Shape memory nanoscale enzyme sponge and preparation method and application thereof

Abstract

The application discloses a shape memory nano-enzyme sponge as well as a preparation method and application thereof, and belongs to the technical field of functional materials. The main structure of the shape memory nano-enzyme sponge is composed of chitosan, poly-N,N'-methylene bisacrylamide and polyacrylic acid, and noble metal nano-enzymes are distributed in the main structure. The nano-enzyme sponge is prepared from a hydrogel, the noble metal nano-enzymes are combined with the shape memory sponge, the reusability of the nano-enzyme sensing and the amplification of the detection signal are realized, the nano-enzyme sensing and detection device is facilitated, and the hydrogen peroxide detection equipment is simple to prepare, stable in property, light in quality and portable.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to a shape memory nanoenzyme sponge, its preparation method, and its application. Background Technology

[0002] Nanozymes are a class of nanomaterials with activities similar to natural enzymes. Since the early use of iron oxide nanoparticles as peroxidases (PODs) for enzyme-linked immunosorbent assays (ELISA), nanozymes have been extensively explored in terms of catalytic mechanisms, material composition, and application scenarios. From an application perspective, developing analyte detection strategies based on nanozymes is the most popular approach. Generally, the typical procedure for using nanozyme sensing involves dispersing the nanozyme into a sample containing the analyte and a co-substrate (e.g., TMB or ABTS). After the enzyme-catalyzed reaction, the absorbance of the oxidation products from the co-substrate, such as oxTMB or oxABTS, is recorded and converted into analyte concentration through calculation. For example, numerous studies have used peroxidase nanozymes to detect substances such as hydrogen peroxide (H2O2), glucose, and uric acid.

[0003] Currently, almost all nanozyme-based detection strategies are performed directly in aqueous solutions. While effective, several challenges remain. First, signal acquisition relies heavily on spectrometers, hindering the development of point-of-care testing (POCT) devices. Second, the high dispersibility of nanozymes makes reusable detection using the same system difficult. Third, amplifying the signal to detect trace analytes in samples is challenging. Traditional lateral chromatography strips, while meeting POCT requirements, are difficult to reuse or further amplify the detection signal.

[0004] Gels are porous materials with large pore surfaces that provide ample space for loading nanozymes. Some studies have attempted to use agarose hydrogels to load nanozymes for analyte sensing within gels, but these hydrogels struggle to utilize their inherent properties to facilitate reproducible and amplified detection of nanozymes. Furthermore, metal aerogels have also been shown to possess nanozyme activity and can be used for analyte detection, but their near-black appearance may mask color signals and also makes it difficult to amplify detection signals; therefore, directly applying gels to nanozyme detection remains a significant challenge. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a shape memory nanozyme sponge, its preparation method and application, so as to solve the problems in the prior art that it is difficult to amplify or further process the sensing signal of nanozyme colorimetric sensing and that nanozyme colorimetric sensing is difficult to reuse.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A shape memory nanozyme sponge, the main body of which is composed of chitosan, polyN,N'-methylenebisacrylamide and polyacrylic acid, with noble metal nanozymes distributed in the main body.

[0008] A method for preparing a shape memory nanozyme sponge includes the following steps:

[0009] Step 1: Add a protective agent solution and a noble metal solution to water, then add a reducing agent solution, and after the reaction, obtain a noble metal nanozyme solution; the noble metal solution is a noble metal salt solution or a noble metal acid solution;

[0010] Step 2: Mix N,N'-methylenebisacrylamide in an aqueous acrylic acid solution, chitosan solution, and noble metal nanozyme solution, and pre-cool. After pre-cooling, add ammonium persulfate solution and potassium metabisulfite solution dropwise. After freeze polymerization, thaw and dry to obtain shape memory nanozyme sponge.

[0011] A further improvement of the present invention is that:

[0012] Preferably, in step 1, the mixing volume ratio of the protective agent solution, the precious metal solution, the reducing agent solution and water is (4-7):(1-10):(3-5):(28-42).

[0013] Preferably, in step 1, the noble metal acid solution is chloroplatinic acid or chloroauric acid, and the noble metal salt solution is ruthenium trichloride.

[0014] Preferably, in step 2, the volume ratio of the N,N'-methylenebisacrylamide aqueous solution in acrylic acid, the chitosan solution, and the noble metal nanozyme solution is (120-180):(60-100):(1-50).

[0015] An application of the above-mentioned shape memory nanozyme sponge, wherein the shape memory nanozyme sponge is used to adsorb positively charged dye molecules or negatively charged dye molecules.

[0016] The positively charged dye is toluidine blue O, crystal violet, methylene blue, or the oxidation product of 3,3',5,5'-tetramethylbenzidine.

[0017] The negatively charged dyes include bromophenol blue, thymol blue, litmus, or the oxidation product of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid).

[0018] Preferably, the shape memory nanozyme sponge enriches positively charged dye molecules onto the sponge body through repeated "drop-addition-squeezing" operations.

[0019] Preferably, the noble metal nanozyme in the shape memory nanozyme sponge can catalyze the reaction of 3,3',5,5'-tetramethylbenzidine and hydrogen peroxide to generate blue oxTMB, which is used to reflect the concentration of hydrogen peroxide.

[0020] Preferably, the reaction between TMB and hydrogen peroxide is as follows: TMB solution, hydrogen peroxide solution and NaAc-HAc buffer solution are mixed evenly and then dropped onto the nanozyme sponge. The "drop-addition-squeeze" operation is repeated until all the reaction solution is added. The concentration of hydrogen peroxide is determined by the color on the nanozyme sponge.

[0021] The volume ratio of TMB, hydrogen peroxide solution, and NaAc-HAc buffer solution is (1-10):(1-10):(280-300).

[0022] Preferably, the shape memory nanoenzyme sponge is subjected to a "drop-squeeze-wash" operation, which causes the negatively charged dye molecules originally contained on the sponge body to detach from the sponge body.

[0023] Preferably, the noble metal nanozyme in the shape memory nanozyme sponge can catalyze the reaction of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) and hydrogen peroxide to generate oxATBS, which is used to reflect the concentration of hydrogen peroxide.

[0024] Preferably, the reaction steps of ABTS and hydrogen peroxide are as follows: ABTS solution, hydrogen peroxide solution and NaAc-HAc buffer solution are mixed evenly in proportion and then dropped onto the nanoenzyme sponge. After the reaction is complete, the concentration of hydrogen hydroxide is determined by the color on the nanoenzyme sponge; the nanoenzyme sponge is then squeezed and cleaned.

