Raman spectra and SERS studies of several carboxyl biomolecules

Surface enhanced Raman scattering (SERS) effect refers to the phenomenon that the absorbed Raman scattering signal is much stronger than the ordinary Raman scattering signal on the surface or sol of some specially prepared metal conductors. Because of its high detection sensitivity, high resolution, small water interference, fluorescence quenching, good stability and suitability for studying interfaces, it is widely used in surface research, adsorbent surface state research, interface orientation and configuration, biomacromolecule conformation research and structure analysis. In this paper, several biomolecules with carboxyl structure were studied by Raman spectroscopy and SERS. , including several protein amino acids, DNA, anticancer drugs and shikimic acid. According to SERS selection law and action mechanism, the action mode and adsorption state of several biomolecules with carboxyl structure on the surfaces of silver particles and gold/silver core-shell composite particles and their changes at different concentrations of pH value were speculated. In addition, Raman spectra were used to study the vibration of corresponding groups in the complexes of several protein amino acids with nonafluorene methoxycarbonyl (Fmoc). 1. The Raman spectra of leucine, isoleucine and valine and their SELLS spectra on the surface of gold/silver core-shell composite nanoparticles were obtained by studying the Fourier transform Raman spectra and SERS. Based on the characteristics of gold/silver core-shell composite particle substrate and SERS mechanism, the different modes of action and adsorption of three branched amino acids on the substrate surface were discussed. The experimental results show that the different SERS of branched amino acids and their different adsorption states on the surface of gold/silver core-shell composite particles are mainly caused by the different vibration modes of the corresponding branched methyl groups in the molecule. However, carboxyl groups obviously interact with gold and silver composite particles in all three molecular structures. Due to the uniformity and high SERS enhancement factor of gold/silver core-shell composite particles, especially at different concentrations and pH values, the SERS and adsorption differences of the three molecules on their surfaces are more prominent. 2.SERS study on the interaction between anticancer drugs and DNA, three anticancer drugs with carboxyl or carboxyl variant structure were selected as probes and studied. The Raman peak was assigned, and the interaction between three anticancer drugs and DNA on the surface of silver particles and its influence changes were studied by comparison. 3.SERS, which provided a meaningful reference for the screening of anticancer drugs in vitro. SERS of three amino acids on the surface of silver particles were obtained, and the adsorption states of three cyclic amino acids, especially the vibrational peaks and adsorption differences of carboxyl groups in molecular structure, were inferred by combining SERS mechanism. Finally, the different interaction modes of amino acids with silver colloid and the effects of different concentrations and pH values on the adsorption state were discussed. At present, it is the only synthetic raw material of Tamiflu, which has been proved to be effective in treating H5N 1 highly pathogenic avian influenza. Shikimic acid also has many other biological properties, such as anti-inflammatory and analgesic effects. The molecular structure of shikimic acid is that one carboxyl group and three hydroxyl groups are substituted in the cyclohexene ring structure. In this paper, the Raman spectra of shikimic acid are measured, and the group disturbance corresponding to each peak position is inferred. At the same time, the adsorption state of shikimic acid on the surface of silver particles, especially the adsorption mechanism of carboxyl groups and the effects of concentration and pH value were investigated, which provided a very useful reference for further study on the role of shikimic acid in the synthesis and development of new drugs and its interaction mechanism with substrates. 5. FT-Raman spectra of molecular complexes of Fmoc- amino acids with leucine, isoleucine, methionine, phenylalanine and valine were obtained, and their characteristic vibration peaks were analyzed. Thus, the vibration model of each special group in the compound of Fmoc- group and five amino acid molecules, especially the vibration of carboxyl group, is deduced, which provides a reference for further study of biomolecules such as amino acids.