A method for preparing silica microspheres and its related applications

Abstract

This invention discloses a method for preparing silica microspheres and their related applications, relating to the fields of materials and biology. The method uses a fluorinated oil or hydrocarbon oil containing silicate compounds and surfactants as the continuous phase, and an alkaline solution containing silicate compounds as the dispersed phase. Uniform water-in-oil droplets are generated in a droplet microfluidic chip. The silicate compounds are catalytically hydrolyzed by an alkaline reagent inside the droplets to obtain silica microspheres. Compared with existing technologies, this method has advantages such as simple operation, high controllability, good product uniformity, low cost, wide application range, and good compatibility.

Description

Technical Field

[0001] This invention relates to the fields of materials and biology, and more specifically, to a method for preparing silica microspheres and their related applications. Background Technology

[0002] Silica microspheres possess characteristics such as low density, high specific surface area, and good mechanical stability. Furthermore, their excellent adsorption, permeability, and non-toxicity make them widely used as carriers for drug release and encapsulation of biomolecules in biomedicine. In 1968, Stober et al. first prepared spherical silica using a silicon source hydrolysis-condensation process, laying the foundation for subsequent in-depth research on silica microspheres.

[0003] With in-depth research into silica microspheres, numerous preparation methods have emerged, primarily focusing on dry and wet methods. Dry methods mainly include gas-phase and arc methods; wet methods include precipitation, sol-gel, and sol-seed methods. While dry-prepared silica exhibits high purity and good monodispersity, the process is complex, requiring sophisticated equipment and suffers from low yield and expensive raw materials. Reverse microemulsion methods, while also yielding well-dispersed microspheres, result in smaller particle sizes, and the solvents used in the preparation process are highly toxic, causing significant environmental pollution. Furthermore, the resulting microspheres often exhibit size inconsistencies, severely limiting their applications.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing silica microspheres and their related applications.

[0006] This invention is implemented as follows:

[0007] In a first aspect, embodiments of the present invention provide a method for preparing silica microspheres, comprising the following steps: using a mixed solution 1 containing a silicate ester compound, a surfactant, and a droplet-generating oil as a continuous phase, wherein the droplet-generating oil includes fluorinated oil or hydrocarbon oil; using a mixed solution 2 containing the silicate ester compound and an alkaline solution as a dispersed phase, and generating droplets in a droplet microfluidic chip;

[0008] After the generated droplets are solidified, silica microspheres are obtained.

[0009] Secondly, embodiments of the present invention provide a reagent combination or kit, comprising: a reagent capable of carrying out the preparation method of silica microspheres described in the foregoing embodiments.

[0010] Thirdly, embodiments of the present invention provide the application of a reagent combination in the preparation of a product for preparing silica microspheres, the reagent combination comprising reagents capable of carrying out the silica microsphere preparation method described in the foregoing embodiments.

[0011] Fourthly, the embodiments of the present invention provide the application of hollow silica microspheres prepared by the preparation method described in the foregoing embodiments as drug carriers in the preparation of sustained-release drugs.

[0012] The present invention has the following beneficial effects:

[0013] This invention uses a mixed solution containing silicate ester compounds, surfactants, and droplet-generating oil as the continuous phase, and a mixed solution containing silicate ester compounds and alkaline solution as the dispersed phase to generate uniform water-in-oil droplets in a microfluidic chip. The silicate ester compounds are catalytically hydrolyzed by an alkaline reagent to form a robust silica shell, thereby obtaining silica microspheres.

[0014] This invention has the following advantages:

[0015] 1. Simple operation: This technology avoids the high-temperature calcination and etching and other violent chemical reactions in the template removal process of traditional methods. It can remove the template and generate microspheres without extra operations. The introduction of microfluidics has the characteristics of instrument miniaturization and effectively reduces the risk of preparation.

[0016] 2. High controllability: The preparation method of silica microspheres provided by this invention has extremely high controllability. The size and internal morphology of the microspheres can be controlled by changing the size of the microfluidic chip and the amount of silicate compound added, so as to obtain silica microspheres with specific particle sizes and realize the transformation of microspheres from hollow to near solid.

[0017] 3. Good product uniformity: The microdroplets prepared by the fluid focusing microchannel of the droplet microfluidic chip have high uniformity. The microspheres prepared by using this droplet as a template have complete morphology, uniform size, and good monodispersity.

