Carbon nitride dot-loaded copper-based MOF contraception-antibacterial material as well as preparation method and application thereof

Abstract

The invention discloses a carbon nitride dot-loaded copper-based MOF contraception-antibacterial material as well as a preparation method and application thereof, and belongs to the field of biomedical materials. The material takes copper-based MOF as a carrier, carbon nitride dots with antibacterial activity are loaded on pores and / or the surface of the carrier, and the preparation method of the material comprises the following steps: firstly synthesizing the carbon nitride dots, and then introducing the carbon nitride dots into Cu-MOF formed on a copper contraceptive ring substrate through a solution impregnation method. Through the synergistic effect of Cu-MOF and carbon nitride dots, the material is endowed with excellent broad-spectrum antibacterial and anti-biofilm capacities while efficient contraception is achieved, and intrauterine infection is effectively prevented; in addition, the slow-release effect of the MOF structure on the copper ions can significantly relieve bleeding, pain and other side effects caused by sudden release of ions in a traditional copper-containing contraceptive device, and the biocompatibility is better. The composite material disclosed by the invention is particularly suitable for preparing a new generation of intrauterine device with comfort, safety and multifunctionality.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials technology, specifically relating to a copper-based MOF contraceptive-antibacterial material loaded with carbon nitrides, its preparation method, and its application. Background Technology

[0002] Copper-containing intrauterine devices (IUDs) are a widely used long-acting contraceptive method globally. Their contraceptive mechanism mainly relies on the local inflammatory response and sperm motility inhibition caused by the continuous release of copper ions. However, after decades of clinical application, traditional copper-containing IUDs have revealed several technical shortcomings that urgently need to be addressed. First, the release of copper ions in the uterine fluid exhibits a significant "burst release effect," meaning that the release rate is extremely high in the initial period after implantation (within 24-48 hours), resulting in a local copper ion concentration far exceeding the therapeutic window. This sudden increase in copper ion concentration can cause endometrial hyperstimulation, manifested as increased vascular permeability, abnormal prostaglandin synthesis, and massive infiltration of inflammatory cells. Clinically, this manifests as abnormal uterine bleeding, lower abdominal pain, and cramps, severely affecting user tolerance and continued use rates. Second, the continuous release of copper ions in the body fluid environment leads to uneven corrosion and oxidation of the material surface, forming a copper oxide layer. This not only alters the release kinetics of copper ions but may also cause local tissue irritation due to particulate matter shedding. Although attempts have been made to regulate the release behavior by adjusting the surface area of ​​the copper wire and changing the carrier structure, these improvements have not fundamentally solved the inherent limitations of direct contact between metallic copper and the biological environment.

[0003] Pelvic inflammatory disease (PID) is one of the most serious complications during the use of copper-containing intrauterine devices (IUDs). Pathogenic microorganisms can ascend along the tail string or be introduced during the initial cervical implantation process, forming a biofilm on and around the IUD. While traditional copper-containing IUDs possess some antibacterial properties, their antibacterial spectrum is limited, showing poor efficacy against certain Gram-positive bacteria (such as Staphylococcus aureus) and anaerobic bacteria, and they cannot effectively inhibit biofilm formation. Once a biofilm forms, it not only significantly enhances the drug resistance of pathogens but also becomes a focus of persistent infection, leading to chronic pelvic pain, abnormal uterine bleeding, and other consequences. In severe cases, the IUD needs to be removed and antibiotic treatment administered. Currently, research is exploring strategies to enhance the antibacterial capabilities of copper-containing IUDs, including silver loading and drug loading (such as indomethacin). However, the cytotoxicity of silver ions and their rapid inactivation in complex body fluid environments limit their application; while antibiotic loading faces the risks of drug resistance development and sudden release. Therefore, developing a novel antibacterial strategy that can provide sustained, broad-spectrum antibacterial activity without relying on antibiotics and can effectively disrupt biofilms has become a key technological requirement for improving the safety of copper-containing intrauterine devices.

