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Silver, gold, and copper nanoparticles are an excellent platform for the manifold of applications not limited to sensing, biomedicine, and nanophotonics [1]. These metal nanostructures demonstrate the remarkable size and shape-determined optical properties related to localized surface plasmon resonance (LSPR) which appears as strong light scattering and/or absorption bands. Dense random ensembles of Ag and Au nanoparticles increase the light fields and are beneficial for surface-enhanced Raman spectroscopy (SERS). Light scattered by the subwavelength period regular arrays of nanoparticles on the surfaces can interact resonantly narrowing down the LSPR peaks into high-quality factor surface lattice resonances (SLR). Such structures are called metasurfaces and find numerous applications in optics and nanophotonics [2]. Different nanomaterial synthesis approaches are developed enabling control of the size, shape, structure, and surface quality of the nanomaterials [3,4]. In this work, silver, gold, and copper nanoparticle colloids were synthesized employing chemical or photophysical synthesis methods seeking applications in metasurface-based SERS substrates, lateral flow assays, and of antiviral surfaces. Nanoparticle colloids were chemically synthesized using the seed growth method or femtosecond laser ablated from pure metal targets employing Yb:KGW femtosecond laser Pharos (Light Conversion). The nanoparticle sizes were inspected with the field emission scanning electron microscope and transmission electron microscopes (FEI). Monodisperse nanoparticles were deposited into polymer replica templates using the capillarity-assisted particle assembly (CAPA) method. The optical density of the colloids and nanoparticle arrays were evaluated with the steady state (Avantes) and transient absorption (Light Conversion) spectrometers. Field enhancement of nanoparticle assemblies was investigated by a Raman spectrometer (Renishaw). Strongly absorbing silver, gold, and copper colloids of yellow, dark green, and pink color were synthesized. Multi-wavelength Raman measurements of SERS substrates with 532 nm matched SLR peak indicated strong signal enhancement for detection of the 2NT analyte molecule. In cooperation with UAB “Imunodiagnostika” the antibody functionalized gold nanoparticles were successfully used to detect SARS-CoV-2 nucleoprotein in lateral flow assay tests. Aerograph spray deposited copper nanoparticles on glass substrates demonstrated antiviral efficacy against BHV-1 and IBV. |
