Hui Huang,Meini Li,Mingwei Hao,Liangli (Lucy) Yu,Yongxin Li
A selective and sensitive colorimetric strategy for sulfide analysis was developed using GMP-Cu nanozymes with a laccase-like activity. This research discovered for the first time that sulfide could significantly enhance the catalytic activity of the GMP-Cu nanozymes by about 3.5 folds. The enhanced laccase activities duo to two reasons. First, Cu 2+ in GMP-Cu nanozymes was reduced to Cu + . The other reason was the formation of Cu–S bond which was beneficial to accelerate the electron transfer rate to improve catalytic activity. Therefore, this method showed an excellent selectivity for sulfide. And it had a linear relationship in the sulfide concentration range of 0–220 μmol/L with a detection limit of 0.67 μmol/L. Furthermore, the proposed method was successfully applied to examine sulfide in the food systems. This new method may be used in sulfide detection to improve food quality and safety.
Abstract Ratiometric fluorescence and colorimetric strategies for detecting activity of butyrylcholinesterase (BChE) in human serum were developed by using g-C 3 N 4 nanosheets, silver ion (Ag + ) and o-phenylenediamine (OPD) as chromogenic agents. The oxidation-reduction reaction of OPD and Ag + generates 2,3-diaminophenazine (oxOPD). Under exciation at 370 nm, g-C 3 N 4 nanosheets and oxOPD emit fluorescence at 440 nm ( F 440 ) and 560 nm ( F 560 ), respectively. Additionally, oxOPD exhibits quenching ability towards g-C 3 N 4 nanosheets via photoinduced electron transfer (PET) process. Thiocholine (TCh), as a product of BChE-catalyzed hydrolysis reaction of butylthiocholine iodide (BTCh), can coordinate with Ag + intensively, and consequently diminish the amount of free Ag + in the testing system. Less amount of free Ag + leads to less production of oxOPD, resulting in less fluorescence quenching towards g-C 3 N 4 nanosheets as well as less fluorescence emission of oxOPD. Therefore, by using g-C 3 N 4 nanosheets and oxOPD as fluorescence indicators, the intensity ratio of their fluorescence ( F 440 /F 560 ) was calculated and employed to evaluate the activity of BChE. Similarly, the color variation of oxOPD indicated by the absorbance at 420 nm ( ΔA 420 ) was monitored for the same purpose. These strategies were validated to be sensitive and selective for detecting BChE activity in human serum, with limits of detection (LODs) of 0.1 U L −1 for ratiometric fluorescence mode and 0.7 U L −1 for colorimetric mode. Graphical abstract
Dongxue Sun,Tianli Liu,Yuming Dong,Qingyun Liu,Xiuming Wu,Guang-Li Wang
Herein, an innovative dehydrogenase invoked tri-enzyme cascade has been successfully constructed and utilized as a powerful and universal colorimetric strategy for dehydrogenase-based bioassays. Specifically, the glucose-6-phosphatedehydrogenase (G6PD) catalyzes the specific dehydrogenation of glucose-6-phosphate (G-6-P) by consuming the oxidized form of β-nicotinamide adenine dinucleotide phosphate (NADP + ) to generate NADPH. And the formed NADPH initiates the irreversible hydroxylation of p-hydroxybenzoate by p-hydroxybenzoate hydroxylase (PHBH) to generate 3,4-dihydroxybenzoate (DHB), which results in the subsequent in situ generation of a photoresponsive nanozyme of DHB coordinated SrTiO 3 (SrTiO 3 /DHB) nanosheets. The photoresponsive nanozyme has intriguing interfacial charge transfer (ICT) characteristics and thus realizes the efficiently catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) under light irradiation for signal readout. Exemplified by G6PD and G-6-P as analytes, the dehydrogenase invoked tri-enzyme cascade achieved efficient signal amplification towards the ultrasensitive colorimetric bioassays. This study opens up the ICT transitions of SrTiO 3 for innovative dehydrogenases-involved enzyme cascades. In addition, it is an entirely new method for dehydrogenases-based bioassays, with the distinctive merits of facile operation, rapid response, high sensitivity, and naked-eye readout. Importantly, it is extensible as a general basis for other numerous targets of interest because of the large numbers of dehydrogenases available for catalysing different reactions.
危险品化学品经营许可证（带存储）