Azo fluorescent compound, preparation method and application thereof, nano antibacterial agent and preparation method thereof

Abstract

The invention relates to the technical field of azo switches, and discloses an azo fluorescent compound, a preparation method and application thereof, a nano antibacterial agent and a preparation method thereof. The compound has a structure as shown in a formula (I). The nano preparation using the azo fluorescent compound as a light-operated component can realize light-operated release of drugs, and the controlled release process of the nano preparation can be visually detected through a fluorescence imaging technology.

Description

Technical Field

[0001] This invention relates to the field of azo switch technology, specifically to azo fluorescent compounds and their preparation methods and applications, and nano-antibacterial agents and their preparation methods. Background Technology

[0002] Azobenzene is a photoswitch that undergoes reversible cis-trans isomerization under light irradiation. This light-triggered switching property has led to the broad application potential of azo molecules in materials science and nanotechnology. In addition, azo photoswitches activated by non-invasive visible light are also used to create photocontrolled biological systems, regulate biomolecular functions, and study cell behavior.

[0003] In biological research, changes in the molecular structure of azo photoswitches and the regulation of cellular behavior by light are primarily manifested at the cellular microenvironment level. Over the past two decades, the rapid development of fluorescence imaging technology has provided an intuitive method for visually tracking and monitoring dynamic biological processes within the cellular microenvironment. Therefore, some researchers have combined fluorescence imaging with azo photoswitches to develop azo fluorescent switches. These switches not only provide intuitive evidence of changes in biological processes, but their own fluorescence changes can also serve as response signals for assessing photoregulatory processes.

[0004] Generally, the basic strategy for constructing azo fluorescent switches is to directly introduce a fluorophore at the end of an azo group or azobenzene. However, azo fluorescent switches synthesized using this method still suffer from problems such as easy fluorescence quenching, poor biocompatibility, and complex synthesis steps.

[0005] Studies show that nanoscale controlled-release systems constructed using azo switches as photoresponsive components can release drugs in an orderly and controllable manner, significantly improving bioavailability. In these controlled-release systems, the azo photoswitches coupled to prodrugs or macromolecular carriers can induce changes in the system's structure and properties at the mesoscale through a photoisomerization process, thereby achieving photocontrolled drug release. If this controlled-release process can be visualized using fluorescence imaging technology, it will not only be possible to locate lesions or disease sites but also to understand the structure-activity relationship between the degree of controlled release and therapeutic effect, thus serving precision medicine.

[0006] Based on the above discussion, it is necessary to develop a novel azo fluorescent switch that can both control release and have imaging performance. Summary of the Invention

[0007] The purpose of this invention is to provide an azo photoswitch with its own fluorescence emission properties and to apply it to a nano-controlled release system.

[0008] To achieve the above objectives, the present invention provides an azo photoswitch with its own fluorescence emission through rational molecular design. This azo photoswitch is based on a phenyl heteroaryl azo backbone and has a donor-acceptor configuration (DA) characteristic.

[0009] To achieve the above objectives, a first aspect of the present invention provides an azo fluorescent compound having the structure shown in formula (I).

[0010]

[0011] In the following description of the present invention, the structure represented by formula (I) will also be referred to as compound 1 or AzoPJ.

[0012] A second aspect of the invention provides the application of the azo fluorescent compound described in the first aspect as a fluorescent light switch.

[0013] A third aspect of the present invention provides a method for preparing the azo fluorescent compound described in the first aspect, the method comprising:

[0014] (1) Under acidic conditions, the compound shown in formula (II) is contacted and mixed with sodium nitrite to obtain a diazonium salt;

[0015] (2) Under conditions of pH ≤ 7.5, in the presence of a solvent, the diazonium salt is reacted with the compound shown in formula (III) to obtain the azo fluorescent compound;

[0016]

[0017] A fourth aspect of the present invention provides a nano-antibacterial agent comprising a nanocarrier and a fluorescent photoswitch and a small molecule drug with a molecular weight not greater than 1000 encapsulated in the nanocarrier; wherein the fluorescent photoswitch is the azo fluorescent compound described in the first aspect.

[0018] The nano-antibacterial agent of the present invention is based on a fluorescent azo molecular switch and uses a surfactant as a nanocarrier, and can simultaneously load small molecule drugs and fluorescent light switches through self-assembly.