[0004] In recent years, metal-organic frameworks (MOFs) have shown great potential in the biomedical field due to their tunable pore structure, high specific surface area, and designable metal ion release behavior. Copper-based MOFs, in particular (such as Cu-BDC, a copper-based MOF coordinated with terephthalic acid H₂BDC), can serve as structured copper ion reservoirs, achieving controlled release of copper ions through slow degradation of the framework, potentially solving the problem of "burst release" in traditional copper materials. However, applying MOF technology to copper-containing intrauterine devices still faces two major challenges: First, the antibacterial properties of pure Cu-MOF materials are still insufficient, especially against biofilms and certain drug-resistant strains, failing to fully meet the needs of preventing PID (proliferative dermatitis); second, the functions of MOF materials are relatively limited, and the key to enhancing their clinical value lies in endowing them with stronger synergistic functions (such as enhanced antibacterial and anti-inflammatory effects) without introducing biosafety risks. Carbon dots (CDs), as a novel zero-dimensional carbon nanomaterial, possess excellent biocompatibility and tunable antibacterial activity. In particular, nitrogen-doped carbon dots (N-CDs) can exert antibacterial effects even under dark conditions through a membrane disruption mechanism. Theoretically, combining them with Cu-MOFs can construct a synergistic system to prepare novel intrauterine devices that combine safety and multifunctionality. Summary of the Invention

[0005] This invention addresses the technical challenges of existing copper intrauterine devices (IUDs), such as abnormal uterine bleeding and pain caused by the initial burst release of copper ions, and the risk of intrauterine infection after long-term implantation. It provides a composite material with controllable release characteristics and highly effective antibacterial function. The purpose of this invention is to achieve an organic combination of contraception and antibacterial functions through material structure innovation, thereby improving the clinical safety and user comfort of IUDs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A copper-based MOF contraceptive-antibacterial material loaded with carbon nitride dots is characterized in that: a copper-based metal-organic framework (copper-based MOF, Cu-MOF) is used as a carrier, and carbon nitride dots (N-CDs) are loaded on its channels and / or surface, wherein the carbon nitride dots are synthesized by hydrothermal method from urea and citric acid.

[0007] Preferably, the particle size of the nitrided carbon dots is 2~10 nm, they emit yellow-green fluorescence under 365 nm ultraviolet light irradiation, and their surface is rich in amino functional groups.

[0008] Preferably, the copper-based MOF is a copper-based metal-organic framework (Cu-BDC) coordinated with terephthalic acid (H2BDC).

[0009] Preferably, the copper-based MOF is a nanowire or nanosheet structure grown in situ on the surface of a copper IUD substrate.

[0010] Preferably, the mass ratio of the carbon nitride dots to the copper-based MOF is 1~10:1, and the carbon nitride dots are fixed on the MOF framework through π-π stacking, coordination bonds and / or electrostatic forces.

[0011] This invention also provides a method for preparing the above-mentioned copper-based MOF contraceptive-antibacterial material loaded with carbon nitrides, comprising the following steps: Step 1, Synthesis of carbon nitride: Dissolve urea and citric acid in deionized water at a molar ratio of 1:2~6, react at 130~180℃ for 2~6 hours, and obtain carbon nitride powder after dialysis purification.

[0012] Step 2, Preparation of Cu-BDC: The copper IUD was ultrasonically cleaned sequentially in 10% dilute sulfuric acid, acetone and deionized water, then immersed in a mixed solution of sodium hydroxide and ammonium persulfate. After removal and washing with deionized water, a copper hydroxide nanowire array grown in situ on the IUD was obtained, denoted as Cu(OH)2-IUD. Cu(OH)2-IUD was added to a terephthalic acid solution, and the resulting mixture was placed in an oven at 60~80℃ for 10~30 min. After the reaction was completed, it was removed, washed with deionized water and dried at room temperature to obtain Cu-BDC grown in situ on the IUD.

[0013] Step 3, Preparation of composite material: The Cu-BDC obtained in step (2) and grown in situ on the IUD is immersed in the solution of carbon nitride obtained in step (1). The carbon nitride is loaded by solution impregnation method to obtain copper-based MOF contraceptive-antibacterial material loaded with carbon nitride, denoted as Cu-BDC@N-CDs.

[0014] Preferably, in step (2), the concentration of sodium hydroxide in the mixed solution of sodium hydroxide and ammonium persulfate is 2-3 M and the concentration of ammonium persulfate is 0.01-0.02 M.

