Composition-Dependent SERS Responses of Structurally Related Dyes on Inkjet-Printed Paper Substrates with Gold and...

Inkjet-printed paper-based surface-enhanced Raman scattering (SERS) substrates incorporating gold triangular nanoprisms (AuTNPs) and silver triangular nanoprisms (AgTNPs) were prepared to investigate how nanoparticle composition influences the SERS response of structurally related dyes, crystal violet (CV) and malachite green (MG). AuTNPs and AgTNPs were synthesized, formulated into printable inks, and deposited side by side onto hydrophobized chromatography paper. Scanning electron microscopy (SEM) and optical characterization confirmed the preservation of nanoprism morphology after printing, while revealing superior spectral reproducibility and storage stability for AuTNP-based substrates compared to AgTNP-based ones. The SERS spectra of CV and MG exhibited composition-dependent vibrational fingerprints, with AuTNPs providing higher enhancement factors and inducing systematic shifts and relative intensity variations in characteristic Raman bands. Multivariate analysis based on artificial neural networks (ANNs) was applied to binary CV/MG mixtures, yielding mean prediction errors (MSE) of 0.080 for the training set and 0.106 for the validation set, with larger deviations associated with lower-enhancement regions. Overall, the results demonstrate that nanoprism composition plays a critical role in shaping SERS spectral features and that combining signals from different plasmonic nanostructures on a printed paper substrate enhances the spectroscopic discrimination and quantitative analysis of closely related molecular species.