A method for preparing a homogeneous Pickering emulsion and its microcapsules based on natural pollen microparticles.
By using a combination of hydrophobic silica nanoparticles and pollen, a homogeneous Pickering emulsion and microcapsules were prepared, solving the problem of heterogeneity in pollen grain template emulsions in the prior art. This achieved uniformity and diversity in the emulsion and microcapsules, expanding their applications in drug carriers and microsensors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGNAN UNIV
- Filing Date
- 2024-01-31
- Publication Date
- 2026-07-17
AI Technical Summary
Existing technologies struggle to prepare uniform Pickering emulsions, especially uniform w/o Pickering emulsions with pollen grains as the aqueous core template. Furthermore, existing methods such as microfluidics and membrane emulsification are costly or compromise uniformity.
Hydrophobic silica nanoparticles were used as emulsifiers to disperse pollen in oil and aqueous phases. A homogeneous Pickering emulsion was prepared by homogenization and low-speed centrifugation, and a double-shell pollen-based microcapsule was formed by sol-gel reaction.
The preparation of homogeneous Pickering emulsions and microcapsules based on natural pollen microparticles has been achieved. The emulsions exhibit good size uniformity and are suitable for applications such as drug carriers, transmembrane communication, and microsensors.
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Figure CN117839466B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of Pickering emulsion technology, and more specifically, to a method for preparing a homogeneous Pickering emulsion and its microcapsules based on natural pollen microparticles. Background Technology
[0002] Traditional Pickering emulsion preparation methods typically involve first mixing the oil and water phases, followed by processes such as stirring, vortexing, or homogenization to form a water-in-oil or oil-in-water emulsion. The shear forces applied during this process result in a wide range of droplet sizes, making it impossible to form a homogeneous emulsion.
[0003] In recent years, some new methods have gradually developed, such as microfluidics and membrane emulsification, which can simplify preparation steps and precisely control droplet size to form homogeneous emulsions. Simultaneously, using Pickering emulsions as templates, microcapsules with colloidal particle shells have been prepared, enriching and expanding the applications of Pickering emulsions in materials science, pharmaceuticals, and life sciences. However, microfluidics are too expensive, and the cost of the chips is prohibitively high. Membrane emulsification, due to the need for precise adjustment of the pore size distribution within the membrane, may compromise some degree of homogeneity.
[0004] Currently, there are no reports on the preparation of homogeneous w / o Pickering emulsions with pollen grains as aqueous core templates, or on the preparation of homogeneous double-shell pollen-based microcapsules using this Pickering emulsion as a template via the sol-gel method. Summary of the Invention
[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.
[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.
[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a uniform Pickering emulsion based on natural pollen microparticles.
[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a uniform Pickering emulsion based on natural pollen microparticles, comprising,
[0009] Hydrophobic silica nanoparticles were used as emulsifiers.
[0010] Hydrophobic silica nanoparticles were dispersed in an oil phase to prepare an oil phase dispersion.
[0011] Bee pollen was washed and dispersed in water to prepare an aqueous dispersion.
[0012] The aqueous dispersion was added to the oil dispersion, homogenized and emulsified, and then washed by low-speed centrifugation to obtain a homogeneous Pickering emulsion.
[0013] As a preferred embodiment of the preparation method described in this invention, the bee pollen includes camellia pollen, rapeseed pollen, lotus pollen, pine pollen, sunflower pollen, lotus pollen, and ragweed pollen, etc.
[0014] As a preferred embodiment of the preparation method described in this invention, the silica nanoparticles are commercially available fumed silica nanoparticles R974 or hydrophobic silica nanoparticles modified with silane coupling agents.
[0015] Among them, silane coupling agents include γ-aminopropyltrimethoxysilane, dichlorodimethylsilane, γ-aminopropyltriethoxysilane, and γ-aminoethylaminopropyltrimethoxysilane.