[0025] By repeatedly adding, squeezing, and washing, the nanozyme sponge can be reused.

[0026] The mixing volume ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is (1-10):(1-10):(280-300).

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention discloses a shape-memory nanozyme sponge. The main structure of this shape-memory nanozyme sponge is composed of chitosan, polyN,N'-methylenebisacrylamide, and polyacrylic acid, with noble metal nanozymes distributed within the main structure. The nanozyme sponge is prepared from hydrogels, which are materials with a porous network structure formed by cross-linking of macromolecules or polymers. After freeze-drying, they can form a sponge-like substance. A typical shape-memory process can be described as follows: in a water-containing state, the water contained in the shape-memory sponge can be squeezed out, resulting in a compressed state. In this state, reabsorbing water allows it to expand back to its original shape. This cycle repeats, allowing the shape-memory sponge to complete multiple rounds of shape-memory effects. The main structure of this invention contains noble metal nanozymes with POD-like activity, which can catalyze the co-reaction of hydrogen peroxide and auxiliary substrates (such as TMB and ABTS) to generate colored products (such as oxTMB and oxABTS). The concentration of hydrogen peroxide can be quantitatively measured by the optical signal of the colored products. Meanwhile, the nanozyme sponge in this invention exhibits strong adsorption of positively charged dye molecules (such as oxTMB) while showing weak adsorption of negatively charged dye molecules (such as oxABTS), thus enabling "enrichment amplification" or "zeroing out" of specific detection signals. Ultimately, by organically combining the catalytic function of noble metal nanozymes, the adsorption capacity of the nanozyme sponge for different enzyme catalytic products, and its own shape memory effect, reusable nanozyme sensing and detection signal amplification are achieved. This also facilitates the deviceization of nanozyme sensing detection, resulting in a simple, stable, lightweight, and portable hydrogen peroxide detection device.

[0029] This invention broadly expands the types of nanozyme materials. The porous structure of the sponge can adsorb analytes, and the different types of analyte molecules result in varying capacities within the sponge. Based on these characteristics, it is expected to achieve cumulative detection or repeatable detection of analytes. Specifically, this shape-memory nanozyme sponge can be used to adsorb positively and negatively charged dye molecules. Positively charged dye molecules will not detach from the sponge body when washed by aqueous solution, while negatively charged dye molecules will detach from the sponge body when washed by aqueous solution. This sensor improves the performance of sensing and detection. Hydrogen peroxide detection was selected as a representative application to evaluate its detection effect. The shape-memory nanozyme sponge described in this invention has excellent peroxidase activity. By reacting with different chromogenic substrates, different detection effects on hydrogen peroxide are achieved. Specific analysis follows:

[0030] (1) The shape memory nanozyme sponge described in this invention, after catalyzing the reaction of hydrogen peroxide and TMB, due to the strong adsorption effect of the generated oxTMB on the sponge, can complete the enrichment and accumulation of oxTMB color signal on the sponge by repeated "drop-addition-squeezing" method, thereby realizing the quantitative detection of low concentration hydrogen peroxide that cannot be completed by traditional nanozyme sensors in a simple aqueous medium, and ultimately improving the detection capability of low concentration hydrogen peroxide.

[0031] The shape memory nanozyme sponge described in this invention quantifies the hydrogen peroxide concentration by measuring the color intensity of the oxidation product oxABTS after catalyzing the reaction between hydrogen peroxide and ABTS. Due to the weak adsorption of the generated oxABTS on the sponge, a "squeeze-wash" process completely washes away newly generated oxABTS each time, restoring the sponge to its initial state, allowing it to continue the next round of detection without interference. Repeating this process enables reusable quantitative detection of hydrogen peroxide, a capability that traditional nanozyme sensors in purely aqueous media cannot achieve. Ultimately, this achieves the goal of multiple detections of hydrogen peroxide using the same detection device, reducing the overall detection cost. Attached Figure Description

[0032] Figure 1 A schematic diagram illustrating the process of achieving shape memory in nanozyme sponges, namely the initial state of the nanozyme sponge, the deformed state of the nanozyme sponge, and the shape recovery state of the nanozyme sponge.

[0033] Figure 2 To assess the cyclic compression performance of shape memory nanozyme sponges.

[0034] Figure 3 The adsorption effect of eight different electrochemical dye molecules on nanozyme sponges.

[0035] Figure 4 The zeta potentials of eight different electrically charged dye molecules and their respective adsorption efficiencies on the nanozyme sponge are shown.

[0036] Figure 5 A standard curve for the detection of hydrogen peroxide using the chromogenic substrate TMB on shape memory nanozyme sponges;

[0037] Figure 6 This is a general operation flowchart for the signal enrichment process in cumulative detection.

[0038] Figure 7 Visual representation of the cumulative detection of hydrogen peroxide using shape memory nanozyme sponge based on chromogenic substrate TMB;

[0039] Figure 8 This study compares the hydrogen peroxide sample detected in a single operation with the theoretical value based on a repeated "drop-and-squeeze" enrichment process.

[0040] Figure 9 A standard curve for the detection of hydrogen peroxide using the chromogenic substrate ABTS in a shape memory nanozyme sponge;

[0041] Figure 10 This is a general operating flowchart for reusable hydrogen peroxide detection.

[0042] Figure 11 Visual effect of shape memory nanozyme sponge for reusable detection of hydrogen peroxide based on chromogenic substrate ABTS;

[0043] Figure 12 To assess the accuracy of reusable detection of hydrogen peroxide based on the "squeeze-wash" operation. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings:

[0045] The first aspect of the present invention discloses a shape memory nanozyme sponge, the main body of which is composed of chitosan, polyN,N'-methylenebisacrylamide and polyacrylic acid, wherein noble metal nanozymes are distributed therein.

[0046] The freeze-drying process described in this invention is carried out in a mold, and the initial shape of the shape memory nanozyme sponge prepared is the shape of the mold. After molding, it can be cut into small pieces for later use.

