Light-enhanced non-lead halide nanoscale enzyme and preparation method and application thereof

Abstract

The application discloses a light-enhanced non-lead halide nanoscale enzyme and a preparation method and application thereof, and belongs to the technical field of nanoscale enzymes and biological detection. 4+ / Er 3+ The co-doped Cs2SnCl6 system is expanded from a near-infrared light-emitting material to a nanoscale enzyme field, the nanomaterial is prepared by a mechanical chemical grinding method, has the near-infrared light-emitting property, and is found to have peroxidase-like activity and catalase-like activity for the first time, and the catalytic activity is significantly enhanced under light conditions. Based on the excellent catalytic performance of the material, a TMB-H2O2 colorimetric system for ascorbic acid detection is constructed, the detection limit is low, the sensitivity is high, and the system can be applied to serum sample analysis and paper-based visual rapid detection. The application realizes the functional leap of a non-lead halide material from'single light emission' to 'catalysis-detection integration', the preparation process is simple, and a new technical scheme is provided for the biological sensing and instant diagnosis field.

Description

Technical Field

[0001] This invention relates to the field of lead-free metal halide nanomaterials, specifically to an ion-doped, light-enhanced lead-free halide nanoenzyme, its preparation method, and its application in biological detection. Background Technology

[0002] Nanozymes are a class of artificial nanomaterials that can mimic the catalytic function of natural enzymes. They possess advantages such as simple preparation, high stability, and low cost, and have attracted widespread attention in fields such as disease diagnosis and treatment, food safety monitoring, and environmental analysis. However, current mainstream nanozyme systems are still mainly based on Fe3O4, CeO2, MnO2, noble metal nanoparticles, and carbon-based materials, which generally suffer from problems such as a limited number of active sites, insufficient catalytic efficiency, weak photoresponse, and difficulty in simultaneously possessing both luminescent and catalytic functions. Especially for biocolorimetric detection, if the material itself cannot simultaneously provide catalytic amplification and optical signal modulation capabilities, the detection system often needs to introduce additional fluorescent probes, chromogenic substrates, or multi-component reaction systems, leading to system complexity, increased background interference, and limiting its application in rapid detection and paper-based visualization detection.

[0003] Cs₂SnCl₆ is a typical lead-free defect-derived double perovskite material with good chemical stability and low biotoxicity. Existing techniques utilize ion doping strategies to modulate its optical properties; however, the primary aim of these studies remains improving luminescence efficiency, controlling photoluminescence, or enhancing photoelectric properties. The resulting materials are micrometer-sized crystals, without addressing their nanozyme catalytic function. Because micrometer-sized crystals typically have a small specific surface area and insufficient exposure of surface active sites, they cannot adequately meet the requirements of high interfacial contact area and high reaction site density in nanozyme catalysis. Therefore, this type of luminescent material cannot directly solve the problems of insufficient catalytic efficiency and detection sensitivity in biocolorimetric detection. Furthermore, some studies have used Cs₂SnCl₆ for photocatalytic degradation or purification of pollutants, focusing on environmental / energy catalysis, without addressing the nanozyme catalytic mechanism or its application in biodetection.

[0004] Regarding patents, existing published patents (such as CN114835546A, WO2021095052A1, US10388898B2, etc.) all focus on luminescence performance, photoelectric performance, or material stability, and none of them involve the nanoenzyme catalytic function and biological detection application of Cs2SnCl6 materials.

[0005] In summary, existing technologies face at least the following technical obstacles that need to be overcome. First, traditional nanozymes mostly lack luminescence and photoresponsive functions, making it difficult to integrate luminescence, catalysis, and detection. Second, existing ion-doped Cs₂SnCl₆ is mostly micron-sized crystals with limited specific surface area and surface active sites, and is primarily used for near-infrared luminescence, without exploring its nanozyme catalytic function. Third, existing Cs₂SnCl₆ photocatalytic technologies mainly serve pollutant degradation, do not involve biocolorimetric detection, and have not disclosed Te-based photocatalysis. 4+ / Er 3+ A scheme for POD / CAT dual enzyme activity, photo-enhanced catalysis, and ascorbic acid detection of co-doped Cs2SnCl6 nanomaterials.