[0016] In a preferred embodiment of the preparation method described in this invention, the oil phase dispersion obtained has a mass-volume ratio of hydrophobic silica nanoparticles to the oil phase of 0.1% to 5% in g:mL.
[0017] In a preferred embodiment of the preparation method described in this invention, the oil phase comprises cyclopentasiloxane silicone oil.
[0018] In a preferred embodiment of the preparation method of the present invention, the aqueous dispersion is prepared in which the amount of bee pollen is 1% to 50% of the mass of water.
[0019] In a preferred embodiment of the preparation method of the present invention, the aqueous dispersion is added to the oil dispersion, wherein the volume ratio of the aqueous dispersion to the oil dispersion is 1:1 to 20.
[0020] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for constructing uniform microcapsules based on natural pollen microparticles, comprising:
[0021] The pollen was acid-hydrolyzed to form hollow pollen, which was then used to replace the untreated original pollen in an aqueous dispersion.
[0022] Hydrophobic silica nanoparticles were dispersed in an oil phase to prepare an oil phase dispersion.
[0023] The aqueous dispersion was added to the oil dispersion and homogenized and emulsified to obtain the Pickering emulsion.
[0024] Tetraethyl orthosilicate was introduced into Pickering emulsion and subjected to a sol-gel reaction at 20-50 °C;
[0025] Centrifugation and washing yielded uniform bishelled pollen-based microcapsules using Pickering emulsion as a template.
[0026] In a preferred embodiment of the preparation method described in this invention, the method for preparing hollow pollen includes:
[0027] Defatted pollen was added to phosphoric acid and refluxed at 80 °C for 5 h;
[0028] The product was washed with hot water, acetone, hydrochloric acid, deionized water, acetone, and ethanol, and then dried to obtain hollow pollen.
[0029] In a preferred embodiment of the preparation method described in this invention, the mass-to-volume ratio of the hydrophobic silica nanoparticles to the oil phase is 0.1% to 5% (g:mL).
[0030] The amount of hollow pollen in the aqueous dispersion is 1% to 50% of the mass of water;
[0031] The volume ratio of the aqueous phase dispersion to the oil phase dispersion is 1:1~20.
[0032] (1) This invention provides a method for preparing a homogeneous Pickering emulsion and microcapsules based on natural pollen microparticles. It is the first time that natural pollen is proposed as a central template in the aqueous phase to limit the size of the emulsion, thereby achieving the effect of a homogeneous emulsion.
[0033] (2) The Pickering emulsion prepared by this invention has uniform size and diverse size (the size of bee pollen ranges from 3 μm to 100 μm), which exactly matches the size range of the emulsion. In addition, the uniform emulsion can be used to prepare microcapsules, which have great application prospects in the fields of drug carrier storage and release of active substances, transmembrane communication, artificial cells and microsensors. Attached Figure Description
[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0035] Figure 1 This is a contact angle image of the hydrophobic silica nanoparticles in Example 1;
[0036] Figure 2 These are scanning electron microscope images of camellia pollen from Example 1;
[0037] Figure 3 This is an optical microscope image of the Pickering emulsion constructed from camellia pollen in Example 1;
[0038] Figure 4 This is an optical microscope image of the Pickering emulsion constructed from camellia pollen in Example 2;
[0039] Figure 5 This is an optical microscope image of the Pickering emulsion constructed from camellia pollen in Example 3;
[0040] Figure 6 This is an optical microscope image of the Pickering emulsion constructed from camellia pollen in Example 4;
[0041] Figure 7 This is an optical microscope image of the Pickering emulsion constructed from camellia pollen in Example 5;
[0042] Figure 8 These are scanning electron microscope images of rapeseed pollen from Example 6;
[0043] Figure 9 This is an optical microscope image of the Pickering emulsion constructed from rapeseed pollen in Example 6;
[0044] Figure 10 This is a scanning electron microscope image of sunflower pollen from Example 7;
[0045] Figure 11 This is an optical microscope image of the Pickering emulsion constructed from sunflower pollen in Example 7;
[0046] Figure 12 This is a laser confocal microscope image of the Pickering emulsion constructed from sunflower pollen in Example 7;
[0047] Figure 13 These are scanning electron microscope images of hollow sunflower pollen after acid hydrolysis in Example 8;
[0048] Figure 14 This is an optical microscope image of the Pickering emulsion constructed from hollow sunflower pollen in Example 8;
[0049] Figure 15These are optical microscope images of the double-shelled pollen-based microcapsules in Example 8;
[0050] Figure 16 These are scanning electron microscope images of the double-shelled pollen-based microcapsules in Example 8;
[0051] Figure 17 This is an optical microscope image of the Pickering emulsion without added bee pollen in Comparative Example 1; Detailed Implementation
[0052] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.
