基于末端脱氧核苷酸转移酶扩增DNA-铜纳米簇荧光传感检测L-组氨酸

利用末端脱氧核苷酸转移酶(TdT)扩增形成聚胸腺嘧啶(T)DNA模板,制备了聚T铜纳米簇(TS-CuNCs),构建了一种用于L-组氨酸(L-His)检测的荧光传感分析新方法.TdT酶在dTTP存在下合成聚T单链DNA核苷酸序列.由于胸腺嘧啶和Cu2+之间的亲合力,聚T单链DNA作为合成铜纳米簇(CuNCs)的模板,加入还原剂后形成CuNCs,荧光强度增强.在L-His存在下,L-组氨酸的咪唑基与Cu2+螯合形成L-His-Cu2+配合物,因而进入聚胸腺嘧啶序列中的Cu2+量减少,使得合成的CuNCs数量减少,导致荧光信号减弱.实验结果表明,体系荧光响应信号与L-His浓度的对数值在5.0×10-9~5.0×10-4 mol/L范围内呈线性关系,检出限达到3.4×10-9 mol/L.本方法用于实际尿液样品中L-组氨酸检测的回收率为97.4%~104.6%,在生物医学及临床诊断中具有潜在应用价值.

Terminal Deoxynucleotidyl Transferase Amplification Based DNA-Copper Nanoclusters Sensor for Detection of L-Histidine

A terminal deoxynucleotidyl transferase ( TdT ) amplification based DNA-copper nanoclusters (CuNCs) sensor was developed for detection of L-histidine ( L-His). Single strand DNA containing poly-thymine ( T) sequences were synthesized by TdT in the presence of dTTP. In blank control, poly-T sequences worked as templates of CuNCs due to the affinity between thymine and copper ions( II) . Fluorescence intensity was enhanced when CuNCs formed with reducing agents. In the presence of L-His, the imidazolyl group of L-His worked as a chelating agent that formed L-His-Cu2+ chelated complex. Thus less copper ions were induced in poly-T sequences, and less CuNCs were obtained to produce week fluorescence signals. A good linear correlation was obtained between fluorescence change and the logarithm of the L-His concentration over the range of 5. 0 ×10-9-5. 0 ×10-4 mol/L. The detection limit was estimated as 3. 4 ×10-9 mol/L. And the recoveries were 97. 4%-104. 6% for the actual urine samples. Compared with other methods of synthetic CuNCs, this method allowed to specifically determining L-histidine without template or labeling, which showed good potential in biomedical and clinical analysis.