A photothermal nano-antibacterial agent made of iron-cobalt oxide and its preparation and application

Abstract

This invention belongs to the field of nanobiomedicine and antibacterial materials technology, specifically disclosing an iron-cobalt oxide photothermal nano-antibacterial agent and its preparation and application. The antibacterial agent includes iron-cobalt oxide, and the concentration of the iron-cobalt oxide is ≤1.3 mg / mL. The iron-cobalt oxide photothermal nano-antibacterial agent exhibits broad-spectrum bactericidal properties under near-infrared light irradiation. Through repeated experiments, the preparation method of the iron-cobalt oxide photothermal nano-antibacterial agent provided by this invention is simple, low-cost, and has good biocompatibility. Under near-infrared laser irradiation, it can efficiently and rapidly kill Gram-positive and Gram-negative bacteria. More importantly, this iron-cobalt oxide photothermal nano-antibacterial agent demonstrates excellent bactericidal and therapeutic effects in treating bacterial keratitis caused by methicillin-resistant Staphylococcus aureus (MRSA), providing a promising option for addressing the difficulty in treating bacterial keratitis caused by drug-resistant bacteria.

Description

Technical Field

[0001] This invention relates to the fields of nanobiomedicine and antibacterial materials technology, and in particular to an iron-cobalt oxide photothermal nano-antibacterial agent and its preparation and application. Background Technology

[0002] Bacterial keratitis is an inflammatory reaction of the cornea caused by bacterial infection. It is a common and frequently occurring disease in ophthalmology and one of the leading causes of vision impairment and blindness worldwide. It often occurs after corneal trauma, wearing contact lenses, or the use of contaminated surgical instruments during ophthalmic surgery. After infection, bacteria invade the corneal tissue, causing a severe inflammatory reaction, usually manifesting as corneal irritation symptoms such as photophobia, pain, tearing, blurred vision, and significant visual impairment, and may even lead to ulceration. The infection usually progresses rapidly, and in severe cases, corneal perforation or even blindness can occur. The first-line treatment for bacterial keratitis is broad-spectrum antibiotics (such as levofloxacin). However, the overuse and even abuse of antibiotics have led to the emergence of multidrug-resistant bacteria, and antibiotics have difficulty penetrating bacterial biofilms, thus affecting treatment efficacy. This poses a significant challenge to the treatment of bacterial infections. Therefore, there is an urgent need to develop a novel antibacterial strategy that can effectively kill drug-resistant bacteria.

[0003] The eyeball is a transparent optical organ composed of a transparent refractive medium, possessing excellent light transmittance. Therefore, phototherapy exhibits significant advantages in treating eye diseases. Photothermal therapy utilizes nanomaterials with photothermal properties. These nanomaterials convert absorbed light energy into heat energy under near-infrared laser irradiation, causing irreversible damage to the structure and components of bacterial cells at the site of infection through high temperatures. Currently, a crucial class of photothermal antibacterial nanomaterials consists of precious metal nanomaterials such as gold, silver, and palladium. These materials are expensive, and large-scale synthesis is costly. Therefore, reducing the cost of photothermal nanomaterials to facilitate industrial production and efficiently killing drug-resistant bacteria using low-cost photothermal nanomaterials is a pressing technical challenge. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an iron cobalt oxide photothermal nano-antibacterial agent and its preparation and application. The preparation method of the iron cobalt oxide photothermal nano-antibacterial agent is simple, low in cost, and has good biosafety. It also has excellent antibacterial properties, especially good bactericidal and therapeutic effects on bacterial keratitis caused by drug-resistant bacteria.

[0005] To achieve the above and other related objectives, the first aspect of the present invention provides an iron cobalt oxide photothermal nano-antibacterial agent, comprising iron cobalt oxide, wherein the concentration of the iron cobalt oxide is ≤1.3 mg / mL; the iron cobalt oxide photothermal nano-antibacterial agent has broad-spectrum bactericidal properties under near-infrared light irradiation.

[0006] Furthermore, the conditions for near-infrared light irradiation include: a near-infrared wavelength of 780–1000 nm and a laser power density of 0.6–0.8 W / cm². 2 The irradiation time is 5 to 10 minutes.

[0007] Furthermore, the iron-cobalt oxide photothermal nano-antibacterial agent can kill Gram-positive and Gram-negative bacteria under near-infrared light irradiation.

[0008] Furthermore, the concentration of the iron-cobalt oxide is 0.25–1.3 mg / mL, preferably 0.75–1.3 mg / mL.

