Light‐Driven, Phase‐Locked Protein Pumping Through a Single Plasmonic Optofluidic Nanopore

Abstract

ABSTRACT Dynamic protein transport through solid‐state nanopores is fundamentally limited at low analyte concentrations by thick electrical double layers (EDLs) and weak electrophoretic forces. Here, a light‐driven, phase‐locked protein pumping mechanism is demonstrated through a ∼20 nm plasmonic nanopore embedded in an ultrathin (In x Ga 1‐x ) 2 O 3 membrane and decorated with self‐assembled Ag nanodomains. Under 488–530 nm excitation, broadband plasmonic resonances (2.3–3.4 eV) generate intense near‐fields and hot‐carrier surface charging, increasing the interfacial EDL capacitance to ∼220 µF·cm − 2 and lowering the protein entry barrier from ∼20 to <3 kBT. A combined static‐dynamic fluorescence reconstruction approach resolves field‐directed transport of FITC‐labeled bovine serum albumin beyond the diffraction limit. Optical maps reveal a concentration‐dependent transition from Brownian diffusion to a vertically extended photo‐EDL conduction column that funnels proteins toward the nanopore. Simultaneous fluorescence‐ionic measurements identify an electro‐optic resonance within the 5–20 Hz modulation window, producing ∼10× fluorescence enhancement under pulsed excitation. The optical pumping event rate increases from ∼0.5–1 to ∼4–5 s − 1 , while the cis‐trans phase delay decreases from ∼450 to <10 ms. These results establish plasmonic nanopores as programmable optofluidic pumps for dynamic, light‐controlled single‐molecule protein transport.