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目的应用荧光猝灭法研究镉离子(Cd2+)与人血清白蛋白(HSA)之间的结合特征及机理,确认荧光猝灭法定量检测镉离子浓度的可行性。方法采用荧光猝灭法测定4种温度(25℃、31℃、37℃、41℃)时、不同镉离子浓度下HSA的荧光猝灭情况,然后根据Stern-Volmer方程描述HSA的荧光强度与Cd2+的浓度、反应体系温度之间的作用规律以及作用参数,并推理Cd2+对HSA荧光的猝灭机理。结果固定HSA的浓度为1×10-5mol/L,Cd2+(浓度为0.67×10-3mol/L~4.67×10-3mol/L)对HSA的荧光猝灭程度随Cd2+浓度的增加而加大,并呈良好的线性关系(r≥0.999 00),而且在4种温度中,随着温度的增加,猝灭常数越来越小。结论 Cd2+对HSA荧光的猝灭机理为静态猝灭,且在一定条件下有规律地猝灭,所以可以运用荧光猝灭法定量检测镉离子的浓度。
Objective To investigate the binding characteristics and mechanism of cadmium (Cd 2+) and human serum albumin (HSA) by fluorescence quenching and to confirm the feasibility of quantitative detection of cadmium by fluorescence quenching. Methods Fluorescence quenching was used to determine the fluorescence quenching of HSA at different concentrations of cadmium at four different temperature (25 ℃, 31 ℃, 37 ℃, 41 ℃). Then the fluorescence intensity of HSA was compared with that of Cd2 + , The action law between the temperature of the reaction system and the action parameters, and deduced the quenching mechanism of fluorescence of HSA by Cd2 +. Results Fluorescence quenching of HSA with 1 × 10-5mol / L HSA and Cd2 + (0.67 × 10-3mol / L ~ 4.67 × 10-3mol / L) increased with the increase of Cd2 + concentration. And showed a good linear relationship (r≥0.99900), and at four temperatures, the quenching constant became smaller with the increase of temperature. Conclusions The fluorescence quenching mechanism of HSA by Cd2 + is static quenching and quenching regularly under certain conditions, so the concentration of Cd2 + can be detected quantitatively by fluorescence quenching.