[0047] The second aspect of this invention discloses a method for preparing shape memory nanozyme sponges, comprising the following steps:

[0048] Step 1, Preparation of noble metal nanozymes stabilized by different protective agents:

[0049] A protective agent solution with a concentration of 1–50 mg / mL is prepared by dissolving the protective agent molecule in water; a noble metal salt or noble metal acid solution with a concentration of 1–100 mM is prepared by dissolving the noble metal salt or noble metal acid solution in deionized water; the protective agent solution and the noble metal salt or noble metal acid solution are gradually added to the deionized water; a reducing agent solution with a concentration of 10–200 mM is added dropwise to the above mixed solution, and the reaction is carried out at room temperature for 30–60 minutes to obtain a noble metal nanozyme solution.

[0050] Step 2: Dissolve N,N'-methylenebisacrylamide (MBA) in an aqueous solution of acrylic acid (AA) to prepare an AA solution with a concentration of 1-20 mg / mL; then add a pre-prepared chitosan (CS) solution; then add the noble metal nanozyme solution prepared in Step 1 to the above mixed solution, place it at -20℃ for pre-cooling, add ammonium persulfate solution and potassium metabisulfite solution dropwise at room temperature to obtain a final solution, freeze-polymerize at -20℃, thaw, soak and wash with deionized water, and dry to obtain a nanozyme sponge with shape memory.

[0051] Preferably, in step 1, the protective agent is chitosan, polyvinylpyrrolidone, glutathione, polydopamine, or albumin, etc.

[0052] Preferably, in step 1, the noble metal salt or acid is chloroplatinic acid, ruthenium trichloride, or chloroauric acid, etc.

[0053] Preferably, in step 1, the reducing agent is ascorbic acid, sodium borohydride, sodium citrate, hydroxylamine, or hydrazine hydrate, etc. The reducing agent can reduce noble metal salts or noble metal acids into metal elemental nanoenzyme particles with enzyme activity.

[0054] Preferably, in step 1, the volume ratio of the protective agent solution, the noble metal salt or acid solution, the reducing agent solution and the deionized water is (4-7):(1-10):(3-5):(28-42).

[0055] Preferably, in step 2, the volume ratio of the AA solution, CS solution and noble metal nanozyme solution of MBA is (120-180):(60-100):(1-50).

[0056] Preferably, in step 2, the concentration of CS in the final solution is 4–10 mg / mL;

[0057] Preferably, in step 2, the metal nanozyme solution has a volume concentration of 0.3-25% in the final solution;

[0058] Preferably, in step 2, the concentrations of the ammonium persulfate solution and the potassium metabisulfite solution in the final solution are both 0.5–2 mg / mL.

[0059] Preferably, in step 2, the precooling time is 10 to 60 minutes.

[0060] Preferably, in step 2, the freeze polymerization time is 5 to 20 hours.

[0061] A third aspect of this invention discloses an application of a shape memory nanozyme sponge, which can be used to adsorb dye molecules, wherein positively charged dye molecules will not detach from the sponge body upon rinsing with an aqueous solution, while negatively charged dye molecules will detach from the sponge body upon rinsing with an aqueous solution. The shape memory nanozyme sponge can enrich the positively charged dye molecules contained on the sponge body through repeated "drop-addition-squeezing" operations, while the negatively charged dye molecules originally contained on the sponge body can detach from the sponge body through "squeezing-washing" operations.

[0062] For example, the positively charged dye can be toluidine blue O (TBO), crystal violet (CV), methylene blue (MB), or the oxidation product of 3,3',5,5'-tetramethylbenzidine (oxTMB).

[0063] For example, the negatively charged dye can be bromophenol blue (BB), thymol blue (TB), litmus, or the oxidation product of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (oxABTS).

[0064] In some embodiments of the present invention, the step of enriching positively charged dye molecules in the sponge body by repeatedly performing a "drop-addition-squeezing" operation is as follows:

[0065] (1) Prepare the corresponding aqueous solution of positively charged dye molecules;

[0066] (2) During the enrichment process, the dye solution from step (1) is uniformly dropped onto the nanozyme sponge. After squeezing out excess water, the same dye solution is added again. By repeatedly performing the "drop-addition-squeezing" operation, the positively charged dye molecules are enriched in the nanozyme sponge.

[0067] In some embodiments of the present invention, the step of removing negatively charged dye molecules from the sponge body by performing a "squeezing-washing" operation is as follows:

[0068] (1) Prepare the corresponding aqueous solution of the negatively charged dye molecules;

[0069] (2) The dye solution from step (1) is evenly dropped onto the nanozyme sponge. During the cleaning process, excess water is removed by squeezing, and the nanozyme sponge is then rinsed with pure water until it returns to its initial colorless state. By performing the same steps multiple times, the negatively charged dye molecules can be removed from the nanozyme sponge each time.

[0070] The fourth aspect of the present invention discloses a sensing and detection application of a shape memory nanozyme sponge, which detects hydrogen peroxide by color change of the oxidation products of 3,3',5,5'-tetramethylbenzidine (TMB) or 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS).

[0071] In some embodiments of the present invention, based on a single detection of hydrogen peroxide using TMB, a noble metal nanozyme catalyzes the reaction between TMB and hydrogen peroxide, allowing the hydrogen peroxide concentration to be displayed by the intensity of color on the sponge. The specific steps are as follows:

[0072] (1) Prepare a TMB solution by dissolving TMB in dimethyl sulfoxide;

[0073] (2) During the detection process, TMB solution, hydrogen peroxide solutions of different concentrations, and NaAc-HAc buffer solution were mixed evenly in proportion and then dropped onto the nanozyme sponge. After complete reaction at a certain temperature, the color signal of the shape memory nanozyme sponge was collected by taking pictures with a smartphone, and the green value was analyzed using ImageJ software. The green value of the unreacted sponge image was recorded as G0, and the green value of the reacted sponge image was recorded as G. The ΔG value (ΔG=(G0-G) / G) had a good linear relationship with the hydrogen peroxide concentration.

[0074] Preferably, the TMB solution concentration is 10-80 mM;

[0075] Preferably, the concentration of the NaAc-HAc buffer solution is 20 mM, and the pH is 3.0–7.0;

[0076] Preferably, the concentration range of hydrogen peroxide is 20–1000 μM;

[0077] Preferably, the volume ratio of TMB solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is (1-10):(1-10):(280-300).

[0078] Preferably, the reaction temperature is room temperature and the reaction time is 5 to 30 minutes.