[0009] Furthermore, the iron-cobalt oxide has a spherical structure with a smooth surface and uniform size, with an average size of 430 nm.

[0010] Furthermore, the iron-cobalt oxide photothermal nano-antibacterial agent also includes a solvent selected from at least one of water and PBS buffer.

[0011] Furthermore, the preparation method of the iron-cobalt oxide includes the following steps:

[0012] (1) Solid cobalt iron glycerate is prepared by adding cobalt salt and iron salt to a mixed solvent and using a solvothermal method; the mixed solvent includes glycerol and isopropanol.

[0013] (2) Solid iron cobalt glycerate was heated and calcined to obtain black iron cobalt oxide powder.

[0014] Furthermore, in step (1), the molar ratio of cobalt ions in the cobalt salt, iron ions in the iron salt, and glycerol is 2–4:1:1.0 × 10⁻⁶. 4 ~2.0×10 4 .

[0015] Furthermore, in step (1), the volume ratio of glycerol to isopropanol in the mixed solvent is 1:3 to 8.

[0016] Furthermore, in step (1), the cobalt salt is selected from at least one of cobalt nitrate, sulfate, chloride, acetate and perchlorate, and the iron salt is selected from at least one of iron nitrate, sulfate, chloride, acetate and perchlorate.

[0017] Furthermore, in step (1), the heating temperature is 160-200℃ and the heating time is 4-8h.

[0018] Furthermore, step (1) also includes: after the solvothermal reaction is completed, the reaction solution is naturally cooled to room temperature, and then centrifuged, washed, and dried to obtain yellow-brown iron cobalt glycerate powder.

[0019] Furthermore, in step (1), the centrifugation speed is 6000-10000 rpm and the centrifugation time is 2-6 min.

[0020] Furthermore, in step (1), the drying temperature is 60-100℃ and the drying time is not less than 4 hours.

[0021] Furthermore, in step (2), the heating rate is 0.5 to 2 °C / min, the calcination temperature is 300 to 400 °C, and the calcination time is 1.5 to 3 h.

[0022] A second aspect of the present invention provides a method for preparing the iron-cobalt oxide photothermal nano-antibacterial agent according to the first aspect, comprising the following steps:

[0023] (I) Solid cobalt iron glycerate is prepared by adding cobalt salt and iron salt to a mixed solvent and using a solvothermal method; the mixed solvent includes glycerol and isopropanol.

[0024] (II) Solid iron cobalt glycerate was heated and calcined to obtain black iron cobalt oxide powder;

[0025] (III) Add iron cobalt oxide powder to a solvent and stir evenly to prepare the iron cobalt oxide photothermal nano antibacterial agent.

[0026] Furthermore, in step (I), the molar ratio of cobalt ions in the cobalt salt, iron ions in the iron salt, and glycerol is 2–4:1:1.0 × 10⁻⁶. 4 ~2.0×10 4 .

[0027] Furthermore, in step (I), the volume ratio of glycerol to isopropanol in the mixed solvent is 1:3 to 8.

[0028] Furthermore, in step (I), the cobalt salt is selected from at least one of cobalt nitrate, sulfate, chloride, acetate and perchlorate, and the iron salt is selected from at least one of iron nitrate, sulfate, chloride, acetate and perchlorate.

[0029] Furthermore, in step (I), the heating temperature is 160–200°C and the heating time is 4–8 hours.

[0030] Furthermore, step (I) also includes: after the solvothermal reaction is completed, the reaction solution is naturally cooled to room temperature, and then centrifuged, washed, and dried to obtain yellow-brown iron cobalt glycerate powder.

[0031] Furthermore, in step (I), the centrifugation speed is 6000-10000 rpm and the centrifugation time is 2-6 min.

[0032] Furthermore, in step (I), the drying temperature is 60–100°C, and the drying time is not less than 4 hours.

[0033] Furthermore, in step (II), the heating rate is 0.5–2 °C / min, the calcination temperature is 300–400 °C, and the calcination time is 1.5–3 h.

[0034] Furthermore, in step (III), the solvent is selected from at least one of water and PBS buffer.

[0035] A third aspect of the present invention provides the use of the iron cobalt oxide photothermal nano-antibacterial agent according to the first aspect and / or the iron cobalt oxide photothermal nano-antibacterial agent prepared according to the method of the second aspect in the use as or in the preparation of a medicament and / or bactericide for treating diseases caused by bacterial infections, wherein the iron cobalt oxide photothermal nano-antibacterial agent is capable of killing bacteria under near-infrared light irradiation.

