Facile and Low-Cost Fabrication of SiO2-Covered Au Nanoislands for Combined Plasmonic Enhanced Fluorescence Microscopy and SERS

Alejandro Vidal; Sergio Molina-Prados; Ana Cros; Núria Garro; Manuel Pérez-Martínez; Raquel Álvaro; Gadea Mata; Diego Megías; Pablo A Postigo

doi:10.3390/nano13192729

Facile and Low-Cost Fabrication of SiO₂-Covered Au Nanoislands for Combined Plasmonic Enhanced Fluorescence Microscopy and SERS

Nanomaterials (Basel). 2023 Oct 8;13(19):2729. doi: 10.3390/nano13192729.

Authors

Alejandro Vidal¹, Sergio Molina-Prados², Ana Cros³, Núria Garro³, Manuel Pérez-Martínez⁴, Raquel Álvaro¹, Gadea Mata⁴, Diego Megías⁴, Pablo A Postigo^{1

5}

Affiliations

¹ Instituto de Micro y Nanotecnología de Madrid (IMN-CSIC), Tres Cantos, 28760 Madrid, Spain.
² GROC-UJI, Institut de Noves Tecnologíes de la Imatge (INIT), Universitat Jamue I, 28760 Tres Cantos, Spain.
³ Institut de Ciència dels Materials (ICMUV), Universitat de València, 46071 Valencia, Spain.
⁴ Confocal Microscopy Unit, Centro Nacional de Investigaciones Oncológicas (CNIO-ISCIII), 28029 Madrid, Spain.
⁵ The Institute of Optics, University of Rochester, Rochester, New York, NY 14627, USA.

Abstract

An easy and low-cost way to fabricate monometallic Au nanoislands for plasmonic enhanced spectroscopy is presented. The method is based on direct thermal evaporation of Au on glass substrates to form nanoislands, with thicknesses between 2 and 15 nm, which are subsequently covered by a thin layer of silicon dioxide. We have used HR-SEM and AFM to characterize the nanoislands, and their optical transmission reveals strong plasmon resonances in the visible. The plasmonic performance of the fabricated substrates has been tested in fluorescence and Raman scattering measurements of two probe materials. Enhancement factors up to 1.8 and 9×10⁴ are reported for confocal fluorescence and Raman microscopies, respectively, which are comparable to others obtained by more elaborated fabrication procedures.

Keywords: Au nanoislands; confocal microscopy; fluorescent beads; localized surface plasmon resonance; nanoplasmonic waves; shell-isolated SERS; surface-enhanced Raman scattering.

Grants and funding

The results were obtained through funding from Spanish Ministerio de Ciencia, Innovación y Universidades (projects RTI2018-100773-B-C32 and RTC2019-007093-8), Comunidad de Madrid (project S2018/NMT-4291 TEC2SPACE), MINECO (project CSIC13-4E-1794), and EU (FEDER, FSE). Additional financial support is also acknowledged: Spanish MICINN/AEI under projects PID2019-104272RB-C53/AEI/10.13039/501100011033, PID2019-110927RB-I00/AEI/10.13039/501100011033, and PID2019-109641RB-I00; Generalitat Valenciana under project PROMETEO/2020/029; and the Advanced Materials programme, supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by Generalitat Valenciana; Grant MFA/2022/007. The authors are very grateful to the “Serveis Centrals d’Instrumentación Científica” of the Universities of València and Jaume I for the use of their facilities.