High-catalytic-performance photoresponsive tpbtd-au nanoszyme and preparation method and application thereof

Abstract

The application discloses a kind of high catalytic performance light response TpBTD-Au nano enzyme and its preparation method and application, belong to nanometer material preparation and analytical detection technical field.By one-step chemical reduction method, noble metal gold nanoparticles (Au NPs) are loaded on TpBTD COF, and the COF composite material (TpBTD-Au) with high-efficiency light response nano enzyme catalytic performance is innovatively prepared.It has stronger visible light absorption capacity than pure TpBTD, ideal band gap and energy band structure and high-efficiency carrier separation efficiency, can significantly promote the generation of more strong oxidative active oxygen free radicals (ROS), thereby improving the light response nano enzyme activity of TpBTD, and it is helpful to better apply it in food safety, environmental protection and biomedical research fields.Meanwhile, using TpBTD-Au as penicillin (PG) colorimetric detection probe, rapid, sensitive and selective detection of PG in environmental water sample is realized.The application not only provides a new technical scheme for light response COF nano enzyme catalytic activity regulation, but also provides a new technical means for rapid detection of antibiotic residues.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation and analysis technology, specifically relating to a photoresponsive TpBTD-Au nanozyme with high catalytic performance, its preparation method, and its application. Background Technology

[0002] Photoresponsive nanozyme catalysis possesses significant advantages such as spatiotemporal controllability and environmental friendliness, making it valuable for applications in food safety, environmental protection, and biomedicine. Regulating the catalytic activity of photoresponsive nanozymes can greatly facilitate their application in various research fields. However, research on regulating the catalytic activity of photoresponsive covalent organic framework (COF) nanozymes remains limited.

[0003] While there are reports of loading noble metal Au nanoparticles (NPs) onto porous materials in the prior art, no research has been published on combining Au NPs with photoresponsive COFs with specific band structures (such as TpBTD COF) to significantly enhance the activity of oxidative mimicry enzymes through their synergistic effect and applying them to penicillin detection. Summary of the Invention

[0004] To address the aforementioned challenges, this invention combines COF with Au NPs, proposing an effective method for regulating the activity of photoresponsive COF nanozymes. On one hand, Au NPs are in situ grown on TpBTD (a COF material prepared by Schiff base condensation reaction of 1,3,5-trialdehyde-resorcinol and 4,4'-(benzo[C][1,2,5]thiadiazole-4,7-diyl)diphenylamine) using a simple one-step chemical reduction method. The resulting photoresponsive TpBTD-Au nanozyme exhibits stronger visible light absorption, an ideal band gap and band structure, and high carrier separation efficiency than pure TpBTD COF, thereby significantly promoting the generation of more highly oxidizing reactive oxygen species (ROS) and enhancing the photoresponsive nanozyme activity of TpBTD. On the other hand, a highly efficient PG colorimetric sensing platform is constructed based on the reactivity principle of penicillin (PG) with ROS, enabling rapid, sensitive, and selective detection of PG in environmental water samples. This invention not only provides a new strategy for the rational design of efficient photoresponsive COF nanozymes, but also provides a new technical means for the rapid detection of antibiotic residues.

[0005] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of the present invention is to provide a photoresponsive TpBTD-Au nanozyme with high catalytic performance, comprising a COF material obtained by Schiff base condensation of 1,3,5-trialdehyde phloroglucinol (Tp) and 4,4'-(benzo[C][1,2,5]thiadiazole-4,7-diyl)diphenylamine (BTD) and Au NPs (gold nanoparticles) loaded on the surface of the COF material.

[0006] Preferably, the loading of Au NPs is 0.7~8.7 wt.%.

[0007] The gold nanoparticles in the photoresponsive TpBTD-Au nanozyme provided by this invention have a particle size of 5-20 nm, exhibit a flower-like entangled morphology, and a specific surface area of ​​300-400 m². 2 / g, with pore sizes concentrated in the range of 1.3~2.5nm.

[0008] The second technical solution of the present invention provides a method for preparing the above-mentioned high-catalytic-performance photoresponsive TpBTD-Au nanozyme, comprising the following steps: 1,3,5-trialdehyde phloroglucinol, 4,4'-(benzo[C][1,2,5]thiadiazole-4,7-diyl)diphenylamine and a catalyst were added to a solvent, and a COF material was obtained through a solvothermal reaction. The COF material was then added to a solution containing a gold precursor, and the pH was adjusted to 3.5-5.0 (more preferably 4.0). After stirring and reacting, the photoresponsive TpBTD-Au nanozyme with high catalytic performance was obtained.

[0009] Preferably, the solvent is an organic mixed solvent, specifically a mixture of 1,4-dioxane and o-dichlorobenzene in a volume ratio of 1:1.

