title: Functionalized Carbon Quantum Dots with Dopamine for Tyrosinase Activity Monitoring and Inhibitor Screening: In Vitro and Intracellular Investigation.
abstract: Sensitive assay of tyrosinase (TYR) activity is in urgent demand for both fundamental research and practical application, but the exploration of functional materials with good biocompatibility for its activity evaluation at the intracellular level is still challenging until now. In this work, we develop a convenient and real-time assay with high sensitivity for TYR activity/level monitoring and its inhibitor screening based on biocompatible dopamine functionalized carbon quantum dots (Dopa-CQDs). Dopamine with redox property was functionalized on the surface of carbon quantum dots to construct a Dopa-CQDs conjugate with strong bluish green fluorescence. When the dopamine moiety in Dopa-CQDs conjugate was oxidized to a dopaquinone derivative under specific catalysis of TYR, an intraparticle photoinduced electron transfer (PET) process between CQDs and dopaquinone moiety took place, and then the fluorescence of the conjugate could be quenched simultaneously. Quantitative evaluation of TYR activity was established in terms of the relationship between fluorescence quenching efficiency and TYR activity. The assay covered a broad linear range of up to 800 U/L with a low detection limit of 7.0 U/L. Arbutin, a typical inhibitor of TYR, was chosen as an example to assess its function of inhibitor screening, and positive results were observed that fluorescence quenching extent of the probe was reduced in the presence of arbutin. It is also demonstrated that Dopa-CQD conjugate possesses excellent biocompatibility, and can sensitively monitor intracellular tyrosinase level in melanoma cells and intracellular pH changes in living cells, which provides great potential in application of TYR/pH-associated disease monitoring and medical diagnostics.
authors.affiliation: College of Chemistry and Life Science, Zhejiang Normal University , Jinhua 321004, China.
authors.forename: Lujing
authors.initials: L
authors.lastname: Chai
authors.affiliation: Beijing National laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences , Bejing 100190, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhou
authors.affiliation: College of Chemistry and Life Science, Zhejiang Normal University , Jinhua 321004, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Feng
authors.affiliation: College of Chemistry and Life Science, Zhejiang Normal University , Jinhua 321004, China.
authors.forename: Cong
authors.initials: C
authors.lastname: Tang
authors.affiliation: College of Chemistry and Life Science, Zhejiang Normal University , Jinhua 321004, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: College of Chemistry and Life Science, Zhejiang Normal University , Jinhua 321004, China.
authors.forename: Zhaosheng
authors.initials: Z
authors.lastname: Qian
mesh_terms: D015374:Biosensing Techniques; D002244:Carbon / Q000737:chemistry; D004298:Dopamine / Q000737:chemistry*; D004579:Electron Transport; D005453:Fluorescence; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D010084:Oxidation-Reduction; D045663:Quantum Dots / Q000737:chemistry*
chemical_list: D002244:Carbon; D014442:Monophenol Monooxygenase; D004298:Dopamine
keywords: carbon quantum dots; fluorometric assay; inhibitor screening; intracellular imaging; tyrosinase