[0006] Therefore, developing an ion-doped Cs2SnCl6 nanoenzyme material that combines near-infrared luminescence, dual enzyme activity, photo-enhanced catalytic ability, and biodetection function is of great scientific significance and application value. Summary of the Invention

[0007] To address the shortcomings in the development of catalytic functions of lead-free halide materials, the lack of photoresponsive nanozyme systems, limited detection sensitivity, and the difficulty in integrating luminescence, catalysis, and detection functions in existing technologies, this invention provides a photoenhanced lead-free halide nanozyme, its preparation method, and its applications.

[0008] On one hand, the present invention provides a light-enhanced lead-free halide nanozyme, wherein the nanozyme is Te 4+ and Er 3+ The co-doped Cs2SnCl6 nanomaterials exhibit near-infrared luminescence properties, peroxidase-like activities, and catalase-like activities, with the peroxidase-like and catalase-like activities being significantly enhanced under light irradiation.

[0009] Furthermore, the Te in the nanozyme 4+ The doping concentration is 0.1–10 mol%, preferably 0.5–5 mol%; Er 3+ The doping concentration is 0.1–20 mol%, preferably 1–10 mol%.

[0010] On the other hand, the present invention provides a method for preparing the above-mentioned light-enhanced lead-free halide nanozyme, comprising the following steps:

[0011] (1) Precursor preparation: Weigh cesium chloride (CsCl), tin tetrachloride (SnCl4), tellurium tetrachloride (TeCl4), and erbium trichloride (ErCl3) as precursor raw materials, and mix them evenly to obtain a mixed precursor raw material; wherein Te 4+ The doping concentration is 0.1–10 mol%, Er 3+ The doping concentration is 0.1–20 mol%;

[0012] (2) Mechanochemical grinding: The mixed precursor raw materials from step (1) are placed in a mechanochemical reaction apparatus, and auxiliary liquid is added to carry out the grinding reaction. The reaction time is 10 to 120 min and the reaction temperature is room temperature.

[0013] (3) Product collection: After the reaction is complete, the powder obtained is collected to obtain Te. 4+ / Er 3+ Co-doped Cs2SnCl6 nanoenzyme material.

[0014] Preferably, in step (1), Te 4+ The doping concentration is 0.5–5 mol%, Er 3+ The doping concentration is 1–10 mol.

[0015] Preferably, in step (2), the auxiliary liquid is selected from one or a combination of ethanol, isopropanol, acetonitrile, and ionic liquids, and the amount added is 5-100 μL of auxiliary liquid per 100 mg of mixed precursor raw material. The addition of auxiliary liquid can improve the mixing uniformity of the precursor and promote the formation of nanoparticles.

[0016] Preferably, the auxiliary liquid is 1-butyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0017] Preferably, the mechanochemical reaction device is an agate mortar or a planetary ball mill, and the reaction time is 20 to 60 minutes.

[0018] In another aspect, the present invention provides the application of the above-mentioned light-enhanced lead-free halide nanozyme in the preparation of detection products for bioreducible molecules, wherein the detection products include kits or biosensors.

[0019] Furthermore, the bioreducing molecule is ascorbic acid; the detection product is achieved by constructing a TMB-H2O2 colorimetric system, specifically including: using the nanozyme to catalyze the activation and oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by hydrogen peroxide to generate a blue product, the ascorbic acid in the sample to be tested causes the blue product to be reduced and faded, and the detection is achieved by measuring the change in absorbance at 652 nm.

