International School of Photonics, Cochin University of Science and Technology, Cochin, Kerala, India.
International School of Photonics, Cochin University of Science and Technology, Cochin, Kerala, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 May 5;272:121011. doi: 10.1016/j.saa.2022.121011. Epub 2022 Feb 7.
Linear and nonlinear optical properties of near-infrared laser grade dye LDS 821 in different solvents and Salmon Deoxyribonucleic acid (DNA) were studied using spectroscopic and Z-scan techniques. UV-Vis absorption spectrum of the dye shows a bathochromic shift with a decrease in the solvent polarity parameter, and in DNA, the dye exhibits a hypochromic shift. The fluorescence spectrum of the dye does not show any notable correlation with the solvent polarity parameter, but in DNA, the fluorescence intensity of the dye decreases with the incremental addition of DNA. Molecular docking studies reveal that the dye intercalates on the major grooves of DNA. Nonlinear optical properties of the dye in different solvents and phosphate buffer solution with varying DNA concentrations were studied using the Z-scan technique using a Q-switched Nd: YAG laser operating at fundamental and second harmonics. A closed and open aperture Z-scan of dye in different solvents was carried out to estimate the nonlinear refractive index, excited-state absorption cross-section, and two-photon absorption coefficient (TPA). The variation in nonlinear optical properties of the dye in different solvents was due to solvent-induced structural modifications. Theoretical investigation on nonlinear optical properties of the dye in different solvents was carried out using density function theory. The theoretical first and second-order hyperpolarizability was calculated using B3LYP functional. The predicated nonlinear optical parameters of the dye in different solvents does not show any direct correlation with solvent polarity. Nonlinear absorption of the dye in phosphate buffer solution (PBS) and DNA were estimated. The nonlinear absorption of the dye in PBS decreases with the addition of DNA. Molecular docking studies were carried out to determine the structural changes induced in dye due to the intercalation with DNA.
采用光谱和 Z 扫描技术研究了近红外激光级染料 LDS 821 在不同溶剂和鲑鱼脱氧核糖核酸（DNA）中的线性和非线性光学性质。染料的紫外-可见吸收光谱显示出随着溶剂极性参数的降低而发生红移，而在 DNA 中，染料表现出减色效应。染料的荧光光谱与溶剂极性参数没有明显的相关性，但在 DNA 中，染料的荧光强度随着 DNA 的逐渐加入而降低。分子对接研究表明，染料在 DNA 的主沟中嵌入。采用 Q 开关 Nd：YAG 激光器在基频和二次谐波下，利用 Z 扫描技术研究了染料在不同溶剂和磷酸盐缓冲溶液中随着 DNA 浓度变化的非线性光学性质。在不同溶剂中进行了染料的闭合和开孔径 Z 扫描，以估计非线性折射率、激发态吸收截面和双光子吸收系数（TPA）。染料在不同溶剂中的非线性光学性质的变化是由于溶剂诱导的结构修饰所致。采用密度泛函理论对染料在不同溶剂中的非线性光学性质进行了理论研究。使用 B3LYP 函数计算了染料的理论一阶和二阶超极化率。不同溶剂中染料的预测非线性光学参数与溶剂极性没有直接关系。估计了染料在磷酸盐缓冲溶液（PBS）和 DNA 中的非线性吸收。染料在 PBS 中的非线性吸收随着 DNA 的加入而降低。进行了分子对接研究，以确定由于与 DNA 的嵌入而引起的染料结构变化。
