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Cleaved DNAzyme substrate induced enzymatic cascade for the exponential amplified analysis of l-histidine
- He, Jing-Lin, Wu, Ping, Zhu, Shuang-Li, Li, Ting, Li, Pan-Pan, Xiang, Jian-Nan, Cao, Zhong
- Talanta 2015 v.132 pp. 809-813
- detection limit, fluorescence, histidine
- A novel strategy of cleaved DNAzyme substrate induced enzymatic cascade has been devised for the exponential amplified detection of l-histidine. The enzyme strand carries out hydrolytic cleavage of the substrate strand in the presence of l-histidine. The cleaved DNAzyme substrates introduce the polymerase/endonuclease reaction cycles as primers. The l-histidine acts as the activator for enzymatic cascade amplification generating a distinguishable fluorescence enhancement. A good nonlinear correlation (R=0.9994) between fluorescence intensity and the logarithm of the l-histidine concentration is obtained over the range from 50nM to 1.0mM. The detection limit was estimated as 30nM. This efficient amplification of the fluorescence signal is attributed to the l-histidine induced cooperation of Klenow Fragment polymerase (exo⁻) and Nb.BbvCI endonuclease reaction. The activation of such enzymatic cascades through analyte-DNAzyme interactions has a substantial impact on the development of exponential amplified DNAzyme sensors.