[0010] Preferably, the mass ratio of the 1,3,5-trialdehyde phloroglucinol to the 4,4'-(benzo[C][1,2,5]thiadiazole-4,7-diyl)diphenylamine is 1:1 to 10.

[0011] Preferably, the catalyst is acetic acid.

[0012] More preferably, the concentration of acetic acid in the reaction system is 6 mM.

[0013] Preferably, the temperature of the solvothermal reaction is 80~200℃ and the time is 12~72h.

[0014] Preferably, the concentration of gold ions in the solution containing the gold precursor is 1~20mM, more preferably 4mM.

[0015] Optionally, the gold precursor is chloroauric acid (HAuCl4).

[0016] Preferably, the stirring reaction time is 4-8 hours, more preferably 6 hours.

[0017] During the stirring reaction, gold ions are reduced in situ to Au NPs by the amino groups on TpBTD COF, thereby obtaining the photoresponsive TpBTD-Au nanozyme with high catalytic performance.

[0018] The third technical solution of the present invention provides an application of the above-mentioned high-catalytic-performance photoresponsive TpBTD-Au nanozyme in penicillin detection.

[0019] Fourth technical solution of the present invention: A colorimetric detection method for penicillin based on the above-mentioned photoresponsive TpBTD-Au nanozyme with high catalytic performance, comprising the following steps: Add the aforementioned photoresponsive TpBTD-Au nanozyme with high catalytic performance, buffer solution, and chromogenic substrate tetramethylbenzidine (TMB) to the test solution containing penicillin. After reacting under light conditions, centrifuge the solution and measure the absorbance of the supernatant using UV-Vis absorption spectroscopy to calculate the penicillin content in the test solution.

[0020] Preferably, the illumination conditions are a wavelength of 350~780nm and a power of 3~5W·cm. -2 The illumination time is ~10 min; the pH value of the buffer solution is 3.0~4.0; the concentration of the high-catalytic-performance photoresponsive COF-Au nanozyme is 50 μg·mL. -1 The concentration of the tetramethylbenzidine is 0.8 mM.

[0021] The linear detection range of penicillin provided by the present invention is 35~17500 ng·mL. -1 The detection limit is 18.6 ng / mL. -1 .

[0022] The beneficial technical effects of the present invention are as follows: This invention is the first to load Au NPs onto TpBTD with a donor-acceptor structure, utilizing the nitrogen-containing groups in the COF backbone to reduce Au in situ. 3+ This method achieves uniform dispersion and robust loading of Au NPs. XPS analysis shows that the electrons for the reduction of HAuCl4 to Au NPs originate from the oxidation of the -NH-C- group in TpBTD, indicating a strong interaction between the amino group and the Au NPs, effectively preventing the aggregation of noble metal nanoparticles. This TpBTD-Au composite catalyst possesses a mesoporous structure and abundant specific surface area, with numerous exposed active sites, making it highly active in photocatalysis.

[0023] The photoresponsive TpBTD-Au nanozyme prepared in this invention exhibits a wider visible light absorption range (significant redshift of the absorption band edge), a narrower band gap (reduced from 2.03 eV to 1.93 eV), and higher photogenerated electron-hole pair separation efficiency than pure TpBTD. PL spectroscopy shows that TpBTD-Au has a weaker fluorescence emission peak intensity and a stronger photocurrent response than TpBTD. EIS AC impedance spectroscopy shows a smaller arc radius, confirming that the loading of Au NPs greatly suppresses electron-hole pair recombination. Kinetic analysis indicates that the maximum reaction rate of TpBTD-Au is... V max Reaching 39.24×10 -8 M·s -1 It is significantly higher than the pure TpBTD of 29.01×10. -8 M·s -1 .

[0024] Free radical quenching experiments and EPR tests confirmed that the main active species generated by the TpBTD-Au photocatalytic reaction is superoxide anion radical (·O2). - ), hole (h + ) and singlet oxygen ( 1 The loading of Au NPs significantly enhances the generation capacity of these reactive oxygen species, thereby improving the catalytic performance of nanozymes. This invention is based on penicillin and O2. - and 1 The colorimetric sensing platform constructed based on the specific reaction with O2 exhibits high selectivity and sensitivity for penicillin. The detection limit is 18.6 ng / mL. -1 The linear range is 35~17500 ng·mL. -1 It outperforms most reported colorimetric methods. It exhibits good recovery rates (91.1%~104.6%) and low RSD (<4.6%) in actual water samples (river water, pond water, tap water).

[0025] The TpBTD-Au nanozyme prepared by this invention showed very little change in photoresponsive nanozyme activity during a two-month storage period. After five photocatalytic cycles, the activity remained above 80%, indicating that the catalyst has excellent stability and reusability.

