Estrogen-loaded magnetic core-shell microspheres, preparation method thereof and application thereof in treating intrauterine adhesion

Abstract

This invention discloses a magnetic core-shell microsphere loaded with estrogen, its preparation method, and its application in the treatment of intrauterine adhesions. The outer phase consists of 1-10% sodium alginate, 1-3% polyvinyl alcohol, and magnetic nanoparticles, while the inner phase is a mixture of estrogen and natural oils at 1-10 ng / mL. Using a coaxial microfluidic electrospinning chip, a voltage of 6.5-8.5 kV is applied to the outer needle tip. After the droplet falls 7-9 cm, it is collected in a 2% calcium chloride solution for solidification, followed by washing and air drying to obtain microspheres with a particle size of 800-1200 μm. These microspheres exhibit magnetic responsiveness and sustained release in vitro for at least 24 hours. In a rat model of intrauterine adhesions, the endometrial thickness of the estrogen-loaded magnetic core-shell microsphere group was 522.33±32.51 μm, the number of glands was 41.67±5.03, and the collagen volume fraction was 0.52±0.03%, showing better efficacy than the estrogen-only group. This invention achieves targeted delivery and sustained release of drugs, providing a new solution for the treatment of intrauterine adhesions.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, specifically to a magnetic core-shell microsphere loaded with estrogen, its preparation method, and its application in the treatment of intrauterine adhesions. Background Technology

[0002] Intrauterine adhesions (IUA), also known as Asherman's syndrome, refer to a pathological condition in which the uterine cavity is partially or completely blocked due to damage to the basal layer of the endometrium. Its core pathological features are: endometrial regeneration disorder, hormonal imbalance, and impaired fertility. Currently, the clinical treatment mainly involves hysteroscopic surgery combined with hormone therapy, but the re-adhesion rate after surgery is as high as 20-60%, and new adjuvant therapy strategies are needed (Science Advance, 2023. 9(46):eadi6488). Estrogen can promote endometrial proliferation, angiogenesis, and inhibit fibrosis by activating the estrogen receptor (ER) signaling pathway in the endometrial cell nucleus, thus making estrogen replacement therapy an important means of relieving intrauterine adhesions (Advanced Materials, 2024. 36(39): e2407750). However, traditional estrogen administration methods have many problems. For example, oral estrogen preparations are affected by gastric acid and other digestive juices as they pass through the gastrointestinal tract, leading to drug degradation and reduced bioavailability (JAMA Surgery, 2023. 158(12): 1265-1273). Furthermore, rapid absorption of estrogen may cause significant fluctuations in estrogen levels in the body, increasing the risk of diseases such as endometrial cancer and breast cancer (Annals of Oncology, 2025. 36(2): 134-148). Therefore, developing a formulation that can stably and continuously release estrogen with enhanced safety is of significant clinical importance.

[0003] Since developing stable, sustained-release estrogen formulations with enhanced safety is the core direction for overcoming the limitations of traditional drug delivery methods (which are prone to hormone level fluctuations and increased disease risk), the key issue of "precise control of drug release rate" must be prioritized in the exploration of carrier technology. Traditional microspheres lack layered structure design, making it difficult to avoid estrogen burst release and achieve long-term stable release. Core-shell structured microspheres, however, can fill this gap with their unique advantages of "internal drug encapsulation to isolate it from external damage and external structure to regulate the release rate." Polyvinyl alcohol (PVA) is a synthetic polymer material with good biocompatibility, non-toxicity, and high chemical stability. PVA forms a hydrogel network structure, which is beneficial for drug encapsulation and release control. Sodium alginate (ALG) is a natural polysaccharide with wide availability and excellent biocompatibility. ALG has unique ionic cross-linking properties, which can rapidly form a gel when in contact with divalent cations (such as calcium ions), further enhancing the structural stability of the microspheres and regulating drug release behavior. Combining PVA and ALG to prepare microspheres can combine the advantages of both, providing a more ideal carrier for drug delivery. The application of droplet microfluidics technology can manipulate the generation and dispersion of droplets at the microscale, and precise control of droplets can be achieved through microfluidic devices, making the droplet preparation process precise, controllable, safe, stable, efficient and low-consumption. Summary of the Invention

[0004] To address the shortcomings of traditional in vivo drug delivery methods, such as difficulty in targeted delivery and high drug loss, this invention provides an estrogen-loaded magnetic core-shell microsphere, its preparation method, and its application in the treatment of intrauterine adhesions. Based on a droplet microfluidic system, this invention designs an estrogen-loaded magnetic core-shell microsphere for targeted delivery of micron-sized drugs. The shell of this estrogen-loaded magnetic core-shell microsphere contains magnetic nanoparticles, and the particle size can reach 800 μm after encapsulating estrogen. This allows for better targeted treatment and sustained drug release, achieving anti-inflammatory effects, promoting cell proliferation, and successful injection into the uterine cavity, thereby effectively treating intrauterine adhesions.