[0053] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.
[0054] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.
[0055] In the embodiments of this invention, the hydrophobic silica nanoparticles are commercially available silica nanoparticles R974, purchased from Evonik Industries; the pollen is a common commercially available product. Example 1
[0056] (1) Take 0.15 g of hydrophobic silica nanoparticles (e.g. Figure 1 (As shown) It was dispersed in 5 mL of cyclopentasiloxane silicone oil as an oil phase dispersion;
[0057] Add 0.025 g of camellia bee pollen (such as...) Figure 2 (As shown) dispersed in 0.25 mL of water as a pre-prepared aqueous dispersion;
[0058] 0.25 mL of the pre-prepared aqueous dispersion was added to 5 mL of the oil dispersion and homogenized and emulsified to obtain the Pickering emulsion.
[0059] (2) Using the emulsion prepared in (1), take 0.5 mL of the emulsion and add 0.5 mL of cyclopentasiloxane silicone oil as the external phase. Centrifuge multiple times to separate the emulsion. Aspirate the upper layer of emulsion without bee pollen and take the lower layer of homogeneous Pickering emulsion containing bee pollen for observation. Figure 3As shown.
[0060] Therefore, it is possible to explore changing different conditions to prepare homogeneous Pickering emulsions based on natural pollen. Example 2
[0061] (1) Wash the camellia bee pollen with ethanol / water multiple times, stirring and sonicating with a glass rod each time to ensure the pollen is completely dispersed in the water, let it settle, pour off the supernatant, repeat the operation, and finally put it in a 50 ℃ oven to dry for later use.
[0062] (2) Disperse 0.1 g of camellia bee pollen in 0.5 mL of water as a pre-prepared aqueous dispersion;
[0063] 0.15 g of hydrophobic silica nanoparticles were dispersed in 5 mL of cyclopentasiloxane silicone oil as the oil phase dispersion.
[0064] 0.5 mL of the pre-prepared aqueous dispersion was added to 5 mL of the oil dispersion and homogenized and emulsified to obtain the Pickering emulsion.
[0065] (3) Using the emulsion prepared in (2), take 0.5 mL of the emulsion and add 0.5 mL of cyclopentasiloxane silicone oil as the external phase. Centrifuge multiple times to separate the emulsion. Aspirate the upper layer of emulsion without pollen and take the lower layer of homogeneous Pickering emulsion containing bee pollen for observation. Figure 4 As shown.
[0066] Therefore, under suitable conditions, it is possible to prepare a homogeneous Pickering emulsion based on natural pollen. Example 3
[0067] (1) Wash the camellia bee pollen with ethanol / water multiple times, stirring and sonicating with a glass rod each time to ensure the pollen is completely dispersed in the water, let it settle, pour off the supernatant, repeat the operation, and finally put it in a 50 ℃ oven to dry for later use.
[0068] (2) Disperse 0.1 g of camellia bee pollen in 1 mL of water as a pre-prepared aqueous dispersion;
[0069] 0.15 g of hydrophobic silica nanoparticles were dispersed in 5 mL of cyclopentasiloxane silicone oil as the oil phase dispersion.