[0015] Preferably, the concentration of terephthalic acid in the terephthalic acid solution in step (2) is 50-60 mM, and the solvent is a mixed solvent composed of deionized water, N,N-dimethylformamide, and ethanol in a volume ratio of 7-9:1.5-2.5:1. Deionized water, as a good solvent, provides a dissolution environment for the terephthalic acid ligands. When its proportion is 7-9 parts, it can ensure that the ligands are fully dissolved, avoiding excessive crystal growth and uneven morphology due to excessively high concentration. If the proportion of deionized water exceeds this range, if it is too high, it will reduce the crystallinity of MOF; if it is too low, the ligand solubility will be insufficient, and a continuous Cu-BDC coating cannot be formed. DMF, as a coordination modifier, can delay Cu 2+The coordination rate with ligands, when the proportion is 1.5~2.5 parts, can guide Cu-BDC to grow in situ into uniform nanowire / nanofacial structures on the IUD substrate. Excessive DMF proportion can easily lead to MOF grain aggregation, while insufficient proportion results in excessively rapid crystal growth and decreased coating adhesion. Ethanol, as a co-solvent, can adjust the polarity of the mixed solvent; a proportion of 1 part can optimize substrate wettability and promote tight bonding between Cu-BDC crystals and the copper IUD surface. When the ethanol proportion exceeds the range, it will disrupt the polarity balance of the solvent system, affecting the growth morphology of the MOF layer.

[0016] Preferably, the solution immersion method in step (3) is as follows: Cu-BDC grown in situ on IUD is placed in a 1-10 mg / mL carbon nitride solution and immersed at 25-60°C for 1-12 hours, and then taken out, washed and dried.

[0017] This invention further provides the application of the copper-based MOF contraceptive-antibacterial material loaded with nitrided carbon dots in the preparation of intrauterine devices (IUDs). This composite material achieves dual core functions through synergistic action: on the one hand, relying on the structured sustained-release properties of copper-based MOFs, it continuously releases copper ions to achieve highly effective contraception; on the other hand, utilizing the membrane disruption mechanism of nitrided carbon dots, it simultaneously exerts broad-spectrum antibacterial and anti-biofilm functions. Verification using a simulated uterine physiological environment showed that the IUD prepared from this composite material maintained the copper ion release within a safe physiological window for a long period, effectively avoiding the initial burst release problem of traditional copper IUDs; and the inhibition rate against common clinical pathogens such as Staphylococcus aureus and Escherichia coli both reached over 80%, significantly reducing the risk of intrauterine infection and pelvic inflammatory disease.

[0018] Compared with the prior art, the present invention has the following significant advantages: 1. Precise and controllable release of copper ions: Relying on the pore confinement effect of copper-based MOF and the interface regulation effect of nitrided carbon dots (N-CDs), a synergistic sustained-release system is constructed to completely solve the problem of initial burst release of traditional copper contraceptive devices, so that copper ions are released within a safe physiological window for a long time, significantly reducing side effects such as abnormal uterine bleeding and lower back pain, and greatly improving clinical tolerability and continued use rate. 2. Excellent antibacterial and anti-biofilm efficacy: Through the membrane disruption mechanism of N-CDs and the antibacterial effect of copper ions, a synergistic effect is formed to achieve broad-spectrum antibacterial function. The inhibition rate against common clinical pathogens such as Staphylococcus aureus and Escherichia coli is over 80%, and it can effectively inhibit biofilm formation, reducing the risk of intrauterine infection and pelvic inflammatory disease (PID) from the source. 3. Significantly improved biocompatibility: The hydrophilic functional groups such as amino groups on the surface of N-CDs not only provide sites for their stable binding with the MOF framework, but also optimize the biocompatibility of the material surface, reduce local tissue irritation, and lower the risk of immune rejection. 4. Outstanding potential for industrial application: The preparation process does not require special high-end equipment, the reaction conditions are mild and controllable (hydrothermal method + solution impregnation method), the operation process is simple and efficient, it is highly compatible with existing medical device production processes, and it has the technical foundation for large-scale mass production. 5. Breakthrough in Functional Synergy: Through the integrated structure-function design of "MOF carrier-carbon dot functional body", the contraceptive and antibacterial functions are organically integrated and synergistically enhanced, breaking through the design limitations of traditional single-function IUDs and providing an innovative and practical technical solution for the performance upgrade of intrauterine contraceptive devices. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the preparation of copper-based MOF contraceptive-antibacterial material loaded with carbon nitride in an embodiment of the present invention.