[0026] This invention uses a one-pot solvothermal method to synthesize COF, and then uses a one-step in-situ reduction method to load Au NPs. The process is simple, the conditions are mild, and the reproducibility is good, making it suitable for large-scale production. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The results show the effect of different Au loadings on catalytic activity in Example 9.

[0029] Figure 2 The results show the effect of different pH conditions on catalytic activity in Example 10.

[0030] Figure 3 The results show the effect of different reaction times on catalytic activity in Example 11.

[0031] Figure 4 The results show the effect of different amounts of TpBTD on catalytic activity in Example 12.

[0032] Figure 5 XRD patterns of the nanozymes prepared in Examples 7 and 13.

[0033] Figure 6 SEM images of the nanozymes prepared in Examples 7(a) and 13(b).

[0034] Figure 7 XPS spectra of the nanozymes prepared in Examples 7 and 13.

[0035] Figure 8 The N2 adsorption-desorption curve and pore size distribution of the photoresponsive TpBTD-Au nanozyme prepared in Example 13.

[0036] Figure 9 The results of the storage stability (a) and recyclability (b) tests for Example 14 are shown.

[0037] Figure 10 The Lineweaver-Burk double reciprocal curves and steady-state dynamic analysis curves of TpBTD-Au and TpBTD in Example 15 are shown below; where (a) is the Lineweaver-Burk double reciprocal curve of TpBTD-Au, (b) is the steady-state dynamic analysis curve of TpBTD-Au, (c) is the Lineweaver-Burk double reciprocal curve of TpBTD, and (d) is the steady-state dynamic analysis curve of TpBTD.

[0038] Figure 11The absorbance values ​​are those obtained by changing the concentration of TpBTD-Au (a), TMB concentration (b), illumination time (c), light intensity (d), and pH of the buffer solution (d) in Example 16.

[0039] Figure 12 The EIS AC impedance spectra of TpBTD and TpBTD-Au in Example 17 are shown.

[0040] Figure 13 TEMP- in different reaction systems under light irradiation in Example 18 1 O2(a), DMPO-•O2 - (b) and TEMP-h + (c) EPR spectrum.

[0041] Figure 14 The UV-Vis absorption spectra of different reaction systems in Example 19 are shown.

[0042] Figure 15 The graph shows the effect of different PG concentrations on absorbance in Example 20 and the linear relationship between absorbance change and PG concentration. Detailed Implementation

[0043] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0044] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0045] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0046] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0047] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0048] Example 1 Preparation of COF materials Preparation of reaction solvent: Take 1 mL of 1,4-dioxane, 1 mL of o-dichlorobenzene and 0.2 mL of acetic acid (catalyst, concentration 6 mM) and mix them evenly as the reaction solvent.

[0049] 10 mg Tp and 20 mg BTD were weighed and added to the above reaction solvent. The mixture was ultrasonically dispersed for 20 min, then transferred to a stainless steel reactor and heated in an oven at 150 °C for 72 h. The reaction product was collected by centrifugation. The red product obtained by centrifugation was washed three times with tetrahydrofuran and acetone, respectively. The centrifugation speed for collection and washing was 12000 rpm / min, and the time was 10 min. Finally, the purified sample was dried in a vacuum drying oven at 100 °C for 12 h to obtain the COF material.

[0050] Example 2 Preparation of photoresponsive TpBTD-Au nanozymes (standard ratio): 10 mL of HAuCl4•4H2O solution (4 mM) was transferred to a 25 mL glass bottle, and the pH of the solution was adjusted to 4.0 using NaOH (0.1 M). Then, 5 mg of the COF material prepared in Example 1 was added, and the resulting mixture was reacted under vigorous stirring (300 rpm) for 6 h. After the reaction was completed, the mixture was centrifuged at 12000 rpm for 20 min, washed three times with ultrapure water, and finally, the photoresponsive TpBTD-Au nanozyme loaded with Au NPs was collected and dispersed in 2 mL of ultrapure water.

[0051] Example 3 Preparation of photoresponsive TpBTD-Au nanozymes synthesized under different pH conditions: Referring to the preparation method of Example 2, the difference is that the pH of the HAuCl4·4H2O solution was adjusted to 3.0, 3.5, 4.5 and 5.0 respectively, while other conditions remained unchanged, to prepare photoresponsive TpBTD-Au nanozymes synthesized under different pH conditions, which were labeled as TpBTD-Au-pH3.0, TpBTD-Au-pH3.5, TpBTD-Au-pH4.5 and TpBTD-Au-pH5.0 respectively.

