RSC Advances View Article Online PAPER View Journal | View Issue A nano-sized Cu-MOF with high peroxidase-like activity and its potential application in colorimetric Cite this: RSC Adv.,2021,11, 26963 detection of H2O2 and glucose† Hao Yu,a Hanliu Wu,a Xuemei Tian,a Yafen Zhou,a Chunguang Ren*b and Zhonghua Wang *a Peroxidase widely exists in nature and can be applied for the diagnosis and detection of H2O2, glucose, ascorbic acid and other aspects. However, the natural peroxidase has low stability and its catalytic efficiency is easily affected by external conditions. In this work, a copper-based metal–organic framework (Cu-MOF) was prepared by hydrothermal method, and characterized by means of XRD, SEM, FT-IR and EDS. The synthesized Cu-MOF material showed high peroxidase-like activity and could be utilized to catalyze the oxidation of o-phenylenediamine (OPDA) and 3,30,5,50-tetramethylbenzidine (TMB) in the presence of H2O2. The steady-state kinetics experiments of the oxidation of OPDA and TMB Creative Commons Attribution-NonCommercial 3.0 Unported Licence. catalyzed by Cu-MOF were performed, and the kinetic parameters were obtained by linear least-squares fitting to Lineweaver–Burk plot. The results indicated that the affinity of Cu-MOF towards TMB and OPDA was close to that of the natural horseradish peroxidase (HRP). The as-prepared Cu-MOF can be applied for colorimetric detection of H2O2 and glucose with wide linear ranges of 5 to 300 mM and 50 to 500 mM for H2O2 and glucose, respectively. Furthermore, the specificity of detection of glucose was Received 23rd June 2021 compared with other sugar species interference such as sucrose, lactose and maltose. In addition, the Accepted 30th July 2021 detection of ascorbic acid and sodium thiosulfate was also performed upon the inhibition of TMB DOI: 10.1039/d1ra04877e oxidation. Based on the high catalytic activity, affinity and wide linear range, the as-prepared Cu-MOF rsc.li/rsc-advances may be used for artificial enzyme mimics in the fields of catalysis, biosensors, medicines and food industry. This article is licensed under a 1. Introduction oxidation.9 Furthermore, Muhammad Fiaz et al. synthesized high efficient oxygen evolution reaction (OER) catalyst Open Access Article. Published on 09 August 2021. Downloaded 10/2/2021 3:16:23 AM. Metal–organic frameworks (MOFs) are crystalline porous NiS@MOF-5, which can be coated on Ni-foam to form framework materials that are formed with organic ligands and NiS@MOF-5/NF and showed OER catalytic activity and excellent 10 metal ions through coordination bonds with a periodic network stability. Besides, Nguyenet et al. found that Ni-MOF-74 structure.1 MOFs have been widely used in catalysis,2 sensing,3 possessed ultrahigh catalytic activity for the arylation of 11 gas adsorption and separation,4 luminescence5 and other elds azoles. due to their large specic surface area, unsaturated sites, and Enzyme, also called biocatalyst, has the characteristics of 12,13 structural and functional diversity.6–8 MOFs materials have been high efficiency, specicity and mild reaction conditions. shown to have great application prospects with more and more Peroxidase is a kind of enzyme, which is widely existed in nature 14 kinds of MOFs and their composite materials having been and can participate in the metabolism of organisms, it can discovered. In the eld of catalysis, MOFs with high catalytic also be used for the diagnosis and detection of H2O2, glucose, 15,16 efficiency have been reported. Qin et al. found that hollow ascorbic acid. However, natural enzymes usually have mesoporous MOF exhibited superior catalytic performance drawbacks of the high cost of preparation and purication, 15,17–20 when loading Pd nanoparticles toward benzyl alcohol special storage conditions and low stability. The enzyme activity can only be best performed under suitable conditions, such as optimal temperature and acid-alkali conditions.13,21,22 aChemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, Therefore, people begin to pay attention to the research of 23–27 College of Chemistry and Chemical Engineering, China West Normal University, articial mimic peroxidase. Nanchong 637002, Sichuan, P. R. China. E-mail: [email protected]; Fax: +86 817- It has been reported that Fe3O4 could catalyze the oxidation 2445233; Tel: +86 817-2568081 of TMB and OPDA to generate blue and orange color reactions, bYantai Institute of Materia Medica, Yantai 264000, Shandong, P. R. China. E-mail: respectively.28 Since then, many researchers have carried out [email protected] † Electronic supplementary information (ESI) available. See DOI: research on the application of Fe3O4 mimic peroxidase in the 29,30 10.1039/d1ra04877e eld of glucose