[0036] Furthermore, the bacteria include Gram-positive bacteria and Gram-negative bacteria.

[0037] Furthermore, the disease is bacterial keratitis, preferably bacterial keratitis caused by methicillin-resistant Staphylococcus aureus infection.

[0038] As described above, the iron-cobalt oxide photothermal nano-antibacterial agent of the present invention, its preparation and application, have the following beneficial effects:

[0039] 1. Compared with traditional antibiotics, the iron-cobalt oxide photothermal nano-antibacterial agent provided by this invention has a unique antibacterial mechanism that not only has excellent killing effect on drug-resistant bacteria, but also effectively avoids inducing bacterial drug resistance.

[0040] 2. The iron-cobalt oxide photothermal nano-antibacterial agent provided by the present invention has strong broad-spectrum bactericidal properties, especially capable of killing drug-resistant Gram-positive and drug-resistant Gram-negative bacteria, including methicillin-resistant Staphylococcus aureus, Escherichia coli, Salmonella, Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, etc., but not limited to these.

[0041] 3. The iron-cobalt oxide photothermal nano-antibacterial agent provided by the present invention can be used to effectively treat bacterial keratitis caused by drug-resistant bacteria. It exhibits a high efficiency of in vivo bactericidal effect at a safe dosage and has good biocompatibility.

[0042] 4. The iron-cobalt oxide photothermal nano-antibacterial agent provided by this invention is simple to prepare and has a lower cost compared to precious metal photothermal nanomaterials such as gold, silver, and palladium, and has great potential for wide application and clinical translation. Attached Figure Description

[0043] Figure 1This is a scanning electron microscope (SEM) image of the iron-cobalt oxide prepared in Example 1 of the present invention;

[0044] Figure 2 The full X-ray photoelectron spectroscopy (XPS) spectrum of the iron-cobalt oxide prepared in Example 1 of this invention;

[0045] Figure 3 In Example 2 of this invention, the temperature continuously increases under near-infrared laser continuous illumination as the concentration of the iron-cobalt oxide solution increases;

[0046] Figure 4 This illustrates the plate inhibition effect of increasing iron-cobalt oxide concentration on methicillin-resistant Staphylococcus aureus in Example 3 of the present invention.

[0047] Figure 5 This invention describes the antibacterial effect of a 1.0 mg / mL iron-cobalt oxide solution on Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus on agar plates in Example 3 of this invention.

[0048] Figure 6 The iron-cobalt oxide solution in Example 4 of this invention has good blood compatibility;

[0049] Figure 7 The results of slit-lamp examinations on days 1, 3, 5, 7, 9, and 11 after the ocular surfaces of mice with bacterial keratitis in the PBS group, PBS + near-infrared (NIR) group, levofloxacin group, iron cobalt oxide group, and iron cobalt oxide + NIR group were treated in Example 5 of this invention. Detailed Implementation

[0050] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0051] One embodiment of the present invention provides an iron cobalt oxide photothermal nano-antibacterial agent, comprising iron cobalt oxide, wherein the concentration of the iron cobalt oxide is ≤1.3mg / mL; the iron cobalt oxide photothermal nano-antibacterial agent has broad-spectrum bactericidal properties under near-infrared light irradiation.

[0052] In some embodiments, the conditions for near-infrared light irradiation include: a near-infrared wavelength of 780–1000 nm and a laser power density of 0.6–0.8 W / cm². 2 The irradiation time is 5–10 minutes. For example, the near-infrared wavelength can be 780nm, 790nm, 800nm, 808nm, 810nm, 850nm, 900nm, 950nm, 1000nm, etc., and the laser power density can be 0.6W / cm². 2 0.65W / cm 2 0.7W / cm 2 0.75W / cm 2 0.8W / cm 2 Irradiation time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc.

[0053] In some embodiments, the iron-cobalt oxide photothermal nano-antibacterial agent can kill Gram-positive and Gram-negative bacteria under near-infrared light irradiation, such as methicillin-resistant Staphylococcus aureus, Escherichia coli, Salmonella, Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, etc., but is not limited to these two types of pathogens.

[0054] In some embodiments, the concentration of the iron-cobalt oxide is 0.25–1.3 mg / mL, preferably 0.75–1.3 mg / mL, such as 0.75 mg / mL, 0.80 mg / mL, 0.85 mg / mL, 0.90 mg / mL, 0.95 mg / mL, 1.0 mg / mL, 1.1 mg / mL, 1.2 mg / mL, 1.3 mg / mL, etc.

