Plasmon Near-Field Coupling in Metal Dimers as a Step toward Single-Molecule Sensing

• Published in: ACS nano Vol. 3; no. 5; pp. 1231 - 1237
• Main Authors: Aćimović, Srdjan S, Kreuzer, Mark P, González, María U, Quidant, Romain
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 26-05-2009
• Subjects: Biosensing Techniques - instrumentation; Crystallization - methods; Dimerization; Equipment Design; Equipment Failure Analysis; Gold - chemistry; Macromolecular Substances - chemistry; Molecular Conformation; Molecular Probe Techniques - instrumentation; Nanostructures - chemistry; Nanostructures - ultrastructure; Nanotechnology - instrumentation; Particle Size; Protein Array Analysis - instrumentation; Surface Plasmon Resonance - instrumentation; Surface Properties; gold dimers; protein detection; e-beam lithography; small organic molecule; localized surface plasmon; near-field coupling
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn900102j

In this study, we report on ultrasensitive protein detection with lithographically prepared plasmonic nanostructures. We have engineered optical nanosensors by the combined approach of negative resist, electron beam lithography, and reactive ion etching to form highly reproducible arrays of gold dimers in which the near-field coupling in their subwavelength gap enables for scaling the sensing volume down to the single-protein scale. In good agreement with recent theoretical predictions, the dimer geometry offers enhanced sensitivity compared to isolated particles for the detection of both small organic molecules and proteins. Beyond, by exploiting size exclusion, we are capable of monitoring the number of proteins able to bind across the gap region through the precise engineering of the structures coupled to the selective binding of a surface-assembled monolayer and covalent attachment of the protein.