[0052] Example 4 Preparation of photoresponsive TpBTD-Au nanozymes with different reaction times: The preparation method of Example 2 was used, except that the stirring reaction time was set to 2h, 4h, 8h and 10h respectively, while other conditions remained unchanged, to prepare photoresponsive TpBTD-Au nanozymes with different reaction times, which were labeled as TpBTD-Au-2h, TpBTD-Au-4h, TpBTD-Au-8h and TpBTD-Au-10h respectively.

[0053] Example 5 Preparation of photoresponsive TpBTD-Au nanozymes with different amounts of TpBTD: The preparation method of Example 2 was followed, except that 2 mg, 4 mg, 6 mg, 8 mg and 10 mg of TpBTD powder prepared in Example 1 were added respectively, while other conditions remained unchanged, to prepare photoresponsive TpBTD-Au nanozymes with different amounts of TpBTD, which were labeled as TpBTD-Au-2 mg, TpBTD-Au-4 mg, TpBTD-Au-6 mg, TpBTD-Au-8 mg and TpBTD-Au-10 mg respectively.

[0054] Example 6 Preparation of photoresponsive TpBTD-Au nanozymes with different TpBTD:Au ratios: To verify the optimal ratio of Au NPs loading in TpBTD-Au, the method of Example 2 was followed, but the Au precursor concentration was changed. The actual Au loading was determined by ICP-MS to obtain samples with different Au loadings: Preparation of solution A: Measure 10 mL of HAuCl4·4H2O solutions of different concentrations (1 mM, 2 mM, 4 mM, 6 mM, 8 mM, 10 mM) and adjust the pH to 4.0 respectively; Preparation of solution B: Weigh 4 mg of the COF material obtained in Example 1; Solutions A and B were mixed and stirred vigorously for 6 hours. After the reaction, the precipitate was collected by centrifugation at 12000 rpm for 20 minutes, washed, and dispersed in 2 mL of ultrapure water to obtain photoresponsive COF-Au nanozymes with different Au loadings, labeled as TpBTD-Au-1, TpBTD-Au-2, TpBTD-Au-3, TpBTD-Au-4, TpBTD-Au-5, and TpBTD-Au-6, respectively. The actual Au loadings were determined by ICP-MS to be 0.7 wt.%, 2.9 wt.%, 4.8 wt.%, 6.4 wt.%, 7.6 wt.%, and 8.7 wt.%, respectively.

[0055] Example 7 Preparation of comparative materials: Pure TpBTD control sample: Take 4 mg of the COF material prepared in Example 1 and disperse it directly in 2 mL of ultrapure water without Au loading treatment. This sample is used as a control sample and labeled as TpBTD.

[0056] Example 8 Photoresponsive TpBTD-Au nanozyme activity assay method: Add HAc-NaAc buffer (0.1M, pH 3.5) and the catalyst dispersion (final concentration 50 μg·mL) to the centrifuge tube in sequence. -1 Mix 0.5 mL of TMB solution (final concentration 0.8 mM) and TMB solution (final concentration 0.8 mM). Immediately after mixing, place the mixture in a photocatalytic reactor (light source wavelength 350~780 nm, power 4.16 W·cm⁻¹). -2 The reaction was irradiated for 4 min. After the reaction, the sample was centrifuged at 9000 rpm for 30 seconds, and the supernatant was collected to measure the UV-Vis absorption spectrum at 652 nm. Pure TpBTD from Example 7 was used as a control, and the catalytic activity was evaluated by absorbance value.

[0057] Example 9 Effect of different Au loadings on catalytic activity: The photoresponsive TpBTD-Au nanozymes (TpBTD-Au-1 to TpBTD-Au-6) with different Au loadings prepared in Example 6 were tested for their photoresponsive TpBTD-Au nanozyme activity according to the method in Example 8.

[0058] Test results are available Figure 1 , Figure 1 The results show that the catalytic activity initially increases and then decreases with increasing Au loading. The catalytic activity reaches its peak when the Au loading is 4.8 wt.% (TpBTD-Au-3, corresponding to 4 mM HAuCl4), with an absorbance at 652 nm approximately 2.5 times that of pure TpBTD. When the Au loading is too high (>8 wt.%), the activity may decrease due to Au NP aggregation. Therefore, the optimal Au loading is determined to be around 4.8 wt.%.

[0059] Example 10 Effect of different pH conditions on catalytic activity: The photoresponsive TpBTD-Au nanozymes synthesized under different pH conditions in Example 3 were tested for their photoresponsive TpBTD-Au nanozyme activity according to the method in Example 8.

[0060] Test results are available Figure 2 , Figure 2 The results showed that the prepared TpBTD-Au exhibited the highest catalytic activity at a synthesis pH of 4.0. pH that was too low (<3.5) may have negatively impacted Au catalytic activity. 3+Insufficient reduction or excessively high pH (>4.5) may lead to excessively large Au NP particle size or agglomeration, both of which affect catalytic performance.

