A method for preparing a pickering emulsion-type natural gel bead of slow-release essence

Abstract

A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance involves uniformly mixing gelatin, sodium alginate, and hydrophilic silica nanoparticles as the aqueous phase, and uniformly mixing fragrance and caprylic / capric triglycerides as the oil phase. The oil and aqueous phases are then mixed and homogenized to form an oil-in-water Pickering emulsion. Finally, the Pickering emulsion is pumped into a silicone tubing via a syringe pump and dripped into a mixed solution of calcium chloride and glutaraldehyde to form fragrance-loaded multi-compartment gel beads. This invention achieves sustained-release fragrance through the dual protection of the nanoparticle membrane and hydrogel of the Pickering emulsion, as well as the multiple compartments encapsulating the fragrance. This method is environmentally friendly, with a fragrance encapsulation rate exceeding 99%, and only 28.6% release after 42 days. It has broad application prospects in the daily chemical, food, and pharmaceutical industries.

Description

Technical Field

[0001] This invention relates to the field of sustained-release fragrances, and more specifically to a method for preparing Pickering emulsion-type natural gel beads for sustained-release fragrances. Background Technology

[0002] Fragrances, as an important additive, are widely used in the food, pharmaceutical, cosmetic, leather, textile, and paper industries. For various products (such as cosmetics, fabrics, household goods, food, and personal care products), a lasting fragrance is a current market demand. However, the poor stability and high volatility of fragrances prevent products from releasing their aroma over a long period, leading to a rapid loss of product performance and significantly limiting their application across various industries.

[0003] Capsules use safe and stable film-forming materials (wall materials) to encapsulate reactive and volatile gases, solids, or liquids (core materials). This allows for control of core material release, improvement of core material physical properties, and isolation from environmental factors. Therefore, encapsulation of flavorings can effectively improve their sustained-release capacity and prolong their retention time. Based on the source of the wall material, encapsulation can be divided into two categories: synthetic and natural.

[0004] Synthetic capsules, while offering excellent performance and ease of synthesis, lack biodegradability, making them a major source of microplastic pollution. Therefore, to meet the trends and requirements of sustainable development and environmental protection, some countries have enacted laws restricting the use of plastic microbeads, thus limiting the application of synthetic capsules. Natural capsules, with their safety, biocompatibility, and biodegradability, are a good alternative. They can be categorized into three types: inorganic, polymer, and inorganic-polymer. For example, Hao et al. synthesized amino-modified monodisperse silica via the sol-gel method with an encapsulation rate of 30.38% (QiuLian Hao, et aL. Reactive nano-essentia silica for sustained release of essentia silica and application to paper[J]. Chinese Chemica Letters,2022, 33(1): 320-323.). Zhang et al. synthesized capsules with maltodextrin and resistant starch as shells via emulsification and spray drying with an encapsulation rate of 38% (Suning Zhang, et aL. Preparation of Natura silica Composite Microcapsules Containing Orchid Black Currant Fragrance and its Sustained-Release Properties on Hair Bundle[J]. Journal of Politics and the Environment, 2022, 30: 136–150. However, the porosity of inorganic wall materials and the pores on the surface of natural polymers cannot fundamentally isolate fragrances from air, thus failing to prevent fragrance evaporation and hindering the long-lasting fragrance of the product.

[0005] By combining inorganic materials and polymers to improve the sealing properties of capsules, Fan et al. synthesized chitosan-coated silica nanocapsules using an interfacial condensation method, achieving an encapsulation rate of 95.5% and a release of 65% in 5 days (Qianqian Fan, et al. FaciLe Synthesis of Chitosan-Coated SiLica Nanocapsules via InterfaciaL Condensation Approach for Sustained ReLease of VaniLLin[J].IndustriaL Engineering Chemistry Research, 2018, 57(18): 6171-6179.). However, the mononuclear capsules cause a sudden release of aroma, which is not conducive to long-term release. In 2023, Berraaouan et al. used calcium alginate and montmorillonite as composite encapsulation materials, employing surfactant-stabilized emulsions and a drop-casting method to encapsulate rosemary. The preparation process was mild and environmentally friendly, achieving an encapsulation rate of 83% and releasing 80% of the fragrance within 10 days (Doha Berraaouan, et al. Hybrid Microcapsules for Encapsulation and Controlled Release of Rosemary Essentia L OiL[J].PoLymers,2023, 15(4): 823-823.). However, during the preparation process, the surfactant-stabilized emulsion was prone to demulsification and aggregation, and the emulsion interface lacked a physical barrier to prevent fragrance release.

