中文摘要：

以Pb2＋和S-腺苷甲硫氨酸（S-Adenosylmethionine,SAM）与聚3-（1-（2-三乙胺乙酰基）哌啶-4-亚甲基）噻吩（poly 3-{[1-（2-hydrazino-2-oxoethyl）piperidin-4-ylidene]methyl}thiophene,PMTH）构建荧光开关,当有Pb2＋存在时,PMTH与Pb2＋之间发生作用,荧光猝灭,即为荧光＂关＂;当Pb2＋-PMTH体系中加入SAM时,SAM能够与Pb2＋形成更稳定的配合物,使PMTH的荧光恢复,即为荧光＂开＂。通过PMTH的荧光开关信号,成功建立了识别和检测SAM的新方法。研究了在水-乙醇（4∶1,V/V）溶液中Pb2＋和PMTH与SAM相互作用对荧光光谱的影响。本方法具有很好的灵敏度和选择性,常见氨基酸和金属离子对SAM的检测无影响,在最佳实验条件下,SAM的浓度在1.0×10-8~2.0×10-6mol/L范围内与相对荧光强度呈线性相关,线性回归方程为ΔI=68.51＋72.32C（μmol/L）,相关系数r=0.9982,检出限为8.72×10-9mol/L;本方法已成功用于SAM检测。

英文摘要：

A novel fluorescent switch was constructed based on poly 3-{[ 1-（ 2-hydrazino-2-oxoethyl ） piperidin-4-ylidene] methyl}thiophene （ PMTH ） in the presence of Pb2﹢ or S-adenosylmethionine （ SAM ） . The switch turned off in the presence of Pb2﹢owing to complex effect, and the fluorescence intensity of PMTH solution was efficiently quenched by Pb2﹢ ions. Upon adding SAM to the Pb2﹢-PMTH solution, which was stronger Pb2﹢ chelators, it could form more stable SAM-Pb2﹢, the Pb2﹢ ion was displaced from PMTH and the fluorescence of PMTH was recovered. By triggering the ＂turn-on＂ signal of PMTH, a new discrimination ability toward SAM method for the determination of SAM was established. The effects of the interaction on the fluorescence spectral characteristics of these Pb2﹢-PMTH and Pb2﹢-SAM complexes in H2 O-CH3 CH2 OH（4：1, V/V） solution, suitable reaction conditions and influencing factors were investigated. This method offered good sensitivity and selectivity for detecting SAM in the presence of amino acids and metal ions. Under optimum conditions, the concentration of SAM in the range from 1. 0 × 10-8-2. 0 × 10-6 mol/L exhibited a linear relationship with the relative fluorescence intensity. The regression equation was △I = 68. 51﹢72. 32c （μmol/L）, the correlation coefficient r=0. 9982. The limit of detection was 8. 72×10-9 mol/L. The system was successfully applied for detecting SAM in human serum, urine and injection samples.