[0019] The fifth aspect of the present invention provides a method for preparing the nano-antibacterial agent described in the fourth aspect, the method comprising: performing a first mixing treatment on a tetrahydrofuran solution I containing a fluorescent photoswitch and a tetrahydrofuran solution II containing a small molecule drug to obtain a first solution; and then performing a second mixing treatment on the first solution and a nano-carrier donor to obtain the nano-antibacterial agent.

[0020] The azo fluorescent compound provided by this invention can be used as a novel azo fluorescent light switch.

[0021] This invention relates to nanoparticles, and the provided fluorescent light switch can switch back and forth between trans and cis configurations under irradiation with visible light of different wavelengths; accompanied by reversible changes in fluorescence, while exhibiting obvious photocontrolled fluorescence characteristics.

[0022] The nano-formulation (i.e., azo nano-antibacterial agent) using the azo fluorescent compound of the present invention as the photocontrol component can not only achieve photocontrolled drug release, but its controlled release process can also be visualized and detected by fluorescence imaging technology.

[0023] The preparation method of the azo fluorescent compound of the present invention is relatively simple.

[0024] Furthermore, the fluorescent photoswitch provided by this invention is expected to offer an effective strategy for the design and synthesis of other azo fluorescent photoswitch. Attached Figure Description

[0025] Figure 1 The azo fluorescent compound 1 (AzoPJ) prepared in Preparation Example 1 of this invention is used as a fluorescent azo switch at 440 nm (50 mW cm⁻¹). -2 ) or 535nm (50mW cm -2 ) Absorption spectrum changes under visible light irradiation; Figure 1 Figure A shows the change in the absorption spectrum of the fluorescent azo switch under 440nm light illumination. Figure 1 B represents the change in the absorption spectrum of the fluorescent azo switch after three minutes of 440nm light irradiation followed by 535nm visible light irradiation.

[0026] Figure 2 The azo fluorescent compound 1 (AzoPJ) prepared in Preparation Example 1 of this invention is used as a fluorescent azo switch at 440 nm (20 W / cm²). -2 ) or 535nm (15W cm -2 Emission spectrum variation under visible light illumination; Figure 2 Figure A shows the emission spectrum change of the fluorescent azo switch under 440nm light illumination. Figure 2 B represents the emission spectrum change after irradiation with 535nm visible light following the fluorescence azo switch isomerization after irradiation with 440nm light;

[0027] Figure 3 The nano-antibacterial agent (AzoPJ-PEPA NPs) prepared in Example 1 of this invention was subjected to 440nm light irradiation (20W cm⁻¹). -2 TEM images and particle size distribution before and after ( ). Figure 3 In this image, A represents the TEM image of the nano-antibacterial agent before and after 440nm light irradiation; Figure 3 In the diagram, B represents the particle size distribution of the nano-antibacterial agent before irradiation with 440nm light; Figure 3 In this diagram, C represents the particle size distribution of the nano-antibacterial agent after irradiation with 440nm light, where the scale bar is 200nm.

[0028] Figure 4 The nano-antibacterial agent (AzoPJ-PEPA NPs) prepared in Example 1 of this invention exhibits performance under 440 nm visible light (20 W cm⁻¹). -2 ) Absorption spectrum changes under irradiation;

[0029] Figure 5 This is a graph showing the absorption spectrum changes of the nano-antibacterial agent (AzoPJ-PEPA NPs) prepared in Example 1 of this invention under natural light irradiation.

[0030] Figure 6 This is a light-controlled drug release image of Rhizoctonia solani stained with the nano-antibacterial agent (AzoPJ-PEPA NPs) prepared in Example 1 of this invention;

[0031] Figure 7 This is a schematic diagram of the synthetic route for preparing nano-antibacterial agents (AzoPJ-PEPA NPs) in Example 1 of the present invention. Detailed Implementation

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] The structural formula of julonidine described in this invention is:

[0034]

[0035] The structural formula of the fluorophenyl ether amide described in this invention is:

[0036]