[0006] Reference 1: CN100392175 A method for preparing polyurethane antibacterial and aromatic microcapsules: The oil phase consists of polyisocyanate, fragrance, inorganic antibacterial agent, and cyclohexane; the aqueous phase consists of sodium hydroxide, sodium alginate, and deionized water; polyethylene glycol and acetone are added to the oil phase, and after mixing with the aqueous phase, the mixture is filtered to obtain a white emulsion with microcapsule particle size of 20-4µm. The capsules are prepared by mixing the oil phase (with fragrance in the oil phase) and the aqueous phase.

[0007] Reference 2: (CN114958480) A method for preparing an aerogel-based sustained-release fragrance: Tetraethyl orthosilicate is prepolymerized into a silicon-based prepolymer, ethanol and water are mixed, and then an alkaline solution is added to catalyze the formation of a gel; the gel is aged in an ethanol solution and then broken into gel fragments; the gel fragments are immersed in a mixed solution of trimethylchlorosilane, n-hexane and ethanol for modification, and then dried to obtain a silica aerogel; the aerogel is impregnated with fragrance and a silane coupling agent under negative pressure to obtain an aerogel-based sustained-release fragrance. Sustained-release properties: 5g of fragrance is weighed and added to a petri dish, and after 24 hours in an oven at 40℃, its mass is weighed as M. The fragrance retention rate is calculated as M / 5g×100%. Examples 1-5 show retention rates of 88.1%, 88.7%, 89.5%, 89.1%, and 88.5%, respectively.

[0008] Neither Reference 1 nor Reference 2 showed good stability or long-lasting sustained-release properties of the fragrance.

[0009] Pickering emulsions are emulsion systems stabilized by solid particles at the oil-water interface. They are considered natural, biodegradable, and safe, thus showing broad application prospects in various fields such as food, cosmetics, and biomedicine. Based on this, an inorganic-polymer multinuclear capsule is formed from Pickering emulsion and composite hydrogel. Through the dual protection of the nanoparticle membrane of the Pickering emulsion and the composite hydrogel, as well as the encapsulation of fragrance in multiple compartments, a high encapsulation rate and long-lasting sustained-release fragrance are achieved. Summary of the Invention

[0010] The purpose of this invention is to propose a method for preparing Pickering emulsion-type natural gel beads for sustained-release fragrances. This method aims to form inorganic-polymer multinuclear capsules through Pickering emulsion and composite hydrogel. The fragrance is encapsulated in multiple compartments by the dual protection of the nanoparticle membrane of Pickering emulsion and composite hydrogel, achieving a high encapsulation rate and long-lasting sustained-release aroma.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0013] Step (1) Weigh out a certain amount of sodium alginate and gelatin respectively and dissolve them in deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to form sodium alginate solution and gelatin solution.

[0014] Step (2) Take a certain amount of sodium alginate solution and gelatin solution into a 50 mL centrifuge tube and add a certain mass of 15 nm hydrophilic silica particles (the three-phase contact angle is 90 degrees: the three phases are particles, water phase, fragrance and GTCC mixture), and then put them into a vortex shaker and shake them evenly as the water phase.

[0015] Step (3) Take a certain amount of flavoring and caprylic / capric triglyceride (GTCC) into a 15 mL centrifuge tube, and vortex it to mix it evenly as the oil phase.

[0016] Step (4) Dissolve a certain amount of calcium chloride and glutaraldehyde in deionized water, and place it in a 100 W ultrasonic cleaning instrument for ultrasonic vibration for 10-15 min as the receiving liquid.

[0017] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion.

[0018] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0019] Furthermore, in step (1), the method for preparing a Pickering emulsion-type natural gel beads with a sustained-release fragrance according to claim 1 is characterized in that the concentration of sodium alginate solution in step (1) is 1 wt% and the concentration of gelatin solution is 2 wt%.