[0018] 4. Low cost: The introduction of droplet microfluidics technology enables high-throughput and rapid product generation with minimal reagents. By simply connecting multiple chips in series, products can be prepared in large quantities in a short time, which is conducive to industrialization and large-scale production of microspheres and avoids the waste of resources caused by the large amount of reagents in traditional preparation methods.

[0019] 5. Wide range of applications: The silica microspheres prepared by this method have good monodispersity, uniform size, and intact morphology, and can be stored for a long time in organic or aqueous phases. They are non-toxic, have good biocompatibility, and can be applied in biomedicine, environmental monitoring, and other fields.

[0020] 6. Good compatibility: This scheme offers a variety of surfactants, fluorinated oils, and silicate compounds in the continuous phase, which can be freely combined according to actual conditions. There are no special requirements for the type of droplet generation chip used; T-junction, flow focusing, and coaxial focusing droplet generation chips can be used, demonstrating good compatibility. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram illustrating the principle of droplet microfluidics.

[0023] Figure 2 A schematic diagram illustrating the principle of microfluidic preparation of silica droplets;

[0024] Figure 3 This is a schematic diagram illustrating the formation principle of silica microspheres.

[0025] Figure 4 A schematic diagram illustrating the principle of modification with amphiphilic silica nanoparticles;

[0026] Figure 5 This is a schematic diagram of the hollow silica microspheres in Example 1. In this diagram, A is an optical micrograph of water-in-oil droplets generated in real time on a droplet microfluidic chip with a cross-channel size of 50 μm; B is an optical micrograph of the hollow silica droplets generated by the microfluidic chip; and C is an SEM image of the solidified hollow silica microspheres.

[0027] Figure 6 This is a schematic diagram showing the results corresponding to different dispersed phase outlet microchannel widths; where A represents the dispersed phase outlet microchannel widths corresponding to different embodiments, and B represents the particle size results of droplets and microspheres prepared with different widths.

[0028] Figure 7 Results showing the effect of different APTES dosages on silica microspheres;

[0029] Figure 8 SEM image of the enlarged hollow silica microsphere shell;

[0030] Figure 9The images show dark-field optical microscopy images of microspheres placed in 1 μM DOX PBS solution for 0 h and 10 h. In the images, a is the dark-field optical microscopy image of microspheres placed in 1 μM DOX PBS solution for 0 h, and b is the dark-field optical microscopy image of microspheres placed in 1 μM DOX PBS solution for 10 h. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0032] Based on the problems existing in the prior art, this application proposes a method for preparing silica microspheres based on droplet microfluidics. Microfluidic droplet technology is a new technique developed in recent years on microfluidic chips for studying the generation, manipulation, and application of microdroplets in the range of a few micrometers to hundreds of micrometers. When two immiscible liquids (oil and water) flow in a microfluidic channel, under the action of liquid / liquid interfacial tension and shear force, one phase of the fluid will form a highly uniform discontinuous flow, i.e., a droplet. Figure 1 ).

[0033] This invention uses a mixed solution 1 containing silicate ester compounds, surfactants, and droplet-generating oil as the continuous phase, and a mixed solution 2 containing silicate ester compounds and an alkaline solution as the dispersed phase. Uniform water-in-oil droplets are generated in a microfluidic chip. The silicate ester compounds are catalyzed by the alkaline solution to undergo hydrolysis, generating silica, thus yielding hollow / solid silica microspheres. This process features rapid generation, high throughput, uniform microsphere size, and simple operation, enabling high-throughput generation of the desired microspheres in a short time. The silica microspheres prepared by this method also exhibit good biocompatibility and adsorption properties, making them suitable as carriers for applications in the biological field.

[0034] On one hand, embodiments of the present invention provide a method for preparing silica microspheres, which includes the following steps:

[0035] A mixed solution 1 containing silicate ester compounds, surfactants, and droplet-generating oil is used as the continuous phase, wherein the droplet-generating oil includes fluorinated oil or hydrocarbon oil; a mixed solution 2 containing silicate ester compounds and an alkaline solution is used as the dispersed phase, and droplets are generated in the droplet microfluidic chip.

[0036] After the generated droplets are solidified, silica microspheres are obtained.