[0070] 1 mL of pre-prepared aqueous dispersion was added to 5 mL of oil dispersion at 20,000 rpm and homogenized to emulsify and obtain Pickering emulsion.
[0071] (3) Using the emulsion prepared in (2), take 0.5 mL of the emulsion and add 0.5 mL of cyclopentasiloxane silicone oil as the external phase. Centrifuge multiple times to separate the emulsion. Aspirate the upper layer of emulsion without pollen and take the lower layer of homogeneous Pickering emulsion containing bee pollen for observation. Figure 5 As shown.
[0072] Findings: Compared with the Pickering emulsion prepared in Example 2, the emulsion obtained by adjusting the oil-water volume ratio was found to be too viscous with a lower oil-water volume ratio, which could not achieve the desired uniformity. Example 4
[0073] (1) Wash the camellia bee pollen with ethanol / water multiple times, stirring and sonicating with a glass rod each time to ensure the pollen is completely dispersed in the water, let it settle, pour off the supernatant, repeat the operation, and finally put it in a 50 ℃ oven to dry for later use.
[0074] (2) Disperse 0.2 g of camellia bee pollen in 0.5 mL of water as a pre-prepared aqueous dispersion;
[0075] 0.15 g of hydrophobic silica nanoparticles were dispersed in 5 mL of cyclopentasiloxane silicone oil as the oil phase dispersion.
[0076] 0.5 mL of the pre-prepared aqueous dispersion was added to 5 mL of the oil dispersion and homogenized and emulsified to obtain the Pickering emulsion.
[0077] (3) Using the emulsion prepared in (2), take 0.5 mL of the emulsion and add 0.5 mL of cyclopentasiloxane silicone oil as the external phase. Centrifuge multiple times to separate the emulsion. Aspirate the upper layer of emulsion without pollen and take the lower layer of homogeneous Pickering droplets containing bee pollen for observation. Figure 6 As shown.
[0078] Findings: Compared with the Pickering emulsion prepared in Example 2, the emulsion obtained by controlling the pollen content was too viscous if the pollen content was too high, and it could not achieve the desired uniformity. Example 5
[0079] (1) Wash the camellia bee pollen with ethanol / water multiple times, stirring and sonicating with a glass rod each time to ensure the pollen is completely dispersed in the water, let it settle, pour off the supernatant, repeat the operation, and finally put it in a 50 ℃ oven to dry for later use.
[0080] (2) Disperse 0.1 g of camellia bee pollen in 0.5 mL of water as a pre-prepared aqueous dispersion;
[0081] 0.15 g of hydrophobic silica nanoparticles were dispersed in 5 mL of cyclopentasiloxane silicone oil as the oil phase dispersion.
[0082] Pickering emulsion was obtained by adding 0.5 mL of pre-prepared aqueous dispersion to 5 mL of oil dispersion at 10000 rpm, 15000 rpm, and 17600 rpm and homogenizing emulsion.
[0083] (3) Using the emulsion prepared in (2), take 0.5 mL of the emulsion and add 0.5 mL of cyclopentasiloxane silicone oil as the external phase. Centrifuge multiple times to separate the emulsion. Aspirate the upper layer of emulsion without pollen and take the lower layer of homogeneous Pickering emulsion containing bee pollen for observation. Figure 7 As shown (the rotation speed increases sequentially from left to right).
[0084] Findings: Compared with the Pickering emulsion prepared in Example 2, by adjusting the speed of the homogenizer, a homogeneous emulsion could not be achieved at low speeds, but the desired effect could be achieved as the speed increased. Example 6
[0085] (1) Put rapeseed pollen (such as Figure 8 (As shown) Wash with ethanol / water multiple times, stirring and sonicating with a glass rod each time to ensure the pollen is completely dispersed in the water. Let it settle, discard the supernatant, repeat the process, and finally dry it in a 50℃ oven for later use.
