Oxidase-like Nanozyme Research Articles

Schiff-Base Chemistry-Coupled Catechol Oxidase-Like Nanozyme Reaction as a Universal Sensing Mode for Ultrasensitive Biosensing.

Expanding sensing modes and improving catalytic performance of nanozyme-based analytical chemistry are beneficial to realizing the desired biosensing of analytes. Herein, Schiff-base chemistry coupled with a novel catechol oxidase-like nanozyme (CHzyme) is designed and constructed, exhibiting two main advantages, including (1) improving catalytic performance by nearly 2-fold compared with only the oxidase-like role of CHzyme; (2) increasing the designability of the output signal by signal transduction of cascade reaction. Thereafter, the substrate sensing modes based on a cascade reaction between the CHzyme-catalyzed reaction and Schiff-base chemistry are proposed and comprehensively studied, containing catalytic substrate sensing mode, competitive substrate sensing mode, and generated substrate sensing mode, expecting to be employed in environmental monitoring, food analyses, and clinical diagnoses, respectively. More meaningfully, the generated substrate sensing mode is successfully applied to construct a cascade reaction coupling ratiometric fluorescent immunoassay for the detection of clenbuterol, increasing 15-fold in detection sensitivity compared with the traditional enzyme-linked immunosorbent assay. It is expected that the expanded universal substrate sensing modes and the Schiff-base chemistry-enhanced nanozyme can enlighten the exploration of innovative biosensors.

Co,N,S co-doped hollow carbon with efficient oxidase-like activity for the detection of Hg2+ and Fe3+ ions

Most nanozymes have limited catalytic ability, and constructing high performance nanozymes is important and challenging. Metal-carbon hybrid materials obtained by integrating transition metals into carbon can not only generate rich active sites, but also enhance their electrical conductivity. Heteroatom doping is shown to be an efficient strategy to improve the catalytic activity of carbon-based nanozymes. Here, by taking advantage of the structural merits of MOFs-derived porous carbon materials combined with sulfur doping strategy, the Co,N,S co-doped hollow carbon material, i.e. Co-N/S-HCN, was fabricated by pyrolyzing a thiomalic acid (TA) modified zeolitic imidazolate framework (ZIF-67@TA) in a nitrogen atmosphere. It exhibits hollow dodecahedron shape with rich defects, high BET specific surface area of 240.75 m2/g and pore volume of 0.27 cm3/g. The electrochemical characterization reveals the doping of S reduces the charge transfer resistance of the Co-N-HCN, accelerates electron transfer rate, and finally boosts its catalytic activity. The Co-N/S-HCN shows superior oxidase-like activity and can convert colorless 3,3′,5,5′-tetramethylbenzidine (TMB), o-phenylenediamine and 2,2′-azo-bis (3-ethylbenzothiazolin-6-sulfonic acid) diammonium salt into visible color substrates without hydrogen peroxide. The oxidase-like activity of Co-N/S-HCN was 2.1 times that of Co-N-HCN. The quenching trials revealed the generation of O2•−, •OH and 1O2 during catalytic TMB oxidation by Co-N/S-HCN. The Co-N/S-HCN oxidase-like nanozyme exhibited good affinity to TMB with a Km value of 0.25 mM and Vmax of 4.19 × 10−7 M s−1. In terms of Soft-Hard Acid-Base principle, Hg2+ combines easily with the sulfur. Thus, the introduction of Hg2+ ions can restrain TMB oxidation catalyzed by Co-N/S-HCN, thereby inhibiting the color reaction. In addition, the addition of 8-hydroxyquinoline can restrain TMB oxidation catalyzed by Co-N/S-HCN, resulting in a decrease in absorbance at 652 nm. However, the color reaction recovers in the presence of Fe3+, resulting in an increase in absorbance at 652 nm. In terms of above fact, a colorimetric sensing platform for determining Hg2+ and Fe3+ ions was established and successfully used for detecting Hg2+ in water samples and Fe3+ in liquors. This work offers a different way to prepare nanozymes with efficient oxidase-like activity and is of great significance for detecting heavy metal ions in environmental and food samples.

Nanozyme: a rising star for cancer therapy.