[0037] In some embodiments, the silicate compound has the chemical formula R. n O mSi(OR') 4-n Where n is an integer, selected from 0 to 4 (specifically, it can be any one or any two of 0, 1, 2, 3, 4), and m is an integer, selected from 0 to 1 (specifically, it can be 0 or 1);

[0038] The R' group is a branched or unsubstituted C2-C atom at the α carbon atom. 20 The substituted group is a hydrocarbon group containing at least one of the following functional groups: vinyl group, ethynyl group, amino group, aldehyde group, epoxy group, thiol group and methanol group.

[0039] The R group is a branched or unsubstituted C2-C atom at the α-carbon atom. 20 A hydrocarbon group, or substituted group, refers to a hydrocarbon group containing at least one of the following functional groups: vinyl group, ethynyl group, amino group, aldehyde group, epoxy group, thiol group, and methanol group.

[0040] Both the continuous phase and the dispersed phase contain silicate compounds. The silicate compounds in the continuous phase and the dispersed phase can be the same or different.

[0041] In some embodiments, the silicate compound includes any one or more of tetraethyl orthosilicate, methyl orthosilicate, and 3-aminopropyltriethoxysilane.

[0042] In some embodiments, the mass fraction of the surfactant in the continuous phase is 0.01% to 20%. Specifically, it can be any one or any two of 0.01%, 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, and 20%.

[0043] In some embodiments, the volume fraction of silicate compounds in the dispersed phase is 0.1% to 30%, specifically any one or any two of 0.1%, 1%, 5%, 10%, 15%, 20%, 25%, and 30%. The internal morphology of the microspheres can be controlled by adjusting the concentration of the silicate compounds. Within this concentration range, the microspheres can be transformed from hollow to solid (0.1% to 3% is hollow, 3% to 30% is solid). Outside this concentration range, droplet instability may occur, making it impossible to obtain microspheres with intact morphology.

[0044] In some embodiments, the volume fraction of silicate compounds in the dispersed phase is 0.1% to 50%. Specifically, it can be any one or any two of 0.1%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%.

[0045] In some embodiments, the surfactant includes any one or more of the following: Span80, Tween20, SDS, PF-octanol, PF-decanol, PF-TD acid, PFPE-COOH, PFPE-PEG, and amphiphilic silica nanoparticles (silica nanoparticles with surface modified with fluorinated and hydrophilic groups). Microspheres prepared with surfactants containing fluorinated silica nanoparticles (amphiphilic silica nanoparticles) will have a layer of silica nanoparticles attached to their surface, which can increase the surface area of ​​the microspheres and adsorb more molecules from the solution.

[0046] The technical solution of this application does not impose any special restrictions on the preparation method of amphiphilic silica nanoparticles (they can be prepared based on existing technologies), as long as they are silica nanoparticles with surface modification of fluorinative and hydrophilic groups.

[0047] In some embodiments, the molar ratio of fluorinative groups to hydrophilic groups on the surface of the amphiphilic silica nanoparticles is 1.5 to 5:1. Specifically, it can be any one or any two of 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, and 5:1. The compound used to form the fluorinative group is selected from at least one of: 1H,1H,2H,2H-perfluorodecyltriethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, triethoxy-1H,1H,2H,2H-tetrafluoro-N-octylsilane, triethoxyfluorosilane, triethoxy(pentafluorophenyl)silane, 3,3,3-trifluoropropyltriethoxysilane, and triethoxy(1H,1H,2H,2H-nonafluorohexyl)silane. The hydrophilic groups include at least one of the following: hydroxyl, carboxylic acid, sulfonic acid, sulfate, phosphate, amino, quaternary ammonium, tertiary amine, amide, and ether groups. Before modification with fluorinative and hydrophilic groups, the particle size of the silica nanoparticles can be 50–700 μm.

[0048] In some embodiments, the amount of amphiphilic silica nanoparticles added in the continuous phase is 0.4% to 4% (mass fraction), specifically any one or any two of 0.4%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, and 4%.

[0049] In some embodiments, the fluorinated oil includes any one or more of HFE, Novec, FC40, FC70, FC77, and FC3283.

[0050] In some embodiments, the pH value of the alkaline solution is 7.1 to 9.0, specifically any one or any two of 7.1, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6, 8.8, and 9.0.