[0005] To address the problems in the existing technology, the technical solution adopted by this invention is as follows:

[0006] A method for preparing estrogen-loaded magnetic core-shell microspheres includes the following steps:

[0007] Step 1, Preparation of external phase solution:

[0008] A hydrogel solution is prepared by mixing 1-5% sodium alginate and 1-3% polyvinyl alcohol polymer material, and then a uniform suspension is prepared by adding magnetic nanoparticles and vibrating at high speed to form the external phase solution.

[0009] Step 2, Preparation of the internal phase solution:

[0010] The solution obtained by mixing estrogen with natural oils at a ratio of 1-10 ng / mL is the internal phase solution;

[0011] Step 3, Microfluidic Device Design:

[0012] Using a glass slide as a substrate, fine capillaries with a diameter of 0.1-0.5 mm are coaxially nested within coarse capillaries with a diameter of 0.3-1.5 mm. Copper wire with a diameter of 0.1-0.3 mm is pre-wound around the outer wall of the fine capillaries to ensure a uniform annular gap between the inner and outer capillaries, avoiding direct contact and thus ensuring the uniformity of the shell thickness. Subsequently, epoxy resin is used to seal and fix the capillary interface needles, forming a complete coaxial microfluidic electrospun chip. The fine and coarse capillaries are respectively connected to independent droplet microfluidic injection pumps via needles. The inner phase solution flows through the fine capillaries to form the core, while the outer phase solution flows through the annular gap between the inner and outer capillaries to form the shell.

[0013] Step 4: The inner phase solution and the outer phase solution are injected stably and uniformly into a coaxial capillary at a set rate. Electrospinning is then performed under the action of a high-voltage electric field. A DC high-voltage current is applied at the outer needle tip, and the capillary outlet is vertically downward, with its bottom end 7-9 cm away from the surface of the calcium chloride solution. The fluid at the outlet is subjected to the synergistic shearing action of the electric field force and the shell phase fluid, forming a stable droplet with a core-shell structure. The droplet is then collected in a 2% (w / w) calcium chloride solution and solidified through an ionic crosslinking reaction to obtain the initial core-shell microsphere product. Finally, it is washed with deionized water until neutral and air-dried at room temperature, thus realizing the continuous preparation of estrogen-loaded magnetic core-shell microspheres.

[0014] Preferably, in step 1, the mixing ratio of magnetic nanoparticles to ion-crosslinked hydrogel solution is 0.5-1 μg: 1 mL.

[0015] Preferably, the natural oil mentioned in step 2 is silkworm pupa oil, soybean oil, olive oil, corn oil, or castor oil.

[0016] Preferably, the diameter of the copper wire in step 3 is 0.1-0.3 mm.

[0017] Preferably, in step 4, the flow rate of the external phase solution is controlled at 24-32 μL / min, and the flow rate of the internal phase solution is controlled at 10-14 μL / min.

[0018] Preferably, the voltage range of the high-voltage electric field in step 4 is 6.5-8.5 kV.

[0019] Preferably, the droplet falling height in step 4 is 7 cm.

[0020] The magnetic core-shell microspheres loaded with estrogen prepared by any of the above methods have a particle size of 800-1200 μm.

[0021] The above-mentioned application of estrogen-loaded magnetic core-shell microspheres in the preparation of drugs for the prevention or treatment of intrauterine adhesions.

[0022] Beneficial effects:

[0023] (1) The magnetic core-shell microspheres loaded with estrogen of the present invention can achieve stepwise drug release by combining the characteristics of the core and the shell, and achieve drug sustained release effect through the blocking effect of the shell.

[0024] (2) The magnetic core-shell microspheres loaded with estrogen of the present invention can achieve directional movement of drug-loaded particles in the uterine cavity by adding magnetic nanoparticles to the shell layer, and can accurately locate and deliver drugs. Attached Figure Description

[0025] Figure 1 The process for preparing estrogen-loaded magnetic core-shell microspheres includes: (a) a microfluidic chip image; (b) a front view of the capillary outlet; (c) a side view of the capillary outlet; (d) a complete microfluidic device; and (e) a real-time image of the generated magnetic core-shell microspheres.

