Nanodelivery carrier composite extracellular matrix microspheres, preparation method and application thereof

Abstract

This invention discloses a nanodelivery carrier composite extracellular matrix microsphere, its preparation method, and its applications. The method involves preparing microspheres from extracellular matrix and a photoinitiator, forming ice crystal templates through freezing, followed by photocrosslinking at low temperatures. After removing the ice crystals by heating, a second crosslinking process is performed to construct microspheres with a three-dimensional interconnected nanoporous structure. These microspheres are co-incubated with a nanodelivery carrier loaded with active ingredients, utilizing the salt charge shielding effect to induce aggregation and physically trap the nanodelivery carrier within the pores. The microspheres possess a high specific surface area and spatially confined structure, improving the loading efficiency of the nanodelivery carrier and maintaining particle size and structural stability during storage and reconstitution. The nanodelivery carrier enables controlled release of active ingredients, while the extracellular matrix itself participates in the regulation of the hair follicle microenvironment, forming a dual mechanism with the nanodelivery system to synergistically promote hair growth, making it suitable for hair loss treatment.

Description

Technical Field

[0001] This invention relates to the fields of biomedical materials and transdermal drug delivery technology, and in particular to a nanodelivery carrier composite extracellular matrix microsphere, its preparation method, and its application. Background Technology

[0002] Hair growth and follicle regeneration depend on the structural stability and continuous regulation of the microenvironment surrounding the hair follicle by bioactive signals. The extracellular matrix (ECM) of the hair follicle basement membrane and its adjacent regions play a crucial role in maintaining the structural integrity of the hair follicle, regulating the proliferation and differentiation of hair follicle stem cells, and mediating growth factor signaling. When the composition or structure of the extracellular matrix changes, the homeostasis of the hair follicle microenvironment is disrupted, which may lead to hair growth cycle disorders or even hair loss.

[0003] In recent years, various active ingredients that promote hair growth have been widely studied and applied, including small molecule drugs, bioactive peptides, protein factors, and nanovesicle systems. However, these active ingredients are prone to diffusion, degradation, or metabolic clearance after local administration, making it difficult to maintain a stable and effective concentration in the hair follicle area, thus limiting their sustained effects. To improve the stability and local retention time of active ingredients, they are often loaded into nanodelivery carriers to achieve sustained release or targeted delivery. On the other hand, extracellular matrix materials are derived from natural tissues and, after decellularization, retain collagen, glycosaminoglycans, and various bioactive binding sites, exhibiting good biocompatibility and tissue mimicry capabilities. Therefore, combining extracellular matrix materials with nanodelivery carriers to construct composite delivery systems is considered helpful in regulating the local microenvironment of hair follicles while delivering active ingredients.

[0004] However, in existing technologies, the binding between extracellular matrix materials and nanodelivery carriers mainly employs covalent cross-linking fixation or electrostatic repair. The former may affect the structure and activity of the nanodelivery carrier and is complex to manufacture; the latter lacks binding stability and is prone to initial burst release. Furthermore, in most existing systems, the release behavior of the nanodelivery carrier depends on the overall degradation process of the extracellular matrix, with the release rhythm highly coupled to the matrix degradation rate, making it difficult to achieve independent regulation of the nanodelivery carrier release behavior.

[0005] Therefore, existing technologies have not yet provided a solution for achieving stable physical confinement of nanodelivery carriers within the ECM without chemical modification, and for restoring their dispersion and release function under physiological ionic strength conditions. In particular, there remains a technological gap in how to achieve reversible aggregation and spatial trapping of nanodelivery carriers through tunable physical mechanisms to balance efficient loading, structural stability, and controllable release. Summary of the Invention

[0006] Objective of the invention: To address the technical problems of existing hair growth promoting agents, such as short local retention time, low utilization rate of active ingredients, limited delivery efficiency, and difficulty in achieving controlled release, this invention provides a nano-delivery carrier composite extracellular matrix microsphere for promoting hair growth and its preparation method.

