3-Aminophenyl Boronic Acid Functionalized Quantum-Dot-Based Ratiometric Fluorescence Sensor for the Highly Sensitive Detection of Tyrosinase Activity

Abstract

Using the commercially available and economical 6-hydroxycoumarin (6-HC) as the substrate, a dual-emission ratiometric fluorescence sensor was developed to detect tyrosinase (TYR) activity based on 3-aminophenyl boronic acid functionalized quantum dots (APBA-QDs). TYR can catalyze 6-HC, a monohydroxy compound, to form a fluorescence-enhancing o-hydroxy compound, 6,7-dihydroxycoumarin. Owing to the special covalent binding between the o-hydroxyl and boric acid groups, APBA-QDs react with 6,7-dihydroxycoumarin to form a five-membered ring ester dual-emission fluorescence probe for TYR. With an increase in TYR activity, the fluorescence at 675 nm originating from the QDs is gradually quenched, whereas that at 465 nm owing to 6,7-dihydroxycoumarin increases. Referencing the decreasing signal of the dual-emission probe at 675 nm to measure the increasing signal at 465 nm, a ratiometric fluorescence method was established to detect the TYR activity with high sensitivity and selectivity. Under the conditions optimized via response surface methodology, a linear range of 0−0.05 U/mL was obtained for the TYR activity. The detection limit was as low as 0.003 U/mL. This sensing strategy can also be adopted for the rapid screening of the TYR inhibitors.

Development of a Selective Assay of Tyrosine and Its Producing and Metabolizing Enzymes Utilizing Pulse-UV Irradiation-Induced Chemiluminescence

“…The analytical performance of the developed method was compared with the previously reported methods for the determination of tyrosinase activity ,− as abridged in Table S5. These methods suffer from several drawbacks, including the dependence on nonselective quenching of a fluorophore by the produced quinone from the enzymatic reaction, ,, the use of synthetic substrates that will react with tyrosinase in several ways different from natural substrates that could lead to false results, ,,,,, complicated synthesis of the sensing probes, ,,,, or the use of time-consuming fluorogenic reaction (1.5 h) . On the other hand, the proposed method is very simple and showed higher sensitivity than many of the previously reported methods − ,,, and similar sensitivity to others, ,,, and thus it could be a better choice for tyrosinase activity assay.…”

Ultrasensitive dynamic light scattering immunosensing platform for NT-proBNP detection using boronate affinity amplification

“…1F, FTIR spectra of SiO 2 and SiO 2 @PBA present two characteristic peaks at 1057 cm −1 and 3273 cm −1 , which correspond to the Si-O band and −OH, respectively [27]. In addition, the FTIR peaks of SiO 2 @PBA at 1633 cm −1 , 1541 cm −1 and 1421 cm −1 correspond to the stretching vibration of a benzene ring skeleton, the peptide bond and −B(OH) 2 , respectively, which were not observed in SiO 2 alone [28]. These findings prove that PBA molecules were successfully modified onto the surface of SiO 2 .…”

Fluorescent probes for visualizing ROS-associated proteins in disease

“…93 Many other uorescent probes have also been developed for the uorescence imaging of tyrosinase activity. [94][95][96][97] Su et al designed a ratiometric uorescence probe, containing redemissive QDs and green-emissive QDs as uorophores to provide ratiometric signals. Dopamine and QDs were conjugated to the surface of silica nanoparticles.…”