Single-Molecule Plasmonic Optical Trapping

Abstract

We develop a strategy to directly trap, investigate, and release single molecules (2 nm) in solution by using an adjustable plasmonic optical nanogap, which opens an avenue to manipulate single molecules and other objects in the size range of primary interest for physics, chemistry, and life and material sciences without the limitations of strong bonding group, ultra-high vacuum, and ultra-low temperature, and makes possible controllable single-molecule manipulation and investigation as well as bottom-up construction of nanodevices and molecular machines.

Electrochemical gating enhances nearfield trapping of single metalloprotein junctions

“…29 Furthermore, laser line tuning would open the route to optomechanical tweaking of EC-PBJ, for example, through achieving self-induced back action to additionally improve the efficiency of nearfield molecular traps. 32,70,71 Combined electrochemically gated nearfield effects…”

Combined quantum tunnelling and dielectrophoretic trapping for molecular analysis at ultra-low analyte concentrations

“…There is currently much to improve in terms of simplicity of fabrication and the possibility to operate in a standalone configuration, using conventional measurement instrumentation. Furthermore, detection largely relies on transport of the analytes by diffusion into the tunnelling junction and there is limited or no control over molecular transport 26 , 27 . This is compounded by the fact that confinement of an analyte in a tunnelling junction is entropically unfavourable, leading to low detection event throughput and the requirement for high analyte concentrations.…”

Nearfield trapping increases lifetime of single-molecule junction by one order of magnitude

“…A similar plasmon-supported increase in single-molecule junction probability has been recently reported by Zhan et al who were able to tune the capturing and releasing of molecules in a nearfield-gap in solution during pulling captures between two electrodes. 36 The single-molecule conductance, on the other hand, is independent of the absence or presence of the nearfield at the investigated laser powers (see Figure S9 and Table S5; detailed analysis in Note S6). The electron transmission eigenchannel of BDT is dominated by the highest occupied molecular orbital (HOMO) level that is located about 2 eV below the Fermi level of Au.…”