[0037] Unless otherwise specified, the azo fluorescent compounds of this invention include their cis and / or trans structures. If it is a mixture of cis and trans structures, there are no special requirements for the mixing ratio; the molar ratio of the cis and trans structures can be 1%:99%, 2%:98%, 3%:97%, 4%:96%, 5%:95%, 6%:94%, 7%:93%, 8%:92%, 9%:91%, 10%:90%, 11%:89%, 12%:88%, 13%:87%, 14%:86%, 15%:85%, 16%:84%, 17%:83%, 18%:82%, 19%:81%, 20%:80%, 25%:75%, 30%:70%, 3... 5%:65%, 40%:60%, 45%:55%, 50%:50%, 55%:45%, 60%:40%, 65%:35%, 70%:30%, 75%:25%, 80%:20%, 81%:19%, 82%:18%, 83%:17%, 84%:16%, 85%:15%, 86%:14%, 87%:13%, 88%:12%, 89%:11%, 90%:10%, 91%:9%, 92%:8%, 93%:7%, 94%:6%, 95%:5%, 96%:4%, 97%:3%, 98%:2%, or 99%:1%.

[0038] As previously described, a first aspect of the present invention provides an azo fluorescent compound having the structure shown in formula (I).

[0039]

[0040] As previously stated, the second aspect of the present invention provides the application of the azo fluorescent compound described in the first aspect as a fluorescent light switch.

[0041] Preferably, the azo fluorescent compound is used as a fluorescent light switch in a nano-controlled release system.

[0042] As previously stated, a third aspect of the present invention provides a method for preparing the azo fluorescent compound described in the first aspect, the method comprising:

[0043] (1) Under acidic conditions, the compound shown in formula (II) is contacted and mixed with sodium nitrite to obtain a diazonium salt;

[0044] (2) Under conditions of pH ≤ 7.5, in the presence of a solvent, the diazonium salt is reacted with the compound shown in formula (III) to obtain the azo fluorescent compound;

[0045]

[0046] In a third aspect of the invention, preferably, the molar ratio of the compound represented by formula (II), the sodium nitrite, and the compound represented by formula (III) is 1:1-1.4:1.1-1.5.

[0047] In a third aspect of the invention, preferably, in step (1), the contact mixing conditions include: a temperature of -10°C to 5°C and a time of 10 min to 50 min. More preferably, in step (1), the contact mixing temperature is 0-5°C.

[0048] In a third aspect of the invention, preferably, in step (1), the acidic conditions are formed by at least one strong acid selected from hydrochloric acid, sulfuric acid and nitric acid.

[0049] In a third aspect of the invention, preferably, the method further includes: before performing step (2), subjecting the diazonium salt obtained in step (1) to pH adjustment so that the pH value of the diazonium salt is ≤7.5 before performing the synthesis reaction in step (2), more preferably the pH value of the diazonium salt is ≤7.0, and particularly preferably the pH value of the diazonium salt is 6.5-7.0.

[0050] In a third aspect of the invention, preferably, the pH adjustment treatment is performed by applying a buffer solution. More preferably, the buffer solution contains NaOH and Na₂CO₃.

[0051] In a third aspect of the invention, preferably, in step (2), the solvent is selected from at least one of water and ethanol.

[0052] In a third aspect of the invention, preferably, in step (2), the conditions for the synthesis reaction include: a temperature of 5°C to 50°C and a time of 0.2h to 10h.

[0053] In a third aspect of the invention, preferably, the method further includes: post-processing the material obtained after the synthesis reaction.

[0054] In the third aspect of the invention, there are no particular requirements for the specific operations and conditions of the post-processing; conventional operations and conditions used in the art can be employed, such as filtering and collecting the obtained precipitate, performing chromatographic purification, drying, etc. The invention is not described in detail herein, and those skilled in the art should not construe it as a limitation of the invention.

[0055] As previously described, a fourth aspect of the present invention provides a nano-antibacterial agent comprising a nanocarrier and a fluorescent photoswitch and a small molecule drug with a molecular weight not greater than 1000 encapsulated in the nanocarrier; the fluorescent photoswitch is the azo fluorescent compound described in the first aspect.

[0056] Preferably, the nanocarrier is at least one surfactant selected from DSPE-mPEG5000 and DSPE-mPEG2000. The present invention does not have particular requirements regarding the source of the nanocarrier; it can be prepared in-house using methods known in the art, or it can be commercially available, for example, from Pengshuo Biotechnology Co., Ltd.

[0057] In the nano-antibacterial agent provided by the present invention, the fluorescent light switch can be encapsulated inside the nano-carrier. During the preparation process, since the nano-carrier (liposome) is amphiphilic, it can form a spherical structure, thereby loading hydrophobic molecules inside, while small molecules that are not loaded can be removed by ultrafiltration centrifugation.

