RESUMEN
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.
RESUMEN
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.