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A simple and feasible strategy was developed for the preparation of fluorescent covalent organic frameworks (COFs) TpPa-1@FL. The TpPa-1-1@FL was prepared via a self-assembly strategy by soaking non-fluorescent COFs TpPa-1 into strong fluorescent fluorescein (FL) solution. A chemiluminescence resonance energy transfer (CRET) system was constructed by the combination strong fluorescent TpPa-1@FL with TCPO-hydrogen peroxide (H 2 O 2 ) reaction. The chemiluminescence (CL) signal of the system was further improved by the addition of bovine serum albumin (BSA). The CRET system can determine H 2 O 2 with a linear range response from 5.0 µmol/L to 20.0 mmol/L and a detection limit of 1.1 µmol/L. The CRET system was further exploited for indirect detection of uric acid with coupling of uricase. A good linear relationship was obtained for uric acid in the 10.0-400.0 µmol/L concentration range with a detection limit of 3.8 µmol/L. The practicability of this method was assessed by the determination of uric acid in real samples of human serum and urine., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Covalent organic frameworks (COFs) are considered to be a promising support material for catalyst due to their highly ordered porous structure. Here, a core-shell structured Fe 3 O 4 magnetic covalent organic framework (Fe 3 O 4 @COF) was synthesized and employed to provide basic sites for immobilization of gold nanoparticles (AuNPs). The AuNPs was in-situ immobilized on the shell of Fe 3 O 4 @COF via a citrate reducing method. The Fe 3 O 4 @COF-AuNP had convenient magnetic separability and exhibited excellent mimicking peroxidase-like activity in catalyzing chemiluminescence (CL) reaction of luminol with hydrogen peroxide (H 2 O 2 ). With acetylcholine chloride (ACh) as substrate of acetylcholinesterase (AChE), a CL method was exploited for sensitive detection of organophosphorus pesticide triazophos due to its irreversible inhibiting effect on the AChE activity and subsequently influences the production of H 2 O 2 under the condition of choline oxidase (ChOx). This method gave a good linearity for triazophos in the range of 5.0-300.0 nmol L -1 , and a limit of detection (LOD) of 1 nmol L -1 was acquired. The applicability of this method was verified by the determination of triazophos in different spiked vegetable samples., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A Fe-porphyrin covalent organic framework (Fe-PorCOF) was prepared through a postmodification strategy and characterized using different techniques. Fe-PorCOF exhibits an inherent peroxidase/oxidase mimetic catalytic activity and sharply accelerates chemiluminescence (CL) reactions between luminol and hydrogen peroxide (H 2 O 2 ) or dissolved oxygen (O 2 ) under alkaline conditions. The catalytic role was attributed to a significant increase in production of reactive oxygen species. Using the imminent peroxidase mimetic catalytic activity of Fe-PorCOF, a new CL method was developed for determination of H 2 O 2 over a linear range from 0.01 to 10.0 μmol·L -1 and with a limit of detection of 5.3 nmol·L -1 . The combination of the peroxidase mimetic catalytic activity of Fe-PorCOF with the catalytic activity of glucose oxidase on glucose oxidation presents a sensitive CL method for glucose assay. The linear range and the detection limit for glucose were 0.05-8.0 μmol·L -1 and 4.0 nmol·L -1 , respectively. The practicability of this method was assessed by determination of glucose in human sera. As a peroxidase/oxidase mimetic, Fe-PorCOF is easy to prepare and exhibits good catalytic efficiency in the luminol reaction. We believe that this strategy will promote the development of a CL field with functional COFs as a catalyst., (© 2020 John Wiley & Sons, Ltd.)

HRP@ZIF-8 nanocomposite was prepared by in situ encapsulation of horseradish peroxidase (HRP) in the frame of zeolitic imidazolate framework-8 (ZIF-8) with a simple one-pot method. The HRP@ZIF-8 nanocomposite displays outstanding thermal stability and efficiently catalyzes the chemiluminescence (CL) reaction of luminol with hydrogen peroxide (H 2 O 2 ) under near-neutral pH condition (pH 7-8). This CL system has a good response to H 2 O 2 with a linear range of 0.1-100.0 μmol L -1 . The limit of detection (LOD) is 0.06 μmol L -1 H 2 O 2 . By marriage with cholesterol oxidase, cholesterol is determined with a linear range from 0.1 to 100.0 μmol L -1 and a LOD of 0.04 μmol L -1 . The relative standard deviations (RSD) are 1.7% and 2.5%, respectively, in 11 repeated measurements of 50.0 μmol L -1 solutions of H 2 O 2 and cholesterol, indicating excellent precision of the method. The method shows good selectivity and has been applied to the determination of total cholesterol in real serum samples. No significant difference has been observed between the results obtained by this method and the cholesterol oxidase-peroxidase coupling method. Graphical abstract Schematic presentation of in situ one-pot synthesis of horseradish peroxidase@zeolitic imidazolate framework-8 (HRP@ZIF-8) nanocomposite and chemiluminescence determination of cholesterol with HRP@ZIF-8 catalyzing luminol-H 2 O 2 system.