[0020] Furthermore, in step (2), the volume ratio of sodium alginate to gelatin is from 6:1 to 1:4, and the mass fraction of emulsifier particles is 0.4 to 1 wt%.

[0021] Furthermore, in step (3), the volume ratio of flavoring to GTCC is from 5:1 to 1:2.

[0022] Furthermore, in step (4), the mass fraction of calcium chloride is 2 wt%, and the mass fraction of glutaraldehyde is 0.01% (V / V).

[0023] Furthermore, in step (5), the volume ratio of the aqueous phase to the oil phase is 1:10 to 10:10.

[0024] Furthermore, in step (6), the flow rate of the injection pump connecting the emulsion is 50~120 µL / min, the rotation speed of the magnetic stirrer for receiving liquid is 100~200 rpm, and the crosslinking time is 2~3 h.

[0025] The reaction principle of this invention is as follows:

[0026] The fragrance is firmly locked in using an O / W type Pickering emulsion. Then, natural materials sodium alginate and gelatin react with the receiving liquid to form gel beads. Through the dual protection of the nanoparticle membrane and composite hydrogel of the Pickering emulsion, and the multiple compartments encapsulating the fragrance, the encapsulation rate and sustained-release performance of the fragrance are improved. This results in the preparation of natural gel beads with high encapsulation efficiency and long-lasting sustained-release fragrance, which has broad application prospects in the daily chemical, food, and pharmaceutical industries. The beneficial effects of this invention are:

[0027] (1) Natural gel beads formed from environmentally friendly sodium alginate and gelatin materials meet the current trend and requirements of human sustainable development and environmental protection, and are conducive to solving the problem of microplastic pollution caused by synthetic capsules during application.

[0028] (2) This method is green and environmentally friendly, with a fragrance encapsulation rate of 99%, achieving a high fragrance encapsulation rate.

[0029] (3) The effect of sustained release of fragrance was achieved by the dual protection of the nanoparticle membrane and hydrogel of Pickering emulsion and the encapsulation of fragrance in multiple compartments. Only 28.6% was released in 42 days. Attached Figure Description

[0030] Figure 1a and 1b The morphology and size of a Pickering emulsion-type natural gel beads.

[0031] Figure 2 The three-phase contact angle of silica (the three-phase contact angle is 90 degrees: the three phases are particles, aqueous phase, fragrance and GTCC mixture).

[0032] Figure 3 Infrared spectra of gel beads, fragrance and GTCC mixed oil phase, GTCC and fragrance.

[0033] Figure 4 This is the standard curve for fragrances.

[0034] Figure 5 Thermogravimetric curves of gel beads encapsulated with fragrance, fragrance, and gel beads without encapsulated fragrance.

[0035] Figure 6 The weight loss curves of the gel beads and fragrance encapsulated at 60℃ are shown.

[0036] Figure 7 Fragrance release curves of gel beads prepared with surfactants at room temperature and gel beads prepared with Pickering.

[0037] Figure 8a To use scanning electron microscopy to photograph the surface morphology of gel beads.

[0038] Figure 8b To magnify the surface morphology of gel beads using scanning electron microscopy.

[0039] Figure 8c To capture the cross-sectional morphology of the gel beads using scanning electron microscopy.

[0040] Figure 8d To magnify the cross-sectional morphology of gel beads using scanning electron microscopy.

[0041] Figure 9 To photograph the morphology of gel beads using laser scanning confocal microscopy Detailed Implementation

[0042] To make the objectives, features and advantages of this invention more readily understood by those skilled in the art, the specific embodiments of this invention will be described in detail below with reference to specific examples.

[0043] Example 1

[0044] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0045] Step (1) Weigh 1 g of sodium alginate and 2 g of gelatin and dissolve them in 100 mL of deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to obtain a 1 wt% sodium alginate solution and a 2 wt% gelatin solution.

[0046] Step (2) Take 3.552 mL of sodium alginate solution and 0.888 mL of gelatin solution into 50 mL centrifuge tubes respectively, and add 0.03552 g of 15 nm hydrophilic silica particles (three-phase contact angle is 90 degrees: the three phases are particles, water phase, fragrance and GTCC mixture), and then shake it in a vortex shaker for 2 min as the water phase. The nanoparticle content in the water phase is 0.8% (w / v).