[0051] In some embodiments, the alkaline solution comprises any one or more of the following: an aqueous solution containing ethanol and ammonia, PBS buffer, and Tris·HCl buffer.

[0052] In some embodiments, the alkaline solution may be an aqueous solution containing ethanol and ammonia. The volume fraction of ethanol in the dispersed phase may be 0.1% to 75%, specifically within any one or any two ranges of 0.1%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75%. The volume fraction of ammonia in the dispersed phase may be 5% to 30%, specifically within any one or any two ranges of 5%, 10%, 15%, 20%, 25%, and 30%.

[0053] In some embodiments, the alkaline solution may be a Tris·HCl buffer solution, wherein the concentration of Tris may be 40–60 mM, specifically any one or any two of 40, 45, 50, 55, and 60 mM.

[0054] In some embodiments, the alkaline solution may also be a PBS buffer solution, and the concentration of PBS may be 40-60 mM, specifically any one or any two of 40, 45, 50, 55, and 60 mM.

[0055] In some embodiments, the alkaline solution is selected from any one or more of the following: an aqueous solution containing ethanol and ammonia (pH 9.0), 50 mM Tris-HCl (pH 8.0), and 50 mM PBS buffer (pH 7.4).

[0056] In some embodiments, the continuous phase consists of the aforementioned silicate ester compound, surfactant, and droplet-generating oil. The dispersed phase consists of the silicate ester compound and an alkaline solution.

[0057] In some embodiments, after the curing process, the preparation method further includes: centrifuging the cured product to remove the lower continuous phase and obtain silica microspheres.

[0058] In some embodiments, the centrifugation conditions for the cured product include: 100–5000 rpm, 2–60 s. The centrifugation speed can specifically be any one or any two of the following: 100, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, and 5000 rpm. The centrifugation time can be any one or any two of the following: 2, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 s.

[0059] In some embodiments, the preparation method further includes washing the obtained silica microspheres.

[0060] In some embodiments, the washing process includes re-dissolving the silica microspheres with a washing solution, centrifuging, removing the lower layer solution, and obtaining the target product; wherein the washing solution includes any one or more of HFE-7100 and anhydrous ethanol.

[0061] In some embodiments, the washing includes washing the silica microspheres with HFE-7100 and anhydrous ethanol.

[0062] In some embodiments, the washing process using HFE-7100 and anhydrous ethanol can be performed 1 to 3 times.

[0063] In some embodiments, the centrifugation conditions during the washing process include: 3000–5000 rpm, 10 s–10 min. Specifically, the centrifugation speed can be any one or a range between any two of 3000, 3500, 4000, 4500, and 5000 rpm. The centrifugation time can be any one or a range between any two of 10 s, 20 s, 40 s, 1 min, 2 min, 4 min, 6 min, 8 min, and 10 min.

[0064] In some embodiments, the curing conditions include: a temperature of 4–50°C and a time of 0.1–5 hours. Specifically, the temperature can be any one or a range between any two of the following: 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50°C. Specifically, the time can be any one or a range between any two of the following: 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 hours.

[0065] In some embodiments, when generating droplets, the flow rate ratio of the continuous phase to the dispersed phase is 1 to 5:2. Specifically, this flow rate ratio can be any one or a range between any two of the following: 1:2, 1.5:2, 2:2, 2.5:2, 3:2, 3.5:2, 4:2, 4.5:2, and 5:2.

[0066] In some embodiments, the flow rate ratio of the continuous phase to the dispersed phase is 2 to 4:2.

[0067] In some embodiments, in the cross-shaped droplet microfluidic chip, the width of the outlet microchannel of the dispersed phase is 10–200 μm. Specifically, it can be any one or any two of 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, and 200 μm.

[0068] In some embodiments, the particle size of the prepared silica microspheres is 10–200 μm. Specifically, it can be any one or any two of 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, and 200 μm.

[0069] On the other hand, embodiments of the present invention provide a reagent combination or kit, comprising: reagents capable of carrying out the preparation method of silica microspheres described in any of the foregoing embodiments.

[0070] In some embodiments, the reagent combination or kit includes the dispersed phase and the continuous phase as described in any of the foregoing embodiments.