[0020] Figure 2 These are excitation and emission spectra of the carbon nitride dots prepared in the embodiments of the present invention, wherein: Figure a shows the emission wavelength of the carbon nitride dots at different excitation wavelengths (300-400 nm), Figure b shows the fluorescence spectrum of the carbon nitride dots, and the inset shows the fluorescence phenomenon of the carbon nitride dot solution under natural light and ultraviolet irradiation.

[0021] Figure 3 These are scanning electron microscope (SEM) comparison images of the Cu-BDC material and the Cu-BDC@N-CDs composite material prepared in the embodiments of the present invention, wherein: images a and b are SEM images of Cu-BDC at different magnifications, and images c and d are SEM images of the Cu-BDC@N-CDs composite material at different magnifications.

[0022] Figure 4 This is a comparison of the Fourier transform infrared (FT-IR) spectra of nitrided carbon dots, Cu-BDC material, and Cu-BDC@N-CDs composite material in the embodiments of the present invention.

[0023] Figure 5 This is a comparison of the X-ray diffraction (XRD) spectra of carbon nitride, Cu-BDC material, and Cu-BDC@N-CDs composite material in the embodiments of the present invention.

[0024] Figure 6 This is a comparison of the copper ion release curves of the Cu-BDC@N-CDs composite material and the untreated Cu contraceptive ring in a simulated uterine environment in the embodiments of the present invention; Figure 7 This is an evaluation diagram of the antibacterial effect of the Cu-BDC@N-CDs composite material against Staphylococcus aureus and Escherichia coli in the embodiments of the present invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. It should be noted that the following embodiments are only for explaining the present invention and should not be construed as limiting the present invention.

[0026] Unless otherwise specified, all reagents and raw materials used in the following examples are commercially available.

[0027] Example 1: Preparation method of copper-based MOF contraceptive-antibacterial material loaded with carbon nitride See Figure 1 As shown, the preparation method of the copper-based MOF contraceptive-antibacterial material loaded with carbon nitrides provided in this embodiment includes the following specific process steps: (1) Synthesis of carbon nitrides: 6.3 g of urea and 4 g of citric acid were weighed and placed in a beaker, and 20 mL of deionized water was added. The mixture was magnetically stirred until completely dissolved. The mixed solution was placed in a forced-air drying oven and reacted at 180 °C for 2 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The resulting deep yellow solution was filtered through a 0.22 μm microporous membrane and then transferred to a dialysis bag with a molecular weight cutoff of 1000 Da. Dialysis was performed in deionized water for 24 hours to remove unreacted small molecule impurities. Black powdered carbon nitrides (N-CDs) were obtained by freeze-drying and stored in a sealed container at 4 °C for later use.

[0028] (2) Preparation of Cu-BDC: The copper IUD was ultrasonically cleaned for 30 min in 10% dilute sulfuric acid, acetone and deionized water, and then immersed in a mixed solution of sodium hydroxide (2.5 M) and ammonium persulfate (0.15 M) for 20 min. After removal and washing with deionized water, Cu(OH)2-IUD was obtained. Cu(OH)2-IUD was immersed in a mixed solution containing 56 mM terephthalic acid (H2BDC) (the solvent was a mixture of deionized water, DMF and ethanol in a volume ratio of 8:2:1) and placed in a 70℃ oven for 20 min. After the reaction was completed, it was removed and washed three times with deionized water and dried at room temperature to obtain Cu-BDC.

[0029] (3) Preparation of composite material: 100 mg of carbon nitride obtained in step (1) was dissolved in 10 mL of deionized water and sonicated until completely dissolved. The Cu-BDC obtained in step (2) was immersed in the carbon nitride solution and stirred at room temperature for 12 h. After washing with deionized water, it was naturally dried at room temperature to obtain copper-based MOF contraceptive-antibacterial material loaded with carbon nitride (denoted as Cu-BDC@N-CDs).