[0026] Figure 2 Optical microscope images of the prepared estrogen-loaded magnetic core-shell microspheres and their magnetic verification. (a) Optical microscope image of the prepared estrogen-loaded magnetic core-shell microspheres, and (bc) verification of the magnetism of the magnetic core-shell microspheres.

[0027] Figure 3 To verify the sustained-release effect of estrogen-loaded magnetic core-shell microspheres, (a, b) show the sustained-release experiment and its quantitative statistics, and (c, d) show the small animal in vivo imaging experiment and its quantitative statistics in the SD rat intrauterine adhesion model.

[0028] Figure 4 HE and Masson slice images of rat uterus 14 days after treatment and related statistics are shown. (a) is the HE slice image, (b) is the Masson slice image, and (ce) are the quantitative statistics of endometrial thickness, gland number and collagen volume fraction, respectively. Detailed Implementation

[0029] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All equivalent transformations or modifications made according to the spirit and essence of the invention should be covered within the protection scope of the invention. Implementation conditions not specified in the embodiments are generally conditions found in conventional experiments.

[0030] This invention utilizes a hydrothermal method to synthesize Fe3O4@MgSiO3 magnetic nanoparticles. Specifically, 1.6 mmol FeCl3, 8.8 mmol NaAc, 1.8 mmol PSSMA, and an appropriate amount of water were dissolved in 16 mL ethylene glycol (EG) and stirred for approximately 30 min. The reaction was then initiated by adding 6 mmol NaOH and stirring for another 30 min. The resulting liquid was transferred to a 20 mL autoclave and heated in a MV furnace at 190 °C for 9 h. The Fe3O4 nanoparticles were then collected and dispersed in 12 mL deionized water. Subsequently, 6 mL of the Fe3O4 dispersion was mixed with 40 mL of ethanol and 2 mL of ammonium hydroxide solution to prepare a mixture. This mixture was ultrasonicated at 50 °C and 6000 rpm for 10 min. After vigorous stirring for 10 min, TEOS (200 µL) was added. The prepared Fe3O4@SiO2 nanoparticles were collected, stirred for 1 h, and then dispersed in ethanol. Next, the nanoparticles were transferred to a solution (10 mL) containing 0.25 mmol MgCl₂·6H₂O, 3.3 mmol NH₄Cl, and 500 µL of ammonia solution (28%). The mixture was then heated at 140 °C for 14 h. After heating, the precipitate was collected and washed three times with ethanol for later use. The particle size of the Fe₃O₄@MgSiO₃ magnetic nanoparticles was measured to be 50.79 nm.

[0031] Example 1: Preparation of silkworm pupa oil

[0032] The preparation of silkworm pupa oil followed the previous study (Insects, 2023, 14(3): 254). Silkworm pupae were molted to remove the outer cocoon shell. After molting, the pupae were further cleaned and dried to remove surface impurities and excess moisture, and then pulverized into powder. The pulverized silkworm pupa powder was then mixed with n-hexane at a ratio of 1:6. The mixture was then placed in a container and extracted at 40 °C and a shaking rate of 1200 r / min. After extraction, the defatted silkworm pupa powder and solvent were separated by filtration to obtain a solvent containing silkworm pupa oil. This solvent was then subjected to centrifugation and rotary evaporation to finally obtain the silkworm pupa oil.

[0033] Example 2 Fabrication of estrogen-loaded magnetic core-shell microspheres

[0034] (1) Preparation steps of magnetic core-shell microsphere inner and outer phase suspension:

[0035] Prepare a 1.5% (m / v) ALG solution, add 1% PVA (m / v) and heat in a water bath for 1 h to form a mixture. Add magnetic nanoparticles to the mixture at a ratio of 0.5-1 μg: 1 mL, and oscillate at 1500 rpm for 5 min to uniformly disperse them to obtain an external phase suspension of magnetic nanoparticle microspheres.

[0036] Estrogen was dissolved in silkworm pupa oil and dispersed evenly by high-speed shaking at 1000 rpm for 5 min to obtain an internal phase suspension of 10 ng / mL estrogen.

[0037] (2) Preparation steps of estrogen-loaded magnetic core-shell microspheres:

[0038] A microfluidic device based on the coaxial co-flow microfluidic-electro-injection synergistic principle was constructed for the continuous preparation of core-shell structured microspheres.

