在pH 5.5的2-(N-吗啉)-乙磺酸缓冲液中,底物DNA和酶DNA杂交形成双链DNA(dsDNA).当加入UO 2+后,dsDNA中的底物DNA链被裂解,释放的裂解链DNA吸附在金纳米粒子(GN)表面,未吸附裂解链DNA的GN在NaCl存在下发生聚集,在610 nm处有一最强的共振散射峰.随着UO 2+的浓度增大,体系中释放的裂解链DNA越多,被裂解链DNA保护的GN越多,聚集的GN越少,导致610 nm处的共振散射峰下降,溶液颜色由蓝色变红色.UO 2+浓度在0.67~60.3 nmol/L范围内与其共振散射峰降低值ΔI610 nm成线性,回归方程为ΔI610 nm=11.9C+6.1,相关系数为0.9972,检出限为0.09 nmol/L UO 2+.该法用于废水中UO 2+的检测,回收率在91.5%~95.7%之间.
In pH 5.5 2-(N-morpholine)-ethyl sulfonic acid buffer solution and in the presence of NaCl,the substrate single stranded DNA hybridized with the DNA enzyme to form double stranded DNA(dsDNA) at 80 ℃.UO22+ can cleaved the substrate strand of the dsDNA to produce short single stranded DNA that adsorbed on the surface of the gold nanoparticle to prevent its aggregation,and the uncombined gold nanoparticles aggregate to big particles that exhibited a resonance scattering(RS) peak at 610 nm.When the UO22+ concentration increased,the short single stranded DNA increased,the combined gold nanoparticles increased,and the aggregated gold nanoparticles decreased,the RS intensity at 610 nm decreased.Under the selected conditions,the decreased RS intensity(ΔI610 nm) is linear to UO22+ concentration in the range of 0.67~60.3 nmol/L,with a regression equation of ΔI610 nm=11.9C+6.1,a correlation coefficient of 0.9972,and a detection limit of 0.09 nmol/L UO22+.This method has been applied to determination of UO22+ in wastewater,with satisfactory results.