[0007] To achieve the above objectives, as one aspect of the present invention, a method for preparing nanodelivery carrier composite extracellular matrix microspheres is provided, comprising the following steps:

[0008] (1) Preparation of extracellular matrix microspheres: The extracellular matrix material is mixed with a photoinitiator to form a precursor solution, the precursor solution is prepared into microspheres, the microspheres are frozen to make at least a portion of the water in the precursor solution form an ice crystal template structure, and photocrosslinking is performed in the frozen state. Then the temperature is raised to remove the ice crystal template and complete the secondary photocrosslinking, thereby forming extracellular matrix microspheres with a three-dimensional interconnected nanopore structure inside;

[0009] (2) Loading of nano-delivery carrier: The nano-delivery carrier loaded with hair growth-promoting active substances is placed in a high-salt buffer system with the extracellular matrix microspheres to induce reversible aggregation of the nano-delivery carrier, so that it is retained in the nanoporous structure of the extracellular matrix microspheres through physical retention; and when the extracellular matrix microspheres loaded with the nano-delivery carrier are under the ionic strength of physiological saline, the nano-delivery carrier is restored to a dispersed state and can be released from the extracellular matrix microspheres.

[0010] This method constructs extracellular matrix microspheres with a three-dimensional interconnected nanopore structure, utilizing the synergistic effect of physical confinement and ionic environment regulation to effectively capture nanoparticles. After the nanodelivery carrier enters the nanopores of the microspheres, its diffusion path is constrained by the geometry of the multi-level channels. Furthermore, because the pore size matches the hydrated particle size of the nanoparticles, the migration rate of the nanoparticles within the channels decreases, leading to gradual retention. Simultaneously, the high-concentration ionic environment reduces the electrostatic repulsion distance on the surface of the nanodelivery carrier, causing close contact and local aggregation between nanoparticles. Upon delivery to the hair follicle site, this aggregated state undergoes reversible dissociation due to dilution by the ionic strength under physiological conditions, restoring the carrier to a monodisperse state and allowing for orderly release. This significantly improves the retention time and delivery efficiency of the active ingredient at the hair follicle target site.

[0011] Alternatively, in combination with any of the above aspects, in another implementation of this aspect, in step (1), the extracellular matrix material is selected from tissues of pig, cow, sheep or human origin and obtained after decellularization.

[0012] Preferably, the extracellular matrix material in step (1) is selected from tissues of pig, cow, sheep or human origin and obtained by decellularization. Specifically, it can be selected from one or more of the following sources: small intestinal submucosal matrix (SIS), decellularized dermal matrix (ADM), bladder matrix (UBM), decellularized adipose tissue matrix (DAT), amniotic matrix (AM), decellularized skin matrix, decellularized cartilage matrix, decellularized heart matrix or myocardial matrix (H-ECM), decellularized liver matrix (L-ECM), and decellularized kidney matrix.

[0013] Optionally, in combination with any of the above aspects, in another implementation of this aspect, in step (1), the concentration of the extracellular matrix in the precursor solution is 2 mg / mL-50 mg / mL, and / or the photoinitiator is vitamin B2.

[0014] Alternatively, in conjunction with any of the above aspects, in another implementation of this aspect, in step (1), the extracellular matrix microspheres are prepared by any one or a combination of microfluidic method, membrane emulsification method, mechanical stirring method, electrostatic spraying method.

[0015] Alternatively, in combination with any of the above aspects, in another implementation of this aspect, in step (1), the freezing treatment is carried out at -80 °C for 5 to 30 minutes.

[0016] Optionally, in combination with any of the above aspects, in another implementation of this aspect, in step (1), the pore size of the extracellular matrix microspheres having a three-dimensional interconnected nanopore structure is 200 nm to 1 μm.

[0017] Optionally, in combination with any of the above aspects, in another implementation of this aspect, in step (2), the active substance is selected from one or more of small molecule drugs, plant extracts, polypeptides, proteins, bioactive factors, and platelet-rich plasma (PRP).

[0018] Optionally, in combination with any of the above aspects, in another implementation of this aspect, in step (2), the nanodelivery carrier is a nanostructure carrier having a surface charge and capable of reversible aggregation under high ionic strength conditions, and / or the nanodelivery carrier is selected from one or more of nanovesicles, exosomes, polymer nanoparticles, micelle systems and nanogels.