[0061] Example 11 Effect of different reaction times on catalytic activity: The photoresponsive TpBTD-Au nanozymes prepared in Example 4 with different reaction times were tested for their photoresponsive TpBTD-Au nanozyme activity according to the method in Example 8.

[0062] Test results are available Figure 3 , Figure 3 The results show that the catalytic activity gradually increases as the reaction time increases from 2 h to 6 h; however, the catalytic activity remains relatively stable after the reaction time exceeds 6 h. Therefore, the optimal reaction time is determined to be 6 h.

[0063] Example 12 Effect of different TpBTD dosages on catalytic activity: The photoresponsive TpBTD-Au nanozymes prepared in Example 5 with different amounts of TpBTD were tested for their photoresponsive TpBTD-Au nanozyme activity according to the method in Example 8.

[0064] Test results are available Figure 4 , Figure 4 The results show that the catalyst exhibits the highest catalytic activity when the amount of TpBTD used during synthesis is 4 mg (corresponding to 10 mL of 4 mM Au precursor). Insufficient TpBTD may lead to excessive loading and aggregation of Au NPs, while excessive TpBTD may lead to insufficient loading of Au NPs, both of which affect catalytic performance.

[0065] Example 13 Preparation of the optimal photoresponsive TpBTD-Au nanozyme: Based on the optimization results of Examples 10-12, the optimal preparation conditions for the photoresponsive TpBTD-Au nanozyme were determined to be: 10 mL of 4 mM HAuCl4·4H2O solution was measured into a 25 mL glass bottle, and the pH of the solution was adjusted to 4.0 with NaOH solution. 4 mg of the COF material prepared in Example 1 was added, and the reaction was carried out under vigorous stirring for 6 h. After the reaction was completed, the precipitate was collected by centrifugation at 12000 rpm for 20 min, washed three times with ultrapure water, and finally dispersed in 2 mL of ultrapure water and stored at 4 °C for later use. The obtained photoresponsive TpBTD-Au nanozyme was labeled as TpBTD-Au, and the Au loading was determined to be 4.8 wt.% by ICP-MS.

[0066] The XRD patterns of the nanozymes prepared in Examples 7 and 13 are shown in Figure 1. Figure 5 .

[0067] SEM images of the nanozymes prepared in Examples 7(a) and 13(b) are shown below. Figure 6 .

[0068] XPS spectra of the nanozymes prepared in Examples 7 and 13 are shown below. Figure 7 .

[0069] The N2 adsorption-desorption curve and pore size distribution of the photoresponsive TpBTD-Au nanozyme prepared in Example 13 are shown in [reference needed]. Figure 8 .

[0070] Example 14 The optimal photoresponsive TpBTD-Au nanozyme prepared in Example 13 was subjected to storage stability and recyclability tests: (1) Storage stability: The TpBTD-Au dispersion was stored in a refrigerator at 4°C. Samples were taken at 0, 7, 15, 30, 45 and 60 days of storage, and its photoresponsive TpBTD-Au nanozyme activity was tested according to the method in Example 8.

[0071] (2) Recyclability: The same batch of TpBTD-Au catalyst was used to carry out photocatalytic reaction according to the method in Example 8. After the reaction, the catalyst was recovered by centrifugation at 9000 rpm, washed three times with ultrapure water, and redispersed for the next reaction. The cycle was repeated 5 times, and the relative activity after each cycle was calculated.

[0072] The storage stability (a) and recyclability (b) test results of Example 14 are shown in [reference needed]. Figure 9 .

[0073] Figure 9 The results showed that the catalytic activity of TpBTD-Au changed by less than 5% during a 60-day storage period; after 5 cycles, the catalytic activity remained above 80%, indicating that the catalyst has good storage stability and reusability.

[0074] Example 15 The optimal photoresponsive TpBTD-Au nanozyme prepared in Example 13 was subjected to steady-state kinetic tests: A 0.5 mL mixture containing HAc-NaAc buffer (0.1 M, pH 3.5), TpBTD-Au aqueous dispersion (50 μg / mL), and TMB was placed under a xenon lamp for 1 min of photoreaction (illuminance 4.16 W·cm⁻¹). -2After the reaction, the sample was rapidly centrifuged for 30 s, and the UV-Vis absorption spectrum of the supernatant at 650 nm was measured. It is noteworthy that the TMB concentration needed to be changed sequentially (0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 mM) for the tests. Furthermore, kinetic parameters... K m and V max The value is derived from the Michaelis-Menten equation using the Lineweaver-Burk formula 1 / υ = K m / V max (1 / [C]+1 / K m )calculate( K m , V max [C] corresponds to the Michaelis constant, maximum reaction rate, and substrate concentration, respectively. The kinetic control experiment of TpBTD is conducted in the same manner as above, except that TpBTD-Au is replaced with an equal mass of TpBTD.