[0058] Preferably, the small molecule drug is selected from at least one of antifungal agents and antibacterial agents.

[0059] Particularly preferably, the small molecule drug is selected from at least one of flufenoxuronamide (PEPA), difenoconazole, and avermectin.

[0060] Preferably, the loading rate of the small molecule drug is 75% or higher, more preferably 80% or higher. The loading rate (EE%) = (total added mass of drug - mass of unloaded drug) / total added mass of drug.

[0061] Preferably, the mass ratio of the fluorescent light switch, the small molecule drug, and the nanocarrier is 1:0.1-0.3:5-15.

[0062] As previously stated, a fifth aspect of the present invention provides a method for preparing the nano-antibacterial agent described in the fourth aspect, the method comprising: performing a first mixing treatment on a tetrahydrofuran solution I containing a fluorescent photoswitch and a tetrahydrofuran solution II containing a small molecule drug to obtain a first solution; and then performing a second mixing treatment on the first solution and a nano-carrier donor to obtain the nano-antibacterial agent.

[0063] The present invention does not have any special requirements for the specific operation of the matrix encapsulation method. Those skilled in the art can use the methods provided in the literature known in the art. The present invention will not elaborate further here, and those skilled in the art should not understand it as a limitation of the present invention.

[0064] Preferably, the first mixing process is performed under first ultrasonic conditions.

[0065] Preferably, the first ultrasonic conditions include: an ultrasonic frequency of 35-45 kHz and an ultrasonic time of 10-30 min.

[0066] Preferably, the second mixing process is performed under second ultrasonic conditions.

[0067] Preferably, the ultrasonic conditions include: an ultrasonic frequency of 20kHz-60kHz and an ultrasonic time of 10min-30min.

[0068] Preferably, the concentration of the fluorescent photoswitch in the tetrahydrofuran solution I is 0.8-1 mg / mL.

[0069] Preferably, in the tetrahydrofuran solution II, the concentration of the small molecule drug is 0.1-0.2 mg / mL.

[0070] According to a particularly preferred embodiment, the method for preparing the nano-antibacterial agent described in the fourth aspect comprises: under ultrasonic conditions, ultrasonicating tetrahydrofuran solution I containing the fluorescent photoswitch and tetrahydrofuran solution II containing the small molecule drug, and then performing the first mixing treatment to obtain a first solution; then adding the first solution to a DSPE-mPEG5000 aqueous solution for a second mixing treatment to obtain the nano-antibacterial agent.

[0071] Preferably, the concentration of DSPE-mPEG5000 in the aqueous solution is 0.8-1 mg / mL.

[0072] The present invention does not have any particular requirements for the preparation methods of the tetrahydrofuran solution I and the tetrahydrofuran solution II. For example, the solute and solvent can be mixed under ultrasonic conditions. Furthermore, there are no particular requirements for the ultrasonic mixing time in this step, which can be, for example, 1 min to 20 min.

[0073] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, the raw materials used are common commercially available products.

[0074] The room temperature mentioned in this invention refers to 25±2℃.

[0075] Preparation Example 1: Synthesis of azo fluorescent compound 1, named AzoPJ, via the following synthetic route:

[0076]

[0077] The specific steps include:

[0078] 1.0 mmol of 4-amino-1,3,5-trimethyl-1H-pyrazole was dispersed in 2 mL of ice water and stirred. Hydrochloric acid (12 M, 0.5 mL) was then added. Subsequently, an aqueous solution of 1.2 mmol of sodium nitrite was slowly added to the solution. After stirring for 30 min under ice water conditions, the pH of the resulting diazonium salt solution was adjusted by adding aqueous solutions of sodium hydroxide and sodium carbonate. When the pH reached 6.5, an ethanolic solution of julonidine (1.3 mmol) was added. The mixture was stirred at room temperature for 3 hours, and the resulting orange-yellow precipitate was collected by vacuum filtration. The crude product was washed with water, ethanol, and petroleum ether, and then purified by column chromatography to obtain an orange solid in 65% yield.

[0079] The characterization results are as follows:

[0080] 1 H NMR (600MHz, CDCl3): δ=7.31(s,2H),3.75(s,3H),3.23(s,4H),2.81(s,4H),2.53(s,3H),2.47(s,3H),1.99(s,4H). LC-MS: m / z=309.1946[M]+; calculated value=309.1953.