[0019] Optionally, in conjunction with any of the above aspects, in another implementation of this aspect, in step (2), the high-salt buffer system is a buffer salt solution containing sodium chloride, the buffer salt solution being selected from one or more of phosphate buffer, Tris buffer solution or HEPES buffer solution, and the concentration of sodium chloride is 1.5 to 4 M.

[0020] As another aspect of the present invention, a nanodelivery carrier composite extracellular matrix microsphere is provided, which is prepared according to the preparation method described in any of the above aspects.

[0021] As another aspect of the present invention, an application of the nanodelivery carrier composite extracellular matrix microspheres described above in promoting hair growth and / or treating hair loss is also provided.

[0022] Preferably, the present invention provides an extracellular matrix microsphere delivery system for promoting hair growth obtained by the above preparation method, which is delivered to the skin or hair follicle tissue via microneedles for promoting hair growth and / or treating hair loss.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] (1) ECM hydrogel microspheres with interconnected nanopores were constructed by microfluidic-freeze-photocuring to form three-dimensional interconnected channels and increase the specific surface area, thereby achieving rapid adsorption and efficient drug loading of nano-delivery carriers and overcoming the problems of slow loading rate and low capacity of traditional dense hydrogels.

[0025] (2) The ECM matrix used has a high degree of homology with natural tissues, which can significantly reduce the stress response at the drug delivery site and is more suitable for sensitive scalp or damaged skin areas. At the same time, a physical drug delivery mechanism without chemical bonding is achieved through salt-induced reversible aggregation: the high-salt environment shields the surface charge of the nano-delivery carrier and induces its reversible aggregation, so that it is stably retained by the pore structure of the ECM microspheres, which significantly reduces the initial burst release while avoiding the risks of chemical modification.

[0026] (3) During the freeze-drying process, the porous structure of ECM provides spatial confinement and structural protection for the nano-delivery carrier. After reconstitution, the particle size and drug loading state of the nano-delivery carrier remain stable, thereby solving the problem of improving the overall stability of the formulation and extending the shelf life of the nano-delivery carrier.

[0027] (4) The ECM gel microspheres and the nano-delivery carrier form a synergistic effect and realize the temporal separation of the release of the nano-delivery carrier and the degradation of ECM: the nano-delivery carrier is controlled to release and deliver active ingredients to the hair follicle area before the overall degradation of ECM. Subsequently, ECM continuously releases bioactive signals that are beneficial to the reconstruction of the hair follicle microenvironment, overcoming the limitation of traditional systems that rely on ECM degradation to release nanoparticles, thereby improving the overall hair growth promotion effect and its sustainability.

[0028] The above summary provides a simplified overview of some concepts, which will be further described in detail in the following specific embodiments. The above summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter. The claimed subject matter is not limited to embodiments that address any or all the shortcomings pointed out in the background art.

[0029] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by means of embodiments thereof. Attached Figure Description

[0030] The accompanying drawings, incorporated in and forming part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without any creative effort. These drawings and textual descriptions are not intended to limit the scope of the concept of this application in any way, but rather to illustrate the concepts of this application to those skilled in the art by referring to specific embodiments.

[0031] Figure 1 This is a schematic diagram of the preparation process of the drug delivery system in this application;

[0032] Figure 2 This is a comparison chart of the finasteride loading rates in Example 1 of this application, which contains microsphere gel, and in Comparative Example 1, which contains block gel.

[0033] Figure 3 The particle size change curves of the liposomes in Example 1 of this application after aggregation and restoration of dispersion are shown.

[0034] Figure 4 This is a comparative diagram of hair growth in AGA mice used in Example 1 of this application.

[0035] Figure 5 This is a statistical chart of hair growth area on day 21 in the AGA mouse animal experiment of Example 1 of this application;

[0036] Figure 6 This is a graph showing the weight of newly grown hair on day 21 in the AGA mouse animal experiment of Example 1 of this application. Detailed Implementation

[0037] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0038] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. It should be further understood that, as used herein, the singular forms "a," "an," and "the" are intended to also include the plural forms, unless the context indicates otherwise. Furthermore, the terms "or," "and / or," "including at least one of the following," etc., as used herein, can be interpreted as inclusive, or mean any one or any combination thereof. Exceptions to this definition only arise when combinations of elements, functions, steps, or operations are inherently mutually exclusive in some manner.