[0020] Furthermore, the present invention provides a colorimetric detection method for ascorbic acid, comprising the following steps:

[0021] (1) The light-enhanced lead-free halide nanozyme, hydrogen peroxide and 3,3',5,5'-tetramethylbenzidine (TMB) prepared above were added to the buffer solution and mixed to form a colorimetric system.

[0022] The concentration of the nanozyme is preferably 0.1–10 mg / mL, more preferably 0.5–5 mg / mL, and even more preferably 2.5 mg / mL; the concentration of hydrogen peroxide is preferably 1–1000 μM, more preferably 10–200 μM, and even more preferably 50 μM; the concentration of TMB is preferably 0.1–20 mM, more preferably 1–10 mM, and even more preferably 4 mM.

[0023] The buffer solution is a buffer system with a pH of 3.0–7.0, preferably pH 4.0–6.0, and more preferably pH 5.0, an acetate-sodium acetate buffer solution. The total volume of the colorimetric system is preferably 0.5–10 mL, more preferably 1–5 mL. Under the catalysis of nanozymes, hydrogen peroxide is activated to generate reactive oxygen species such as hydroxyl radicals, which further oxidize TMB to generate a blue oxidation product (ox-TMB), producing a characteristic absorption signal at 652 nm. In a preferred embodiment, the volume ratio of nanozyme, hydrogen peroxide, and TMB is (0.5–5):(0.5–5):(0.5–5); more preferably 1:1:1.

[0024] (2) Add the sample to be tested to the color development system in step (1). If the sample to be tested contains ascorbic acid, the blue oxidation product will be reduced, resulting in a decrease in absorbance at 652 nm.

[0025] (3) The concentration of ascorbic acid was quantitatively detected by measuring the change in absorbance at 652 nm and based on the pre-established standard curve between the change in absorbance and the concentration of ascorbic acid.

[0026] Preferably, in the detection method, step (2) further includes a step of carrying out a catalytic reaction under illumination to enhance the detection sensitivity, wherein the illumination is selected from white LED, xenon lamp, visible light source or near-infrared light source.

[0027] In another aspect, the present invention provides a paper-based visualization detection platform, which fixes the light-enhanced lead-free halide nanozyme, hydrogen peroxide and 3,3',5,5'-tetramethylbenzidine prepared above onto the surface of filter paper for rapid visualization detection of ascorbic acid, especially for the detection of ascorbic acid in serum samples.

[0028] The beneficial effects of this invention are:

[0029] (1) Implemented Te 4+ The construction of rare-earth ion co-doped Cs₂SnCl₆ nanozymes expands the functional application range of lead-free halide materials.

[0030] Existing publicly available technologies mainly include Te 4+ / Er 3+Co-doped Cs₂SnCl₆ is used for near-infrared luminescence research, and this invention is the first to apply this system to the field of nanozymes. Through Te... 4+ Synergistic regulation with rare earth ions and the construction of nanostructures enable the material to possess both catalytic and photoresponsive capabilities, enabling lead-free halide materials to expand from a single luminescent function to catalytic and detection functions, and providing a new application direction for the development of lead-free double perovskite materials.

[0031] (2) Nanostructures significantly improve the utilization efficiency of surface active sites and catalytic reaction efficiency.

[0032] This invention uses a mechanochemical method to prepare nanoscale Te 4+ Rare earth ion co-doped Cs₂SnCl₆ particles. Compared to previously reported micron-sized Te particles... 4+ / Er 3+ Co-doped Cs2SnCl6 luminescent materials have nanoparticles with higher specific surface area, shorter electron transport paths, and more exposed active sites, which is conducive to full contact between reactants and catalytic centers, improving the adsorption and activation capacity of H2O2, thereby improving the efficiency of catalytic reaction.

[0033] (3) For the first time, the integration of the activities of peroxidase-like and catalase-like enzymes was achieved.

