic sensors can be used for studying membrane-mediated biorecognition events. Reprinted from ref. ¹¹ with permission. d Nanohole arrays can be used as nanofluidic channels. In this “flow-through” sensing scheme, the response time can be improved compared with the conventional “flow-over” approach. Adapted from ref. ²⁰ with permission. e Gold nanohole array plasmonic sensor is integrated with microfluidics for in situ detection of cell-secreted molecules. f Electron micrograph of a single cell attached to the gold nanohole array. g Sideview schematic of the system. h Measured binding kinetics of cytokines secreted from a single cell inside a microfluidic chamber. Reprinted from ref. ¹⁵ with permission.