[0039] The device is assembled as follows: Using a glass slide as a substrate, a thin capillary tube (inner layer) with a diameter of 0.1-0.5 mm is coaxially nested in a thicker capillary tube (outer layer) with a diameter of 0.3-1.5 mm; copper wire with a diameter of 0.1-0.3 mm is pre-wound around the outer wall of the inner capillary tube to ensure that a uniform annular gap is formed between the inner and outer capillaries, avoiding direct contact and thus ensuring the uniformity of the shell thickness; then epoxy resin is used to seal and fix the capillary interface needle to form a complete coaxial microfluidic electrospun chip.

[0040] During the fluid control and preparation process, the inner and outer capillaries are connected to independent droplet microfluidic injection pumps via needles: the inner channel (fine capillary) delivers the core phase fluid at a controlled flow rate of 10–14 μL / min; the outer channel (annular gap) delivers the shell phase fluid at a controlled flow rate of 24–32 μL / min, while a 6.5–8.5 kV DC high voltage is applied at the outer needle. The two phases form a stable laminar interface within the coaxial channel. The capillary outlet is vertically downward, with its bottom 7–9 cm from a solidification dish containing 2% CaCl2 solution. At the outlet, the fluid is subjected to the combined shearing action of the electric field and the shell phase fluid, forming stable droplets with a defined core-shell structure. These droplets are then collected in a calcium chloride solution and solidified via ionic crosslinking, achieving a one-step continuous preparation of core-shell microspheres.

[0041] The suspension was dropped into a 2% CaCl2 solution, and the droplets were separated and rapidly solidified into hydrogel microspheres under the action of a high-voltage electric field. After all the suspension had solidified into microspheres, the solidified estrogen core-shell microspheres were washed repeatedly with deionized water until the pH of the washing solution reached neutral. Finally, the washed microspheres were air-dried at room temperature to obtain estrogen-loaded magnetic core-shell microspheres with an average particle size of 500-1500 μm. The preparation steps of estrogen-loaded magnetic core-shell microspheres can be found in [link to relevant documentation]. Figure 1 The obtained estrogen-loaded magnetic core-shell microspheres are visible. Figure 2 Table 1 shows the variation in the particle size of the microspheres produced.

[0042] Table 1. Particle size variation of microspheres under different voltages, heights, and inward / outward flow velocities.

[0043]

[0044] Based on the data in Table 1, the optimal parameters for the preparation process of this invention are: internal flow rate of 10 μL / min, external flow rate of 24 μL / min, voltage of 6.5 kV, and height of 7 cm. Subsequent tests were conducted using magnetic core-shell microspheres prepared under these optimal hyperparameters.

[0045] Example 3: Magnetronically Controlled Experiment of Magnetic Core-Shell Microspheres

[0046] The estrogen-loaded magnetic core-shell microspheres prepared in Example 2 were placed in a bottle containing a 2% CaCl2 solution. It was observed that, without external magnetic attraction, the microspheres, due to their lower density, suspended in the upper part of the solution. When a magnet was placed at the bottom of the bottle, the estrogen-loaded magnetic core-shell microspheres aggregated at the bottom. Figure 2 b and c.

[0047] The estrogen-loaded magnetic core-shell microspheres prepared in Example 2 were placed in a petri dish and immersed in a 2% calcium chloride solution or a 0.9% physiological saline solution. A magnet was moved across the bottom of the dish. Due to the external attraction of the magnet, the microspheres could move directionally with the movement of the magnet, demonstrating that the microspheres possess the ability to move in a directional manner. See details below. Figure 2 d and e.

[0048] Example 4: Drug sustained-release experiment of estrogen-loaded magnetic core-shell microspheres

[0049] Following the preparation method of estrogen-loaded magnetic core-shell microspheres prepared in Example 2, oil-soluble small molecule Nile Red was used instead of estrogen for drug sustained-release experiments. Microspheres were placed in a beaker containing PBS, ensuring the PBS completely submerged the microspheres, and stirred at a low speed of 200 rpm at (37.0 ± 0.5) °C. Samples were taken at 0, 2, 4, 8, 12, and 24 h, and photographed under a fluorescence microscope. The results were recorded as follows: Figure 3 As shown in Figure a. The fluorescence intensity of the microspheres at different time points was statistically analyzed using ImageJ, and release curves were plotted, as shown in Figure a. Figure 3 As shown in Figure b. The results demonstrated a steady decrease in fluorescence intensity that lasted for at least 24 hours, confirming the sustained-release effect of the estrogen-loaded magnetic core-shell microspheres.

