ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
<p><b>BACKGROUND</b>Several kinds of intercellular adhesion molecules closely relate to hepatitis B. The complex of CD(2) and CD58 plays an important role in enhancing the adhesion of T lymphocytes to target cells, hyperplasia and activation of T lymphocytes. In this study, we explored the relationship between the expression of CD58 in liver tissue and chronic hepatitis B infection.</p><p><b>METHODS</b>We determined the expression of the CD58 molecule on the surface of hepatocytes by using immunohistochemistry and the levels of serum HBV DNA from patients with HBV infection and from normal controls. The biochemical parameters of hepatic function were analyzed as well.</p><p><b>RESULTS</b>CD58 expression in hepatocytes significantly increased with the severity progression of chronic HBV infection. The IOD levels (log10) of CD58 in the control, mild, moderate, and severe chronic HBV infection groups were 0, (7.20+/-4.64) x 10(3), (25.63+/-7.41) x 10(3) and (37.47+/-11.17) x 10(3) respectively (P<0.05 compared with the control group, respectively).</p><p><b>CONCLUSION</b>CD58 probably increases cell mediated immunity to eliminate hepatitis B virus and leads to damage of hepatocytes.</p>