[0079] In some embodiments of the present invention, the step of detecting hydrogen peroxide based on TMB accumulation is as follows:

[0080] (1) Dissolve TMB in DMSO to prepare a TMB solution;

[0081] (2) During the detection process, TMB solution, hydrogen peroxide solutions of different concentrations, and NaAc-HAc buffer solution were mixed evenly in proportion and then dropped onto the nanozyme sponge. The "drop-addition-squeezing" operation was repeated until all the reaction solution was added. After the reaction was completed at a certain temperature, the color signal of the shape memory nanozyme sponge was collected by taking pictures with a smartphone, and the green value was analyzed using ImageJ software. The green value of the unreacted sponge image was recorded as G0, and the green value of the reacted sponge image was recorded as G. The ΔG value (ΔG=(G0-G) / G0) had a good linear relationship with the hydrogen peroxide concentration.

[0082] Preferably, the concentration of the DMSO solution for TMB is 10-80 mM;

[0083] Preferably, the concentration of the NaAc-HAc buffer solution is 20 mM, and the pH is 3.0–7.0;

[0084] Preferably, the concentration range of hydrogen peroxide is 20–1000 μM;

[0085] Preferably, the volume ratio of TMB solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is (1-10):(1-10):(280-300).

[0086] Preferably, the "drop-squeeze" operation is completed within 5 minutes.

[0087] Preferably, the reaction temperature is room temperature and the reaction time is 5 to 30 minutes.

[0088] In some embodiments of the present invention, based on a single ABTS detection of hydrogen peroxide, noble metal nanozymes can catalyze the reaction between ABTS and hydrogen peroxide, allowing the hydrogen peroxide concentration to be displayed by the intensity of color on the sponge. The specific steps are as follows:

[0089] An ABTS solution was prepared by dissolving ABTS in deionized water.

[0090] During the detection process, ABTS solution, hydrogen peroxide solutions of different concentrations, and NaAc-HAc buffer solution were mixed evenly in a certain proportion and then dropped onto the nanozyme sponge. After complete reaction at a certain temperature, the color signal of the shape memory nanozyme sponge was collected by taking pictures with a smartphone, and the green value was analyzed using ImageJ software. The green value of the unreacted sponge image was recorded as G0, and the green value of the reacted sponge image was recorded as G. The ΔG value (ΔG=(G0-G) / G0) showed a good linear relationship with the hydrogen peroxide concentration.

[0091] Preferably, the concentration of the ABTS aqueous solution is 10-80 mM;

[0092] Preferably, the concentration of the NaAc-HAc buffer solution is 20 mM, and the pH is 2.0–5.0;

[0093] Preferably, the concentration range of hydrogen peroxide is 10–1000 μM;

[0094] Preferably, the ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is (1-10):(1-10):(280-300).

[0095] In some embodiments of the present invention, the step of reproducible detection of hydrogen peroxide based on ABTS is as follows:

[0096] An ABTS solution was prepared by dissolving ABTS in deionized water.

[0097] During the detection process, ABTS solution, hydrogen peroxide solutions of different concentrations, and NaAc-HAc buffer solution were mixed evenly in a specific ratio and then dropped onto the nanozyme sponge. After complete reaction, a smartphone was used to capture the color signal of the shape memory nanozyme sponge, and the green value was analyzed using ImageJ software. The green value of the unreacted sponge image was recorded as G0, and the green value of the reacted sponge image was recorded as G. The ΔG value (ΔG = (G0 - G) / G0) showed a good linear relationship with the hydrogen peroxide concentration. By performing a "squeeze-wash" operation, the dye on the sponge could be washed away, thus restoring the nanozyme sponge to its original state. By repeating the above steps, multiple hydrogen peroxide detections could be performed using the same sensing device.

[0098] Preferably, the concentration of the ABTS aqueous solution is 10-80 mM;

[0099] Preferably, the concentration of the NaAc-HAc buffer solution is 20 mM, and the pH is 2.0–5.0;

[0100] Preferably, the concentration range of hydrogen peroxide is 10–1000 μM;

[0101] Preferably, the ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is (1-10):(1-10):(280-300).

[0102] Preferably, the "drop-squeeze-clean" operation is completed within 5 minutes.

[0103] Preferably, the reaction temperature is room temperature and the reaction time is 5 to 30 minutes.

[0104] Preferably, the molecular weight of chitosan in this invention is 30 kDa, 50 kDa, 200 kDa, and 500 kDa.

[0105] The following description, in conjunction with specific embodiments, provides further details.

[0106] Example 1: Preparation of shape memory nanozyme sponge sample 1

[0107] Step 1: Preparation of CS-Pt nanozymes

[0108] First, 10 mg of chitosan was dissolved in 10 mL of 0.4% (v / v) aqueous acetic acid solution. Then, 100 μL of chloroplatinic acid solution (H2PtCl6, 20 mM) and 680 μL of deionized water were added to 120 μL of chitosan solution. 100 μL of sodium borohydride (NaBH4, 0.1 M) solution was added dropwise to the above mixed solution, and the mixture was reacted at room temperature for 30 minutes to obtain the CS-Pt nanozyme solution.

[0109] Step 2: Preparation of shape-memory CS-Pt nanozyme sponge

[0110] First, 125 mg of MBA was dissolved in 16 mL of 6% (v / v) AA aqueous solution, followed by the addition of 7.5 mL of 2% (m / m) chitosan solution. Then, the CS-Pt nanozyme solution prepared in step 1 was added to the above mixed solution. After mixing, the solution was placed at -20°C for 10 minutes for freeze polymerization, and then removed. Ammonium persulfate solution and potassium metabisulfite solution were added dropwise at room temperature. In the final mixed solution, the final concentration of chitosan was 6 mg / mL, the final concentration of CS-Pt nanozyme was 2% (v / v), and the final concentrations of ammonium persulfate and potassium metabisulfite were 0.8 mg / mL. After reacting the above homogeneous mixed solution at -20°C for 15 hours, the solution was removed, soaked and washed with a large amount of deionized water, and dried to obtain the shape memory nanozyme sponge.

[0111] Example 2: Preparation of shape memory nanozyme sponge sample 2

[0112] Step 1: Preparation of CS-Pt nanozymes

[0113] First, 10 mg of chitosan was dissolved in 10 mL of 0.4% (v / v) acetic acid aqueous solution; then, 100 μL of chloroplatinic acid solution (H2PtCl6, 20 mM) and 700 μL of deionized water were added to 100 μL of chitosan solution; 100 μL of ascorbic acid (0.1 M) solution was added dropwise to the above mixed solution, and the mixture was reacted at room temperature for 30 minutes to obtain CS-Pt nanozyme solution.