[0075] The Lineweaver-Burk double reciprocal curves and steady-state dynamic analysis curves of TpBTD-Au and TpBTD are shown below. Figure 10 Among them, (a) is the Lineweaver-Burk double reciprocal curve of TpBTD-Au, (b) is the steady-state dynamic analysis curve of TpBTD-Au, (c) is the Lineweaver-Burk double reciprocal curve of TpBTD, and (d) is the steady-state dynamic analysis curve of TpBTD.

[0076] from Figure 10 As can be seen, both TpBTD and TpBTD-Au have low... K m and higher V max The value is more satisfactory, and TpBTD-Au has a more satisfactory value. K m and V max The above results strongly demonstrate that loading Au NPs can significantly enhance the photoresponsive nanozyme activity of TpBTD.

[0077] Example 16 Using the optimal photoresponsive TpBTD-Au nanozyme prepared in Example 13, and based on the experimental method of Example 8, the optimal catalytic activity conditions for the TpBTD-Au nanozyme were investigated: Add 0.1M HAc-NaAc buffer, the catalyst dispersion, and TMB solution sequentially to a centrifuge tube, with a total volume of 0.5 mL. After mixing, immediately place the tube in a photocatalytic reactor (light source wavelength 350–780 nm) for photocatalytic reaction. Optimize the reaction conditions by sequentially changing the TpBTD-Au concentration, TMB concentration, irradiation time, light intensity, and buffer solution pH. After the reaction, centrifuge at 9000 rpm for 30 seconds, and measure the UV-Vis absorption spectrum at 652 nm using the supernatant.

[0078] The absorbance values ​​corresponding to changes in TpBTD-Au concentration (a), TMB concentration (b), illumination time (c), light intensity (d), and buffer solution pH (d) are shown in the figure. Figure 11 .

[0079] from Figure 11 It can be seen from this that 50 μg·mL -1 TpBTD-Au catalyst dosage, 0.8 mM TMB substrate concentration, 7 min illumination time, 4.16 W·cm⁻¹ -2 Ideal reaction conditions were achieved with high light intensity and a buffer pH of 3.5. Under these conditions, TpBTD-Au exhibited optimal photoresponsive nanozyme catalytic performance.

[0080] Example 17 The optimal photoresponsive TpBTD-Au nanozyme prepared in Example 13 and the TpBTD prepared in Example 7 were used to test their electrochemical impedance spectroscopy: Electrochemical impedance spectroscopy (EIS) measurements were performed on a CHI660E electrochemical workstation using a standard three-electrode system (working electrode: glassy carbon electrode (GCE), counter electrode: Pt electrode, reference electrode: Ag / AgCl electrode). Additionally, the workstation was connected to a PEAC 200A photoelectrochemical module (blue LED lamp (20 mW·cm⁻¹)). -2 (As a light source). It is worth noting that the potentials need to be determined using the formula: E NHE =E Ag / AgCl +E θAg / AgCl (E θAg / AgCl =0.199 V) for conversion.

[0081] The EIS AC impedance spectra of TpBTD and TpBTD-Au are shown below. Figure 12 .

[0082] from Figure 12 As can be seen from the EIS AC impedance spectroscopy, TpBTD-Au exhibits a smaller arc radius, indicating that TpBTD-Au possesses lower charge transfer impedance. This suggests that the loading of Au NPs significantly suppresses e - / h+ The combination of these elements achieves high efficiency. - / h + The separation of these components explains the significantly enhanced photoresponsive nanozyme activity of TpBTD-Au.

[0083] Example 18 The optimal photoresponsive TpBTD-Au nanozyme prepared in Example 13 was used to further investigate the mechanism of the significantly enhanced photoresponsive nanozyme catalytic activity of TpBTD-Au, and the ROS generated in the photocatalytic reaction was verified: ROS generated during the photocatalytic reaction was measured by adding different quenchers. In short, different quenchers (2 mM BQ, AO, NaN3, or IPA) were added sequentially to centrifuge tubes containing HAc-NaAc buffer (0.1 M, pH 3.5), TpBTD-Au aqueous dispersion (50 μg / mL), and 0.2 mM TMB solution, with a total volume of 0.5 mL in each tube. After thorough mixing, the reaction solutions were placed in a photocatalytic reactor and irradiated for 2 min (light power: 4.16 W·cm⁻¹). -2 After the reaction was completed, the supernatant was rapidly centrifuged for 30 seconds, and then the absorbance of the supernatant was measured using a UV-Vis spectrophotometer. The types of ROS generated were evaluated based on the changes in absorbance.