[0081] Tests were performed on AzoPJ, and the absorption and fluorescence emission spectra (excitation wavelength 350 nm) of AzoPJ are as follows: Figure 1 , Figure 2 As shown.

[0082] Figure 1 Figure A shows the change in the absorption spectrum of the fluorescent azo switch under 440nm illumination. Figure 1 B represents the change in absorption spectrum of the fluorescent azo switch after three minutes of 440nm light irradiation followed by 535nm visible light irradiation. From... Figure 1 As can be seen, after irradiation with 440nm blue light in DMSO, the ultraviolet absorption spectrum changed significantly, with two absorption peaks appearing at 376nm and 453nm, respectively, indicating that trans-AzoPJ underwent photoisomerization to generate the cis-AzoPJ isomer.

[0083] To verify the reversibility of the cis-trans isomerism of AzoPJ, subsequent irradiation of cis-AzoPJ with 535 nm green light revealed that its absorption spectrum could almost completely recover to its initial state. These photoisomerization properties not only demonstrate that AzoPJ possesses excellent photoisomerization properties, but also indicate that this azo molecule is a typical visible light-induced molecular switch.

[0084] To determine whether the electron donor julonidine unit can effectively suppress the TICT process in the molecule and thus improve its fluorescence intensity, the fluorescence spectrum of AzoPJ was further tested, and the results are as follows: Figure 2 As shown, Figure 2 Figure A shows the emission spectrum change of the fluorescent azo switch under 440nm illumination. Figure 2 B represents the emission spectrum change after irradiation with 535nm visible light following isomorphic isomerization of the fluorescent azo dye after 440nm illumination. (Example:) Figure 2 As shown, in DMSO, AzoPJ produces a distinct emission peak at 507 nm and a weaker emission can be observed at 420 nm. When irradiated with 440 nm blue light, its fluorescence spectrum changes significantly. With prolonged irradiation time, the trans-azo molecule isomerizes to form the cis-azo molecule, and the fluorescence of its ultraviolet emission peak gradually increases (λ). em =420nm); while the emission peak originally located at 507nm gradually weakens. When irradiated with 535nm green light, its fluorescence spectrum can be restored to the initial state. The above experimental results show that AzoPJ has good optical switching performance and optically controlled fluorescence characteristics.

[0085] Example 1: Synthesis of nano-antibacterial agents (i.e., nano-antibacterial agents)

[0086] The synthesis route in this embodiment is as follows: Figure 7 The process, as shown, includes: self-assembling a surfactant with an antibacterial agent (drug molecule) and AzoPJ (fluorescent azo photoswitch) to obtain a nano-antibacterial agent loaded with drug molecules and AzoPJ, named AzoPJ-PEPA NPs. The specific synthesis steps include:

[0087] Azo fluorescent photoswitcher AzoPJ and fluorophenyl ether amide (analytical grade, drug molecule) were dissolved separately in THF and sonicated for 5 minutes each. The two were then mixed and sonicated for 30 minutes to form a uniform orange solution. Subsequently, the mixed solution was added to 9 mL of DSPE-mPEG5000 aqueous solution, and THF was removed by nitrogen gas flow. After centrifugation in an ultrafiltration tube, the volume was adjusted to obtain the nano-antibacterial agent AzoPJ-PEPA NPs.

[0088] Performance tests were conducted on the nano-antibacterial agent AzoPJ-PEPA NPs. Specifically, the transmission electron microscopy images and particle size distribution of the nano-antibacterial agent AzoPJ-PEPA NPs before and after visible light irradiation are shown below. Figure 3 As shown, in which, Figure 3 In this image, A represents the TEM image of the nano-antibacterial agent before and after 440nm light irradiation; Figure 3 In the diagram, B represents the particle size distribution of the nano-antibacterial agent before irradiation with 440nm light; Figure 3In the diagram, C represents the particle size distribution of the nano-antibacterial agent after irradiation with 440nm light.

[0089] from Figure 3 As can be seen, the size of the nanoparticles increased significantly after irradiation with 440 nm light; DLS results showed that the average particle size increased from 136 nm to 230 nm. This is mainly attributed to the isomerization of the azo switch component in the nano-formulation under 440 nm light irradiation, which led to the increase in the cavity size of the nanoparticles.

