基于硫代黄素T诱导G-四联体构成的生物传感器检测铅离子

硫代黄素T(ThT)荧光分子在自由状态下荧光强度很弱,通过在Tris-HCl缓冲液中加入Pb²⁺的适配体即富含G的DNA序列,可与ThT荧光分子形成G-四联体结构,使荧光信号迅速增强;向溶液中加入Pb²⁺,Pb²⁺与其适配体有很好的结合特异性,可生成更牢固的G-四联体结构,使ThT分子被释放出来,导致溶液的荧光强度降低,基于此可检测溶液中的Pb²⁺离子.实验中优化了缓冲溶液组成、ThT荧光分子浓度、Pb²⁺适配体浓度及反应时间等条件.结果表明,在10 mmol/L Tris-HCl(pH=8. 3,含2 mmol/L MgCl₂)缓冲溶液中,ThT荧光分子和Pb²⁺适配体的浓度分别为10μmol/L和200 nmol/L,反应10 min时,随着溶液中Pb2+浓度的增加,荧光强度减弱.Pb²⁺浓度在20～1000 nmol/L范围内时,荧光强度与Pb²⁺的浓度呈现良好的线性关系(R^...

Highly Sensitive Sensor for Lead Ion Based on Thioflavin T-induced G-quadruplex Formation †

The simple and rapid Pb²⁺ detection method is constructed by using a fluorescent aptasensor that is based on G-quadruplex formation in Tris-HCl buffer solution. In the absence of Pb²⁺, the Thioflavin T (ThT) dye binds to the G-rich Pb²⁺ aptamer and forms a Pb²⁺ aptamer/ThT G-quadruplex complex, which results in high fluorescence intensity. Upon addition of Pb²⁺, the Pb²⁺ aptamer/ThT complex will be replaced by the formation of a Pb²⁺ aptamer/Pb²⁺ complex and the fluorescence intensity of the solution decreases dramatically.The experimental conditions such as the buffer solution, the concentration of ThT fluorescent molecules, the concentration of Pb²⁺ aptamer, and the reaction time were optimized. When the concentrations of ThT fluorescent molecules and Pb²⁺ aptamers were 10 μmol/L and 200 nmol/L, respectively, the fluorescence intensity decreased with the increase of Pb ²⁺ concentration in 10 mmol/L Tris-HCl(pH=8.3, containing 2 mmol/L MgCl₂) buffer solution. When the concentration of Pb²⁺ was in the range of 20—1000 nmol/L, there was a good linear relationship between the fluorescence intensity and the concentration of Pb²⁺(R²=0.9941), and this fluorescence aptasensor was highly sensitive and rapid, with a detection limit of 1 nmol/L and a total reaction time of only 10 min. Furthermore, this method is cost-effective and simple, removing the requirement for labeling the detection reagents with a fluorophore-quencher pair.