[0071] In some embodiments, the reagent combination or kit further includes the washing solution described in any of the foregoing embodiments.

[0072] On the other hand, embodiments of the present invention also provide the application of reagent combinations in the preparation of products for preparing silica microspheres, the reagent combinations including reagents capable of carrying out the preparation method of silica microspheres described in any of the foregoing embodiments.

[0073] In some embodiments, the reagent combination includes the dispersed phase and the continuous phase as described in any of the foregoing embodiments.

[0074] In some embodiments, the reagent combination further includes the washing solution described in any of the foregoing embodiments.

[0075] Furthermore, this invention also provides the application of hollow silica microspheres prepared by the preparation method described in any of the foregoing embodiments as drug carriers in the preparation of sustained-release drugs.

[0076] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0077] Example 1

[0078] A method for preparing silica microspheres includes the following steps, the principle of which can be found in [reference needed]. Figure 2 , Figure 3 :

[0079] (1) Fluorinated oil containing silicate esters (in this embodiment, the silicate esters are methyl orthosilicate TEOS) and amphiphilic silica nanoparticle suspension is used as the continuous phase; wherein, the mass ratio of amphiphilic silica nanoparticles (F-SiO2-NPs) to methyl orthosilicate TEOS is 12:1 (2 μM methyl orthosilicate TEOS is added for every 1 mg of nanoparticles).

[0080] The preparation method of the amphiphilic silica nanoparticles is as follows:

[0081] (a) 7.2 mL of igepal CO-520, 2.4 mL of TEOS, and 2.3 mL of 25% (v / v) ammonia were added to 120 mL of cyclohexane solution and stirred at 8000 rpm for 18 hours at room temperature to obtain solution I; (b) After the reaction was completed, 8 mL of anhydrous ethanol was added to solution I to terminate the reaction, and silica nanoparticles were obtained. After centrifugation at 12000 rpm for 10 min, the supernatant was discarded, and the nanoparticles were washed repeatedly with anhydrous ethanol at least three times; (c) After washing, the precipitate (180 mg) was redissolved in 30 mL of anhydrous ethanol to obtain solution II, which was then fluorinated; (d) Perfluorodecyltriethoxysilane (FAS-17) and ammonia (120 μL per 6 mL of 6 mg / mL solution II) were added to solution II. (e) FAS-17 and 154 μL ammonia solution were reacted in a constant temperature oven at 37 °C for 1 hour; (f) After the reaction was completed, the mixture was centrifuged at 12000 rpm for 20 min, the supernatant was discarded, and the silica nanoparticles were redissolved in 36 mL HFE-7100; (g) The solution from step (e) was ultrasonically dispersed, and after uniform dispersion, it was centrifuged at 12000 rpm for 20 min, the supernatant was discarded, and the precipitate was redissolved in HFE-7100. This washing step was repeated twice; (g) After washing, the silica nanoparticles were vacuum dried, weighed, and then added at a mass fraction of 5% (w / w) to an appropriate amount of HFE-7500 for ultrasonic redissolution of the silica nanoparticles, thus completing the preparation of amphiphilic silica nanoparticles (F-SiO2-NPs). The schematic diagram is shown below. Figure 4 As shown.

[0082] (2) A silicate compound (3-aminopropyltriethoxysilane (APTES) was selected in this embodiment) was added to an ethanol-ammonia solution (the volume ratio of anhydrous ethanol, ammonia (volume fraction of 25%), and water was 6:1:5) as the dispersion phase; wherein, the final concentration of APTES in the dispersion phase was 4 μM.

[0083] (3) The continuous phase and dispersed phase obtained above are added to the liquid-carrying syringe respectively, and the flow rates are set to 600 μL / h and 200 μL / h respectively. Droplets are generated in the cross-shaped droplet microfluidic chip and collected in the EP tube. In this embodiment, the width of the outlet microchannel of the dispersed phase is 50 μm.

[0084] (4) Place the droplets collected in step (3) in a constant temperature oven at 37°C for 0.5 h to react and solidify;

[0085] (5) After solidification, centrifuge the sample at 4000 rpm for 20 s, discard the lower continuous phase, add 30-50 mL of HFE-7100 to reconstitute, mix gently, centrifuge at 4000 rpm for 1 min, discard the lower solution, and repeat twice. Reconstitute in anhydrous ethanol, mix well, centrifuge at 4000 rpm for 1 min, discard the supernatant, and repeat the washing step twice.