[0034] The light-enhanced lead-free halide nanozyme prepared in this invention not only catalyzes the generation of hydroxyl radicals (·OH) from H₂O₂ and further oxidizes 3,3',5,5'-tetramethylbenzidine (TMB), exhibiting significant peroxidase-like activity, but also promotes the decomposition of H₂O₂ to produce oxygen, exhibiting catalase-like activity. The synergistic effect of these two enzyme activities improves the utilization efficiency of hydrogen peroxide. This nanozyme can function as a peroxidase-like enzyme and / or a catalase-like enzyme, expanding its application scenarios in biocatalysis and analytical detection.

[0035] (4) Photoenhanced catalysis was achieved, which improved the reactive oxygen species generation capacity and detection sensitivity.

[0036] This invention introduces rare-earth photoresponsive centers, endowing the material with both photoresponsive properties and catalytic activity. Under illumination, the light-enhanced lead-free halide nanozymes prepared by this invention can effectively utilize external light energy to promote electron migration and interfacial redox reactions, increasing the efficiency of reactive oxygen species generation, thereby enhancing the catalytic performance of peroxidase-like and catalase-like enzymes. Compared with dark conditions, the catalytic efficiency is significantly improved under illumination, which is beneficial for further enhancing the sensitivity of biological detection.

[0037] (5) An ascorbic acid detection system based on nanozyme catalysis was established.

[0038] This invention utilizes nanozymes to catalyze the oxidation of TMB to generate a blue oxidation product, and then achieves a signal response through the reduction of the oxidation product by ascorbic acid, thus constructing an ascorbic acid colorimetric detection system. This method is simple to operate, has a fast response speed, and low detection cost. It can detect target analytes without complex instruments and has good practical application value.

[0039] (6) It has achieved the ability to detect complex biological samples.

[0040] The detection system established by this invention can be applied to the analysis of complex biological samples such as serum, realizing the quantitative detection of target substances in actual samples, thus improving the practicality and promotion value of the detection system.

[0041] (7) A paper-based visual inspection platform was constructed.

[0042] This invention immobilizes nanozymes on the surface of a paper-based carrier to construct a portable paper-based detection platform. Results can be directly interpreted through color changes during the detection process, eliminating the need for large instruments and equipment. It offers advantages such as simple operation, low cost, and ease of on-site testing, providing a new technical solution for point-of-care testing (POCT).

[0043] (8) It realizes the integration of luminescence-catalysis-detection functions.

[0044] The light-enhanced lead-free halide nanozymes prepared in this invention simultaneously possess near-infrared luminescence properties, dual-enzyme activity, and biodetection capabilities, achieving the integration of luminescence, catalysis, and detection functions. Compared to existing single-functional materials, this invention offers higher functional integration and a wider range of applications, providing a new technical route for developing novel multifunctional lead-free halide nanoplatforms.

[0045] (9) The preparation process is simple and easy to scale up.

[0046] This invention uses a mechanochemical method to prepare materials, which does not require high temperature and high pressure reaction conditions. It has the advantages of short reaction time, low energy consumption, simple equipment requirements and easy large-scale production, and has good prospects for industrial application. Attached Figure Description

[0047] Figure 1 This is a schematic diagram illustrating the overall technical route of a specific embodiment of the present invention.

[0048] Figure 2 This is a schematic diagram of the overall process of the present invention.

[0049] Figure 3 This is a schematic diagram of the detection system according to a specific embodiment of the present invention.

[0050] Figure 4 Example 1 of the present invention, Te 4+ / Er 3+XRD pattern of co-doped Cs2SnCl6 nanomaterials.

[0051] Figure 5 Example 1 of the present invention, Te 4+ / Er 3+ TEM image of co-doped Cs2SnCl6 nanomaterials.

[0052] Figure 6 Example 1 of the present invention, Te 4+ / Er 3+ Near-infrared emission spectrum of co-doped Cs2SnCl6 nanomaterials.

[0053] Figure 7 This is a diagram showing the peroxidase-like catalytic results of the nanozyme of this invention.