[0030] Example 2: Excitation-emission fluorescence spectroscopy characterization of aqueous solutions of carbon nitride dots The carbon nitride powder obtained in step (1) of Example 1 was dispersed in deionized water at a concentration of 0.1 mg / mL and sonicated to dissolve completely, resulting in a homogeneous and transparent aqueous solution of carbon nitride. The resulting solution was placed in a quartz cuvette, and its fluorescence emission and excitation spectra were measured using a fluorescence spectrophotometer at room temperature. During the test, the emission and excitation slit widths were set to standard values, and the scan rate was moderate to ensure a good signal-to-noise ratio. The excitation wavelengths were set to 300 nm, 320 nm, 340 nm, 360 nm, 380 nm, and 400 nm, respectively. The emission spectra of the samples were recorded in the 400-700 nm band. Figure 2 As shown. The results indicate that the fluorescence emission intensity reaches its maximum when the excitation wavelength is 361 nm, indicating that this wavelength is the preferred excitation wavelength for the nitrided carbon dots in this embodiment. At the optimal excitation wavelength, the emission spectrum of the carbon dots shows a strong emission peak around approximately 482 nm, with a symmetrical peak shape and a moderate full width at half maximum (FWHM). Figure 2 As shown in the illustration, the aqueous solution of carbon nitride dots is a pale yellow transparent liquid under natural light; under 365 nm ultraviolet light irradiation, the solution emits a bright yellow-green fluorescence, and the uniform luminescence can be clearly observed with the naked eye. This phenomenon is consistent with the results of fluorescence spectroscopy tests, further demonstrating that the carbon dots of this invention have excellent fluorescence emission performance in the visible light region.

[0031] Example 3: Morphological characterization of Cu-BDC and Cu-BDC@N-CDs composite materials The Cu-BDC sample obtained in step (2) of Example 1 and the Cu-BDC@N-CDs composite material obtained in step (3) were placed in a vacuum drying oven and dried at 60°C for 1 h to obtain dried samples. These samples were then attached to conductive adhesive, adhered to the sample stage, and placed in the sample chamber of a scanning electron microscope. Morphological observation was performed under an accelerating voltage of 3.0 kV, obtaining SEM images at different magnifications. Figure 3 As shown in (a) and (b), Cu-BDC exhibits a uniformly stacked flower-like / plate-like aggregate structure, composed of numerous regularly stacked nanosheets. The crystal edges are clear, and the morphology is complete, indicating that the prepared Cu-BDC possesses good crystallinity and a typical plate-like hierarchical structure, proving that Cu-BDC has been successfully prepared. Figure 3 As shown in (c) and (d), the composite material obtained after loading carbon dots still maintains a similar flower-like / plate-like stacking morphology to the original Cu-BDC. The nanosheet structure did not show obvious collapse or breakage, with only slight local surface roughness. Compared with Cu-BDC, the plate size and stacking mode of Cu-BDC@N-CDs are basically the same, indicating that the carbon dot loading process did not cause significant damage to the Cu-BDC framework, and the Cu-BDC structure remained stable after loading carbon dots.

[0032] Example 4: Fourier transform infrared spectroscopy characterization of N-CDs, Cu-BDC, and Cu-BDC@N-CDs composite materials. Approximately 1–2 mg of each of the carbon nitride powder, Cu-BDC, and Cu-BDC@N-CDs obtained in Example 1 were thoroughly ground with dry KBr, compressed into tablets, and analyzed using a Fourier transform infrared spectrometer. The results are as follows: Figure 4 As shown, it can be seen that: N-CDs samples at approximately 3200–3500 cm⁻¹ -1 A broad and strong absorption band appears at 1600 cm⁻¹, corresponding to the stretching vibrations of the surface -OH and -NH bonds; -1 There are obvious absorption peaks nearby, which can be attributed to the stretching vibration of the C=O bond; in the range of 1400–1200 cm⁻¹ -1 The stretching vibration characteristic peaks of C=N bonds can be observed in the range, indicating that the surface of the obtained carbon nitrides is rich in nitrogen-containing functional groups, which is conducive to interaction with metal-organic frameworks.