In recent years, nanozymes have attracted enormous attention due to their effectiveness in promoting various catalytic reactions. To date, thousands of nanozymes have been discovered, including oxidase-like nanozymes, peroxidase-like nanozymes, and catalase-like nanozymes, covering noble metal, transition metal, and carbon nanomaterials. These nanozymes have been widely applied in various fields, including environmental protection, biosensing and nanomedicine. There are many reviews about this rising star being used in analytical chemistry. However, few works about nanozymes were related to cancer therapy. In this study, we comprehensively summarize the latest research advances on the strategies for cancer therapy based on different nanozymes. With traditional cancer treatment (including chemotherapy, radiotherapy, phototherapy), nanozyme catalytic therapy exhibited a synergistic effect for limiting the growth of tumors. Opportunities and trends for nanozymes in future cancer therapy are also discussed.

Light-gated specific oxidase-like activity of a self-assembled Pt(II) nanozyme for environmental remediation.

Artificial enzyme equivalents, also known as nanozymes, are a practical tool for environmental remediation when compared to their natural counterparts due to their high operational stability, efficiency, and cost-effectiveness. Specific oxidase mimicking nanozymes are well suited to degrade toxic chemicals from industrial waste such as phenols and azo dyes. Therefore, photocatalytic nanozymes using visible/sunlight would provide a viable strategy for sustainable environmental remediation. Herein, we introduce an aggregation-induced emissive Pt(II) complex, which self-assembles in water providing NanoPtA nanotapes. These structures exhibit a specific oxidase-like nanozyme activity driven by light. The NanoPtA structure assists in the photogeneration of singlet oxygen in water via a triplet excited 3MMLCT state, leading to a specific oxidase-like activity instead of a peroxidase-like activity. The self-assembled nanozyme showed great stability under harsh environmental conditions and exhibited photo-induced specific oxidase-mimetic activity, which was considerably more efficient than the natural enzyme or other specific nanozymes. We demonstrated efficient NanoPtA-induced photocatalytic degradation of various phenolic compounds and azo dyes within 5-10 minutes of light irradiation. Notably, the system operates under sunlight and exhibits reusability over twenty cycles of catalytic reactions. Another fascinating aspect of NanoPtA is the unaltered catalytic performance for more than 75 days, providing a robust enzyme-equivalent for practical sustainable environmental remediation.

Zeolitic imidazolate frameworks as light-responsive oxidase-like mimics for the determination of adenosine triphosphate and discrimination of phenolic pollutants.

In this study, 3,3',5,5'-tetramethylbenzidine (TMB) was selected as a chromogenic substrate to evaluate the light-responsive oxidase-like activity of different zeolitic imidazolate frameworks (ZIFs). The synthesized ZIFs were systematically characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infraredspectroscopy, and X-ray diffraction analysis. Several main operational parameters, including ZIFs and TMB concentrations, pH value, radiation time, and working current, in the reaction process were optimized. The kinetic measurement results show that ZIF-90 exhibits higher affinity to thesubstrate than horseradish peroxidase. Furthermore, given that adenosine triphosphate (ATP) can specifically combine with Zn2+ binding site and destroy the structure of ZIF-90, a specific and sensitive colorimetric method was established for the quantitative detection of ATP within the range 10 - 240μM. In addition, on the basis that phenolic pollutants can impact the reaction kinetics diversely on different ZIFs, a sensor array was constructed and successfully applied to differentiate five phenolic pollutants in lake water samples. This work is expected to shed light on the establishment of ZIF-based light-responsive oxidase-like nanozymes for the highly selective colorimetric detection and sensor array.

2D Co metal-organic framework nanosheet as an oxidase-like nanozyme for sensitive biomolecule monitoring

2D Co metal-organic framework nanosheet as an oxidase-like nanozyme for sensitive biomolecule monitoring

Spectrophotometric Determination of Alkaline Phosphatase in Serum by A Copper Prussian Blue Analog as A Novel Polyphenol Oxidase-Like Nanozyme

Nanomaterials with natural enzyme-like activities have attracted widespread interest and hence their development is significant. Here, a copper Prussian blue analogue named Cu-HCF was prepared and its polyphenol oxidase (PPO)-like activity was investigated for the first time. Cu-HCF nanozyme showed nearly 7-fold higher substrate affinity than natural PPO and was more stable under alkaline conditions, high temperature, high salt concentrations, and long-time storage. The catalytic activity of Cu-HCF nanozyme was reduced by pyrophosphate (PPi). Alkaline phosphatase (ALP) hydrolyzed PPi to orthophosphate (Pi) and hence the PPO-like activity of Cu-HCF nanozyme was restored. A method was therefore developed for selective determination of the ALP activity. The linear range was from 1 to 50 mU/mL with a limit of detection (LOD) of 0.35 mU/mL. This approach was validated in human serum samples, showing its potential in diagnostic applications.