[0114] Step 2: Preparation of shape-memory CS-Pt nanozyme sponge

[0115] Same as step 2 in Example 1.

[0116] Example 3: Preparation of shape memory nanozyme sponge sample 3

[0117] Step 1 is the same as step 1 in Example 1.

[0118] Step 2: Preparation of shape-memory CS-Pt nanozyme sponge

[0119] First, 125 mg of MBA was dissolved in 16 mL of 6% (v / v) AA aqueous solution, followed by the addition of 7.5 mL of 2% (m / m) chitosan solution. Then, the CS-Pt nanozyme solution prepared in step 1 was added to the above mixed solution. After mixing, the mixture was placed at -20°C for 10 minutes for freeze polymerization, and then removed. Ammonium persulfate solution and potassium metabisulfite solution were added dropwise at room temperature. In the final mixed solution, the final concentration of chitosan was 6 mg / mL, the final concentration of CS-Pt nanozyme was 4% (v / v), and the final concentrations of ammonium persulfate and potassium metabisulfite were 0.8 mg / mL. After reacting the above homogeneous mixed solution at -20°C for 15 hours, the mixture was removed, soaked and washed with a large amount of deionized water, and dried to obtain the shape memory nanozyme sponge.

[0120] Example 4: Preparation of shape memory nanozyme sponge sample 4.

[0121] Step 1 is the same as step 1 in Example 1.

[0122] Step 2: Preparation of shape-memory CS-Pt nanozyme sponge

[0123] First, 125 mg of MBA was dissolved in 16 mL of 6% (v / v) AA aqueous solution, followed by the addition of 7.5 mL of 2% (m / m) chitosan solution. Then, the CS-Pt nanozyme solution prepared in step 1 was added to the above mixed solution. After mixing, the mixture was placed at -20°C for 10 minutes for freeze polymerization, and then removed. Ammonium persulfate solution and potassium metabisulfite solution were added dropwise at room temperature. In the final mixed solution, the final concentration of chitosan was 6 mg / mL, the final concentration of CS-Pt nanozyme was 6% (v / v), and the final concentrations of ammonium persulfate and potassium metabisulfite were 0.8 mg / mL. After reacting the above homogeneous mixed solution at -20°C for 15 hours, the mixture was removed, soaked and washed with a large amount of deionized water, and dried to obtain the shape memory nanozyme sponge.

[0124] Example 5: Preparation of shape memory nanozyme sponge sample 5.

[0125] Step 1: Preparation of CS-Ru nanozymes

[0126] First, 10 mg of chitosan was dissolved in 10 mL of 0.4% (v / v) aqueous acetic acid solution. Then, 100 μL of ruthenium trichloride solution (RuCl3, 20 mM) and 680 μL of deionized water were added to 120 μL of chitosan solution. 100 μL of sodium borohydride solution (NaBH4, 0.1 M) was added dropwise to the above mixed solution, and the mixture was reacted at room temperature for 30 minutes to obtain the CS-Pt nanozyme solution.

[0127] Step 2: Preparation of shape-memory CS-Ru nanozyme sponge

[0128] First, 125 mg of MBA was dissolved in 16 mL of 6% (v / v) AA aqueous solution, followed by the addition of 7.5 mL of 2% (m / m) chitosan solution. Then, the CS-Ru nanozyme solution prepared in step 1 was added to the above mixed solution. After mixing, the mixture was placed at -20°C for 10 minutes for freeze polymerization, and then removed. Ammonium persulfate solution and potassium metabisulfite solution were added dropwise at room temperature. In the final mixed solution, the final concentration of chitosan was 6 mg / mL, the final concentration of CS-Ru nanozyme was 2% (v / v), and the final concentrations of ammonium persulfate and potassium metabisulfite were 0.8 mg / mL. After reacting the above homogeneous mixed solution at -20°C for 15 hours, the mixture was removed, soaked and washed with a large amount of deionized water, and dried to obtain the shape memory nanozyme sponge.

[0129] Example 6: Preparation of shape memory nanozyme sponge sample 6

[0130] Step 1: Preparation of CS-Au nanozymes

[0131] First, 10 mg of chitosan was dissolved in 10 mL of 0.4% (v / v) aqueous acetic acid solution. Then, 100 μL of chloroauric acid solution (HAuCl4, 20 mM) and 680 μL of deionized water were added to 120 μL of chitosan solution. 100 μL of sodium borohydride (NaBH4, 0.1 M) solution was added dropwise to the above mixed solution, and the mixture was reacted at room temperature for 30 minutes to obtain CS-Au nanozyme solution.

[0132] Step 2: Preparation of shape-memory CS-Au nanozyme sponge

[0133] First, dissolve 125 mg of MBA in 16 mL of 6% (v / v) AA aqueous solution, then add...

[0134] 7.5 mL of 2% (m / m) chitosan solution was added; then, the CS-Au nanozyme solution prepared in step 1 was added to the above mixed solution; after mixing, the mixture was placed at -20℃ for 10 minutes for freeze polymerization, and then removed. Ammonium persulfate solution and potassium metabisulfite solution were added dropwise at room temperature. In the final mixed solution, the final concentration of chitosan was 6 mg / mL, the final concentration of CS-Au nanozyme was 2% (v / v), and the final concentrations of ammonium persulfate and potassium metabisulfite were 0.8 mg / mL. After reacting the above homogeneous mixed solution at -20℃ for 15 hours, it was removed, soaked and washed with a large amount of deionized water, and dried to obtain the shape memory nanozyme sponge.

[0135] Example 7: Characterization of the shape memory function of shape memory nanozyme sponge

[0136] Example 1 was selected for shape memory function characterization. From... Figure 1 As can be seen, the shape of the freeze-dried nanozyme sponge hardly changes after being soaked in water. After squeezing to remove the absorbed water, the nanozyme sponge becomes a flattened cylinder, and its shape changes significantly. When the squeezed nanozyme sponge is soaked in water again, it can quickly return to its initial shape. Figure 2 The cyclic compression stress-strain curve shows that, at 80% compression strength, the nanozyme sponge can still recover its original shape after 10 cycles of compression, indicating that the nanozyme sponge has excellent shape memory function, which is beneficial for the application of nanozyme sponge in multiple cumulative detection and repeatable detection.