[0039] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application. Unless otherwise specified, the materials, reagents, etc., used in the following embodiments are commercially available. Experimental methods not specifically described in the embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0040] The technical solution of the present invention will be further described below in conjunction with its implementation.

[0041] Example 1

[0042] The following will combine Figure 1 The schematic diagram shown illustrates Example 1.

[0043] (1) Preparation of extracellular matrix-finasteride liposome delivery system

[0044] S1. Preparation of extracellular matrix precursor solution

[0045] Weigh 10 mg of decellularized porcine small intestinal mucosal matrix into a centrifuge tube, add 1 mL of hydrochloric acid solution (0.01 M) to dissolve it. After dissolution, adjust the pH of the digestion solution to 7.4 with 0.1 M NaOH, add 10×PBS solution at a volume ratio of 10:1 to achieve ion balance, and add 1% (w / v) vitamin B2. After dissolution, the hydrogel precursor solution is obtained and stored at 4°C.

[0046] S2. Preparation of extracellular matrix microspheres

[0047] The ECM precursor solution was designated as dispersed phase A1. A surfactant (FE-surf) was dissolved in fluorinated oil to prepare a continuous phase B1 with a mass fraction of 2%. The prepared solutions were connected to a microfluidic chip via pipes. The flow rate of continuous phase B1 was adjusted to 40 μL / min, and the flow rate of dispersed phase A1 was adjusted to 4 μL / min. Stable monodisperse droplets were prepared using the microfluidic chip. After collecting the microspheres for 2 hours, they were immediately placed in liquid nitrogen for freezing for 10 minutes. The rapid freezing and high proportion of water formed ice crystals as pore templates. In the presence of ice crystals, the polymer was crosslinked by irradiation with ultraviolet light to form a crosslinked network structure. After freezing and crosslinking, the microspheres were removed and thawed at 37 °C. After the ice crystals melted, they became pores, resulting in ECM microspheres with a mesoporous / macroporous structure.

[0048] S3, loading of finasteride liposomes

[0049] Porous decellularized porcine small intestinal mucosal matrix (ECM) microspheres prepared by freeze-photocrosslinking were equilibrated in PBS buffer (pH 7.4) for 2 h to remove residual oil phase and surfactants and restore hydration. Subsequently, the ECM microsphere suspension was mixed with a finasteride liposome solution prepared beforehand using a thin-film hydration method at a mass ratio of 1:5. The mixture was incubated at 4°C or room temperature with gentle shaking at 60 rpm for 6–12 h, allowing the liposomes to diffuse into the porous structure of the ECM microspheres and achieve adsorption loading through electrostatic interactions, hydrogen bonding, and physical intercalation. After incubation, the microspheres were separated by low-speed centrifugation and gently washed 1–2 times with PBS buffer to remove unadsorbed liposomes, yielding the finasteride liposome-loaded ECM composite microsphere formulation. The liposome-loaded extracellular matrix microsphere formulation was freeze-dried and stored for 7 days before reconstitution, and the liposome particle size distribution was measured. Figure 3 The liposomes recovered immediately after freeze-drying (blue) and the liposomes released after rehydration in ECM hydrogel microspheres after 7 days of storage (red) both showed a single-peak approximate normal distribution, without obvious multi-peak aggregation, indicating that the freeze-drying-rehydration process did not cause damage to the liposome structure.

[0050] Comparative Example 1:

[0051] Take 480 μL of ECM precursor solution, transfer it to a 2 mL centrifuge tube, and immediately freeze it in liquid nitrogen for 10 min. Rapid freezing followed by UV irradiation in the presence of ice crystals causes polymer crosslinking, forming a crosslinked network structure. After freezing and crosslinking, thaw at 37 °C. The melting ice crystals create pores, yielding a blocky ECM gel with a mesoporous / macroporous structure. Perform finasteride liposome loading using the same steps as in S3. After 10 minutes of incubation, measure the concentration of finasteride within the gel to indirectly determine the liposome loading. Figure 2 As shown, the adsorption rate of extracellular matrix microspheres is faster than that of bulk gels.