[0054] Figure 8 This is a diagram showing the catalase-like catalytic results of the nanozyme of this invention.

[0055] Figure 9 This is a diagram showing the photo-enhanced catalytic results of the nanozyme of this invention.

[0056] Figure 10 The figure shows the results of the nanozyme of this invention used for ascorbic acid detection and its application in actual samples. Detailed Implementation

[0057] This invention provides a method for preparing a light-enhanced lead-free halide nanozyme, comprising the following steps:

[0058] (1) Precursor preparation: Cesium chloride (CsCl), tin tetrachloride (SnCl4), tellurium tetrachloride (TeCl4), and erbium trichloride (ErCl3) are weighed as precursor raw materials and mixed evenly to obtain a mixed precursor raw material; wherein, the molar ratio of cesium source to tin source is preferably 1.5-2.5:1, more preferably 1.8-2.2:1, and more preferably 2:1, to ensure the formation of the Cs2SnCl6 main lattice; wherein Te 4+ The doping concentration can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, or 10 mol%, Er 3+ The doping concentration can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, or 20.0 mol%; preferably, Te 4+The doping concentration is 0.5–5 mol%, Er 3+ The doping concentration is 1–10 mol.

[0059] (2) Mechanochemical grinding: The mixed precursor raw materials from step (1) are placed in a mechanochemical reaction apparatus, and an auxiliary liquid is added. The auxiliary liquid is selected from one or more combinations of ethanol, isopropanol, acetonitrile, and ionic liquid. The amount of auxiliary liquid added is 5-100 μL per 100 mg of mixed precursor raw materials. The grinding reaction is carried out for 10-120 min, preferably 20-90 min, and more preferably 30-60 min. The grinding speed is 5000-30000 r / min, preferably 10000-25000 r / min, and more preferably 18000-25000 r / min. The ball-to-material ratio (the ratio of the mass of the grinding balls to the total mass of the precursor) is 5:1-50:1, preferably 10:1-30:1. The diameter of the grinding balls is 1-20 mm, preferably 3-10 mm. The reaction temperature is room temperature.

[0060] Preferably, the auxiliary liquid is 1-butyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium tetrafluoroborate. The mechanochemical reaction apparatus is an agate mortar or a planetary ball mill, and the reaction time is preferably 20–60 min.

[0061] (3) Product collection: After the reaction is complete, the powder obtained is collected to obtain Te. 4+ / Er 3+ Co-doped Cs2SnCl6 nanoenzyme material.

[0062] The present invention will be further described below with reference to specific embodiments, such as... Figure 1 As shown, the overall technical route includes steps such as raw material preparation, mechanochemical preparation, obtaining nanozymes, detecting enzyme activity, photo-enhanced catalysis, ascorbic acid colorimetric detection, and paper-based detection.

[0063] Example 1

[0064] This embodiment provides a method for preparing light-enhanced lead-free halide nanozymes, such as... Figure 2 As shown, it includes the following steps:

[0065] (1) Precursor preparation: Weigh 0.0840 g of cesium chloride (CsCl), 0.0520 g of tin tetrachloride (SnCl4), 0.0080 g of tellurium tetrachloride (TeCl4) and 0.0152 g of erbium trichloride (ErCl3) as precursor raw materials, and mix them evenly to obtain a mixed precursor raw material; wherein Te 4+ The doping concentration is 2 mol%, Er 3+The doping concentration is 5 mol%;

[0066] (2) Mechanical and chemical grinding: The mixed precursor raw materials from step (1) were placed in an agate mortar, and 20 μL of 1-butyl-3-methylimidazolium chloride was added as an auxiliary liquid. The mixture was mechanically and chemically ground for 30 min at room temperature. The reaction time was 30 min.

[0067] (3) Product collection: After the reaction is complete, the powder obtained is collected to obtain Te. 4+ / Er 3+ Co-doped Cs2SnCl6 nanoenzyme material.

