| As two important biological substrates,proteins and nucleic acids play key roles in biological systems.Scientists have developed various techniques to study its structure and function,among which surface-enhanced Raman spectroscopy（SERS）is widely used in the detection of nucleic acids,proteins and other biomolecules.However,it remains a challenge to obtain unlabeled,sensitive,and reproducible SERS signals while maintaining the native structure of nucleic acids,proteins.Therefore,in this paper,two detection methods were developed to detect the molecular structure of proteins and nucleic acids respectively.The specific contents are as follows:（1）Detection of Protein Molecular Structure Using SERS SpectroscopyIn this study,dichloromethane（DCM）and calcium ions were used to optimize the aggregation state of silver nanoparticles,and the protein was analyzed comprehensively.Calcium ions removed citrate ions from the surface of silver nanoparticles inducing hot spots and achieving high-sensitivity SERS signals of proteins.Furthermore,we used this method to analyze 20 random samples of 0.5μg/m L hemoglobin.The obtained spectra showed good repeatability and a high signal-to-noise ratio.Using the peak intensity of DCM as internal parameter,we analyzed differences in peak intensities at the same position to distinguish different proteins and to evaluate changes in protein structure.Subsequently,we quantified the protein content in protein mixtures and serum and obtained a good linear relationship between peak intensity and protein concentration.This method shows great promise in the fields of food testing and clinical diagnosis.（2）Detection of ribonucleic acid molecular structure by SERS spectroscopy miRNA plays a vital role in many biological processes by regulating the expression of target genes and is considered to be a promising disease biomarker.Herein,titanium ions were used as aggregating agents to induce the aggregation of silver nanoparticles,forming hot spots,and the fingerprint information of miRNAs was successfully obtained.This method was used to determine the RNA sequence of homopolymeric bases and peak position of each base in the Raman spectrum.The obtained RNA spectrum was normalized with the signal intensity of ribose at 959 cm-1 and the base contents of a series of mature miRNA sequences were quantified.Subsequently,by studying the process of RNA hairpin structure formation,the characteristic SERS signal of the RNA hybridization event was obtained,and the role of precursor mir-21 to regulate the target streptomycin sulfate was successfully analyzed.The changes in the SERS signal intensity at the interaction site were accurately identified.This method has potential applications in biological functions of miRNAs,molecular diagnosis,disease treatment,and targeted drug design. |