[0033] Cu-BDC samples at approximately 3400 cm -1 A broad peak is also observed nearby, mainly attributed to the -OH stretching vibration of adsorbed water molecules in the framework; in the range of 1700–1400 cm⁻¹. -1 A pair of strong and sharp absorption peaks appear within the range, corresponding to the carboxyl group (-COO) of the terephthalic acid ligand. - The antisymmetric and symmetric stretching vibrations of Cu-BDC-like metal-organic frameworks are typical characteristics; in the range of 900–600 cm⁻¹ -1 The presence of aromatic ring CH bending vibration peaks in the region indicates that the terephthalic acid ligand in the obtained material was successfully coordinated to copper ions, and the Cu-BDC framework structure was successfully constructed.

[0034] The infrared spectrum of the Cu-BDC@N-CDs composite material simultaneously exhibits the main characteristic peaks of Cu-BDC and N-CDs, indicating that N-CDs interact with the Cu-BDC framework through surface functional groups and are stably loaded on its surface and / or within its pores, achieving effective composite without destroying the overall coordination structure of Cu-BDC.

[0035] Example 5: X-ray diffraction characterization of N-CDs, Cu-BDC, and Cu-BDC@N-CDs composite materials. like Figure 5As shown, the N-CDs sample exhibits a broad and weak diffuse diffraction peak in the approximately 20–30° range, without any obvious sharp diffraction peaks, indicating that the N-CDs as a whole have an amorphous or weakly crystalline carbon structure, which is a typical diffraction characteristic of carbon dot materials. The Cu-BDC sample shows a series of strong and sharp diffraction peaks in the low and medium angle regions, with peak positions basically consistent with the simulated diffraction pattern of Cu-BDC, indicating that the prepared material is a well-crystallized Cu-BDC metal-organic framework structure. No other impurity phase diffraction peaks were observed, indicating that Cu-BDC has been successfully constructed and has high phase purity. In the XRD pattern of the Cu-BDC@N-CDs composite material, a series of diffraction peaks at the same positions as Cu-BDC can still be clearly observed, with peak positions basically consistent with pure Cu-BDC, only with a slight decrease in peak intensity, indicating that the crystal structure of Cu-BDC remains intact after loading N-CDs, without significant decomposition or phase transformation.

[0036] Example 6: Copper ion release performance of Cu-BDC@N-CDs composite material in a simulated uterine environment The Cu-based intrauterine contraceptive ring and the Cu-BDC@N-CDs obtained in step (3) of Example 1 were placed in sealed containers containing a fixed volume of simulated uterine fluid and incubated at 37°C. At preset time points, a certain volume of the soaking solution was removed, and after replenishing the original volume with deionized water, the Cu content in the solution was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). 2+ The concentration was used to calculate the amount of copper ions released at different times, and a release curve was plotted. Figure 6 As shown, a comparison with an untreated Cu-based sterilization ring substrate reveals that the Cu-BDC@N-CDs composite material of this invention significantly slows down the reaction of Cu... 2+ The release rate and total release amount in a simulated uterine environment help reduce adverse reactions caused by excessive release of copper ions during the use of intrauterine devices.

[0037] Example 7: Evaluation of the antibacterial properties of Cu-BDC@N-CDs composite material against Staphylococcus aureus and Escherichia coli. Staphylococcus aureus and Escherichia coli standard strains were selected as representative Gram-positive and Gram-negative bacteria, respectively. The strains were pre-cultured in nutrient broth at 37°C with shaking until the logarithmic growth phase, and the bacterial concentration was adjusted to approximately 1 × 10⁻⁶. 6CFU / mL was prepared for use. The Cu-BDC@N-CDs composite material obtained in step (3) of Example 1 was sterilized with 75% ethanol and dried. The sample was placed in the above bacterial solution and cultured at 37°C for 120 min. Every 20 min, 30 µL of bacterial solution was dropped onto a pre-prepared TSB solid medium agar plate, spread evenly with a plate spreader, and inverted in a 37°C constant temperature biological incubator for 12 h before being taken out for observation.

