化学
脱氧核酶
血红素
G-四倍体
检出限
吸光度
阿布茨
过氧化物酶
肉眼
半胱氨酸
适体
组合化学
谷胱甘肽
寡核苷酸
色谱法
核化学
生物化学
DNA
酶
血红素
抗氧化剂
生物
DPPH
遗传学
作者
Xue-Hui Zhou,De‐Ming Kong,Han‐Xi Shen
摘要
Some G-quadruplex−hemin complexes are DNAzyme peroxidases that efficiently catalyze H2O2-mediated reactions, such as the oxidation of ABTS (2,2′-azinobis(3-ethylbenzothiozoline)-6-sulfonic acid) by H2O2. Since Ag+ chelates guanine bases at the binding sites are involved in G-quadruplex formation, the presence of Ag+ may disrupt these structures and inhibit the peroxidase activity of G-quadruplex−hemin DNAzymes. On the basis of this principle, a highly sensitive and selective Ag+-detection method was developed. The method allows simple detection of aqueous Ag+ with a detection limit of 64 nM and a linear range of 50−3000 nM. Cysteine (Cys) is a strong Ag+-binder and competes with quadruplex-forming G-rich oligonucleotides for Ag+-binding, promoting the reformation of G-quadruplexes and increasing their peroxidase activity. Therefore, the Ag+-sensing system was also developed as a Cys-sensing system. This “turn-on” process allowed the detection of Cys at concentrations as low as 50 nM using a simple colorimetric technique. The Cys-sensing system could also be used for the detection of reduced glutathione (GSH). Neither the Ag+-sensing nor the Cys-sensing systems required labeled oligonucleotides. In addition, both gave large changes in absorbance signal that could be observed by the naked eye. Thus, a simple visual method for Ag+- or Cys-detection was developed.
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