[0055] In some embodiments, the iron-cobalt oxide is a spherical nanoparticle with a smooth and uniform surface and an average size of ~430 nm.

[0056] In some embodiments, the iron cobalt oxide photothermal nano-antibacterial agent further includes a solvent, wherein the solvent is selected from at least one of water and PBS buffer; wherein the water is selected from deionized water, ultrapure water, etc.; and the PBS buffer can be selected as 0.01M PBS buffer with pH 7.0 to 7.8.

[0057] In some embodiments, the method for preparing the iron-cobalt oxide includes the following steps:

[0058] (1) Solid cobalt iron glycerate is prepared by adding cobalt salt and iron salt to a mixed solvent and using a solvothermal method; the mixed solvent includes glycerol and isopropanol.

[0059] (2) Solid iron cobalt glycerate was heated and calcined to obtain black iron cobalt oxide powder.

[0060] In some embodiments, in step (1), the molar ratio of cobalt ions in the cobalt salt, iron ions in the iron salt, and glycerol is 2–4:1:1.0 × 10⁻⁶. 4 ~2.0×10 4 For example, 2:1:1.0×10 4 2:1:1.5×10 4 2:1:2.0×10 4 3:1:1.5×10 4 3:1:1.5×10 4 3:1:2.0×10 4 4:1:1.5×10 4 4:1:1.5×10 4 4:1:2.0×10 4 wait.

[0061] In some embodiments, in step (1), the volume ratio of glycerol to isopropanol in the mixed solvent is 1:3 to 8, for example, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, etc.

[0062] In some embodiments, in step (1), the cobalt salt is selected from at least one of cobalt nitrate, sulfate, chloride, acetate, and perchlorate, and the iron salt is selected from at least one of iron nitrate, sulfate, chloride, acetate, and perchlorate. For example, the cobalt salt can be cobalt nitrate hexahydrate, cobalt sulfate hexahydrate, cobalt sulfate heptahydrate, cobalt chloride, cobalt acetate, cobalt perchlorate, etc., and the iron salt can be ferric nitrate nonahydrate, ferric sulfate, ferric chloride, ferric acetate, ferric perchlorate, etc. In some embodiments, in step (1), the heating temperature is 160–200°C, and the heating time is 4–8 hours. For example, the heating temperature can be 160°C, 170°C, 180°C, 190°C, 200°C, etc., and the heating time can be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.

[0063] In some embodiments, step (1) further includes: after the solvothermal reaction is completed, the reaction solution is naturally cooled to room temperature, and then centrifuged, washed, and dried to obtain yellow-brown iron cobalt glycerate powder.

[0064] In some embodiments, in step (1), the centrifugation speed is 6000-10000 rpm and the centrifugation time is 2-6 min. For example, the centrifugation speed can be 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 10000 rpm, etc., and the centrifugation time can be 2 min, 3 min, 4 min, 5 min, 6 min, etc.

[0065] In some embodiments, in step (1), the drying temperature is 60-100℃ and the drying time is not less than 4 hours. For example, the drying temperature can be 60℃, 70℃, 80℃, 90℃, or 100℃, and the drying time can be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0066] In some embodiments, in step (2), the heating rate is 0.5–2 °C / min, the calcination temperature is 300–400 °C, and the calcination time is 1.5–3 h. For example, the heating rate can be 0.5 °C / min, 1.0 °C / min, 1.5 °C / min, 2 °C / min, etc., the calcination temperature can be 300 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, etc., and the calcination time can be 1.5 h, 2.0 h, 2.5 h, 3.0 h, etc.

[0067] Another embodiment of the present invention provides a method for preparing an iron-cobalt oxide photothermal nano-antibacterial agent according to the above embodiments / examples, comprising the following steps:

[0068] (I) Solid cobalt iron glycerate is prepared by adding cobalt salt and iron salt to a mixed solvent and using a solvothermal method; the mixed solvent includes glycerol and isopropanol.

[0069] (II) Solid iron cobalt glycerate was heated and calcined to obtain black iron cobalt oxide powder;

[0070] (III) Add iron cobalt oxide powder to a solvent and stir evenly to prepare the iron cobalt oxide photothermal nano antibacterial agent.

