The Raman Spectroscopic Of DNA Molecules

Deoxyribose DNA is the carrier of genetic information.Since the discovery of its double helix structure in 1953, the research in DNA becomme deeper and deeper. Many reports about Raman spectra of DNA which study by high-sensitivity Raman spectroscopy,emerged at home and abroad. In recent decades, lot of literature reported Raman spectra of DNA on variety surface-enhanced Raman scattering substrate.Surface-enhanced Raman scattering(SERS) can provide rich information about the structure of molecular and a strong SERS Raman signal which due to the electromagnetic fields enhancement and the chemical enhancement.The total enhancement factor is about103-1014,when the chemical enhancement factor is about 10-100,so the electromagnetic fields enhancement dominants. electromagnetic fields enhancement due to the interaction between the incident electric field and the electronic from metal surfaces,which causes surface plasmon collective resonance.The largest SERS enhancement, also single-molecule SERS, often appears in the fractal space between aggregated metal nanoparticles. Brus et al. pointed out that the the active sites possibly located at the junction between two or more silver nanoparticles. In their work, they found that enhancement of isolated nanoparticles is litte,while large enhancement was found for aggregates with multiple particles. This is due to huge electromagnetic field which cause by plasmon coupling between closely nanoparticles. Based on these aggregates silver particles or gold particles are likely to form an effective and reliable SERS substrate. Silver particles with stable and intense enhancement is generally used as a surface-enhanced Raman scattering substrate. The most common used silver colloid are produced either by reduction of silver nitrate with sodium citrate, which is called Lee-Meisel method, or by reduction of silver nitrate with sodium borohydride, which is base on Creighton process. The main content of this paper:1.The silver colloid preparation and testing .First, according to Creighton method, silver nitrate colloid is prepared by reduction of silver nitrate using sodium borohydride.Then added alcohol adenine to cause silver colloid aggregate. UV Spectrophotometer and atomic force microscopy were used to observe their absorption spectra and surface morphology.2.Rhodamine B (RhB), rhodamine 6G (R6G) were ofen used as a probe molecule for the detection of surface-enhanced Raman scattering of the substrate which formed by aggregates silver colloid which cause by added alcohol or adenine.Experiment shows that"active site"in the aggregates silver colloid that added adenine was more active than that of induced by alcohol.3.Deprived of DNA Raman spectra on SERS substrates which formed by aggregates silver colloid that caused by adenine.