Wang Linlin, Yao Tianming, Shi Shuo, Cao Yanlin, Sun Wenliang
Department of Chemistry, Tongji University, Shanghai 200092, China.
Sci Rep. 2014 Jun 17;4:5320. doi: 10.1038/srep05320.
A novel, selective and sensitive switch-on fluorescent sensor for Hg(2+) and switch-off fluorescent probe for biothiols was developed by using Ru(bpy)₂(pip) as the signal reporter and graphene oxide (GO) as the quencher. Due to the affinity of GO towards single-stranded DNA (ss-DNA) and Ru(bpy)₂(pip), the three components assembled, resulting in fluorescence quenching. Upon addition of Hg(2+), a double-stranded DNA (ds-DNA) via T-Hg(2+)-T base pairs was formed, and Ru(bpy)₂(pip) intercalated into the newly formed ds-DNA. Then, Ru(bpy)₂(pip) and ds-DNA were removed from the surface of GO, resulting in the restoration of fluorescence. Subsequently, upon addition of biothiols, Hg(2+) was released from ds-DNA, due to the higher affinity of Hg(2+) to the sulfur atoms of biothiols, which could induce ds-DNA unwinding to form ss-DNA. Then ss-DNA and Ru(bpy)₂(pip) were adsorbed on the surface of GO, the fluorescence of Ru(bpy)₂(pip) was quenched again. Therefore, the changes in emission intensity of Ru(bpy)₂(pip) directly correlated to the amount of detection target (Hg(2+) or biothiols) in solution. The assay exhibited high sensitivity and selectivity, with the limits of detection for Hg(2+), cysteine (Cys) and glutathione (GSH) to be 2.34 nM, 6.20 nM and 4.60 nM, respectively.
以[Ru(bpy)₂(pip)]²⁺作为信号报告分子、氧化石墨烯(GO)作为猝灭剂，开发了一种新型、选择性好且灵敏的Hg²⁺开启型荧光传感器和生物硫醇关闭型荧光探针。由于GO对单链DNA(ss-DNA)和[Ru(bpy)₂(pip)]²⁺具有亲和力，三种组分组装在一起，导致荧光猝灭。加入Hg²⁺后，通过T-Hg²⁺-T碱基对形成双链DNA(ds-DNA)，[Ru(bpy)₂(pip)]²⁺插入新形成的ds-DNA中。然后，[Ru(bpy)₂(pip)]²⁺和ds-DNA从GO表面去除，导致荧光恢复。随后，加入生物硫醇后，由于Hg²⁺对生物硫醇硫原子的亲和力更高，Hg²⁺从ds-DNA中释放出来，这会诱导ds-DNA解旋形成ss-DNA。然后ss-DNA和[Ru(bpy)₂(pip)]²⁺吸附在GO表面，[Ru(bpy)₂(pip)]²⁺的荧光再次被猝灭。因此，[Ru(bpy)₂(pip)]²⁺发射强度的变化与溶液中检测目标(Hg²⁺或生物硫醇)的量直接相关。该分析方法具有高灵敏度和选择性，对Hg²⁺、半胱氨酸(Cys)和谷胱甘肽(GSH)的检测限分别为2.34 nM、6.20 nM和4.60 nM。