[0084] TEMP- in different reaction systems under light irradiation 1 O2(a), DMPO-•O2 - (b) and TEMP-h + The EPR spectrum of (c) is shown below. Figure 13 .

[0085] from Figure 13 As can be seen from the EPR test results, the TpBTD is stronger after loading Au NPs. - h + and 1 O2 generation capability. Based on valence band structure, photoelectrochemical characterization, and ROS verification results, the following reaction mechanism can be deduced: the e-generated electrons generated during photocatalysis... - It readily transfers to the TpBTD-Au surface and participates in the reduction and generation of O2. - And h on VB + Extremely easy and • O2 - Oxidation reaction occurs, promoting 1 O2 is generated. - h + and 1 O2 synergistically enhances the photoresponsive nanozyme catalytic performance of TpBTD-Au.

[0086] Example 19 The optimal photoresponsive TpBTD-Au nanozyme prepared in Example 13 and the TpBTD prepared in Example 7 were used to investigate the catalytic ability of different reaction systems for PG: Add the following solutions sequentially to five centrifuge tubes containing HAc-NaAc buffer (0.1 M, pH 3.5): ① TMB solution (final concentration 0.8 mM); ② TpBTD (final concentration 50 μg / mL). -1 ) + TMB solution (final concentration 0.8 mM) + PG; ③ TpBTD-Au (final concentration 50 μg·mL) -1 ) + TMB solution (final concentration 0.8 mM); ④ TpBTD (final concentration 50 μg·mL) -1 ) + TMB solution (final concentration 0.8 mM) + PG; ⑤ TpBTD-Au (final concentration 50 μg·mL) -1 Add TMB solution (final concentration 0.8 mM) and PG, controlling the total volume of solution in each centrifuge tube to 0.5 mL. After mixing, immediately place in a photocatalytic reactor (light source wavelength 350~780 nm, power 4.16 W·cm⁻¹). -2 Irradiate the sample for 4 minutes. After the reaction, centrifuge at 9000 rpm for 30 seconds, and take the supernatant from five centrifuge tubes to measure the UV-Vis absorption spectrum at 652 nm.

[0087] The UV-Vis absorption spectra of different reaction systems are shown in the figure. Figure 14 .

[0088] from Figure 14 As can be seen, both TpBTD and TpBTD-Au can catalyze the oxidation of TMB, with TpBTD-Au exhibiting superior photoresponsive nanozyme activity. Furthermore, the addition of PG to both the TpBTD-TMB and TpBTD-Au-TMB systems for photocatalytic reaction inhibited the color development of oxTMB, which well explains the interaction between PG and •O2. - and 1 The reaction between O2.

[0089] Example 20 The optimal photoresponsive TpBTD-Au nanozyme prepared in Example 13 was used to investigate its degradation ability for different concentrations of PG: First, different concentrations of PG were added sequentially to separate centrifuge tubes. Each tube was pre-filled with 0.1 M HAc-NaAc buffer, TpBTD-Au aqueous dispersion (50 μg / mL), and 0.8 mM TMB solution, with a total volume of 0.5 mL for each mixture. After vortexing to mix, the mixture was immediately subjected to light irradiation for 7 min. The supernatant was then rapidly centrifuged and collected for UV-Vis absorption spectroscopy. A standard curve was plotted based on the absorbance changes at different PG concentrations.

[0090] The effect of different PG concentrations on absorbance and the linear relationship between absorbance change and PG concentration are shown in the figure. Figure 15 .

[0091] from Figure 15 As can be seen, a significant change in absorbance value is observed with increasing PG concentration. Based on this, a graph was plotted showing the relationship between the corresponding absorbance change value (A0-A, where A and A0 represent the absorbance values ​​with and without PG, respectively) and PG concentration, thus obtaining a linear curve for PG detection. The absorbance values ​​ranged from 35 to 17500 ng·mL. -1 Within the specified range, the absorbance change value established a good linear relationship with the PG concentration. This indicates that the sensor has a comparable LOD value and a wide linear range. Therefore, the TpBTD-Au-based colorimetric sensing platform has potential practical application value in monitoring PG content.