[0137] Example 8: Test of Adsorption of Different Electrochemical Dyes by Shape Memory Nanozyme Sponge

[0138] Example 1 was selected to test the adsorption of dyes with different electrical properties by shape memory nanozyme sponges.

[0139] Four positively charged dye molecules—toluidine blue O, crystal violet, methylene blue, and oxTMB—were selected for adsorption testing. The steps for enriching the positively charged dye molecules within the sponge bulk through repeated "drop-addition-squeezing" operations are as follows:

[0140] (1) Prepare the corresponding aqueous solution of positively charged dye molecules;

[0141] (2) During the enrichment process, the dye solution from step (1) is uniformly dropped onto the nanozyme sponge. After squeezing out excess water, the same dye solution is added again. By repeatedly performing the "drop-addition-squeezing" operation, the positively charged dye molecules are enriched in the nanozyme sponge.

[0142] Four negatively charged dye molecules—bromophenol blue, thymol blue, litmus, and oxABTS—were selected for elution testing. The steps for removing negatively charged dye molecules from the sponge body through repeated "drop-addition-squeezing-washing" operations were as follows:

[0143] (1) Prepare the corresponding aqueous solution of the negatively charged dye molecules;

[0144] (2) The dye solution from step (1) is evenly dropped onto the nanozyme sponge. During the cleaning process, excess water is removed by squeezing, and the nanozyme sponge is then rinsed with pure water until it returns to its initial colorless state. By performing the same steps multiple times, the negatively charged dye molecules can be removed from the nanozyme sponge each time.

[0145] The adsorption effects of the above eight different electrochromic dye molecules on the nanozyme sponge are as follows: Figure 3 As shown. Figure 4 The zeta potentials of the eight different electrically charged dye molecules and their respective adsorption efficiencies on the nanozyme sponge are shown.

[0146] Example 9: Single-shot detection of hydrogen peroxide based on TMB

[0147] Example 1 was selected for a single detection of hydrogen peroxide based on TMB.

[0148] The reaction temperature was kept constant at room temperature, the reaction system was a NaAc-HAc buffer solution (pH 5.5), and the reaction time was 10 minutes.

[0149] A certain concentration of hydrogen peroxide solution, 40 mM TMB solution, and NaAc-HAc buffer solution (pH 5.5) were mixed thoroughly to prepare the test solution. The volume ratio of hydrogen peroxide solution, TMB solution, and NaAc-HAc buffer solution (pH 5.5) was 6:3:290. 300 μL of the above mixed solution was added dropwise onto a shape memory CS-Pt nanozyme sponge disc with a diameter of 1 cm and a thickness of 0.5 cm. After reacting at room temperature for 10 minutes, the color signal of the shape memory nanozyme sponge was collected by taking a picture with a smartphone, and the green value was analyzed using ImageJ software. The green value of the unreacted sponge image was recorded as G0, and the green value of the reacted sponge image was recorded as G. The ΔG value (ΔG = (G0 - G) / G0) showed a good linear relationship with the hydrogen peroxide concentration. The linear equation of the standard curve for hydrogen peroxide detection based on TMB using the CS-Pt nanozyme sponge was ΔG = 0.1496 + 0.1931C. H2O2 The correlation coefficient is 0.9957, such as Figure 5 As shown.

[0150] Example 10: TMB-based detection of hydrogen peroxide accumulation

[0151] Example 1 was selected for TMB-based hydrogen peroxide accumulation detection.

[0152] The reaction temperature was kept constant at room temperature, the reaction system was a NaAc-HAc buffer solution (pH 5.5), and the reaction time was 10 minutes.

[0153] Prepare a series of test solutions by thoroughly mixing a certain concentration of hydrogen peroxide solution, 40 mM TMB solution, and NaAc-HAc buffer solution (pH 5.5). The volume ratio of hydrogen peroxide solution, TMB solution, and NaAc-HAc buffer solution (pH 5.5) is 6:3:290. Add 300 μL of the above mixed solution dropwise onto a shape memory CS-Pt nanozyme sponge disc with a diameter of 1 cm and a thickness of 0.5 cm. After fully squeezing, remove the reaction solution and add a new test solution. Repeat the above steps until all test solutions have been added. Figure 6 The process of adding the test solution dropwise, squeezing, and adding dropwise was completed within 1 minute. After reacting at room temperature for 10 minutes, the color signal of the shape memory nanozyme sponge was collected by taking pictures with a smartphone, and the green value was analyzed using ImageJ software. The green value of the unreacted sponge image was recorded as G0, and the green value of the reacted sponge image was recorded as G. The total hydrogen peroxide content in the test solution could be calculated based on the linear relationship between the ΔG value (ΔG = (G0-G) / G0) obtained in Example 7 and the hydrogen peroxide concentration. Dividing this by the cumulative number of detections, the hydrogen peroxide content in the test solution was calculated.

[0154] Figure 7 These are colorimetric images of the CS-Pt nanozyme sponge obtained after the test solution containing 100 μM hydrogen peroxide was subjected to 7 repeated drop-squeeze operations. As can be seen from the images, the color gradually deepened after 7 repeated drop-squeeze operations.

[0155] Figure 8 The enrichment operation is based on repeated drop-squeeze and the comparison between the hydrogen peroxide sample detected in a single operation and the theoretical value (the final concentration of hydrogen peroxide after enrichment is the same as the concentration of hydrogen peroxide in a single operation). The data in the figure shows that the enrichment detection is close to the theoretical value, indicating that the detection results are reliable.

[0156] Example 11: Single-shot detection of hydrogen peroxide based on ABTS

[0157] Example 1 was selected for a single detection of hydrogen peroxide based on ABTS.

[0158] The reaction temperature was fixed at room temperature, the reaction system was NaAc-HAc (pH 3.0), and the reaction time was 10 minutes.

[0159] A certain concentration of hydrogen peroxide solution, 50 mL of MTB solution, and NaAc-HAc buffer solution (pH 3.0) were mixed thoroughly to prepare the test solution. The volume ratio of hydrogen peroxide solution, MTB solution, and NaAc-HAc buffer solution (pH 3.0) was 6:3:290. 300 μL of the above mixed solution was added dropwise onto a shape memory CS-Pt nanozyme sponge disc with a diameter of 1 cm and a thickness of 0.5 cm. After reacting at room temperature for 10 minutes, the color signal of the shape memory nanozyme sponge was collected by taking a picture with a smartphone, and the green value was analyzed using ImageJ software. The green value of the unreacted sponge image was recorded as G0, and the green value of the reacted sponge image was recorded as G. Based on the good linear relationship between ΔG value (ΔG = (G0 - G) / G0) and hydrogen peroxide concentration, the linear equation of the standard curve for hydrogen peroxide detection based on ABTS for CS-Pt nanozyme sponge was ΔG = 0.0680 + 0.0894C. H2O2 The correlation coefficient is 0.9994, such as Figure 9 As shown.

