A label-free fluorescent probe for Hg2+ and biothiols based on graphene oxide and Ru-complex

• Published in: Scientific reports Vol. 4; no. 1; p. 5320
• Main Authors: Wang, Linlin, Yao, Tianming, Shi, Shuo, Cao, Yanlin, Sun, Wenliang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.06.2014; Nature Publishing Group
• Subjects: 639/638/11/872; 639/638/11/874; 9/10; 96/33; 96/34; Affinity; Base pairs; Biosensing Techniques - methods; Cysteine; Cysteine - analysis; Cysteine - chemistry; Deoxyribonucleic acid; DNA; DNA - chemistry; DNA, Single-Stranded - chemistry; Fluorescence; Fluorescent Dyes - chemistry; Glutathione; Glutathione - analysis; Glutathione - chemistry; Graphite - chemistry; Humanities and Social Sciences; Mercury - analysis; Mercury - chemistry; Microscopy, Atomic Force; Microscopy, Electron, Transmission; multidisciplinary; Organometallic Compounds - chemistry; Oxides - chemistry; Reproducibility of Results; Ruthenium - chemistry; Science; Single-stranded DNA; Spectrometry, Fluorescence; Sulfhydryl Compounds - analysis; Sulfhydryl Compounds - chemistry; Sulfur; Unwinding
• ISSN: 2045-2322; 2045-2322
• 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)] 2+ 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)] 2+ , 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)] 2+ intercalated into the newly formed ds-DNA. Then, [Ru(bpy) 2 (pip)] 2+ 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)] 2+ were adsorbed on the surface of GO, the fluorescence of [Ru(bpy) 2 (pip)] 2+ was quenched again. Therefore, the changes in emission intensity of [Ru(bpy) 2 (pip)] 2+ 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.