[0086] (6) After washing, the sample was dispersed again in PBS solution (10mM, pH 7.0) containing 0.1% (v / v) Triton-X100 to complete the preparation of silica microspheres.

[0087] Results reference Figure 5 , Figure 5 In the image, A represents the generation of silica droplets on a "cross"-shaped droplet microfluidic chip, B represents the collected silica droplets, and C represents the solidified hollow silica microspheres.

[0088] Examples 2-4

[0089] The preparation methods of silica microspheres are provided respectively, which are roughly the same as those in Example 1. The difference is that the width of the outlet microchannel of the dispersed phase at the cross-shaped intersection is different. The widths of Examples 2 to 4 are 50, 80 and 110 μm, respectively.

[0090] Examples 5-7

[0091] The preparation methods for silica microspheres are provided separately, which are largely the same as those in Example 1, except that the final concentration of APTES in the dispersed phase is different. In Example 1, the volume fraction of APTES in the dispersed phase is 0.1%. In Examples 5-7, the volume fractions of APTES in the dispersed phase are 2%, 3%, and 5.5%, respectively.

[0092] Experimental Example 1

[0093] To verify the effect of the outlet microchannel width of the dispersed phase at the cross-shaped intersection in a droplet microfluidic chip on the particle size and uniformity of hollow silica microspheres.

[0094] Silica microspheres were prepared using the methods provided in Examples 1-4, and particle size analysis was performed. The results are as follows: Figure 6 As shown.

[0095] Depend on Figure 6 It can be seen that by adjusting the width of the outlet microchannel of different dispersed phases, silica microspheres with a particle size distribution of 30μm-120μm can be prepared, and each size of microsphere has good uniformity.

[0096] Experimental Example 2

[0097] To verify the effect of the concentration of APTES in the dispersed phase on the morphology of silica microspheres.

[0098] Silica microspheres were prepared using the methods provided in Examples 1, 5-7 (1 μM FITC-Silane was added to the continuous phase to label silicon, and the resulting microspheres were characterized by confocal imaging and fluorescence intensity analysis). The results are as follows. Figure 7 As shown.

[0099] Depend on Figure 7 It can be seen that by changing the proportion of APTES in the dispersed phase, the microspheres can be controlled from hollow to nearly solid. When the volume fraction of APTES is between 0.1% and 3%, the microspheres are hollow; when the volume fraction of APTES is between 3% and 8%, the microspheres are nearly solid; when the volume fraction is greater than 8%, the droplets are unstable and it is difficult to obtain microspheres with complete morphology.

[0100] Experimental Example 3

[0101] The silica microspheres prepared in Example 1 were subjected to SEM analysis.

[0102] The microspheres prepared using amphiphilic silica nanoparticles as a surfactant in Example 1 of this invention have a layer of silica nanoparticles attached to their surface. Figure 8 This can effectively increase the surface area of ​​microspheres, which is beneficial for the adsorption of macromolecules in solution.

[0103] The silica microspheres prepared in Example 1 can enrich macromolecular drugs such as DOX in an aqueous phase. Dark-field images of the microspheres after 0 h and 10 h in 1 μM DOX PBS solution are shown in the optical microscope images. Figure 9 The results showed that the brightness of the microspheres increased significantly, indicating that they have an enrichment effect on macromolecular drugs and can be used as a stable drug delivery tool in the biomedical field.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing silica microspheres, characterized in that, It includes the following steps: A mixed solution 1 containing silicate ester compounds, surfactants, and droplet-generating oil is used as the continuous phase, wherein the droplet-generating oil includes fluorinated oil or hydrocarbon oil; a mixed solution 2 containing silicate ester compounds and an alkaline solution is used as the dispersed phase, and droplets are generated in the droplet microfluidic chip. After the generated droplets are solidified, silica microspheres are obtained.