[0047] Step (3) Take 1.78 mL of fragrance and 1.78 mL of GTCC into a 15 mL centrifuge tube, and then vortex it for 2 min to obtain the oil phase. The volume ratio of fragrance to GTCC in the oil phase is 1:1.

[0048] Step (4) Dissolve 5 g of calcium chloride and 100 μL of glutaraldehyde in 250 mL of deionized water, and then place it in a 100W ultrasonic cleaner and ultrasonically vibrate for 10 min as the receiving liquid.

[0049] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion with a volume ratio of oil phase to aqueous phase of 8:10.

[0050] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0051] After washing, the gel beads were dissolved in deionized water to observe their morphology and size. Figure 1a The prepared gel beads exhibited good morphology, being spherical. Figure 1b The gel beads shown are 2 mm in size.

[0052] Example 2

[0053] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0054] Step (1) Weigh 1 g of sodium alginate and 2 g of gelatin and dissolve them in 100 mL of deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to obtain a 1 wt% sodium alginate solution and a 2 wt% gelatin solution.

[0055] Step (2) Take 3.552 mL of sodium alginate solution and 0.888 mL of gelatin solution into 50 mL centrifuge tubes respectively, and add 0.0266 g of 15 nm hydrophilic silica particles (three-phase contact angle is 90 degrees: the three phases are particles, water phase, fragrance and GTCC mixture), and then shake it in a vortex shaker for 2 min as the water phase. The nanoparticle content in the water phase is 0.6% (w / v).

[0056] Step (3) Take 2.67 mL of fragrance and 0.89 mL of GTCC into 15 mL centrifuge tubes respectively, and then shake them in a vortex shaker for 2 min to obtain the oil phase. The volume ratio of fragrance to GTCC in the oil phase is 3:1.

[0057] Step (4) Dissolve 5 g of calcium chloride and 100 μL of glutaraldehyde in 250 mL of deionized water, and then place it in a 100W ultrasonic cleaner and ultrasonically vibrate for 10 min as the receiving liquid.

[0058] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion with a volume ratio of oil phase to aqueous phase of 8:10.

[0059] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0060] like Figure 2 As shown, the Pickering emulsion formed by this silica is very stable, as demonstrated by measuring the three-phase contact angle of 15 nm hydrophilic silica nanoparticles (the three phases being particles, aqueous phase, fragrance, and GTCC mixture) to be 90 degrees.

[0061] Example 3

[0062] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0063] Step (1) Weigh 1 g of sodium alginate and 2 g of gelatin and dissolve them in 100 mL of deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to obtain a 1 wt% sodium alginate solution and a 2 wt% gelatin solution.

[0064] Step (2) Take 4.264 mL of sodium alginate solution and 1.066 mL of gelatin solution into 50 mL centrifuge tubes respectively, and add 0.0426 g of 15 nm hydrophilic silica particles (three-phase contact angle is 90 degrees: the three phases are particles, water phase, fragrance and GTCC mixture), and then shake it in a vortex shaker for 2 min as the water phase. The nanoparticle content in the water phase is 0.8% (w / v).

[0065] Step (3) Take 1.335 mL of fragrance and 1.335 mL of GTCC into a 15 mL centrifuge tube, and then vortex it for 2 min to obtain the oil phase. The volume ratio of fragrance to GTCC in the oil phase is 1:1.

[0066] Step (4) Dissolve 5 g of calcium chloride and 100 μL of glutaraldehyde in 250 mL of deionized water, and then place it in a 100W ultrasonic cleaner and ultrasonically vibrate for 10 min as the receiving liquid.

[0067] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion with a volume ratio of oil phase to aqueous phase of 5:10.

[0068] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0069] Depend on Figure 3 It can be seen that the prepared gel beads are basically consistent with the characteristic peaks of fragrance and GTCC, and the weak peak value indicates that the mixed core material has entered the gel beads.

[0070] Example 4

[0071] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0072] Step (1) Weigh 1 g of sodium alginate and 2 g of gelatin and dissolve them in 100 mL of deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to obtain a 1 wt% sodium alginate solution and a 2 wt% gelatin solution.

