Abstract

We present a Raman and surface-enhanced Raman scattering (SERS) study of the following proteins containing S–S group(s): α chymotrypsin (α-CHT), insulin, lysozyme, oxytocin (OXT),<i> Streptomyces</i> subtilisin inhibitor (SSI), and trypsin inhibitor (STI). The SERS study is performed in order to understand the adsorption mechanism of the above-mentioned proteins on a colloidal silver surface. The SERS spectra presented here show bands associated mainly with aromatic amino acid vibrations. In addition, two distinct vibrations of the –C–S–S–C– fragment are observed in the Raman and SERS spectra, i.e., ν(SS) and ν(CS). The enhancement of the ν(SS) vibration in the SERS spectra yields evidence that the intact disulfide bridge(s) is (are) located near the silver surface. This finding is supported by the presence of the ν(CS) mode(s). The presence of ν_s(COO^–) and ν(C–COO^–) in the SERS spectra in the 1384–1399 cm^–1 and 909–939 cm^–1 regions, respectively, indicate that the negatively charged COO^– groups (aspartic and glutamic acids) assist in the binding on the positively charged silver surface. The Raman amide I and III bands observed in the 1621–1633 and 1261–1289 cm^–1 ranges, respectively, indicate that the α-helical conformation is favored for binding to the surface over the random coil or β-sheet conformations. In addition, the presence of the imino group of Trp and/or His indicates that these amino acid residues may also bind to the silver sol.

Analysis of SARS-CoV-2 spike RBD binding to ACE2 and its inhibition by fungal cohaerin C using surface enhanced Raman spectroscopy

Christoph Wetzel, Linda Jansen-Olliges, Marc Stadler, Frank Surup, Carsten Zeilinger, and Bernhard Roth
Biomed. Opt. Express 14(8) 4097-4111 (2023)

Label free hepatitis B detection based on serum derivative surface enhanced Raman spectroscopy combined with multivariate analysis

Yudong Lu, Yisheng Lin, Zuci Zheng, Xiaoqiong Tang, Jinyong Lin, Xiujie Liu, Mengmeng Liu, Guannan Chen, Sufang Qiu, Ting Zhou, Yao Lin, and Shangyuan Feng
Biomed. Opt. Express 9(10) 4755-4766 (2018)

Surface enhanced Raman scattering (SERS) of citrate ion adsorbed on colloidal silver

M. Kerker, O. Siiman, L. A. Bumm, and D.-S. Wang
Appl. Opt. 19(19) 3253-3255 (1980)

Colorectal cancer detection by gold nanoparticle based surface-enhanced Raman spectroscopy of blood serum and statistical analysis

Duo Lin, Shangyuan Feng, Jianji Pan, Yanping Chen, Juqiang Lin, Guannan Chen, Shusen Xie, Haishan Zeng, and Rong Chen
Opt. Express 19(14) 13565-13577 (2011)

Identification of late-life depression and mild cognitive impairment via serum surface-enhanced Raman spectroscopy and multivariate statistical analysis

Denghui Yan, Changchun Xiong, Qingshan Zhong, Yudong Yao, Shuo Chen, Xi Mei, and Shanshan Zhu
Biomed. Opt. Express 14(6) 2920-2933 (2023)