Ascorbate oxidase-like nanozyme with high specificity for inhibition of cancer cell proliferation and online electrochemical DOPAC monitoring

Despite the extensive investigation of the nanozymes exhibit their favorable performance compared to natural enzymes, nevertheless, the highly specific nanozyme still needs to be developed so that it can meet the requirements of exploring the mechanism as well as administration of related diseases and selective monitoring in biological system. In this study, self-assembled glutathione-Cu/Cu2O nanoparticles (GSH-Cu/Cu2O NPs) that exhibits specific ascorbic acid (AA) oxidase-like catalytic activity were constructed for AA-activated and H2O2-reinforced cancer cell proliferation inhibition and selective neurochemical monitoring. Cu/Cu2O NPs demonstrates effective AA oxidase-like activity and no common characteristics of other redox mimic enzymes often present in nanozyme. In particular, we found that the AA oxidase-like activity of GSH-Cu/Cu2O nanozyme was significantly improved by about 40% by improving the activation ability toward oxygen. The synthesized nanozyme can induce the generation of active oxygen by accelerating the oxidation of AA, which effectively suppresses the proliferation of cancer cells. We constructed an online electrochemical system (OECS) though loading nanozyme with enhanced ascorbate oxidase activity into a microreactor and setting it in the upstream of the detector. This GSH-Cu/Cu2O NPs-integrated microreactor can completely eliminate AA interference of the physical level toward 3,4-dihydroxy phenylacetic acid (DOPAC) electrochemical measurement, and the nanozyme-based OECS is able to continuously capture DOPAC alteration in rat brain acidosis model. Our findings may inspire rational design of nanozymes with high specificity as well as nanozyme-based selectivity solution for in vivo detection and show promising opportunities for their involvement in neurochemistry investigation.

Carbon dots as light-responsive oxidase-like nanozyme for colorimetric detection of total antioxidant capacity in fruits

Evaluation of total antioxidant capacity (TAC) in fruits is essential for dietary guidance and health monitoring. Here, we have exploited light-response carbon dots (CDs) as oxidase-like nanozyme to determine the TAC of fruits. The CDs possess excellent oxidase-like activity with light stimulation due to the accelerated intramolecular charge transfer caused by abundant electron donating/drawing groups in precursors. The scavenger experiment reveals that the catalytic intermediate could be hydroxyl radical, which can oxidize the colorimetric substrate. With the introduction of antioxidants, the oxidization of colorimetric substrate will be alleviated due to the scavenging of this intermediate by antioxidants. Based on this, we have successfully detected three antioxidants and obtained TAC of fruits with desirable results. This work affords a rapid, cost-effective and convenient analysis tool for TAC, as well as building a strong bridge between CDs and the development of photo-responsive oxidase-like nanozymes.

MnO2 Nanozyme-Mediated CRISPR-Cas12a System for the Detection of SARS-CoV-2.

The CRISPR-Cas system was developed into a molecular diagnostic tool with high sensitivity, low cost, and high specificity in recent years. Colorimetric assays based on nanozymes offer an attractive point-of-care testing method for their low cost of use and user-friendly operation. Here, a MnO2 nanozyme-mediated CRISPR-Cas12a system was instituted to detect SARS-CoV-2. MnO2 nanorods linked to magnetic beads via a single-stranded DNA (ssDNA) linker used as an oxidase-like nanozyme inducing the color change of 3,3',5,5'-tetramethylbenzidine, which can be distinguished by the naked eye. The detection buffer color will change when the Cas12a is activated by SARS-CoV-2 and indiscriminately cleave the linker ssDNA. The detection limit was 10 copies per microliter and showed no cross-reaction with other coronaviruses. The nanozyme-mediated CRISPR-Cas12a system shows high selectivity and facile operation, with great potential for molecular diagnosis in point-of-care testing applications.