2. The preparation method according to claim 1, characterized in that, The chemical formula of the silicate compound is R n O m Si(OR') 4-n Where n is selected from 0 to 4, and m is selected from 0 to 1; The R' group is a branched or unsubstituted C2-C atom at the α carbon atom. 20 The substituted group is a hydrocarbon group containing at least one of the following functional groups: vinyl group, ethynyl group, amino group, aldehyde group, epoxy group, thiol group and methanol group. The R group is a branched or unsubstituted C2-C atom at the α-carbon atom. 20 A hydrocarbon group, or substituted group, refers to a hydrocarbon group containing at least one of the following functional groups: vinyl group, ethynyl group, amino group, aldehyde group, epoxy group, thiol group, and methanol group.

3. The preparation method according to claim 1, characterized in that, The silicate compounds include any one or more of tetraethyl orthosilicate, methyl orthosilicate, and 3-aminopropyltriethoxysilane.

4. The preparation method according to claim 1, characterized in that, In the continuous phase, the volume fraction of the silicate ester compound is 0.1% to 30%.

5. The preparation method according to claim 1, characterized in that, In the dispersed phase, the volume fraction of silicate compounds is 0.1% to 50%.

6. The preparation method according to claim 1, characterized in that, The surfactants include any one or more of the following: Span80, Tween20, SDS, PF-octanol, PF-decanol, PF-TD acid, PFPE-COOH, PFPE-PEG, and silica nanoparticles with surface-modified fluorinative and hydrophilic groups.

7. The preparation method according to claim 1, characterized in that, In the continuous phase, the mass fraction of the surfactant is 0.01% to 20%.

8. The preparation method according to claim 1, characterized in that, The fluorinated oil includes any one or more of HFE, Novec, FC40, FC70, FC77 and FC3283.

9. The preparation method according to claim 1, characterized in that, The hydrocarbon oil includes any one or more of hexadecane, mineral oil, and dodecane.

10. The preparation method according to claim 1, characterized in that, The pH value of the alkaline solution is 7.1 to 9.

0.

11. The preparation method according to claim 1, characterized in that, The alkaline solution includes any one or more of the following: an aqueous solution containing ethanol and ammonia, PBS buffer, and Tris·HCl buffer.

12. The preparation method according to any one of claims 1 to 11, characterized in that, After the curing process, the preparation method further includes centrifuging the cured product to remove the lower continuous phase, thereby obtaining silica microspheres.

13. The preparation method according to claim 12, characterized in that, The centrifugation conditions for the cured product include: 100~5000 rpm, 2~300s.

14. The preparation method according to claim 1, characterized in that, The preparation method further includes washing the obtained silica microspheres.

15. The preparation method according to claim 14, characterized in that, The washing process includes re-dissolving the silica microspheres in a washing solution, centrifuging, removing the lower layer solution, and obtaining the target product; wherein the washing solution includes any one or more of HFE-7100, anhydrous ethanol, and water.

16. The preparation method according to any one of claims 1 to 11, characterized in that, The curing conditions include a temperature of 4~50℃ and a time of 0.1~5h.

17. The preparation method according to any one of claims 1 to 11, characterized in that, When generating droplets, the flow rate ratio of the continuous phase to the dispersed phase is 1 to 5:

2.

18. The preparation method according to claim 17, characterized in that, The flow rate ratio of the continuous phase to the dispersed phase is 2~4:

2.

19. The preparation method according to any one of claims 1 to 11, characterized in that, In the cross-shaped droplet microfluidic chip, the width of the outlet microchannel of the dispersed phase is 1~200μm.

20. A reagent combination or kit, characterized in that, It includes: A reagent capable of carrying out the preparation method of silica microspheres according to any one of claims 1 to 19.

21. The reagent combination or kit according to claim 20, characterized in that, The reagent combination or kit comprises: the dispersed phase and the continuous phase as described in any one of claims 1 to 19.

22. The reagent combination or kit according to claim 21, characterized in that, The reagent combination or kit further includes the washing solution as described in claim 15.

23. The application of a reagent combination in the preparation of products for the preparation of silica microspheres, characterized in that, The reagent combination includes reagents capable of carrying out the preparation method of silica microspheres according to any one of claims 1 to 19.

24. The application according to claim 23, characterized in that, The reagent combination comprises the dispersed phase and the continuous phase as described in any one of claims 1 to 19.

25. The application according to claim 24, characterized in that, The reagent combination also includes the washing solution as described in claim 15.

26. The application of silica microspheres prepared by the preparation method according to any one of claims 1 to 19 as drug carriers in the preparation of sustained-release drugs.

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