次甲基蓝与DNA作用的共振光散射光谱研究及机理分析

The investigation of resonance light scattering spectra and interaction mechanism between deoxyribonucleic acid and methylene blue

基于脱氧核糖核酸（DNA）在pH 3.51-4.49的介质中对有机染料次甲基蓝（MB）的共振光散射的增强效应,提出了一种测定DNA的共振光散射法,并对介质酸度、离子强度、DNA热变性、共存物质干扰等实验条件进行了优化.在最佳条件下绘制了工作曲线,该方法线性范围为0-1 440 ng·mL^-1,检出限可达14.1ng·mL^-1,用于合成样品中DNA的测定,结果令人满意.通过研究红外光谱、紫外-可见吸收光谱及离子强度的影响,初步探讨了MB与DNA相互作用的机理,MB可能是通过静电作用等以DNA为模板在DNA分子表面进行聚集和长距组装,这种聚集导致MB共振光散射信号的增强,这也是该方法的理论基础.

A detection assay is proposed based on the enhancement of resonance light scattering（RLS） signal of methylene blue（MB） by DNA in the pH range of 3.51～4.49.The effects of pH,ionic strength,denatured ctDNA and coexisting substances on the RLS enhancement were discussed,respectively.The intensity of RLS signal is proportional to the concentration of DNA in the range from 0 to 1 440 ng·mL^-1 with the determination limit（3σ） of 14.1 ng·mL^-1.This novel method has been applied to the assay for three synthetic samples with satisfactory results.Infra-red and uv-vis spectra are used to study the interaction mechanism.The long range assembly of MB on the molecular surfaces of DNA occurred with electrostatic interaction,which results in enhanced resonance light scattering（RLS） signals.