[0050] Example 5: In vivo imaging experiment of small animals in the SD rat intrauterine adhesion model

[0051] DiD (a red fluorescent probe for cell membranes) was mixed with estrogen solution at a volume ratio of 1:1000, and the mixture was shaken for 1 hour in the dark. Subsequently, the DiD probe and estrogen solution were co-incubated for 30 minutes to obtain a DiD-labeled estrogen solution. Using these fluorescently labeled estrogen solutions, estrogen-loaded magnetic core-shell microspheres were prepared according to the method in Example 2. The DiD-labeled estrogen solution (concentration of 10 ng / mL) and the estrogen-loaded magnetic core-shell microspheres were then bilaterally injected into the uterus of mice with intrauterine adhesions (IUA). At different time points after injection, the uterus was dissected, and the retention of the estrogen solution and estrogen-loaded magnetic core-shell microspheres was observed using an in vivo imaging system.

[0052] The intrauterine adhesions (IUA) model used was derived from healthy female Sprague-Dawley (SD) rats aged 4-6 weeks, weighing 180-220 g, housed in an SPF-grade environment. The experimental protocol was approved by the ethics committee (25ZALAS75). An endometrial injury model was established using a mechanical scraping method: a sterile curette was used to uniformly scrape the inner side of the uterine wall from top to bottom 100 times, simulating the pathological characteristics of clinical intrauterine adhesions (IUA).

[0053] The results showed that estrogen alone was completely released within 24 hours, while the estrogen-loaded magnetic core-shell microspheres remained after 48 hours, as can be seen in the following figures. Figure 3 c and Figure 3 As shown in d.

[0054] Example 6: Treatment of Intrauterine Adhesions in SD Rats

[0055] The estrogen-loaded magnetic core-shell microspheres prepared in Example 2 were used as experimental subjects to verify the therapeutic effect of the magnetic core-shell microspheres. The specific experimental steps are as follows:

[0056] (1) Laboratory animals and grouping

[0057] Healthy female Sprague-Dawley (SD) rats aged 4-6 weeks, weighing 180-220 g, were selected and housed in an SPF-grade environment. The experimental protocol was approved by the ethics committee (25ZALAS75). An endometrial injury model was established using a mechanical scraping method: a sterile curette was used to uniformly scrape the inner wall of the uterus from top to bottom 100 times, simulating the pathological features of clinical intrauterine adhesions (IUA). The rats were randomly divided into five groups (n = 6 / group):

[0058] Blank control group: Only the uterus was exposed through abdominal surgery, without mechanical damage;

[0059] Simple injury group: bilateral mechanical injury to the uterus, without any treatment;

[0060] Simple microsphere group: 1 mL of estrogen-free magnetic core-shell microspheres were injected into one uterus after injury;

[0061] Estrogen-only group: 1 mL of estrogen solution with a concentration of 10 ng / mL was injected into one uterus after injury;

[0062] Estrogen-loaded magnetic core-shell microspheres: After injury, 1 mL of magnetic core-shell microspheres loaded with 10 ng / mL estrogen were injected into one unilateral uterus.

[0063] It should be noted that: a 1.5% (m / v) ALG solution was prepared, 1% PVA (m / v) was added, and the mixture was heated in a water bath for 1 h to form a mixture. Magnetic nanoparticles were added to the mixture at a ratio of 0.5-1 μg:1 mL, and the mixture was shaken at 1500 rpm / min for 5 min to uniformly disperse the magnetic nanoparticle microspheres into an outer phase suspension. Using silkworm pupa oil as the inner phase, the preparation steps were the same as for estrogen-loaded magnetic core-shell microspheres, ultimately yielding estrogen-free core-shell microspheres.

[0064] (2) Intervention and data collection

[0065] Fourteen days after the operation (covering the entire estrous cycle), the rats were euthanized by overdose anesthesia, and the bilateral uterine tissues were completely dissected, fixed with 4% paraformaldehyde for 24 h, dehydrated by graded ethanol, and then embedded in paraffin.

[0066] (3) Histological analysis

[0067] Hematoxylin-eosin (H&E) staining: The sections were 5 μm thick and observed using a Nikon TE2000-U inverted phase contrast microscope. The endometrial thickness (vertical distance from the basement membrane to the luminal epithelium), gland density (number of glands / high power field) and degree of fibrosis (collagen volume fraction) were measured.