[0071] In some embodiments, in step (I), the molar ratio of cobalt ions in the cobalt salt, iron ions in the iron salt, and glycerol is 2–4:1:1.0 × 10⁻⁶. 4 ~2.0×10 4 For example, 2:1:1.0×10 4 2:1:1.5×10 4 2:1:2.0×10 4 3:1:1.5×10 4 3:1:1.5×10 43:1:2.0×10 4 4:1:1.5×10 4 4:1:1.5×10 4 4:1:2.0×10 4 wait.

[0072] In some embodiments, in step (I), the volume ratio of glycerol to isopropanol in the mixed solvent is 1:3 to 8, for example, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, etc.

[0073] In some embodiments, in step (I), the cobalt salt is selected from at least one of cobalt nitrate, sulfate, chloride, acetate, and perchlorate, and the iron salt is selected from at least one of iron nitrate, sulfate, chloride, acetate, and perchlorate. Exemplarily, the cobalt salt can be cobalt nitrate hexahydrate, cobalt sulfate hexahydrate, cobalt sulfate heptahydrate, cobalt chloride, cobalt acetate, cobalt perchlorate, etc., and the iron salt can be ferric nitrate nonahydrate, ferric sulfate, ferric chloride, ferric acetate, ferric perchlorate, etc.

[0074] In some embodiments, in step (I), the heating temperature is 160–200°C, and the heating time is 4–8 hours. For example, the heating temperature can be 160°C, 170°C, 180°C, 190°C, 200°C, etc., and the heating time can be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.

[0075] In some embodiments, step (I) further includes: after the solvothermal reaction is completed, the reaction solution is naturally cooled to room temperature, and then centrifuged, washed, and dried to obtain yellow-brown iron cobalt glycerate powder.

[0076] In some embodiments, in step (I), the centrifugation speed is 6000-10000 rpm and the centrifugation time is 2-6 min. For example, the centrifugation speed can be 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 10000 rpm, etc., and the centrifugation time can be 2 min, 3 min, 4 min, 5 min, 6 min, etc.

[0077] In some embodiments, in step (I), the drying temperature is 60–100°C, and the drying time is not less than 4 hours. For example, the drying temperature can be 60°C, 70°C, 80°C, 90°C, or 100°C, and the drying time can be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0078] In some embodiments, in step (II), the heating rate is 0.5–2 °C / min, the calcination temperature is 300–400 °C, and the calcination time is 1.5–3 h. For example, the heating rate can be 0.5 °C / min, 1.0 °C / min, 1.5 °C / min, 2 °C / min, etc., the calcination temperature can be 300 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, etc., and the calcination time can be 1.5 h, 2.0 h, 2.5 h, 3.0 h, etc.

[0079] In some embodiments, in step (III), the solvent is selected from at least one of water and PBS buffer; wherein the water is selected from deionized water, ultrapure water, etc.; the PBS buffer can be selected as 0.01M PBS buffer with pH 7.0 to 7.8.

[0080] In another embodiment of the present invention, the iron cobalt oxide photothermal nano-antibacterial agent described in the above embodiments / examples can be used as a drug and / or bactericide for treating diseases caused by bacterial infections, or used to prepare a drug and / or bactericide for treating diseases caused by bacterial infections, wherein the iron cobalt oxide photothermal nano-antibacterial agent can kill bacteria under near-infrared light irradiation.

[0081] In some embodiments, the bacteria include Gram-positive and Gram-negative bacteria, such as methicillin-resistant Staphylococcus aureus, Escherichia coli, Salmonella, Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, etc., but are not limited to these two types of pathogens.

[0082] In some embodiments, the disease is bacterial keratitis, preferably bacterial keratitis caused by methicillin-resistant Staphylococcus aureus infection.

[0083] The following specific examples illustrate the present invention in detail. It should also be understood that the following examples are only for specific illustrative purposes and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0084] Example 1

[0085] This embodiment prepares an iron-cobalt oxide, and the specific steps are as follows:

[0086] (1) Preparation of cobalt iron glycerate nanoparticles: Using a solvothermal method, 0.073 g of cobalt nitrate hexahydrate and 0.032 g of ferric nitrate nonahydrate were slowly added to a mixed solvent consisting of 8 mL of glycerol and 40 mL of isopropanol at room temperature. The mixture was stirred continuously until it was completely dissolved. The resulting solution was heated to 180 °C in an air atmosphere and kept for 6 h. After it was naturally cooled to room temperature, it was centrifuged at 8000 rpm for 4 min, washed, and dried at 80 °C for 6 h to obtain yellow-brown cobalt iron glycerate powder.