[0073] Step (2) Take 1.336 mL of sodium alginate solution and 0.334 mL of gelatin solution into 50 mL centrifuge tubes respectively, and add 0.0134 g of 15 nm hydrophilic silica particles (three-phase contact angle is 90 degrees: the three phases are particles, water phase, fragrance and GTCC mixture), and then shake it in a vortex shaker for 2 min as the water phase. The nanoparticle content in the water phase is 0.8% (w / v).

[0074] Step (3) Take 0.665 mL of fragrance and 0.665 mL of GTCC into 15 mL centrifuge tubes respectively, and then vortex them for 2 min to obtain the oil phase. The ratio of fragrance to GTCC in the oil phase is 1:1.

[0075] Step (4) Dissolve 5 g of calcium chloride and 100 μL of glutaraldehyde in 250 mL of deionized water, and then place it in a 100W ultrasonic cleaner and ultrasonically vibrate for 10 min as the receiving liquid.

[0076] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion with a volume ratio of oil phase to aqueous phase of 8:10.

[0077] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0078] Depend on Figure 4 The standard curve for lavender fragrance can be determined by extracting the supernatant, showing an encapsulation rate of 99.6% and a drug loading rate of 48%.

[0079] Example 5

[0080] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0081] Step (1) Weigh 1 g of sodium alginate and 2 g of gelatin and dissolve them in 100 mL of deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to obtain a 1 wt% sodium alginate solution and a 2 wt% gelatin solution.

[0082] Step (2) Take 2.665 mL of sodium alginate solution and 2.665 mL of gelatin solution into 50 mL centrifuge tubes respectively, and add 0.0426 g of 15 nm hydrophilic silica particles (three-phase contact angle is 90 degrees: the three phases are particles, water phase, fragrance and GTCC mixture), and then shake it in a vortex shaker for 2 min as the water phase. The nanoparticle content in the water phase is 0.8% (w / v).

[0083] Step (3) Take 1.335 mL of fragrance and 1.335 mL of GTCC into 15 mL centrifuge tubes respectively, and then shake them in a vortex shaker for 2 min to obtain the oil phase. The ratio of fragrance to GTCC in the oil phase is 1:1.

[0084] Step (4) Dissolve 5 g of calcium chloride and 100 μL of glutaraldehyde in 250 mL of deionized water, and then place it in a 100W ultrasonic cleaner and ultrasonically vibrate for 10 min as the receiving liquid.

[0085] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion with a volume ratio of oil phase to aqueous phase of 5:10.

[0086] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0087] Depend on Figure 5It can be seen that the gel beads lose moisture before 100℃. Compared with lavender fragrance which begins to release at room temperature and evaporates rapidly at around 150℃, the gel beads have a good protective effect, which can slow down the release rate of fragrance and significantly improve thermal stability.

[0088] Example 6

[0089] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0090] Step (1) Weigh 1 g of sodium alginate and 2 g of gelatin and dissolve them in 100 mL of deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to obtain a 1 wt% sodium alginate solution and a 2 wt% gelatin solution.

[0091] Step (2) Take 1.336 mL of sodium alginate solution and 0.334 mL of gelatin solution into 50 mL centrifuge tubes respectively, and add 0.0134 g of 15 nm hydrophilic silica particles (three-phase contact angle is 90 degrees: the three phases are particles, water phase, fragrance and GTCC mixture), and then shake it in a vortex shaker for 2 min as the water phase. The nanoparticle content in the water phase is 0.8% (w / v).

[0092] Step (3) Take 0.9975 mL of fragrance and 0.3325 mL of GTCC into 15 mL centrifuge tubes respectively, and then shake them in a vortex shaker for 2 min to obtain the oil phase. The ratio of fragrance to GTCC in the oil phase is 3:1.

[0093] Step (4) Dissolve 5 g of calcium chloride and 100 μL of glutaraldehyde in 250 mL of deionized water, and then place it in a 100W ultrasonic cleaner and ultrasonically vibrate for 10 min as the receiving liquid.

[0094] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion with a volume ratio of oil phase to aqueous phase of 8:10.

