以富含胸腺嘧啶(thymine)的Hg^(2+)特异性DNA为识别元件,利用SYBR GREEN I分子光"开关"的特性,建立了一种高灵敏、高选择性荧光均相检测Hg^(2+)的新方法。该检测体系由两条非标记、含有5个thymine-thymine(T-T)错配碱基对的DNA探针组成。T-T错配使两条DNA探针以单链形式存在于溶液中,而Hg^(2+)通过T-Hg^(2+)-T配位作用可以与两条DNA探针结合并形成稳定的双链结构。在优化条件下,荧光强度与Hg^(2+)浓度在0-100 nmol/L范围呈线性,检测限为2nmol/L(S/N=3),而其他金属离子也不会对Hg^(2+)检测造成干扰。该方法简单快速,有望应用于水体中Hg^(2+)的检测。
[Objective] In order to study the relations among different positions, degrees of substitution and antioxidant ability. [Method] N, O-carboxymethyl chitosan （NOA, NOB and NOC）with various degrees of substitution （DS）were obtained by etherizing chito-oligosacchaside. Their structure and substituted degree were characterized and their antioxldant activity to·OH was evaluated. [ Result] The IC50 s of NOA ,NOB and NOC were 0.15 ,0. 29 ,0. 23 mg/ml while their DSs of -NH2 position（DSN） were 0.51,0.29 and 0.38 and DSo were 0. 74 ,0. 84 ,0. 97respectively.[ Conclusion] With the increase of DSN ,antioxidant activity of N,O-carboxymethyl chitosan oligosaccharide to·OH was up.
