DNA酶裂解-纳米金共振瑞利散射光谱法测定痕量Cu2+

在pH 7.0HEPES(4-羟乙基哌嗪乙磺酸)缓冲溶液中和0.19mol.L-1 NaCl存在下,单链底物DNA(SS)和酶链DNA(ES)在80℃杂交形成双链DNA(dsDNA)。Cu2+可切割dsDNA中的底物链释放出单链DNA(ssDNA),此ssDNA与金纳米粒子(NG)作用形成NGssDNA结合物不被NaCl聚集,而未保护的NG聚集形成较大粒径的聚集体(NGA),在627nm处有一个较强的共振瑞利散射峰。随着Cu2+浓度的增大,该共振瑞利散射峰降低,其降低值ΔI与Cu2+浓度在15～1 250nmol.L-1范围呈线性关系,其回归方程为ΔI=0.17c-2.3,线性相关系数为0.989 5,检出限为8nmol.L-1。据此建立了一个高灵敏、高选择性、简便测定Cu2+的共振瑞利散射光谱分析法。该法用于水样中Cu2+的检测,结果满意。

DNAzyme Cracking-Nanogold Resonance Rayleigh Scattering Spectral Method for the Determination of Trace CuCu2+

In the condition of pH 7.0 HEPES buffer solution and 0.19 mol·L-1 NaCl, the substrate strand DNA (SS) and the enzyme strand DNA (ES) hybridized into a double-stranded DNA (dsDNA) at 80 ℃. The substrate chain of dsDNA could be cracked by Cu2+, and the released single-stranded DNA (ssDNA) were adsorbed on the nanogold(NG) surface to produce a stable NGssDNA conjugate. The unprotected NG was aggregated to form NG aggregation (NGA) that exhibited a resonance Rayleigh scattering (RRS) peak at 627 nm. When the Cu2+ was added, the NGssDNA increased, and the NGA decreased that caused the RRS intensity decreasing at 627 nm, and the solution color changed from blue to red. The decreased RS intensity ΔI was linear with the Cu2+ was added, the NGssDNA increased, and the NGA decreased that caused the RRS intensity decreasing at 627 nm, the solution color changed from blue to red. The decreased RS intensity ΔI was linear to the Cu2+ concentration in the range of 15～1 250 nmol·L-1, with a regression equation of ΔI = 0.17c-2.3, coefficient of 0.989 5 and a detection limit of 8 nmol·L-1 Cu2+. In addition, the influence of foreign substances on the determination of 0.75 μmol·L-1 Cu2+ was considered. The results show that 3 μmol·L-1 Ca2+, Pb2+ and Hg2+, 2 μmol·L-1 Fe2+, 1 μmol·L-1 Sn2+, 4 μmol·L-1 Al3+, 12 μmol·L-1 Mn2+, 4 μmol·L-1 Co2+ and Ni2+ did not interfered with the determination. This indicates that this method has good selectivity. This new, rapid, sensitive, selective RRS method was applied to the determination of Cu2+ in water, with satisfactory results.