[0068] Masson trichrome staining: 4 μm sections were used to observe collagen fiber deposition, and the degree of fibrosis was quantitatively analyzed using ImageJ 1.53 software. Images of sections stained with H&E and Masson staining, along with their quantitative statistical results, are shown below. Figure 4 .

[0069] Data statistics: Five non-overlapping fields of view were randomly selected from each slice. The results are expressed as mean ± standard deviation. One-way ANOVA was used to compare between groups, and P < 0.05 was considered statistically significant.

[0070] Table 2. Results of endometrial thickness, glandular number, and collagen volume fraction in rats under different treatment groups.

[0071]

[0072] The above experimental results indicate that estrogen therapy significantly increases endometrial thickness, reduces the number of endometrial glands, and alleviates the degree of fibrosis. Furthermore, administration of estrogen via magnetic core-shell microsphere loading results in better therapeutic effects.

[0073] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent modifications or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing estrogen-loaded magnetic core-shell microspheres, characterized in that, Includes the following steps: Step 1, Preparation of external phase solution: A hydrogel solution is prepared by mixing 1-5% sodium alginate and 1-3% polyvinyl alcohol polymer material, and then a uniform suspension is prepared by adding magnetic nanoparticles and oscillating at high speed as the external phase solution. Step 2, Preparation of the internal phase solution: The solution obtained by mixing estrogen with natural oils at a ratio of 1-10 ng / mL is the internal phase solution; Step 3, Microfluidic Device Design: Using a glass slide as a substrate, fine capillaries with a diameter of 0.1-0.5 mm are coaxially nested within coarse capillaries with a diameter of 0.3-1.5 mm. Copper wire with a diameter of 0.1-0.3 mm is pre-wound around the outer wall of the fine capillaries to ensure a uniform annular gap between the inner and outer capillaries, avoiding direct contact and thus ensuring the uniformity of the shell thickness. Subsequently, epoxy resin is used to seal and fix the capillary interface needles, forming a complete coaxial microfluidic electrospun chip. The fine and coarse capillaries are respectively connected to independent droplet microfluidic injection pumps via needles. The inner phase solution flows through the fine capillaries to form the core, while the outer phase solution flows through the annular gap between the inner and outer capillaries to form the shell. Step 4: The inner phase solution and the outer phase solution are injected stably and uniformly into a coaxial capillary at a set rate. Electrospinning is then performed under the action of a high-voltage electric field. A DC high-voltage current is applied at the outer needle tip, and the capillary outlet is vertically downward, with its bottom end 7-9 cm away from the surface of the calcium chloride solution. The fluid at the outlet is subjected to the synergistic shearing action of the electric field force and the shell phase fluid, forming a stable droplet with a core-shell structure. The droplet is then collected in a 2% (w / w) calcium chloride solution and solidified through an ionic crosslinking reaction to obtain the initial core-shell microsphere product. Finally, it is washed with deionized water until neutral and air-dried at room temperature, thus realizing the continuous preparation of estrogen-loaded magnetic core-shell microspheres.

2. The method for preparing estrogen-loaded magnetic core-shell microspheres according to claim 1, characterized in that, In step 1, the mixing ratio of magnetic nanoparticles to ion-crosslinked hydrogel solution is 0.5-1 μg: 1 mL.

3. The method for preparing estrogen-loaded magnetic core-shell microspheres according to claim 1, characterized in that, The natural oils mentioned in step 2 are silkworm pupa oil, soybean oil, olive oil, corn oil, or castor oil.

4. The method for preparing estrogen-loaded magnetic core-shell microspheres according to claim 1, characterized in that, In step 4, the flow rate of the external phase solution is controlled at 24-32 μL / min, and the flow rate of the internal phase solution is controlled at 10-14 μL / min.

5. The method for preparing estrogen-loaded magnetic core-shell microspheres according to claim 1, characterized in that, The voltage range of the high-voltage electric field mentioned in step 4 is 6.5-8.5 kV.

6. The method for preparing estrogen-loaded magnetic core-shell microspheres according to claim 1, characterized in that, The droplet falls to a height of 7 cm in step 4.

7. The estrogen-loaded core-shell microspheres prepared by the preparation method according to any one of claims 1-6, characterized in that, The estrogen-loaded magnetic core-shell microspheres have a particle size of 800-1200 μm.

8. The use of estrogen-loaded magnetic core-shell microspheres according to any one of claims 1-6 in the preparation of a medicament for the prevention or treatment of intrauterine adhesions.

Images