Bioengineered Carboxymethylcellulose-Peptide Hybrid Nanozyme Cascade for Targeted Intracellular Biocatalytic-Magnetothermal Therapy of Brain Cancer Cells.

Glioblastoma remains the most lethal form of brain cancer, where hybrid nanomaterials biofunctionalized with polysaccharide peptides offer disruptive strategies relying on passive/active targeting and multimodal therapy for killing cancer cells. Thus, in this research, we report for the first time the rational design and synthesis of novel hybrid colloidal nanostructures composed of gold nanoparticles stabilized by trisodium citrate (AuNP@TSC) as the oxidase-like nanozyme, coupled with cobalt-doped superparamagnetic iron oxide nanoparticles stabilized by carboxymethylcellulose ligands (Co-MION@CMC) as the peroxidase-like nanozyme. They formed inorganic–inorganic dual-nanozyme systems functionalized by a carboxymethylcellulose biopolymer organic shell, which can trigger a biocatalytic cascade reaction in the cancer tumor microenvironment for the combination of magnetothermal–chemodynamic therapy. These nanoassemblies were produced through a green aqueous process under mild conditions and chemically biofunctionalized with integrin-targeting peptide (iRDG), creating bioengineered nanocarriers. The results demonstrated that the oxidase-like nanozyme (AuNP) was produced with a crystalline face-centered cubic nanostructure, spherical morphology (diameter = 16 ± 3 nm), zeta potential (ZP) of −50 ± 5 mV, and hydrodynamic diameter (DH) of 15 ± 1 nm. The peroxide-like nanostructure (POD, Co-MION@CMC) contained an inorganic crystalline core of magnetite and had a uniform spherical shape (2R = 7 ± 1 nm) which, summed to the contribution of the CMC shell, rendered a hydrodynamic diameter of 45 ± 4 nm and a negative surface charge (ZP = −41 ± 5 mV). Upon coupling both nanozymes, water-dispersible colloidal supramolecular vesicle-like organic–inorganic nanostructures were produced (AuNP//Co-MION@CMC, ZP = −45 ± 4 mV and DH = 28 ± 3 nm). They confirmed dual-nanozyme cascade biocatalytic activity targeted by polymer–peptide conjugates (AuNP//Co-MION@CMC_iRGD, ZP = −29 ± 3 mV and DH = 60 ± 4 nm) to kill brain cancer cells (i.e., bioenergy “starvation” by glucose deprivation and oxidative stress through reactive oxygen species generation), which was boosted by the magneto-hyperthermotherapy effect when submitted to the alternating magnetic field (i.e., induced local thermal stress by “nanoheaters”). This groundwork offers a wide avenue of opportunities to develop innovative theranostic nanoplatforms with multiple integrated functionalities for fighting cancer and reducing the harsh side effects of conventional chemotherapy.

Oxidase-like ZnCoFe Three-Atom Nanozyme as a Colorimetric Platform for Ascorbic Acid Sensing.

Great enthusiasm in single-atom catalysts for various catalytic reactions continues to heat up. However, the poor activity of the existing single/dual-metal-atom catalysts does not meet the actual requirement. In this scenario, the precise design of triple-metal-atom catalysts is vital but still challenging. Here, a triple-atom site catalyst of FeCoZn catalyst coordinated with S and N, which is doped in the carbon matrix (named FeCoZn-TAC/SNC), is designed. The FeCoZn catalyst can mimic the activity of oxidase by activating O2 into •O2- radicals by virtue of its atomically dispersed metal active sites. Employing this characteristic, triple-atom catalysts can become a great driving force for the development of novel biosensors featuring adequate sensitivity. First, the property of FeCoZn catalyst as an oxidase-like nanozyme was explored. The obtained FeCoZn-TAC/SNC shows remarkably enhanced catalytic performance than that of FeCoZn-TAC/NC and single/dual-atom site catalysts (FeZn, CoZn, FeCo-DAC/NC and Fe, Zn, Co-SAC/NC) because of trimetallic sites, demonstrating the synergistic effect. Further, the utility of the oxidase-like FeCoZn-TAC/SNC in biosensor field is evaluated by the colorimetric sensing of ascorbic acid. The nanozyme sensor shows a wide concentration range from 0.01 to 90 μM and an excellent detection limit of 6.24 nM. The applicability of the nanozyme sensor in biologically relevant detection was further proved in serum. The implementation of TAC in colorimetric detection holds vast promise for further development of biomedical research and clinical diagnosis.

