Study On Surfactant-induced Compaction And Decompaction Of CtDNA Molecules With SERS Based On Nano-solid Substrate

DNA molecules compaction and decompaction is of great significance for the exploration of basic life processes and the research of biotechnology and biomedical,etc.Studying DNA molecules compaction and decompaction caused by various surfactants is helpful to understand biological processes in vitro such as DNA transcription and replication,and is also conducive to promoting the development of some technologies such as DNA extraction,DNA purification and gene therapy,etc.However,the detailed mechanism of DNA molecules compaction and decompaction caused by surfactants has not been fully solved so far and remains a challenging problem.The main work of this paper is summarized as follows:?1?A sort of novel solid substrate,Nano PAA-Zn Cl₂-AuLs,was prepared by self-assembly technology,and it was found that the substrate surface is rich in large-scale ordered nano-scale structures,such as nanogaps and nanotips;Using rhodamine 6G?R6G?as a probe molecule to evaluate its SERS performance,the experiment results showed that the minimum concentration detection limit on this substrate was as low as 10^-11 M,and its enhancement factor?EF?was as high as 9.18×10⁷,and the intensity deviation of SERS bands was less than 20%,that is,the nanoPAA-Zn Cl₂-AuLs substrate has the good SERS performance,such as high sensitivity and good repeatability and stability.?2?Based on the new solid substrate,surface-enhanced Raman scattering?SERS?technology was employed to investigate surfactant-induced compaction and decompaction of ctDNA molecules.Firstly,SERS spectra of calf thymus DNA?ctDNA?,cetyl trimethyl ammonium bromide?CTAB?and sodium dodecyl sulfate?SDS?with a concentration as low as 10^-9 M were collected,respectively;Then,SERS spectra of interactions between ctDNA molecules and surfactant molecules were collected,that is,SERS spectra of the ctDNA-CTAB composite and the ctDNA-CTAB-SDS composite;Next,the interactions between ctDNA molecules and surfactant molecules were analyzed by comparing the changes of SERS spectra,e.g.,disappearance,appearance and relative intensity change of SERS bands,the results showed that CTAB resulted in the compaction of DNA molecules while SDS induced the decompaction of ctDNA-CTAB complex;Moreover,the UV-Visible spectrophotometry?UV-Vis?was employed to demonstrate the compaction and decompaction of ctDNA molecules caused by surfactants;Lastly,based on the spatial structure of the acting molecules,the local binding modes between ctDNA molecules and surfactant molecules were expounded.This work is helpful for understanding biological processes such as DNA compaction and recombination within cells,and contribute to the development of gene therapy technology.