detection. Later, it has been discovered that © 2021 The Author(s). Published by the Royal Society of Chemistry RSC Adv.,2021,11, 26963–26973 | 26963 View Article Online RSC Advances Paper 31 32 33 Co3O4 nanoparticles, V2O5 nanowires, CuO nanoparticles, transform infrared (FT-IR) spectrometer (Nicolet-6700) was 34 21 MnO2 microspheres and Ag2O, etc. also have intrinsic cata- applied to record FTIR spectroscopy. Scanning electron lytic activity on classic peroxidase substrates in the presence of microscopy (SEM) image and energy dispersive X-ray spectros- H2O2. At present, colorimetry is the most widely used method copy (EDS) image were taken by a Hitachi S4800 scanning for glucose detection. The principle is that glucose oxidase electron microscope. (GOX) catalyzes the oxidation of glucose and the reduction of O2 to H2O2, then the simulated peroxidase catalyzes H2O2 to 2.3. Cu-MOF preparation produce hydroxyl free groups to oxidize substrates (TMB, DAB, The Cu-MOF was prepared by using hydrothermal method. OPDA, etc.) to produce color reaction.35 Briey, 0.45 g (2.14 mmol) H3BTC was dissolved in 48 mL As a peroxidase mimetic enzyme, MOFs have substantive absolute ethanol and stirred for 10 min. Next, addition of 0.75 g applications in colorimetric detection of some substances such (3.1 mmol) of Cu(NO3)2$3H2O to the above solution and as H2O2 and glucose. It has been reported that some iron- 36 37 continued stirring for 10 min. Then, transferred the mixed containing MOFs, such as MIL-53(Fe), MIL-88(Fe) and MIL- 38 solution into a Te on-lined stainless autoclave. A er heated at 68(Fe) possess the properties of peroxidase mimics. In the 120 C for 12 h and cooled down to the room temperature, presence of H2O2, the hydrothermally synthesized MIL-53(Fe) collected the Cu-MOF by centrifugation and washed 3 times can catalyze the oxidation of TMB and OPDA, which has been with absolute ethanol, then dried in a vacuum drying-oven for applied to the detection of actual samples such as glucose and 24 h at 60 C to obtain the target product.44 serum with a good linear range and selectivity. Later, it was 39 found that precious metals such as Au and other metals, and 2.4. Peroxidase-like activity composite metals (such as bimetallic) also have the catalytic activity of mimetic enzymes,40 which makes MOFs as a popular The catalytic oxidation of TMB by H2O2 was performed in ff new material in the simulation of peroxidase. 100 mM acetate bu er (pH 4.0) in the presence of Cu-MOF À1 ff catalyst. Briey, 2.4 mL of 0.06 mg mL Cu-MOF (Cu-MOF Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Several Cu-MOFs were reported previously that di erent ff organic compounds were used as coordination ligands, such as solid was dispersed in acetate bu er by ultrasonication), 300 41 42 mL TMB (0.3 mM, dissolve the DMF) and 300 mLH2O2 (0.6 mM) uric acid, 2-aminoterephthalic acid and 1,10-phenanthroline- 43 were mixed and reacted for 20 min at 30 C. The maximum 2,9-dicarboxylic acid. In this work, we prepared a Cu-MOF by 45 using a simple hydrothermal method with 1,3,5-benzene- absorption wavelength of TMB oxidized product (652 nm) was tricarboxylic acid (H BTC) as ligand. The peroxidase-like activity of measured with a UV-Vis spectrophotometer. For OPDA oxida- 3 À1 the as-prepared Cu-MOF was investigated by the oxidation reaction tion, 1 mL of 0.06 mg mL Cu-MOF solution (Cu-MOF solid was dispersed in deionized water), 1 mL OPDA (0.4 mM, of TMB and OPDA with H2O2. The Cu-MOF showed high dissolve the deionized water) and 1 mL H2O2 (0.6 mM) were peroxidase-like activity, which can be used for catalyzing OPDA This article is licensed under a reacted for 20 min at 30 C. The maximum absorption wave- and TMB to generate colored products in the presence of H2O2.To 15 investigate the possible oxidation mechanism of the Cu-MOF, length of OPDA oxidized product (416 nm) was measured by typical Michaelis–Menten curves were obtained through steady- a UV-Vis spectrophotometer. Open Access Article. Published on 09 August 2021. Downloaded 10/2/2021 3:16:23 AM. state kinetic experiments. Furthermore, the color reaction of 2.5. Cu-MOF kinetics measurements TMB with H2O2 can be inhibited by some reductive substances. Based on these ndings, we obtained satised results with the Cu- First, 6 mg Cu-MOF solid was dispersed in 100 mL acetate buffer À1 MOF for colorimetric detection of H2O2, ascorbic acid, sodium (pH 4.0) to prepare 0.06 mg mL Cu-MOF solution. The thiosulfate and glucose. concentration of the TMB was xed at 0.2 mM and a series of H2O2 with different concentrations (10 mM–90 mM) were 2. Experimental prepared. During the reaction, 2.6 mL Cu-MOF solution, 0.1 mL H2O2 solution and 0.3 mL TMB were mixed with a total volume 2.1.