新型“内标”式双重荧光自组装膜的制备和DNA的界面传感

为了有效降低依据单一荧光强度定量分析的误差, 充分发挥自组装膜设计灵活、制备简单且分析灵敏度高的优点, 提高荧光定量分析的准确度和灵敏度, 本文提出构建“内标”式自组装膜, 即于硅烷化石英表面分别组装吖啶橙(AO)和量子点CdTe. 以AO为内标, CdTe为荧光探针, 通过静电吸引作用于AO和CdTe之间, 依次组装聚苯乙烯磺酸钠(PSS)和壳聚糖(CS). PSS和CS的组装有效地“屏蔽”了AO, 使其荧光强度I1不随分析物种浓度的引入而变化, 这样既可发挥荧光内标作用, 又使膜外层量子点CdTe的荧光强度I2随分析物种浓度的改变而改变. 所构建的自组装膜双重荧光强度比I2/I1不随激发光强度的波动和传感器位置的移动等微环境变化而变化, 但与被分析物种的浓度呈良好的线性关系, 从而实现了直接利用I2/I1准确定量的“内标”式荧光分析, 显著提高了荧光分析的准确度.

Preparation of Novel Dual Fluorescent Self-assembled Multilayer Film Bearing a Fluorescent Internal Standard for Interfacial Sensing

In this paper we described the construction of a novel dual fluorescent film sensor using fluorescent dye Acridine Orange(AO) as an internal standard and CdTe as a fluorescent probe. Poly-sodium-4-styrenesulfonate(PSS) and Chitosan(CS) were respectively assembled between AO and CdTe. The constructed selfassembly multilayers, Quartz/APES/PSS/AO/PSS/CS/CdTe, emits dual fluorescence at 600 and 530 nm, respectively. AO is shielded effectively by the assembled PSS and CS and thus its fluorescent intensity I1 doesn’t change with the variation of the analyte concentration, thereby acting as an internal standard to provide reference signal. The ratio of dual fluorescence intensities of the thus constructed film sensor is not affected by the variations of the external environment factors such as excitation intensity and sensor position in the cell holder. A good linear relationship was found between dual fluorescence intensity ratio and DNA concentration over 0—250 ng/L. Quartz/APES/PSS/AO/PSS/CS/CdTe film is capable of an extremely highly sensitive detection for DNA with a detection limit of 6.6 ng/L. The analysis based on dual fluorescent self-assembled multilayers bearing a fluorescent internal standard would greatly improve the detection accuracy.