title: Ubiquinone-quantum dot bioconjugates for in vitro and intracellular complex I sensing.
abstract: Quantum dots (QDs) have attracted increasing interest in bioimaging and sensing. Here, we report a biosensor of complex I using ubiquinone-terminated disulphides with different alkyl spacers (QnNS, n = 2, 5 and 10) as surface-capping ligands to functionalise CdSe/ZnS QDs. The enhancement or quenching of the QD bioconjugates fluorescence changes as a function of the redox state of QnNS, since QDs are highly sensitive to the electron-transfer processes. The bioconjugated QnNS-QDs emission could be modulated by complex I in the presence of NADH, which simulates an electron-transfer system part of the mitochondrial respiratory chain, providing an in vitro and intracellular complex I sensor. Epidemiological studies suggest that Parkinson's patients have the impaired activity of complex I in the electron-transfer chain of mitochondria. We have demonstrated that the QnNS-QDs system could aid in early stage Parkinson's disease diagnosis and progression monitoring by following different complex I levels in SH-SY5Y cells.
authors.affiliation: State Key Laboratory of Bioreactor Engineering & Department of Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.forename: Li-Xia
authors.initials: LX
authors.lastname: Qin
authors.forename: Feng-Tao
authors.initials: FT
authors.lastname: Liu
authors.forename: Zhen
authors.initials: Z
authors.lastname: Gu
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Zhi Gang
authors.initials: ZG
authors.lastname: Pan
authors.forename: Tony D
authors.initials: TD
authors.lastname: James
authors.forename: Yi-Tao
authors.initials: YT
authors.lastname: Long
mesh_terms: D015374:Biosensing Techniques; D002104:Cadmium / Q000737:chemistry; D055664:Electrochemical Techniques; D004579:Electron Transport; D042967:Electron Transport Complex I / Q000378:metabolism*; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010300:Parkinson Disease / Q000175:diagnosis / Q000378:metabolism; D045663:Quantum Dots; D012119:Respiration; D012643:Selenium / Q000737:chemistry; D014451:Ubiquinone / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
chemical_list: D002104:Cadmium; D009243:NAD; D014451:Ubiquinone; D042967:Electron Transport Complex I; D012643:Selenium; D015032:Zinc