[0038] Depend on Figure 7 As can be seen, both strains formed dense bacterial moss with a large number of colonies on the blank control plate, indicating that the bacteria could grow and reproduce normally without the addition of the material. However, after the addition of Cu-BDC@N-CDs, the number of colonies on each treatment plate was significantly reduced, and the bacterial moss area was significantly shrunk. After 120 min of treatment, only sporadic or sparse colonies were visible on the plate, indicating that the composite material has a significant inhibitory effect on Staphylococcus aureus and Escherichia coli, providing experimental evidence for its application in medical devices such as intrauterine devices that require long-term use and have anti-infection functions.

[0039] The above embodiments are merely specific descriptions of preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles thereof, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A copper-based MOF loaded with carbon nitride dots for contraceptive-antibacterial material, characterized by: A copper-based MOF is used as a carrier, and carbon nitride dots N-CDs are loaded in the pores and / or on the surface of the copper-based MOF, wherein the carbon nitride dots are synthesized from urea and citric acid by a hydrothermal method.

2. The nitrogen-doped g-C3N4 point-decorated copper-based MOF contraceptive-antiseptic material according to claim 1, characterized by: The carbon nitride dots have a particle size of 2-10 nm, emit yellow-green fluorescence under irradiation of 365 nm ultraviolet light, and are rich in amino functional groups on the surface.

3. The nitrogenated carbon dot loaded copper-based MOF contraceptive-antibacterial material of claim 1, wherein: The copper-based MOF is a copper-based metal organic framework Cu-BDC coordinated with terephthalic acid H2BDC.

4. The C3N4 nanoparticle loaded copper-based MOF contraceptive-antiseptic material according to claim 1 or 3, characterized in that: The copper-based MOF is a nanowire or nanosheet structure formed in situ on the surface of a copper-based IUD base.

5. The nitrogenated carbon dot loaded copper-based MOF contraceptive-antibacterial material of claim 1, wherein: The mass ratio of the carbon nitride dots to the copper-based MOF is 1-10:1, and the carbon nitride dots are fixed on the MOF framework by π-π stacking, coordination bonding and / or electrostatic force.

6. A method of preparing the copper-based MOF loaded with carbon nitride dots of the contraceptive-antibacterial material according to any one of claims 1-5, characterized by, The method comprises the following steps: Step 1: Synthesis of carbon nitride dots: urea and citric acid are dissolved in deionized water at a molar ratio of 1:2-6, and reacted at 130-180℃ for 2-6 hours, and then the carbon nitride dots powder is obtained after dialysis purification; Step 2: Preparation of Cu-BDC: a copper-based IUD is sequentially ultrasonically cleaned in dilute sulfuric acid, acetone and deionized water, then immersed in a mixed solution of sodium hydroxide and ammonium persulfate, taken out and washed with deionized water, and then a copper hydroxide nanowire array grown in situ on the IUD is obtained, denoted as Cu(OH)2-IUD; the Cu(OH)2-IUD is added to a terephthalic acid solution, and then the obtained mixed system is placed in an oven at 60-80℃ for 10-30 min, after the reaction is completed, the Cu-BDC grown in situ on the IUD is taken out, washed with deionized water and dried at room temperature; Step 3: Preparation of the composite material: the Cu-BDC grown in situ on the IUD obtained in step (2) is immersed in the solution of the carbon nitride dots prepared in step (1), and the carbon nitride dots are loaded by solution immersion method to obtain a copper-based MOF contraceptive-antibacterial material loaded with carbon nitride dots, denoted as Cu-BDC@N-CDs.

7. The method of claim 6, wherein: In step (2), the concentration of sodium hydroxide in the mixed solution of sodium hydroxide and ammonium persulfate is 2-3 M, and the concentration of ammonium persulfate is 0.01-0.02 M.

8. The method of claim 6, wherein: In step (2), the concentration of terephthalic acid in the terephthalic acid solution is 50-60 mM, and the solvent is a mixed solvent composed of deionized water, N,N-dimethylformamide and ethanol at a volume ratio of 7-9:1.5-2.5:

1.

9. The method of claim 6, wherein: In step (3), the solution immersion method is specifically as follows: the Cu-BDC-IUD is placed in a 1-10 mg / mL carbon nitride dot solution, immersed at 25-60℃ for 1-12 hours, and then taken out, washed and dried.

10. Use of the copper-based MOF contraceptive-antibacterial material loaded with carbon nitride dots according to any one of claims 1-5 in the preparation of an intrauterine device.

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