title: Kinetic and sensitive analysis of tyrosinase activity using electron transfer complexes: in vitro and intracellular study.
abstract: Tyrosinase is an important marker of human diseases such as the neurodegeneration associated with Parkinson's disease and melanoma. Sensitive detection of tyrosinase activity in vitro and inside cells is of great significance to medical diagnostics and skin disorder treatments. With unique photophysical properties, semiconductor quantum dots (QDs) are employed as photoluminescent platforms for various biosensing, in particular for the detection of enzyme activities. In this work, QDs are functionalized with tyrosine and zwitterionic molecules to construct a nanometer-scale scaffold (QD-Tyr conjugate), and this is used to test tyrosinase activity in vitro and inside cells. Tyrosinase oxidizes tyrosine to dopachrome and switches on the electron-transfer access, which relates to fluorescence quenching. High quenching efficiency is achieved by shortening the distance between the electron donors and acceptors, which is attributed to the small size of the conjugated tyrosine. Enzymatic process curves reveal the enhanced enzymatic activity on the conjugated nanoparticle substrate, which leads to highly sensitive detection of tyrosinase (as low as 1 nM). It is also demonstrated that QD-Tyr conjugates can sensitively probe intracellular tyrosinase in melanoma cells, which promises great potential in disease monitoring and medical diagnostics.
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory for Chemical Biology of Fujian Province and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
authors.forename: Xianglong
authors.initials: X
authors.lastname: Zhu
authors.forename: Juan
authors.initials: J
authors.lastname: Hu
authors.forename: Zhenghuan
authors.initials: Z
authors.lastname: Zhao
authors.forename: Mingjun
authors.initials: M
authors.lastname: Sun
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Chi
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Wang
authors.forename: Jinhao
authors.initials: J
authors.lastname: Gao
mesh_terms: D000364:Agaricus / Q000201:enzymology; D000818:Animals; D002138:Calibration; D003198:Computer Simulation; D004579:Electron Transport; D006367:HeLa Cells; D006801:Humans; D045563:Indolequinones / Q000378:metabolism; D042541:Intracellular Space / Q000378:metabolism*; D007700:Kinetics; D008546:Melanoma, Experimental; D051379:Mice; D018613:Microscopy, Confocal; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010084:Oxidation-Reduction; D045663:Quantum Dots / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D045563:Indolequinones; C001123:dopachrome; D014442:Monophenol Monooxygenase
keywords: electron-transfer; enzymatic activity; enzymes; intracellular; quantum dots; tyrosinase