[0095] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0096] Depend on Figure 6 It can be seen that when the unencapsulated lavender fragrance has almost completely evaporated, about 50% of the fragrance remains in the gel beads, and the release rate of the lavender fragrance in the gel beads decreases with the extension of the sustained-release time. This indicates that the gel beads have good sustained-release properties and good thermal stability.

[0097] Example 7

[0098] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0099] Step (1) Weigh 1 g of sodium alginate and 2 g of gelatin and dissolve them in 100 mL of deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to obtain a 1 wt% sodium alginate solution and a 2 wt% gelatin solution.

[0100] Step (2) Take 3.552 mL of sodium alginate solution and 0.888 mL of gelatin solution into 50 mL centrifuge tubes respectively, and add 0.0355 g of 15 nm hydrophilic silica particles (three-phase contact angle is 90 degrees: the three phases are particles, water phase, fragrance and GTCC mixture), and then shake it in a vortex shaker for 2 min as the water phase. The nanoparticle content in the water phase is 0.8% (w / v).

[0101] Step (3) Take 2.67 mL of fragrance and 0.89 mL of GTCC into 15 mL centrifuge tubes respectively, and then vortex them for 2 min to obtain the oil phase. The ratio of fragrance to GTCC in the oil phase is 3:1.

[0102] Step (4) Dissolve 5 g of calcium chloride and 100 μL of glutaraldehyde in 250 mL of deionized water, and then place it in a 100W ultrasonic cleaner and ultrasonically vibrate for 10 min as the receiving liquid.

[0103] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion with a volume ratio of oil phase to aqueous phase of 8:10.

[0104] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0105] Depend on Figure 7 It can be seen that the release has two stages: the initial stage of rapid release is related to the loss of fragrance adsorbed on the surface of the gel beads. In the second stage, due to the multiple protections of the gel beads, the fragrance is released slowly, proving that the gel beads have a good sustained-release effect, and only 28.6% was released after 42 days.

[0106] Example 8

[0107] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0108] Step (1) Weigh 1 g of sodium alginate and 2 g of gelatin and dissolve them in 100 mL of deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to obtain a 1 wt% sodium alginate solution and a 2 wt% gelatin solution.

[0109] Step (2) Take 4.71 mL of sodium alginate solution and 3.29 mL of gelatin solution into 50 mL centrifuge tubes respectively, and add 0.0355 g of 15 nm hydrophilic silica particles (three-phase contact angle is 90 degrees: the three phases are particles, water phase, fragrance and GTCC mixture), and then shake it in a vortex shaker for 2 min as the water phase. The nanoparticle content in the water phase is 0.8% (w / v).

[0110] Step (3) Take 1.19 mL of fragrance and 2.37 mL of GTCC into 15 mL centrifuge tubes respectively, and then vortex them for 2 min to obtain the oil phase. The ratio of fragrance to GTCC in the oil phase is 1:2.

[0111] Step (4) Dissolve 5 g of calcium chloride and 100 μL of glutaraldehyde in 250 mL of deionized water, and then place it in a 100W ultrasonic cleaner and ultrasonically vibrate for 10 min as the receiving liquid.

[0112] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion with a volume ratio of oil phase to aqueous phase of 7:10.

[0113] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0114] Depend on Figure 8a It can be seen that the gel beads have a good morphology and are spherical. Figure 8b The uneven surface of gel beads is due to the accumulation of countless Pickering emulsions on their surface. Figure 8c The gel beads show numerous tiny pores inside, forming multiple compartments.

[0115] Example 9

[0116] A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized by comprising the following steps:

[0117] Step (1) Weigh 1 g of sodium alginate and 2 g of gelatin and dissolve them in 100 mL of deionized water. Then, dissolve them evenly in a constant temperature heating stirrer at 80℃ and 40℃ to obtain a 1 wt% sodium alginate solution and a 2 wt% gelatin solution.

[0118] Step (2) Take 1.336 mL of sodium alginate solution and 0.334 mL of gelatin solution into 50 mL centrifuge tubes respectively, add 0.0167 g of 20 nm hydrophilic monodisperse silica fluorescent microspheres, and then shake them in a vortex shaker for 2 min to form an aqueous phase. The nanoparticle content in the aqueous phase is 1% (w / v).