[0092] In summary, this invention synthesized a photoresponsive TpBTD COF via a solvothermal method and prepared a series of photoresponsive TpBTD-Au nanozymes by uniformly loading different amounts of Au NPs onto its surface using a one-step in-situ reduction method. By adjusting the Au precursor concentration, reaction pH, reaction time, and TpBTD dosage, the optimal Au loading of approximately 4.8 wt.% for the TpBTD-Au catalyst was obtained. Various physical characterization methods, including scanning electron microscopy and transmission electron microscopy, were used to investigate the catalyst's structure and morphology, confirming the flower-like entanglement morphology of TpBTD and the uniform distribution of Au NPs on the TpBTD surface. Figure 5 The crystal structure of the catalyst was investigated using X-ray powder diffraction, confirming the successful synthesis of TpBTD and the loading of Au NPs. Figure 6 X-ray photoelectron spectroscopy analysis revealed the interaction between Au NPs and amino groups in TpBTD, confirming the interaction between Au NPs and amino groups in TpBTD. 3+ Restored to Au in situ 0 The mechanism ( Figure 7 Simultaneously, nitrogen adsorption-desorption was used to investigate the pore size and specific surface area of ​​the catalyst. The results showed that TpBTD-Au has a mesoporous structure and a rich specific surface area (approximately 360 m²).2 / g), which helps expose more active sites ( Figure 8 UV-Vis diffuse reflectance spectroscopy and photoelectrochemical assays showed that loading Au NPs significantly broadened the light absorption range of TpBTD, reduced the band gap (from 2.03 eV to 1.93 eV), and improved the separation efficiency of photogenerated electron-hole pairs. Radical trapping experiments and electron paramagnetic resonance spectroscopy confirmed that TpBTD-Au can generate more highly oxidizing ·O2 under illumination. - h + and 1 O2 and other ROS were detected. Through a series of characterization and performance tests, the synthesis of a TpBTD-Au nanozyme with excellent photoresponsive oxidative mimicry activity was demonstrated. The catalyst was synthesized via COF synthesis and in-situ reduction of noble metals; this method is simple, mild, and highly reproducible. Based on the specific reaction between penicillin and ROS, a highly sensitive and selective penicillin colorimetric sensing platform was successfully constructed, with a detection limit as low as 18.6 ng·mL⁻¹. -1 The linear range is wide, ranging from 35 to 17500 ng·mL. -1 The invention demonstrated good recovery rate and stability in actual water samples. It not only provides a new technical solution for the rational design of efficient photoresponsive COF nanozymes, but also a new technical means for the rapid detection of antibiotic residues, and is expected to play an important role in environmental monitoring, food safety, and biomedicine.

[0093] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A photoresponsive TpBTD-Au nanozyme with high catalytic performance, characterized in that, The COF material includes a COF material obtained by Schiff base condensation reaction of 1,3,5-trialdehyde phloroglucinol and 4,4'-(benzo[C][1,2,5]thiadiazole-4,7-diyl)diphenylamine and Au NPs loaded on the surface of the COF material.

2. The high-catalytic-performance photoresponsive TpBTD-Au nanozyme according to claim 1, characterized in that, The loading of Au NPs is 0.7~8.7 wt.%.

3. A method for preparing the high-catalytic-performance photoresponsive TpBTD-Au nanozyme according to claim 1 or 2, characterized in that, Includes the following steps: 1,3,5-trialdehyde phloroglucinol, 4,4'-(benzo[C][1,2,5]thiadiazole-4,7-diyl)diphenylamine and a catalyst were added to a solvent, and a COF material was obtained through a solvothermal reaction. The COF material was then added to a solution containing a gold precursor, the pH was adjusted to 3.5-5.0, and the reaction was stirred to obtain the photoresponsive TpBTD-Au nanozyme with high catalytic performance.

4. The preparation method according to claim 3, characterized in that, The solvent is an organic mixed solvent, specifically a mixture of 1,4-dioxane and o-dichlorobenzene in a volume ratio of 1:

1.

5. The preparation method according to claim 3, characterized in that, The mass ratio of the 1,3,5-trialdehyde phloroglucinol to the 4,4'-(benzo[C][1,2,5]thiadiazole-4,7-diyl)diphenylamine is 1:1~10.

6. The preparation method according to claim 3, characterized in that, The catalyst is acetic acid.

7. The preparation method according to claim 3, characterized in that, The temperature of the solvothermal reaction is 80~200℃ and the time is 12~72h; and or, the stirring reaction time is 4~8h.

8. The preparation method according to claim 3, characterized in that, The concentration of gold ions in the solution containing the gold precursor is 1~20mM.

9. The application of the photoresponsive TpBTD-Au nanozyme with high catalytic performance as described in claim 1 or 2 in penicillin detection.

10. A colorimetric detection method for penicillin based on the high-catalytic-performance photoresponsive TpBTD-Au nanozyme as described in claim 1 or 2, characterized in that, Includes the following steps: Add the photoresponsive TpBTD-Au nanozyme with high catalytic performance as described in claim 1 or 2, buffer solution, and chromogenic substrate tetramethylbenzidine to the test solution containing penicillin. After reaction under light conditions, centrifuge and measure the absorbance of the supernatant by ultraviolet-visible absorption spectroscopy to calculate the penicillin content in the test solution.

Images