[0068] like Figure 3 As shown, the detection system of the present invention includes a sample processing unit, a nanozyme reaction unit, a light enhancement unit, a signal acquisition unit, and a result analysis unit. The sample processing unit is used for preprocessing ascorbic acid standard samples, serum samples, and paper-based detection samples; the nanozyme reaction unit is used to complete the catalytic colorimetric reaction; the light enhancement unit is used to provide visible or near-infrared light illumination; the signal acquisition unit is used to acquire absorbance change signals; and the result analysis unit is used to output detection results based on a standard curve.

[0069] Material characterization:

[0070] like Figure 4 As shown, the Te prepared in Example 1 4+ / Er 3+ The X-ray diffraction (XRD) peaks of the co-doped Cs₂SnCl₆ nanozyme material are consistent with the standard crystal phase of Cs₂SnCl₆, indicating that Te 4+ and Er 3+ It successfully entered the crystal lattice without disrupting the main structure. For example... Figure 5 As shown, transmission electron microscopy (TEM) results indicate that the obtained sample exhibits a uniform nanoparticle morphology and good dispersibility. The nanoscale structure significantly increases the specific surface area of ​​the material and enhances the exposure of surface active sites, thereby facilitating catalytic reactions. Figure 6 As shown, the material exhibits Er 3+ The characteristic near-infrared emission peak (~1540 nm) indicates that the material maintains good photoresponse characteristics.

[0071] Enzymatic performance testing:

[0072] • Peroxidase-like activity: The nanozyme was added to acetate buffer (pH 4.0), followed by the addition of hydrogen peroxide and 3,3',5,5'-tetramethylbenzidine (TMB). For example... Figure 7As shown, under the catalysis of nanozymes, hydrogen peroxide is activated and further oxidizes TMB to generate a blue oxidation product (ox-TMB), which shows a significant absorption peak at 652 nm, thus proving that the material has peroxidase-like activity.

[0073] • Catalase-like activity: Nanozymes were added to a hydrogen peroxide solution, and the amount of oxygen generated was measured using a dissolved oxygen detector. For example... Figure 8 As shown, oxygen generation was detected, indicating that the material has catalase-like activity and can catalyze the decomposition of hydrogen peroxide to produce oxygen.

[0074] • Through the two catalytic reactions described above, the material of this invention simultaneously possesses both peroxidase-like and catalase-like dual enzyme activities.

[0075] • Photo-enhanced catalysis: Under the same reaction conditions, a dark state group and a light state group (white LED) are set up. For example... Figure 9 As shown, the absorption intensity of the illuminated group at 652 nm is significantly higher than that of the dark group, about 2.3 times that of the dark group, indicating that illumination can significantly enhance the catalytic activity of the material, thereby achieving photo-enhanced catalytic effect.

[0076] Applications of ascorbic acid detection:

[0077] • Colorimetric detection: First, a colorimetric system is constructed using nanozymes, hydrogen peroxide, and TMB to generate blue ox-TMB. Then, different concentrations of ascorbic acid (0-100 μM) are added. For example... Figure 10 As shown, the absorbance at 652 nm decreases with increasing ascorbic acid concentration. By establishing a standard curve between absorbance change and ascorbic acid concentration, quantitative detection of ascorbic acid can be achieved, and this method can be used for spiked recovery experiments of ascorbic acid in human serum samples.