[0160] Example 12: ABTS-based detection of reusable hydrogen peroxide

[0161] Example 1 was selected for ABTS-based detection of hydrogen peroxide reusability.

[0162] The reaction temperature was fixed at room temperature, the reaction system was NaAc-HAc (pH 3.0), and the reaction time was 10 minutes.

[0163] A series of test solutions were prepared by mixing a certain concentration of hydrogen peroxide solution, 50 mL AMBTS solution, and NaAc-HAc buffer solution (pH 3.0). The volume ratio of hydrogen peroxide solution, TMB solution, and NaAc-HAc buffer solution (pH 3.0) was 6:3:290. 300 μL of the above mixed solution was added dropwise onto a shape memory CS-Pt nanozyme sponge disc with a diameter of 1 cm and a thickness of 0.5 cm. After reacting at room temperature for 10 minutes, the color signal of the shape memory nanozyme sponge was collected by taking a picture with a smartphone, and the green value was analyzed using ImageJ software. The green value of the unreacted sponge image was recorded as G0, and the green value of the reacted sponge image was recorded as G. The hydrogen peroxide content in the test solution could be calculated based on the linear relationship between the ΔG value (ΔG = (G0-G) / G0) obtained in Example 9 and the hydrogen peroxide concentration. After the reaction, the nanozyme sponge was soaked in deionized water, thoroughly squeezed and washed to restore its original morphology and color, and then fresh test solution was added. Figure 10 Each test was conducted at room temperature for 10 minutes, and the above steps for color signal acquisition and analysis were repeated.

[0164] Figure 11 These are colorimetric images of the CS-Pt nanozyme sponge obtained after 10 wash-repeated addition operations of the test solution containing 500 μM hydrogen peroxide. As can be seen from the images, the CS-Pt nanozyme sponge still has excellent colorimetric performance after 10 wash-repeated addition operations.

[0165] Figure 12 This is a colorimetric quantitative chromatogram for the repeatable detection of hydrogen peroxide based on the "squeeze-wash" operation. As can be seen from the figure, the initial and final values ​​remain basically consistent in each repeat detection cycle, indicating that the repeat detection effect is good.

[0166] Example 13

[0167] In this embodiment, the mixing volume ratio of chitosan solution, chloroplatinic acid solution, sodium borohydride and deionized water is 70 μL: 100 μL: 40 μL: 350 μL to obtain CS-Pt nanozyme solution;

[0168] The volume ratio of MBA's AA solution, chitosan solution, and noble metal nanozyme solution was 18 mL: 10 mL: 0.5 mL to obtain a mixed solution for preparing noble metal nanozyme sponges.

[0169] The remaining parts not covered are the same as in Example 1.

[0170] Example 14

[0171] In this embodiment, the mixing volume ratio of chitosan solution, chloroplatinic acid solution, sodium borohydride, sodium borohydride and deionized water is 40 μL: 10 μL: 30 μL: 400 μL to obtain CS-Pt nanozyme solution 1.

[0172] The volume ratio of MBA's AA solution, chitosan solution, and noble metal nanozyme solution was 12 mL: 6 mL: 3 mL to obtain a mixed solution for preparing noble metal nanozyme sponges.

[0173] The remaining parts not covered are the same as in Example 1.

[0174] Example 15

[0175] In this embodiment, the mixing volume ratio of chitosan solution, chloroplatinic acid solution, sodium borohydride and deionized water is 70 μL: 100 μL: 40 μL: 420 μL to obtain CS-Pt nanozyme solution;

[0176] The volume ratio of MBA's AA solution, chitosan solution, and noble metal nanozyme solution was 12 mL: 10 mL: 5 mL to obtain a mixed solution for preparing noble metal nanozyme sponges.

[0177] The remaining parts not covered are the same as in Example 1.

[0178] Example 16

[0179] In this embodiment, the mixing volume ratio of chitosan solution, chloroplatinic acid solution, sodium borohydride, sodium borohydride and deionized water is 40 μL: 10 μL: 30 μL: 280 μL to obtain CS-Pt nanozyme solution 1.

[0180] The volume ratio of MBA's AA solution, chitosan solution, and noble metal nanozyme solution was 16 mL: 7.5 mL: 0.1 mL to obtain a mixed solution for preparing noble metal nanozyme sponges.

[0181] The remaining parts not covered are the same as in Example 1.

[0182] Example 17

[0183] In this embodiment, the final concentration of chitosan is 4 mg / mL, the final concentration of the metal nanozyme solution is 0.5%, and the final concentrations of the ammonium persulfate solution and potassium metabisulfite solution are 0.5 mg / mL. The remaining parts are the same as in Example 1.

[0184] Example 18

[0185] In this embodiment, the final concentration of chitosan is 10 mg / mL, the final concentration of the metal nanozyme solution is 10%, and the final concentrations of the ammonium persulfate solution and potassium metabisulfite solution are 2 mg / mL. The remaining parts are the same as in Example 1.

[0186] Example 19

[0187] In this embodiment, the protective agent is polyvinylpyrrolidone, the noble metal is ruthenium trichloride, the reducing agent is sodium borohydride, and the remaining parts are the same as in Example 1.

[0188] Example 20

[0189] In this embodiment, the protective agent is glutathione, the precious metal is ruthenium trichloride, the reducing agent is hydroxylamine, and the other unrelated parts are the same as in Example 1.

[0190] Example 21

[0191] In this embodiment, the protective agent is sodium citrate, the reducing agent is hydrazine hydrate, and the other unrelated parts are the same as in Example 1.

[0192] Example 22

[0193] In this embodiment, the volume ratio of TMB solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 1:1:280, and the other parts not involved are the same as in Example 7.

[0194] Example 23

[0195] In this embodiment, the volume ratio of TMB solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 10:10:300, and the remaining parts are the same as in Example 7.

[0196] Example 24

[0197] In this embodiment, the volume ratio of TMB solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 4:2:290, and the remaining parts are the same as in Example 7.