[0087] (2) Preparation of iron cobalt oxide nanoparticles: Iron cobalt glycerate powder was placed in a ceramic alumina crucible and heated from room temperature to 350°C in a muffle furnace at a heating rate of 1°C / min under air atmosphere for 2 hours to obtain black iron cobalt oxide powder.

[0088] Figure 1 This is a scanning electron microscope image of the iron cobalt oxide powder prepared in this embodiment. The iron cobalt oxide nanoparticles have a spherical structure, uniform size, and an average size of ~430 nm.

[0089] Figure 2 The X-ray photoelectron spectroscopy (XPS) spectrum of the iron cobalt oxide powder prepared in this embodiment shows the peaks of the main structural groups and surface functional groups of the iron cobalt oxide nanoparticles and their corresponding binding energies.

[0090] Example 2

[0091] This embodiment studies the photothermal properties of the iron-cobalt oxide prepared in Example 1. The specific process is as follows:

[0092] Iron-cobalt oxide powder was prepared into aqueous solutions of different concentrations (0.25, 0.50, 0.75, 1.0 mg / mL) and subjected to laser power density of 0.75 W / cm². 2 The solution was irradiated with 808nm near-infrared light, and the temperature change of the solution was monitored at different times (0, 2, 4, 6, 8, 10 min) using a near-infrared imager. The real-time temperature was recorded every 30 seconds using an electronic thermometer to test its photothermal heating effect.

[0093] like Figure 3 As shown, near-infrared images taken at different time points (0, 2, 4, 6, 8, 10 min) clearly reveal the temperature rise trend of aqueous solutions of iron-cobalt oxide at different concentrations. With time, the higher the concentration of iron-cobalt oxide, the higher the temperature rise under near-infrared laser irradiation, and the heating rate exhibits a clear concentration dependence. This indicates that the iron-cobalt oxide provided by this invention possesses excellent photothermal properties and has the potential to serve as a photothermal nano-antibacterial agent.

[0094] Example 3

[0095] This embodiment studies the antibacterial properties of the aqueous solution of iron-cobalt oxide prepared in Example 1. The specific process is as follows:

[0096] Based on the photothermal performance study results of iron-cobalt oxide obtained in Example 2, this example uses methicillin-resistant Staphylococcus aureus (MRSA), a Gram-positive bacterium, to verify the photothermal antibacterial effect of its aqueous solution. The specific method is as follows:

[0097] The MRSA strain was inoculated into LB broth medium and then incubated at 37°C for 4–6 hours. Its logarithmic growth phase was determined using a micro-UV spectrophotometer. The optical density (OD) at 600 nm was measured. 600 When the concentration is 0.5, the bacteria grow to 10 per milliliter. 8 1 colony-forming units (CFU / mL). The bacterial suspension was then diluted to 10⁻⁶ CFU / mL with PBS buffer (0.01 M, pH 7.4). 6 CFU / mL was used to obtain the MRSA bacterial dispersion for the experiment. Bacterial dispersions without samples and without laser irradiation were used as control groups. Iron cobalt oxide powder was prepared into solutions of different concentrations (0.25, 0.50, 0.75, 1.0, 1.3 mg / mL) with PBS buffer. Then, 100 μL of the bacterial dispersion was mixed with 100 μL of PBS buffer and different concentrations of iron cobalt oxide solution, and 10 μL of each solution was evenly spread onto solid culture medium. The plates were incubated at 37℃ for approximately 16 hours, and the bacterial colonies on the plates were observed and photographed. Simultaneously, 10 μL of the above bacterial dispersion was transferred to a 96-well plate, and 200 μL of LB liquid medium was added to each well. The plates were incubated overnight at 37℃, and the absorbance at 600 nm was measured using a microplate reader. The near-infrared light source was an 808 nm semiconductor laser with a laser irradiation power of 0.75 W / cm². 2 The irradiation time is 10 minutes.

[0098] Figure 4 This image shows the plate-mounted antibacterial effect of different concentrations of iron-cobalt oxide solutions on MRSA in this embodiment. Figure 4 As shown, the effect on MRSA activity is negligible in the absence of near-infrared radiation, indicating that the iron cobalt oxide solution itself has almost no killing effect on bacteria without laser irradiation. Under near-infrared light excitation, the number of colonies in the plate gradually decreases with the increase of iron cobalt oxide concentration, indicating that iron cobalt oxide exhibits a significant killing effect on MRSA, and the killing effect is concentration-dependent.

