Simultaneous SERS detection using hexagonal hollow Au-Ag nanoparticles with near infrared plasmon

• Published in: Vibrational spectroscopy 2021-05, Vol.114, p.103233, Article 103233
• Main Authors: Rekha, C.R., Jiji, S.G., Nayar, V.U., Gopchandran, K.G.
• Format: Article
• Language: English
• Subjects: Hexagonal silver nanoparticles; Hollow Au-Ag hexagonal silver nanostructures; Loading plots; Near infrared plasmons; PCA analysis; Score plots; Surface enhanced Raman scattering
• ISSN: 0924-2031; 1873-3697
• DOI: 10.1016/j.vibspec.2021.103233

[Display omitted] •Synthesis of hollow Au-Ag nanostructures using galvanic replacement.•SERS measurements with three different types of probe molecules and their mixtures.•Principal component analysis of SERS spectra.•Associating principal components with Raman shifts using score and loading plots.•Substrates for multiplexed SERS sensing suitable for biomedical applications. Hexagonal hollow Au-Ag nanostructures were synthesized using galvanic replacement mechanism with silver nanoparticles as sacrificial templates. The cavity dimension in the hollow structures was found to be dependent on the amount of HAuCl4 used. X-ray photoelectron spectroscopy was used to understand the replacement mechanism took place between Ag and Au and Ag: Au ratio was found to be 88.80:11.20 in the optimum case. The surface enhanced Raman scattering (SERS) activity of these hollow nanostructures has been investigated using three probe molecules viz., crystal violet (CV), malachite green (MG) and nile blue chloride (NBC) under two laser excitation sources viz., visible (514.4 nm) and near infrared (784.8 nm). The multivariate analysis of the SERS spectra obtained with different probe molecules was done using principal component analysis (PCA). The SERS spectral data collected were transformed orthogonally to a lower dimension and the spectral information containing maximum variance of the original data was represented as principal components in the new dimension. It was found that the first two principal components represented significant spectral information, and the percentages of variance obtained were 63.43 and 32.22 %, respectively. Segregations of the probe molecules were evident in the score plots drawn in the transformed dimension. The correlation between Raman shifts in the SERS spectra and the principal components was obtained from loading plots. The results suggest that Au-Ag hollow nanostructures can be used as a reliable substrate for multiplexed SERS detection in various applications.