[0090] The absorption spectrum of the nano-antibacterial agent (AzoPJ-PEPA NPs) in this embodiment after irradiation with visible light at 440 nm is as follows: Figure 4 As shown. From Figure 4 As can be seen, before illumination, a low characteristic absorption peak of the drug was observed at 260 nm; after irradiation with 440 nm light, the peak value gradually increased. This result indicates that the fungicide is slowly released under 440 nm light irradiation. Furthermore, from... Figure 5 It is known that this nano-formulation can also achieve controlled release of bactericides under natural light irradiation.

[0091] The fluorescence-guided drug release microscopic imaging results of the nano-antibacterial agent (AzoPJ-PEPA NPs) in this embodiment are as follows: Figure 6 As shown. From Figure 6 As can be seen, after Rhizobium thuringiensis was incubated with the nano-antibacterial agent AzoPJ-PEPA NPs for 48 hours, under 405nm light excitation, by collecting fluorescence signals in the 460nm-580nm range, bright green fluorescence of Rhizobium thuringiensis cells could be observed, and complete hyphal structures could be observed. After co-incubation for 48 hours, it was further irradiated with 440nm visible light, as shown... Figure 6 As shown, a decrease in fluorescence signal, hyphal deformation, and hyphal rupture can be observed. This result indicates that the controlled release process of this nano-formulation can be visualized and monitored using fluorescence imaging technology.

[0092] The above results demonstrate that the azo fluorescent compound provided by this invention possesses photo-switching properties and can serve as a novel azo fluorescent photo-switching device. Furthermore, nano-formulations using the azo fluorescent compound of this invention as a photocontrol component can not only achieve photocontrolled drug release, but the controlled release process can also be visualized and detected using fluorescence imaging technology.

[0093] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An azo fluorescent compound, characterized in that, The compound has the structure shown in formula (I).

2. The application of the azo fluorescent compound according to any one of claims 1 as a fluorescent light switch; Preferably, the azo fluorescent compound is used as a fluorescent light switch in a nano-controlled release system.

3. A method for preparing the azo fluorescent compound according to any one of claims 1, characterized in that, The method includes: (1) Under acidic conditions, the compound shown in formula (II) is contacted and mixed with sodium nitrite to obtain a diazonium salt; (2) Under conditions of pH ≤ 7.5, in the presence of a solvent, the diazonium salt is reacted with the compound shown in formula (III) to obtain the azo fluorescent compound; 4. The method according to claim 3, characterized in that, In step (1), the conditions for contact mixing include: a temperature of -10°C to 5°C and a time of 10 min to 50 min; Preferably, the acidic conditions are formed by at least one strong acid selected from hydrochloric acid, sulfuric acid, and nitric acid; Preferably, in step (2), the solvent is selected from at least one of water and ethanol; Preferably, the conditions for the synthesis reaction include: a temperature of 5-50°C and a time of 0.2-10 h.

5. A nano-antibacterial agent, characterized in that, This nano-antibacterial agent contains a nanocarrier and a fluorescent photoswitch and a small molecule drug with a molecular weight of no more than 1000 encapsulated in the nanocarrier; The fluorescent photoswitch is the azo fluorescent compound described in claim 1.

6. The nano-antibacterial agent according to claim 6, characterized in that, The donor of the nanocarrier is at least one surfactant selected from DSPE-mPEG5000 and DSPE-mPEG2000.

7. The nano-antibacterial agent according to claim 5 or 6, characterized in that, The small molecule drug is selected from at least one of a fungicide and a bactericide. Preferably, the small molecule drug has a loading rate of 75% or higher.

8. A method for preparing the nano-antibacterial agent according to any one of claims 5-7, characterized in that, The method includes: using a matrix encapsulation method, performing a first mixing treatment on tetrahydrofuran solution I containing a fluorescent photoswitch and tetrahydrofuran solution II containing a small molecule drug to obtain a first solution; and then performing a second mixing treatment on the first solution and a nanocarrier donor to obtain the nano-antibacterial agent.

9. The method according to claim 8, characterized in that, The first mixing process is performed under the first ultrasonic conditions; Preferably, the first ultrasonic conditions include: an ultrasonic frequency of 35-45 kHz and an ultrasonic time of 10-30 min.

10. The method according to claim 8, characterized in that, The second mixing process is performed under the second ultrasonic conditions; Preferably, the ultrasonic conditions include: an ultrasonic frequency of 20kHz-60kHz and an ultrasonic time of 10min-30min.

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