Single-Molecule Nonresonant Wide-Field Surface-Enhanced Raman Scattering from Ferroelectrically Defined Au Nanoparticle Microarrays

• Published in: ACS omega Vol. 3; no. 3; pp. 3165 - 3172
• Main Authors: Al-Shammari, Rusul M, Al-attar, Nebras, Manzo, Michele, Gallo, Katia, Rodriguez, Brian J, Rice, James H
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 31-03-2018
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.7b01285

Single-molecule detection by surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique that is of interest for the sensor development field. An important aspect of optimizing the materials used in SERS-based sensors is the ability to have a high density of “hot spots” that enhance the SERS sensitivity to the single-molecule level. Photodeposition of gold (Au) nanoparticles through electric-field-directed self-assembly on a periodically proton-exchanged lithium niobate (PPELN) substrate provides conditions to form well-ordered microscale features consisting of closely packed Au nanoparticles. The resulting Au nanoparticle microstructure arrays (microarrays) are plasmon-active and support nonresonant single-molecule SERS at ultralow concentrations (<10–9–10–13 M) with excitation power densities <1 × 10–3 W cm–2 using wide-field imaging. The microarrays offer excellent SERS reproducibility, with an intensity variation of <7.5% across the substrate. As most biomarkers and molecules do not support resonance enhancement, this work demonstrates that PPELN is a suitable template for high-sensitivity, nonresonant sensing applications.