[0198] Example 25

[0199] In this embodiment, the volume ratio of TMB solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 1:1:280, and the other parts not involved are the same as in Example 8.

[0200] Example 26

[0201] In this embodiment, the volume ratio of TMB solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 10:10:300, and the other parts not involved are the same as in Example 8.

[0202] Example 27

[0203] In this embodiment, the volume ratio of TMB solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 8:3:300, and the other parts not involved are the same as in Example 8.

[0204] Example 28

[0205] In this embodiment, the volume ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 1:1:280, and the other parts not involved are the same as in Example 9.

[0206] Example 29

[0207] In this embodiment, the volume ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 10:10:300, and the other parts not involved are the same as in Example 9.

[0208] Example 30

[0209] In this embodiment, the volume ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 5:5:300, and the remaining parts are the same as in Example 9.

[0210] Example 31

[0211] In this embodiment, the volume ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 1:1:280, and the other parts not involved are the same as in Example 10.

[0212] Example 32

[0213] In this embodiment, the volume ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 10:10:300, and the other parts not involved are the same as in Example 10.

[0214] Example 33

[0215] In this embodiment, the volume ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is 6:2:290, and the other parts not involved are the same as in Example 10.

[0216] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A shape memory nanoenzyme sponge, characterized in that, The main body is composed of chitosan, polyN,N'-methylenebisacrylamide and polyacrylic acid, and noble metal nanozymes are distributed in the main body; The shape memory nanozyme sponge is used to adsorb positively charged dye molecules or negatively charged dye molecules; The positively charged dye is toluidine blue O, crystal violet, methylene blue, or the oxidation product of 3,3',5,5'-tetramethylbenzidine; The negatively charged dye is bromophenol blue, thymol blue, litmus, or the oxidation product of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid); The noble metal nanozymes in the shape memory nanozyme sponge can catalyze the reaction of 3,3',5,5'-tetramethylbenzidine and hydrogen peroxide to generate blue oxTMB, which is used to reflect the concentration of hydrogen peroxide. The noble metal nanozymes in the shape memory nanozyme sponge can catalyze the reaction of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) and hydrogen peroxide to generate oxATBS, which is used to reflect the concentration of hydrogen peroxide. The method for preparing the shape memory nanozyme sponge is as follows: Step 1: Add a protective agent solution and a noble metal solution to water, then add a reducing agent solution, and obtain a noble metal nanozyme solution after the reaction; the noble metal solution is a noble metal salt solution or a noble metal acid solution; wherein, the mixing volume ratio of the protective agent solution, the noble metal solution, the reducing agent solution and water is (4~7):(1~10):(3~5):(28~42). Step 2: Mix N,N'-methylenebisacrylamide in an aqueous acrylic acid solution, chitosan solution, and noble metal nanozyme solution, and pre-cool. After pre-cooling, add ammonium persulfate solution and potassium metabisulfite solution dropwise. After freeze polymerization, thaw and dry to obtain shape memory nanozyme sponge.

2. A method for preparing the shape memory nanozyme sponge according to claim 1, characterized in that, Includes the following steps: Step 1: Add a protective agent solution and a precious metal solution to water, then add a reducing agent solution, and after the reaction, obtain a precious metal nanozyme solution; The noble metal solution is a noble metal salt solution or a noble metal acid solution; Step 2: Mix N,N'-methylenebisacrylamide in an aqueous acrylic acid solution, chitosan solution, and noble metal nanozyme solution, and pre-cool. After pre-cooling, add ammonium persulfate solution and potassium metabisulfite solution dropwise. After freeze polymerization, thaw and dry to obtain shape memory nanozyme sponge.

3. The method for preparing a shape memory nanozyme sponge according to claim 2, characterized in that, In step 1, the noble metal acid solution is chloroplatinic acid or chloroauric acid, and the noble metal salt solution is ruthenium trichloride.

4. The method for preparing a shape memory nanozyme sponge according to claim 2, characterized in that, In step 2, the volume ratio of N,N'-methylenebisacrylamide aqueous solution in acrylic acid, chitosan solution and noble metal nanozyme solution is (120~180):(60~100):(1~50).

5. An application of the shape memory nanoenzyme sponge according to claim 1, characterized in that, The shape memory nanozyme sponge is used to adsorb positively charged dye molecules or negatively charged dye molecules; The positively charged dye is toluidine blue O, crystal violet, methylene blue, or the oxidation product of 3,3',5,5'-tetramethylbenzidine; The negatively charged dyes include bromophenol blue, thymol blue, litmus, or the oxidation product of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid).

6. The application according to claim 5, characterized in that, The shape memory nanozyme sponge enriches positively charged dye molecules onto the sponge body through repeated "drop-addition-squeezing" operations.

7. The application according to claim 6, characterized in that, The reaction between TMB and hydrogen peroxide is as follows: TMB solution, hydrogen peroxide solution and NaAc-HAc buffer solution are mixed evenly and then dropped onto the nanozyme sponge. The "drop-addition-squeezing" operation is repeated until all the reaction solution is added. The concentration of hydrogen peroxide is determined by the color on the nanozyme sponge. The volume ratio of TMB, hydrogen peroxide solution, and NaAc-HAc buffer solution is (1~10):(1~10):(280~300).

8. The application according to claim 5, characterized in that, The shape memory nanozyme sponge uses a "drop-squeeze-wash" operation to detach the negatively charged dye molecules that were originally contained on the sponge body from the sponge body.

9. The application according to claim 8, characterized in that, The noble metal nanozymes in the shape memory nanozyme sponge can catalyze the reaction of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) and hydrogen peroxide to generate oxATBS, which is used to reflect the concentration of hydrogen peroxide.

10. The application according to claim 9, characterized in that, The steps for the reaction of ABTS and hydrogen peroxide are as follows: ABTS solution, hydrogen peroxide solution and NaAc-HAc buffer solution are mixed evenly in proportion and then dropped onto the nanoenzyme sponge. After the reaction is complete, the concentration of hydrogen hydroxide is determined by the color on the nanoenzyme sponge. The nanoenzyme sponge is then squeezed and cleaned. By repeatedly adding, squeezing, and washing, the nanozyme sponge can be reused. The mixing volume ratio of ABTS solution, hydrogen peroxide solution, and NaAc-HAc buffer solution is (1~10): (1~10): (280~300).

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