[0119] Step (3) Take 0.9975 mL of fragrance and 0.3325 mL of GTCC into 15 mL centrifuge tubes respectively, and then shake them in a vortex shaker for 2 min to obtain the oil phase. The ratio of fragrance to GTCC in the oil phase is 3:1.

[0120] Step (4) Dissolve 5 g of calcium chloride and 100 μL of glutaraldehyde in 250 mL of deionized water, and then place it in a 100W ultrasonic cleaner and ultrasonically vibrate for 10 min as the receiving liquid.

[0121] Step (5) Pour the oil phase into the aqueous phase and homogenize and emulsify to form an oil-in-water (O / W) Pickering emulsion with a volume ratio of oil phase to aqueous phase of 8:10.

[0122] Step (6) Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary tube with a silicone tube (inner diameter of 0.3 mm and tube length of 100 mm). Place the syringe needle perpendicular to the surface of the receiving liquid at a distance of 3~5 cm and adjust the injection pump to a flow rate of 50~120 μm / min to drip into the receiving liquid. The receiving liquid is rotated with a magnetic stirrer to ensure good sphericity of the gel beads. After 3 hours, the gel beads are formed and removed. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance.

[0123] Depend on Figure 9 It can be seen that the capsules were formed using 20 nm monodisperse silica fluorescent microspheres, and the nanofilm structure of the capsules was confirmed by laser scanning confocal microscopy.

Claims

1. A method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance, characterized in that, The specific steps are as follows: Step (1): Weigh out a certain amount of sodium alginate and gelatin respectively and dissolve them in deionized water. Dissolve them in a constant temperature heating stirrer at 80℃ and 40℃ to obtain sodium alginate solution and gelatin solution. Step (2): Take a certain amount of sodium alginate solution and gelatin solution into 50 mL centrifuge tubes respectively, add a certain mass of hydrophilic nano silica particles with a three-phase contact angle of 90 degrees, and then shake them evenly in a vortex shaker to form the aqueous phase. Step (3): Take a certain amount of flavoring and caprylic / capric triglyceride (GTCC) into a 15 mL centrifuge tube, and then vortex them to obtain the oil phase. Step (4): Dissolve 5g of calcium chloride and 100µL of glutaraldehyde in 250mL of deionized water, and then place it in a 100W ultrasonic cleaner and shake for 10~15 min as the receiving solution. Step (5): The oil phase is poured into the aqueous phase and homogenized and emulsified to form an oil-in-water O / W type Pickering emulsion; Step (6): Prepare natural gel beads with a diameter of millimeters by dripping. Use a commercially available 5 mL syringe to draw Pickering emulsion, attach a syringe needle with an inner diameter of 0.35~0.45 mm, and then connect the syringe needle to a glass spotting capillary with a silicone tube. The capillary has an inner diameter of 0.3 mm and a length of 100 mm. It is perpendicular to the surface of the receiving liquid at 3~5 cm. Adjust the injection pump to drip into the receiving liquid at a speed of 50~120 μm / min. The receiving liquid is rotated with a magnetic stirrer to achieve good sphericity of the gel beads. After 3 hours, the gel beads are formed and taken out. Wash them several times with deionized water. The washed gel beads are the Pickering emulsion type natural gel beads with slow-release fragrance. In step (1), the concentration of sodium alginate solution is 1 wt% and the concentration of gelatin solution is 2 wt%. In step (2), the volume ratio of sodium alginate to gelatin is 1:1, 1.4316:1, or 4:1, and the mass-volume concentration (w / v) of nano-silica in the aqueous phase is 0.6%, 0.8%, or 1%. In step (5), the volume ratio of the oil phase to the water phase is 5:10, 7:10, or 8:

10.

2. The method for preparing Pickering emulsion-type natural gel beads with sustained-release fragrance according to claim 1, characterized in that, In step (3), the volume ratio of fragrance to GTCC is 1:1, 1:2, or 3:

1.

3. The method for preparing a Pickering emulsion-type natural gel bead for sustained-release fragrance according to claim 1, characterized in that, In step (6), the flow rate of the injection pump connecting the emulsion is 50~120 µL / min, and the rotation speed of the magnetic stirrer receiving the liquid is 100~200 rpm.

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