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Single-entity electrochemistry is of fundamental importance and shows promise for ultrasensitive biosensing applications. Recently, we have demonstrated that various charged nanoparticles can be detected individually based on the non-redox open-circuit potential (OCP) changes induced by their collision events on a floating carbon nanoelectrode (CNE). Unlike the widely used amperometry approach, the potentiometric method provides the label-free detection of individual nanoscale entities without redox mediators in the solution. However, the CNE lacks specificity for molecular recognition during the collision events because of the limited methods of surface functionalization for carbon surfaces. Herein, we used surface-functionalized gold nanoelectrode (GNE) to overcome this limitation of CNE. The GNE modified with Raman reporter molecule also enabled surface-enhanced Raman spectroscopy (SERS) measurements. By using simultaneous time-resolved OCP and SERS measurements, both the OCP and SERS signals induced by the “hit-n-run” type of gold nanoparticle (GNP) collision events can be better understood. Also, by introducing a zwitterionic molecule, we formed near “stealth” surface and demonstrated that the non-specific adsorptions of GNPs to the surface of GNE have been suppressed, allowing continuous detection of hit-n-run events for over 30 min.
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Monitoring the Dynamic Process of Formation of Plasmonic Molecular Junctions during Single Nanoparticle Collisions
Abstract The capability to study the dynamic formation of plasmonic molecular junction is of fundamental importance, and it will provide new insights into molecular electronics/plasmonics, single‐entity electrochemistry, and nanooptoelectronics. Here, a facile method to form plasmonic molecular junctions is reported by utilizing single gold nanoparticle (NP) collision events at a highly curved gold nanoelectrode modified with a self‐assembled monolayer. By using time‐resolved electrochemical current measurement and surface‐enhanced Raman scattering spectroscopy, the current changes and the evolution of interfacial chemical bonding are successfully observed in the newly formed molecular tunnel junctions during and after the gold NP “hit‐n‐stay” and “hit‐n‐run” collision events. The results lead to an in‐depth understanding of the single NP motion and the associated molecular level changes during the formation of the plasmonic molecular junctions in a single NP collision event. This method also provides a new platform to study molecular changes at the single molecule level during electron transport in a dynamic molecular tunnel junction.
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- Award ID(s):
- 1647837
- PAR ID:
- 10053959
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Small
- Volume:
- 14
- Issue:
- 15
- ISSN:
- 1613-6810
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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