[0052] (2) Extracellular matrix-finasteride liposome delivery system for mouse hair growth

[0053] S1, Mouse modeling

[0054] Male C57BL / 6 mice (18-22 g) aged 6-7 weeks were selected and acclimatized for three days in an environment with a temperature of (22±2 ℃) and humidity of (55±5%) before the formal experiment. Mice were randomly divided into a control group, a model group, and an experimental group using a blinded sorting method. The model group consisted of AGA mice and an AGA mouse + minoxidil group. All mice were fed a basal diet and had free access to drinking water. First, the hair on the backs of the C57BL / 6 mice was shaved using a power animal shaver, followed by hair removal cream. Except for the control group, all other groups received subcutaneous injections of 5 mg / kg testosterone propionate on their backs for 21 consecutive days to induce androgenetic alopecia. The control and model groups received a placebo of 100 μL of saline solution daily, while the experimental group received a placebo daily. Hair growth on the backs of the mice was tracked and photographed regularly, and the regrowth coverage was analyzed using ImageJ software.

[0055] Experimental results are as follows Figure 4 , 5 As shown in Figures 6 and 7, in a mouse model of androgenetic alopecia induced by testosterone propionate, hair regeneration on the back of the model group was significantly inhibited, verifying the successful establishment of the model. Compared with the model group, the positive control minoxidil significantly promoted hair regeneration, as evidenced by increased hair coverage area and increased weight of regenerated hair. After treatment with the nano-delivery carrier composite extracellular matrix microspheres prepared in the examples, hair regeneration on the back of mice was significantly accelerated, and the coverage of black hair was more uniform and complete; quantitative analysis showed that the hair growth area and weight of regenerated hair were significantly higher than those in the model group, and the overall level reached or approached that of minoxidil treatment.

[0056] Example 2

[0057] (1) Preparation of extracellular matrix-platelet-rich plasma (PRP) delivery system

[0058] S1. Preparation of extracellular matrix precursor solution

[0059] Weigh 10 mg of decellularized porcine small intestinal mucosal matrix into a centrifuge tube, add 1 mL of hydrochloric acid (0.01 M) to dissolve it, and after dissolution, adjust the pH of the digestion solution to 7.4 with 0.1 M NaOH. Add 10×PBS solution at a volume ratio of 10:1 to achieve ion balance, and add 1% (w / v) vitamin B2. After dissolution, the hydrogel precursor solution is obtained and stored at 4°C.

[0060] S2. Preparation of extracellular matrix microspheres

[0061] The ECM precursor solution was designated as the dispersed phase A1. A surfactant (FE-surf) was dissolved in fluorinated oil to prepare a continuous phase B1 with a mass fraction of 2%. The prepared solutions were connected to a microfluidic chip via pipes. The flow rate of the oil phase B1 was adjusted to 40 μL / min, and the flow rate of the aqueous phase A1 was adjusted to 4 μL / min. Stable monodisperse droplets were prepared using the microfluidic chip. Microspheres were collected for 2 hours and immediately placed in liquid nitrogen for 10 minutes to freeze rapidly. The high proportion of water formed ice crystals as pore templates. In the presence of ice crystals, the polymer was crosslinked by ultraviolet light to form a crosslinked network structure. After freezing and crosslinking, the ice crystals melted and became pores, resulting in ECM microspheres with a mesoporous / macroporous structure.