Ultrathin covalent organic framework nanosheet-based photoregulated metal-free oxidase-like nanozyme

Ultrathin covalent organic framework nanosheet-based photoregulated metal-free oxidase-like nanozyme

Starvation, Ferroptosis, and Prodrug Therapy Synergistically Enabled by a Cytochrome c Oxidase like Nanozyme.

Nanozymes, which are inorganic nanomaterials mimicking natural enzyme activities, are bringing enormous opportunities to theranostics. Herein, a cytochrome c oxidase-like nanozyme (copper-silver alloy nanoparticle, Cu-Ag NP) is demonstrated for nanocatalytic cancer therapy. Loaded with bioreductive predrug (AQ4N), this Cu-Ag nanozyme unprecedentedly enables simultaneous starvation, ferroptosis, and chemical therapy with high specificity, and is able to totally eliminate tumor and greatly prolong the survival rate for 4T1-tumor-bearing mice. The underlying working mechanism is revealed both experimentally and theoretically.

Construction of Donor-Acceptor Heteroporous Covalent Organic Frameworks as Photoregulated Oxidase-like Nanozymes for Sensing Signal Amplification.

Nanomaterials with enzyme-like characteristics (called nanozymes) show their extreme potentials as alternatives to natural enzymes. Covalent organic frameworks (COFs) as metal-free nanozymes have attracted huge attention for catalytic applications due to their flexible molecular design and synthetic strategies and conjugated, porous, and chemically stable architectures. Designing high-performance two-dimensional (2D) porous COF materials embedded with functional building units for modulating nanozymes' catalytic activity is of immense importance in contemporary research. The proper combination of donor-acceptor (D-A) fragments within a porous COF skeleton is an effective strategy to decrease the band gap and provide a strong charge-transfer pathway for highly effective charge separation. Herein, two donor-acceptor heteroporous COFs using an electron-deficient 4,4'-(thiazolo[5,4-d]thiazole-2,5-diyl)dibenzaldehyde (Tz) unit or 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzaldehyde (Td) unit and electron-rich tetrakis(4-aminophenyl)ethane (ETTA) linkers were presented. The resulting crystalline and heteroporous COFs showed outstanding oxidase-like activity under light irradiation, which can catalyze the oxidation of typical substrates and corresponding evolution in color and absorption. The light-activatable ETTA-Tz COF with prominent oxidase-like activity can serve as a colorimetric probe for quantitative detection of sulfide ions with a linear range of 1-50 μM and a detection limit of 0.27 μM within 3 min. The colorimetric approach could also be used for sulfide ion detection in human serum samples. The research demonstrated the future potential of D-A motifs within fully conjugated COFs to obtain excellent mimic enzyme activity.

Mesoporous Core-Shell Pd@Pt Nanospheres as Oxidase Mimics with Superhigh Catalytic Efficiency at Room Temperature.

Mesoporous Pt-Pd bimetallic core-shell nanospheres (mPd@Pt NSs) with palladium-rich cores and platinum-rich shells were synthesized via a simple, two-step, wet chemical strategy mediated by nitrogen-doped carbon dots. The BET surface area of mPd@Pt NSs was found to be 210.4 m2·g-1, which is significantly higher than the currently reported unsupported Pt-based nanomaterials. Because of the large active surface area, the as-prepared mPd@Pt NSs show superhigh oxidase activity and exhibit excellent oxidase-like catalytic efficiency with a catalytic constant (Kcat) as high as 2.1 × 103 s-1 at room temperature, which is of the same order of magnitude as the natural horseradish peroxidase (HRP) (Kcat = 4.3 × 103 s-1) at 37 °C and five-fold greater than the reported Kcat values of oxidase-like nanozyme obtained at 30 °C.

Heterojunction MnO2-nanosheet-decorated Ag nanowires with enhanced oxidase-like activity for the sensitive dual-mode detection of glutathione.