[0086] (2) Disperse 0.1 g of rapeseed bee pollen in 0.5 mL of water as a pre-prepared aqueous dispersion;
[0087] 0.15 g of hydrophobic silica nanoparticles were dispersed in 5 mL of cyclopentasiloxane silicone oil as the oil phase dispersion.
[0088] 1 mL of the pre-prepared aqueous dispersion was added to 5 mL of the oil dispersion and emulsified at 20,000 rpm to obtain the Pickering emulsion.
[0089] (3) Using the emulsion prepared in (2), take 0.5 mL of the emulsion and add 0.5 mL of cyclopentasiloxane silicone oil as the external phase. Centrifuge multiple times to separate the emulsion. Aspirate the upper layer of emulsion without pollen and take the lower layer of homogeneous Pickering emulsion containing bee pollen for observation. Figure 9 As shown.
[0090] Findings: Rapeseed flower bee pollen can also achieve the same effect as the Pickering emulsion prepared in Example 2. Example 7
[0091] (1) Wash the sunflower bee pollen with ethanol / water multiple times, stirring and sonicating with a glass rod each time to ensure that the pollen is completely dispersed in the water. Let it settle, pour off the supernatant, repeat the operation, and finally put it in a 50 ℃ oven to dry for later use.
[0092] (2) Add 0.1 g of sunflower bee pollen (such as...) Figure 10 (As shown) dispersed in 0.5 mL of water as a pre-prepared aqueous dispersion;
[0093] 0.15 g of hydrophobic silica nanoparticles were dispersed in 5 mL of cyclopentasiloxane silicone oil as the oil phase dispersion.
[0094] 0.5 mL of the pre-prepared aqueous dispersion was added to 5 mL of the oil dispersion and homogenized and emulsified to obtain the Pickering emulsion.
[0095] (3) Using the emulsion prepared in (2), take 0.5 mL of the emulsion and add 0.5 mL of cyclopentasiloxane silicone oil as the external phase. Centrifuge multiple times to separate the emulsion. Aspirate the upper layer of emulsion without pollen and take the lower layer of homogeneous Pickering droplets containing bee pollen for observation. Figure 11 As shown.
[0096] (4) When hydrophobic silica nanoparticles are stained with nylon red, the pollen, due to its autofluorescence, can be observed in blue light, such as... Figure 12 As shown;
[0097] Findings: Sunflower bee pollen can achieve the same effect as the Pickering emulsion prepared in Example 2. Example 8
[0098] (1) The steps for preparing hollow bee pollen are as follows:
[0099] Purification: Wash 20 g of block bee pollen (such as sunflower pollen) three times with ethanol and deionized water until the supernatant is clear, and transfer it to a flask.
[0100] Defatting with acetone: Wash twice with 20 mL of acetone, reflux the pollen with 20 mL of acetone at 50 °C overnight, and collect the defatted pollen by vacuum filtration. Transfer to a glass dish or beaker and dry.
[0101] Acid hydrolysis: 3.5 g of defatted pollen was added to 20 mL of 85% phosphoric acid and refluxed at 80 °C for 5 h. The product was washed with hot water ×3, acetone ×2, 2M hydrochloric acid ×1, and deionized water ×3 to obtain hollow sunflower bee pollen, as shown below. Figure 13 As shown;
[0102] Drying: Place in a 50℃ oven to dry for later use.
[0103] (2) 2.5% (w / v) hollow sunflower bee pollen was used to replace the original pollen and dispersed in water as an aqueous dispersion;
[0104] 3% (w / v) of hydrophobic silica nanoparticles were dispersed in cyclopentasiloxane silicone oil as the oil phase dispersion;
[0105] The aqueous dispersion was added to the oil dispersion and homogenized and emulsified to obtain a Pickering emulsion;
[0106] (3) Using the emulsion prepared in (2), take 0.5 mL of the emulsion and add 0.5 mL of cyclopentasiloxane silicone oil as the external phase. Centrifuge multiple times to separate the emulsion. Aspirate the upper layer of emulsion without pollen and take the lower layer of homogeneous Pickering emulsion containing bee pollen for observation. Figure 14 As shown.
