Inkjet Printing of Ag and Polystyrene Nanoparticle Emulsions for the One-Step Fabrication of Hydrophobic Paper-Based Surface-Enhanced Raman Scattering Substrates

authors	Martins, NCT; Fateixa, S; Fernandes, T; Nogueira, HIS; Trindade, T
nationality	International
journal	ACS APPLIED NANO MATERIALS
author keywords	SERS; hydrophobic surfaces; paper sensors; metal nanoparticles; pesticides
keywords	FILTER-PAPER; SILVER-NANOPARTICLES; SERS PLATFORM; PESTICIDES; NANOSTRUCTURES; SPECTROSCOPY; NANOSTARS; RESIDUES; SENSORS; FRUIT
abstract	Hydrophobic substrates for surface-enhanced Raman scattering (SERS) of adsorbate species are of great interest in chemical analysis because they can concentrate the analyte molecules in a small area of the surface, thereby improving the SERS sensitivity. Here, we propose a general strategy to fabricate hydrophobic paper-based substrates for SERS applications. The paper substrates have been manufactured by inkjet printing of aqueous emulsions containing Ag and polystyrene (PS) colloidal nanoparticles. In a first stage, the SERS performance of the substrates was optimized by varying the relative amounts of polymer/metal colloidal nanoparticles, the number of printing layers, and the degree of hydrophobicity of the substrates, using crystal violet as a molecular probe, which is well known for its strong SERS activity. In these conditions, the strongest surface Raman enhancement was observed for the highest water contact angle (146 degrees) achieved. The selected Ag/PS-coated paper substrates showed wide applicability for several analytes, but in this study, a detailed analysis is provided for the pesticide thiram as a proof of concept. Several samples spiked with thiram have been analyzed by SERS, giving a detection limit of 0.024 ppm thiram in mineral water and apple juice, while in apple peel, the detection limit achieved for the same pesticide was 600 ng/cm(2). We suggest that this one-step fabrication method produces a hydrophobic coating whose nanoscale features improve the SERS performance of the paper substrates.
publisher	AMER CHEMICAL SOC
isbn	2574-0970
year published	2021
volume	4
issue	5
beginning page	4484
ending page	4495
digital object identifier (doi)	10.1021/acsanm.1c00112
web of science category	12
subject category	Nanoscience & Nanotechnology; Materials Science, Multidisciplinary
unique article identifier	WOS:000657373800022