[0062] S3, Platelet-Rich Plasma (PRP) Loading

[0063] Porous decellularized porcine small intestinal mucosal matrix (ECM) microspheres prepared by freeze-photocrosslinking were equilibrated in PBS buffer (pH 7.4) for 2 h to remove residual oil phase and surfactants and restore hydration. Subsequently, the ECM microsphere suspension was mixed with a pre-prepared mouse autologous platelet-rich plasma (PRP) solution at a mass ratio of 1:5 and incubated with gentle shaking at 60 rpm for 6–12 h at 4 ℃ or room temperature. This allowed liposomes to diffuse into the porous structure of the ECM microspheres and achieve adsorption loading through electrostatic interactions, hydrogen bonding, and physical intercalation. After incubation, the microspheres were separated by low-speed centrifugation and gently washed 1–2 times with PBS buffer to remove unadsorbed liposomes, thus obtaining the platelet-rich plasma (PRP) loaded extracellular matrix microsphere formulation.

[0064] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0065] In this application, the same or similar terms, concepts, technical solutions and / or application scenario descriptions are generally described in detail only when they appear for the first time. When they appear again, they are generally not repeated for the sake of brevity. When understanding the technical solutions and other contents of this application, the same or similar terms, concepts, technical solutions and / or application scenario descriptions that are not described in detail later can be referred to their previous relevant detailed descriptions.

[0066] In this application, the descriptions of the various embodiments have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0067] The technical features of the present application can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the present application.

[0068] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for preparing nanodelivery carrier composite extracellular matrix microspheres, characterized in that, Includes the following steps: (1) Preparation of extracellular matrix microspheres: The extracellular matrix material is mixed with a photoinitiator to form a precursor solution, the precursor solution is prepared into microspheres, the microspheres are frozen to make at least a portion of the water in the precursor solution form an ice crystal template structure, and photocrosslinking is performed in the frozen state. Then the temperature is raised to remove the ice crystal template and complete the secondary photocrosslinking, thereby forming extracellular matrix microspheres with a three-dimensional interconnected nanopore structure inside; (2) Loading of nano-delivery carrier: The nano-delivery carrier loaded with hair growth-promoting active substances is placed in a high-salt buffer system with the extracellular matrix microspheres to induce reversible aggregation of the nano-delivery carrier, so that it is retained in the nanoporous structure of the extracellular matrix microspheres through physical retention; and when the extracellular matrix microspheres loaded with the nano-delivery carrier are under the ionic strength of physiological saline, the nano-delivery carrier is restored to a dispersed state and can be released from the extracellular matrix microspheres.

2. The preparation method according to claim 1, characterized in that, In step (1), the extracellular matrix material is selected from tissues of pig, cow, sheep or human origin and obtained after decellularization.

3. The preparation method according to claim 1, characterized in that, In step (1), the concentration of the extracellular matrix in the precursor solution is 2 mg / mL-50 mg / mL, and / or the photoinitiator is vitamin B2.

4. The preparation method according to claim 1, characterized in that, In step (1), the extracellular matrix microspheres are prepared by any one or a combination of microfluidic method, membrane emulsification method, mechanical stirring method, electrostatic spraying method.

5. The preparation method according to claim 1, characterized in that, In step (1), the freezing process is carried out at -80 ℃ for 5 to 30 minutes.

6. The preparation method according to claim 1, characterized in that, In step (1), the extracellular matrix microspheres with a three-dimensional interconnected nanopore structure have a pore size of 200 nm to 1 μm.

7. The preparation method according to claim 1, characterized in that, In step (2), the active substance is selected from one or more of small molecule drugs, plant extracts, polypeptides, proteins, bioactive factors, and platelet-rich plasma (PRP).

8. The preparation method according to claim 1, characterized in that, In step (2), the nanodelivery carrier is a nanostructure carrier with surface charge that can reversibly aggregate under high ionic strength conditions, and / or the nanodelivery carrier is selected from one or more of nanovesicles, exosomes, polymer nanoparticles, micelle systems and nanogels.

9. The preparation method according to claim 1, characterized in that, In step (2), the high-salt buffer system is a buffer salt solution containing sodium chloride, which is selected from one or more of phosphate buffer, Tris buffer solution or HEPES buffer solution, and the concentration of sodium chloride is 1.5 to 4 M.

10. Nanodelivery carrier composite extracellular matrix microspheres prepared by the preparation method according to any one of claims 1-9.

11. The use of the nanodelivery carrier composite extracellular matrix microspheres according to claim 10 in promoting hair growth and / or treating hair loss.

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