[0099] The antibacterial rates corresponding to each concentration can be obtained through calculation and analysis, as shown in Table 1. The antibacterial rates of iron cobalt oxide solutions with concentrations of 0.25 mg / mL, 0.50 mg / mL, 0.75 mg / mL, 1.0 mg / mL, and 1.3 mg / mL are 25.48%, 57.19%, 94.62%, 94.75%, and 94.88%, respectively. When the concentration reaches 0.75 mg / mL, it can completely kill MRSA.

[0100] Table 1. Antibacterial rate of MRSA against iron-cobalt oxide solutions of different concentrations

[0101] Iron cobalt oxide (mg / mL) 0 0.25 0.50 0.75 1.0 1.3 Antibacterial rate (%) 0 25.48 57.19 94.62 94.75 94.88

[0102] Five common clinical pathogens, namely Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus, were cultured according to the above method, and the bacterial colonies on the plates were observed and photographed.

[0103] Figure 5 This image shows the plate inhibition effect of a 1.0 mg / mL iron-cobalt oxide solution against *Escherichia coli*, *Salmonella typhimurium*, *Pseudomonas aeruginosa*, *Acinetobacter baumannii*, and *Staphylococcus aureus*. Figure 5 It can be seen that under near-infrared light excitation, iron cobalt oxide solution has a highly effective bactericidal effect on the above five common clinical pathogens, indicating that iron cobalt oxide has good broad-spectrum bactericidal properties.

[0104] Example 4

[0105] This embodiment evaluates the blood compatibility of the iron-cobalt oxide prepared in Example 1. The specific process is as follows:

[0106] Take 1 mL of whole blood from a healthy person, add 7 mL of 0.9% NaCl solution to suspend the blood, centrifuge at 8000 rpm for 2.5 min, discard the supernatant, and wash repeatedly with 0.9% NaCl until the supernatant is no longer red or slightly yellow. Resuspend the lower layer of red blood cells with 4 volumes of 0.9% NaCl to obtain a red blood cell suspension. Prepare iron cobalt oxide powder into iron cobalt oxide solutions of different concentrations (0.25, 0.50, 0.75, 1.0, 1.3 mg / mL) with PBS buffer (0.01 M, pH 7.4), and then mix them with the above red blood cell suspensions respectively. Incubate in a 37℃ water bath for 1 h. After incubation, centrifuge at 6000 rpm for 5 min, observe the color of the supernatant of each group and measure the ultraviolet absorption at 545 nm, and calculate the hemolysis rate.

[0107] Figure 6 Iron-cobalt oxides of different concentrations exhibit good blood compatibility. For example... Figure 6 As shown, the supernatant of iron cobalt oxide solutions of different concentrations (0, 0.25, 0.50, 0.75, 1.0 mg / mL) mixed with red blood cell suspension was relatively clear with no obvious red color. The measured UV absorption at 545 nm and 576 nm was similar to that of the negative control (0.9% NaCl). The hemolysis rate of iron cobalt oxide solution in the range below 1.3 mg / mL did not exceed 5%, indicating that iron cobalt oxide solution has good blood compatibility as a photothermal nano-antibacterial agent.

[0108] Example 5

[0109] In this embodiment, the iron-cobalt oxide prepared in Example 1 was used to conduct a treatment experiment for bacterial keratitis caused by drug-resistant bacteria. The specific process is as follows:

[0110] Six- to seven-week-old female BALB / c mice were selected. After intraperitoneal anesthesia with 2.5% chloral hydrate, local anesthesia was administered with 0.5% promecaine hydrochloride eye drops. Using a disposable sterile needle, 3-5 parallel incisions, each 1 mm long, were gently made on the corneal surface. Logarithmic growth phase MRSA bacterial solution (1×10⁻⁶) was then injected. 7CFU / mL (20 μL) was instilled into the scratched area of ​​the eye, and then the upper and lower eyelids of the mice were closed to allow the bacterial solution to remain for a sufficient time. After 24 hours of feeding, all mice showed varying degrees of conjunctival hyperemia, corneal opacity, and decreased corneal transparency, which indicated successful establishment of a bacterial keratitis mouse model. The successfully modeled mice were randomly divided into 5 groups: PBS group, PBS+NIR group, levofloxacin group, iron cobalt oxide group, and iron cobalt oxide+NIR group, with 3 mice in each group. According to the group, the corresponding material was instilled into the right eye of the mice by eye drops, 10 μL each time. The PBS group and PBS+NIR group were instilled with deionized water, the levofloxacin group was instilled with levofloxacin aqueous solution with a concentration of 1.0 mg / mL, and the iron cobalt oxide group and iron cobalt oxide+NIR group were instilled with iron cobalt oxide aqueous solution with a concentration of 1.0 mg / mL. Following drug administration, the right eye of mice in the PBS+NIR group and the iron cobalt oxide+NIR group was irradiated with an 808 nm near-infrared laser (0.75 W / cm²). 2 (5 min). Temperature changes in the infected eye area of ​​mice throughout the treatment process were captured by near-infrared thermal imaging. The severity of the eye infection and treatment progress were continuously observed from day 1, and all observations were performed under a slit-lamp microscope.