[0078] • Paper-based detection: Nanozymes are dispersed in deionized water to prepare a nanozyme dispersion with a concentration of 0.5–10 mg / mL, preferably 1–5 mg / mL, and more preferably 2.5 mg / mL. The nanozyme dispersion, hydrogen peroxide solution, and 3,3',5,5'-tetramethylbenzidine (TMB) solution are mixed in a predetermined ratio and then dropped onto the surface of filter paper. The mixture is dried at room temperature or below 40 °C to obtain a paper-based detection platform with a pre-loaded colorimetric system. During detection, the sample containing ascorbic acid is dropped onto the surface of the paper-based detection platform. Because the pre-formed oxidized TMB (ox-TMB) on the paper surface can be reduced by ascorbic acid, the paper color gradually changes from dark blue to light blue until it becomes nearly colorless as the ascorbic acid concentration increases. The reaction time is preferably 1–10 min, more preferably 5 min. Semi-quantitative detection of ascorbic acid by the naked eye or quantitative detection by image analysis is achieved based on the degree of color change of the paper. In a preferred embodiment, the hydrogen peroxide concentration is 10–500 μM, more preferably 50 μM; the TMB concentration is 0.5–10 mM, more preferably 4 mM.

[0079] Example 2

[0080] This embodiment, based on the above experimental method, can produce Te 4+ / Er 3+ The co-doped Cs₂SnCl₆ nanozyme material is used in the preparation of detection products for bioreducing molecules, including kits or biosensors. The bioreducing molecule is ascorbic acid.

[0081] Example 3

[0082] This embodiment provides a colorimetric detection method for ascorbic acid, including the following steps:

[0083] (1) 1.0 mL of light-enhanced lead-free halide nanozyme with a concentration of 2.5 mg / mL, 1.0 mL of hydrogen peroxide with a concentration of 50 μM and 1.0 mL of 3,3',5,5'-tetramethylbenzidine (TMB) with a concentration of 4 mM prepared in the above example were mixed in acetic acid buffer to form a colorimetric system. Under the catalysis of the nanozyme, hydrogen peroxide was activated and further oxidized TMB to generate a blue oxidation product (ox-TMB).

[0084] (2) Add the sample to be tested to the color development system of step (1). If the sample to be tested contains ascorbic acid, the blue oxidation product is reduced, resulting in a decrease in absorbance at 652 nm. The step of carrying out a catalytic reaction under illumination to enhance the detection sensitivity, wherein the illumination conditions are selected from white LED, xenon lamp, visible light source or near-infrared light source.

[0085] (3) The concentration of ascorbic acid was quantitatively detected by measuring the change in absorbance at 652 nm and based on the pre-established standard curve between the change in absorbance and the concentration of ascorbic acid.

[0086] Example 4

[0087] This embodiment provides a paper-based visualization detection platform for the rapid visualization detection of ascorbic acid, particularly for the detection of ascorbic acid in serum samples. Specifically, a 2.5 mg / mL light-enhanced lead-halide nanoenzyme dispersion, a 50 μM hydrogen peroxide solution, and a 4 mM 3,3',5,5'-tetramethylbenzidine (TMB) solution are mixed evenly and then drop-coated onto the surface of filter paper. After drying at room temperature, a paper-based detection platform with a pre-loaded colorimetric system is obtained.

[0088] During detection, the ascorbic acid sample to be tested is dropped onto the surface of the paper-based detection platform. The nanoenzyme pre-loaded on the paper surface catalyzes the oxidation of TMB by hydrogen peroxide to generate a blue oxidation product (ox-TMB). Ascorbic acid further reduces ox-TMB, causing the paper's color to gradually change from dark blue to light blue until it becomes nearly colorless. After 5 minutes of reaction, the degree of color change allows for semi-quantitative detection of ascorbic acid by visual inspection or quantitative detection by image analysis.

[0089] In one specific embodiment, the paper-based detection platform is prepared using filter paper discs with a diameter of 6 mm. Each disc is loaded with 50 μL of nanoenzyme dispersion, 50 μL of hydrogen peroxide solution, and 50 μL of TMB solution.

Claims

1. A light-enhanced lead-free halide nanoenzyme, characterized in that: The nanozyme is Te 4+ and Er 3+ The co-doped Cs2SnCl6 nanomaterials exhibit near-infrared luminescence, peroxidase-like activity, and catalase-like activity, with the peroxidase-like and catalase-like activities being significantly enhanced under light irradiation.

