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3Periodically spallated Ag film as a high-performing SERS substrate for biogenic amines detection
A. Pilnik1, E. Mitsai1*, A. Kuchmizhak1
1-Institute of Automation and Control Processes of the FEB RAS, 5 Radio St., 690041 Vladivostok, Russia
One of the important areas in modern society is quality control of food products. A common method of control is to determine the concentration of biogenic amines, which usually indicates the quality and freshness of the product. SERS spectroscopy methods are often used to detect biogenic amines, which require a large number of disposable substrates for every experiment. In this regard, there is a need for a method for fast, cheap, productive and chemically clean production of SERS substrates. The technology of metal films ablation with a pulsed fs-laser meets these criteria.
In this work, we used 500-nm Ag films deposited on glass by electron beam evaporation, that were modified by wide laser beam with a size of 12^0.6 ^m. This method allows for fast modification of the surface on a mm2-scale (Fig. 1a).
Fig. 1. (a) SEM image of periodically spallated Ag film. The inset shows close-up details of the morphology. (b) Raman spectrum of histamine (black line) and SERS spectra of histamine adsorbed on spallated Ag film (blue line). Both spectra have a signal accumulation time of 100 s.
The chemosensing performance of the spallated surfaces is demonstrated by SERS-detection of methanol solution of histamine at a concentration of 10-8 M. The substrate was immersed in a solution for an hour. Measurements were carried out after complete drying of the substrate with a CW laser (^=473 nm) that was focused by dry microscope objective (NA=0.9, 100*) with a resulting intensity of 1.33 mW/|im2.
Fig. 1b demonstrates typical SERS spectrum of histamine adsorbed on spallated Ag film with main peaks highlighted. Comparison of Raman and SERS spectra shows that molecular vibrational modes exhibit significant frequency shifts due to interaction with the Ag surface [1]. SERS bands associated with the characteristic vibrational modes of histamine observed at 692, 768, 810, 934, 1055, 1327 and 1401 cm-1 are attributed to C-C ring bending, ring A stretching coupled with bending CH2CH2NH2 group, outer ring A stretching, C-H in-plane torsion bending, C-H in-plane torsion bending coupled with N-H in-plane stretching and C-H in-plane bending, respectively [2]. Therefore, this quickly produced SERS-substrate demonstrates the possibility of detecting biological analytes at low concentrations found in food products or in biofluids, that can be a promising tool for the diagnosis of biogenic amines-related diseases.
This work was supported by the Russian Science Foundation (Grant No. 24-19-00541).
[1] W.C. Lin, T.R. Tsai, H.L. Huang, C.Y. Shiau, H.P. Chiang, SERS study of histamine by using silver film over nanosphere structure, Plasmonics, 7, 709-716, (2012).
[2] T. Zhang, G. Wang, J. Bao, C. Liu, W. Li, Z. Kong, X. Sun, J. Li, R. Lu, Fabrication of an Ag-based SERS nanotag for histamine quantitative detection, Talanta, 256, 124256, (2023).