[0111] The results are as follows Figure 7 As shown, slit-lamp examination revealed that during the treatment period, mice in the PBS group, PBS+NIR group, levofloxacin group, and iron cobalt oxide group exhibited significant central corneal suppuration and stromal infiltration, accompanied by conjunctival hyperemia, with no significant improvement even on day 11. Compared to the PBS group, the corneal infection lesions in the iron cobalt oxide+NIR group showed a trend of improvement on day 3, with the lesions becoming more localized and corneal edema reduced; by day 11, the infection lesions were completely eliminated, the cornea regained transparency, and the iris texture and pupil were clearly visible. These results indicate that treatment with iron cobalt oxide can significantly cure infections caused by drug-resistant bacteria on the ocular surface of mice, confirming that iron cobalt oxide solution, as a photothermal nano-antibacterial agent, has good in vitro and in vivo bactericidal and anti-infective efficacy.

[0112] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. The application of an iron-cobalt oxide photothermal nano-antibacterial agent in the preparation of drugs and / or bactericides for treating diseases caused by bacterial infections, characterized in that, The iron-cobalt oxide photothermal nano-antibacterial agent includes iron-cobalt oxide, which has broad-spectrum bactericidal properties under near-infrared light irradiation and can kill bacteria. The preparation method of the iron-cobalt oxide photothermal nano-antibacterial agent includes the following steps: (I) Solid cobalt iron glycerate is prepared by adding cobalt salt and iron salt to a mixed solvent and using a solvothermal method; the mixed solvent includes glycerol and isopropanol; the molar ratio of cobalt ions in the cobalt salt, iron ions in the iron salt, and glycerol is 2~4 : 1 : 1.0×10 4 ~2.0×10 4 The heating temperature is 160~200 ℃, and the heating time is 4~8 h; (II) Solid iron cobalt glycerate was heated and calcined at a heating rate of 0.5~2 ℃ / min, a calcination temperature of 300~400℃, and a calcination time of 1.5~3 h to obtain black iron cobalt oxide powder; (III) Add iron cobalt oxide powder to a solvent and stir evenly to prepare the iron cobalt oxide photothermal nano antibacterial agent.

2. The application according to claim 1, characterized in that: The conditions for near-infrared light irradiation include: a near-infrared wavelength of 780~1000 nm and a laser power density of 0.6~0.8 W / cm². 2 The irradiation time is 5-10 minutes.

3. The application according to claim 1, characterized in that: The iron-cobalt oxide has a spherical structure with a smooth surface and uniform size, with an average size of 430 nm.

4. The application according to claim 1, characterized in that: The iron-cobalt oxide photothermal nano-antibacterial agent also includes a solvent, which is selected from at least one of water and PBS buffer.

5. The application according to claim 1, characterized in that, The preparation method of the iron-cobalt oxide photothermal nano-antibacterial agent is selected from at least one of the following ① to ④: ① In step (Ⅰ), the volume ratio of glycerol to isopropanol in the mixed solvent is 1:3~8; ② In step (I), the cobalt salt is selected from at least one of cobalt nitrate, sulfate, chloride, acetate and perchlorate, and the iron salt is selected from at least one of iron nitrate, sulfate, chloride, acetate and perchlorate; ③ Step (I) further includes: after the solvothermal reaction is completed, the reaction solution is naturally cooled to room temperature, centrifuged, washed, and dried to obtain yellow-brown iron cobalt glycerate powder; ④ In step (Ⅲ), the solvent is selected from at least one of water and PBS buffer.

6. The application according to claim 1, characterized in that: The bacteria include Gram-positive and Gram-negative bacteria.

7. The application according to claim 1, characterized in that: The disease is bacterial keratitis.

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