2. The light-enhanced lead-free halide nanoenzyme according to claim 1, characterized in that: Te in nanozymes 4 + The doping concentration is 0.1–10 mol%; Er 3+ The doping concentration is 0.1–20 mol%.

3. A method for preparing a light-enhanced lead-free halide nanozyme, characterized in that: Includes the following steps: (1) Precursor preparation: Weigh cesium chloride, tin tetrachloride, tellurium tetrachloride and erbium trichloride as precursor raw materials, mix them evenly to obtain mixed precursor raw materials; wherein Te 4+ The doping concentration is 0.1–10 mol%, Er 3+ The doping concentration is 0.1–20 mol%; (2) Mechanochemical grinding: The mixed precursor raw materials from step (1) are placed in a mechanochemical reaction apparatus, and auxiliary liquid is added to carry out the grinding reaction. The reaction time is 10 to 120 min and the reaction temperature is room temperature. (3) Product collection: After the reaction is complete, the powder obtained is collected to obtain Te. 4+ / Er 3+ Co-doped Cs2SnCl6 nanozyme materials.

4. The method for preparing a light-enhanced lead-free halide nanozyme according to claim 3, characterized in that: In step (1), Te 4+ The doping concentration is 0.5–5 mol%, Er 3+ The doping concentration is 1–10 mol.

5. The method for preparing a light-enhanced lead-free halide nanozyme according to claim 3, characterized in that: In step (2), the auxiliary liquid is selected from one or a combination of ethanol, isopropanol, acetonitrile and ionic liquid, and the amount added is 5 to 100 μL of auxiliary liquid per 100 mg of mixed precursor raw material; the ionic liquid is 1-butyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium tetrafluoroborate.

6. The application of the light-enhanced lead-free halide nanozyme according to any one of claims 1-2, or the application of the light-enhanced lead-free halide nanozyme prepared by any one of claims 3-5, characterized in that: Applications in the preparation of detection products for bioreducible molecules.

7. The application according to claim 6, characterized in that: The bioreducing molecule is ascorbic acid; the detection product is achieved by constructing a TMB-H2O2 colorimetric system, which utilizes the nanozyme to catalyze the activation and oxidation of 3,3',5,5'-tetramethylbenzidine by hydrogen peroxide to generate a blue product. The ascorbic acid in the sample to be tested causes the blue product to be reduced and faded, and the detection is achieved by measuring the change in absorbance at 652 nm.

8. A colorimetric detection method for ascorbic acid, characterized in that: Includes the following steps: (1) A light-enhanced lead-free halide nanozyme according to any one of claims 1-2, or a light-enhanced lead-free halide nanozyme prepared by any one of claims 3-5, is mixed with hydrogen peroxide and 3,3',5,5'-tetramethylbenzidine in a buffer solution to form a colorimetric system; (2) Add the sample to be tested to the color development system of step (1). If the sample to be tested contains ascorbic acid, the blue oxidation product will be reduced, resulting in a decrease in absorbance at 652 nm. (3) The concentration of ascorbic acid was quantitatively detected by measuring the change in absorbance at 652 nm and based on the pre-established standard curve between the change in absorbance and the concentration of ascorbic acid.

9. The colorimetric detection method for ascorbic acid according to claim 8, characterized in that: Step (2) also includes a step of carrying out a catalytic reaction under illumination to enhance detection sensitivity, wherein the illumination is selected from white LED, xenon lamp, visible light source or near-infrared light source.

10. A paper-based visualization detection platform, comprising fixing a light-enhanced lead-free halide nanozyme as described in any one of claims 1-2, or a light-enhanced lead-free halide nanozyme prepared by any one of the preparation methods of claims 3-5, with hydrogen peroxide and 3,3',5,5'-tetramethylbenzidine on the surface of filter paper for rapid visualization detection of ascorbic acid.

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