The biocatalytic design of nanomaterials with enzyme-like activity is considered a reliable and promising toolkit for the generation of diagnostic agents in complex biological microenvironments. However, the preparation of nanomaterials while maintaining a high catalytic activity in tumor cells (pH 6.0-6.5) poses a prominent challenge. Herein, we constructed a biomimetic enzyme-trigged dual-mode system with colorimetry at 652 nm and photothermal biosensors to detect glutathione based on hollow MnO2-nanosheet-decorated Ag nanowires (Ag@MnO2) as an oxidase-like nanozyme. As expected, Ag@MnO2 catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the absence of H2O2, leading to a blue-colored oxidized TMB (oxTMB) that displayed oxidase-like activity in pH 6.0. Interestingly, the portable dual-mode colorimetry and photothermal method for GSH was developed based on the redox reaction between GSH and oxTMB. This detection method exhibited a wide linear range of 0.1-55 μM for GSH with a low detection limit of 0.08 μM. This work highlights a new insight into nanotechnology by taking advantage of biomimetic design in biological analysis.

Coupling diazotization with oxidase-mimetic catalysis to realize dual-mode double-ratiometric colorimetric and electrochemical sensing of nitrite

Nitrite is often utilized as coloring and preservative agents in food industry, but excessive nitrite in drinking water and food causes great threats to human health, requiring convenient and reliable methods for its monitoring. In comparison with common single-signal assays, multimodal detection can not only expand application scenarios but also offer self-correction and self-validation to obtain more reliable results. However, how to achieve the multimodal sensing of nitrite remains a challenge. Here we report a novel dual-mode double-ratiometric colorimetric and electrochemical method for nitrite quantification by coupling diazotization with oxidase-mimicking catalysis. Carbon-supported Mn3O4 particles were explored as an oxidase-like nanozyme with excellent activity to catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue TMBox. On the one hand, the presence of nitrite can induce the diazotization of TMBox, not only decreasing the visible signal of TMBox at 652 nm but also generating a new signal assigned to diazotized TMBox at 445 nm. On the other hand, the existence of nitrite triggers the decrease of the TMB homogeneous electro-oxidation signal, but offers a new electro-oxidation signal attributed to nitrite itself. With such an interesting sensing principle, a dual-mode double-ratiometric colorimetric and electrochemical approach was developed to detect nitrite with good sensitivity and specificity. Reliable applications of the method in monitoring nitrite in several matrices were also demonstrated, implying its great promise in food safety supervision and environmental monitoring.

Peroxidase-like and oxidase-like nanozyme activities of reusable Mn–Co–S–Se/Ni foam for antibacterial application

Developing a stable and reusable material for antibacterial application in an enzyme-like system is still a challenge. Herein, Mn–Co–S–Se (MnCo2SxSe4–x)/Ni foam (NF) are synthesized by introducing S2– and Se2– in MnCo2O4/NF with a facile hydrothermal approach. With the different molar ratios of S/Se, the surface morphology of MnCo2SxSe4–x/NF shows different growth and the catalytic activity also presents regular changes. MnCo2S3.1Se0.9/NF possesses a high enzyme-like ability with higher Vmax than natural horseradish peroxidase. Due to the outstanding peroxidase-like activity, MnCo2S3.1Se0.9/NF also exhibits broad-spectrum bactericidal performance towards Escherichia coli and Staphylococcus aureus which stems from the formation of ·O2– from H2O2. In the reutilization experiment, the enzyme-like activity keeps a stable value after 25 cyclic tests and the bactericidal performance is still stable after 10 cyclic tests, proving that MnCo2S3.1Se0.9/NF possesses relative stability and reusability. This research showed the great prospect of new energy and environmental catalysis.

Dextran-stabilized Fe-Mn bimetallic oxidase-like nanozyme for total antioxidant capacity assay of fruit and vegetable food

The total antioxidant capacity (TAC) has become increasingly vital for evaluating antioxidant food quality in the field of healthcare. Herein, a convenient and sensitive method for TAC assay was proposed based on the absorbance difference of reaction systems between various antioxidants existed in food and Dex-FeMnzyme/oxTMB. Under the optimum condition, the limit of detection (LOD) of the colorimetric sensor was 1.17 μM with the linear concentration range from 1 μM to 30 μM. The analysis results demonstrated the excellent feasibility of practical application in fruit and vegetable food, which offered a new avenue for the establishment of colorimetric biosensors.