[0107] (4) Using the emulsion prepared in (2), add 1 mL of tetraethyl orthosilicate to 1 mL of the emulsion and react in an oven at 50 °C for 20 h to achieve the formation of bishelled pollen-based microcapsules using Pickering emulsion as a template, such as Figures 15-16 As shown. Comparative Example 1
[0108] (1) Prepare 0.25 mL of deionized water;
[0109] (2) Take 0.15 g of hydrophobic silica nanoparticles and disperse them in 5 mL of cyclopentasiloxane silicone oil as the oil phase;
[0110] (3) Add 0.25 mL of deionized water to 5 mL of oil phase dispersion at 20000 rpm and homogenize to obtain Pickering emulsion, as shown below. Figure 17 As shown.
[0111] Compared to the 30 μm~40 μm pollen-based homogeneous Pickering emulsion prepared in Example 1, the emulsion that does not contain bee pollen cannot produce homogeneous droplets.
[0112] Discovery: The size of bee pollen particles limits the size of the emulsion droplets, thus achieving the effect of preparing a uniform Pickering emulsion.
[0113] This invention provides a method for preparing a homogeneous Pickering emulsion and microcapsules based on natural pollen microparticles. It is the first to propose using natural pollen as a template to limit the size of the emulsion, thereby achieving a homogeneous emulsion. The prepared Pickering emulsion exhibits both size uniformity and size diversity (bee pollen sizes range from 3 μm to 100 μm), which precisely matches the size range of emulsions. Furthermore, the homogeneous emulsion can be used to prepare microcapsules, which have enormous application potential as drug carriers for storing and releasing active substances, for transmembrane communication, in artificial cells, and in microsensors.
[0114] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A method for constructing uniform microcapsules based on natural pollen microparticles, characterized in that: include, The pollen was acid-hydrolyzed to form hollow pollen, which was then used to replace the untreated original pollen in an aqueous dispersion. Hydrophobic silica nanoparticles were dispersed in an oil phase to prepare an oil phase dispersion. The aqueous dispersion was added to the oil dispersion and homogenized and emulsified to obtain the Pickering emulsion. Tetraethyl orthosilicate was introduced into Pickering emulsion and subjected to a sol-gel reaction at 20-50 °C; Centrifugation and washing yielded uniform bishelled pollen-based microcapsules using Pickering emulsion as a template.
2. The method as described in claim 1, characterized in that: The pollen includes camellia pollen, rapeseed pollen, pine pollen, sunflower pollen, lotus pollen, and ragweed pollen.
3. The method as described in claim 1 or 2, characterized in that: The silica nanoparticles are commercially available fumed silica nanoparticles R974 or hydrophobic silica nanoparticles modified with silane coupling agents. Among them, silane coupling agents include γ-aminopropyltrimethoxysilane, dichlorodimethylsilane, γ-aminopropyltriethoxysilane, and γ-aminoethylaminopropyltrimethoxysilane.
4. The method as described in claim 1, characterized in that: The oil phase comprises cyclopentasiloxane silicone oil.
5. The method as described in claim 1, characterized in that: The method for preparing hollow pollen includes, Defatted pollen was added to phosphoric acid and refluxed at 80 °C for 5 h; The product was washed with hot water, acetone, hydrochloric acid, deionized water, acetone, and ethanol, and then dried to obtain hollow pollen.
6. The method as described in claim 1, characterized in that: The mass-to-volume ratio of the hydrophobic silica nanoparticles to the oil phase is 0.1% to 5% (g:mL). The amount of hollow pollen in the aqueous dispersion is 1% to 50% of the mass of water; The volume ratio of the aqueous phase dispersion to the oil phase dispersion is 1:1~20.