A method for preparing a pickering emulsion from metal-phenolic network coating particles

Abstract

The application discloses a method for preparing a Pickering emulsion by using metal-phenolic network coating particles, which comprises the following steps: adding the metal-phenolic network coating particles into water, uniformly dispersing to obtain a dispersion liquid; adding an oil phase into the dispersion liquid, and ultrasonic emulsifying, and the concentration of the metal-phenolic network coating particles in the oil-water mixture is 0.2-6 mg / mL; the metal-phenolic network coating particles are obtained by ultrasonic-Fenton reaction of nanoparticles, soluble metal salt and hydrophobic phenolic compound in water. The droplet particle size of the stable Pickering emulsion is uniform, the Pickering emulsion has excellent storage stability, and has the antioxidant property of polyphenol and the pH responsiveness of the metal-phenolic network coating.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of Pickering emulsion preparation, and particularly relates to a method for preparing Pickering emulsion by using metal-phenolic network coating particles. BACKGROUND

[0002] The statements herein are provided only to enhance understanding of the application and are not necessarily intended to constitute the prior art.

[0003] Pickering emulsion is a solid particle-stabilized emulsion, which has high stability, low toxicity, low cost, easy recovery and other advantages compared with traditional surfactant-stabilized emulsion. Due to the partial wettability of solid particles and the insolubility in either phase, solid particles are irreversibly adsorbed on the interface of two immiscible liquids and can be used as a steric barrier to stabilize the emulsion and effectively prevent the coalescence of the emulsion. Pickering emulsion was discovered a century ago (Pickeing, 1907), and initially, the application of Pickering emulsion did not attract much attention due to the limited selection of materials. In recent years, with the development of material science and technology, many particles with adjustable surface wettability have been designed and synthesized for stabilizing Pickering emulsion, which has broadened the application of Pickering emulsion in drug delivery, food, cosmetics, catalysis and petroleum and other fields. However, the existing strategies for regulating the surface wettability of particles usually require complex surface modification, involving chemical modification, adsorption of surfactants or polymers, and addition of polyelectrolytes. Such modification strategies are usually expensive and time-consuming, cannot be mass-produced, and often use toxic organic solvents in the preparation process. In addition, the Pickering emulsion prepared by such modification strategies sometimes cannot maintain high stability and may also cause health and environmental problems, which limits the development and application of Pickering emulsion. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a method for preparing Pickering emulsion by using metal-phenolic network coating particles.

[0005] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0006] In the first aspect, the present application provides a method for preparing Pickering emulsion by using metal-phenolic network coating particles, which comprises the following steps: adding the metal-phenolic network coating particles into water, uniformly dispersing to obtain a dispersion liquid; adding an oil phase into the dispersion liquid and ultrasonically emulsifying, and the concentration of the metal-phenolic network coating particles in the oil-water mixture is 0.2-6 mg / mL.

[0007] The metal-phenolic network coating particles are obtained by ultrasonic reaction of nanoparticles, soluble metal salt and hydrophobic phenolic compound in water.

[0008] The present application adopts ultrasonic-Fenton reaction to prepare functionalized metal-phenolic network coating on the surface of particles, and adjusts the surface properties of the particles by selecting different types of hydrophobic phenolic compounds. The wettability of the prepared coating particles can be adjusted in the range of 65.7-88.2°, and the surface charge ranges from-41.1 mV to-21.7 mV. The droplet size of the stable Pickering emulsion prepared by the particles is uniform, and the Pickering emulsion not only has excellent storage stability, but also has the antioxidant property of polyphenol and the pH responsiveness of metal-phenolic network coating.

[0009] In some embodiments, the volume percentage of the oil phase in the oil-water mixture is 5-60%, v / v.

[0010] In some embodiments, the power of ultrasonic emulsification is 50-400 W, and the time of ultrasonic emulsification is 1-10 min.

[0011] Preferably, the power of ultrasonic emulsification is 100-200 W, and the time of ultrasonic emulsification is 1-2 min.

[0012] In some embodiments, the hydrophobic phenolic compound is selected from one or a combination of astragalin, quercetin, hesperetin, tricetin, resveratrol, rutin, naringin or curcumin.

[0013] In some embodiments, the concentration of the hydrophobic phenolic compound is 0.2-10 mg / mL.

[0014] Preferably, the mass ratio of the soluble metal salt to the hydrophobic phenolic compound is 2:1-5:1.

[0015] In some embodiments, the nanoparticles are selected from one or a combination of polystyrene microspheres, calcium carbonate particles, ZIF-8 nanoparticles, mesoporous silica nanoparticles or silica particles.

[0016] Preferably, the nanoparticles are silica nanoparticles.

[0017] In some embodiments, the time of ultrasonic reaction is 0.5-4 h.

[0018] Preferably, the power of ultrasonic reaction is 30-60 W.

[0019] In the second aspect, the present application provides a Pickering emulsion prepared by the preparation method.

[0020] The beneficial effects achieved by one or more embodiments of the present application are as follows:

[0021] The metal-phenolic network coating particles have controllable surface properties by adjusting the hydrophobic phenolic compound species, with adjustable surface wetting range (65.7-88.2°) and surface charge range (-41.1--21.7 mV). The Pickering emulsion is prepared by using the metal-phenolic network coating particles as stabilizers in the preparation process, and the Pickering emulsion prepared on this basis has uniform liquid particle size, excellent storage stability, and the antioxidant property of polyphenol and the pH responsiveness of the metal-phenolic network coating. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings accompanying the specification of the present application serve to provide further understanding of the present application, and the illustrative embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application.

[0023] Figure 1 The scanning electron microscope images of the iron-resveratrol network coating silica particles prepared in Example 1 of the present application by using silica particles as a base material and divalent iron ions and resveratrol as building units, wherein a is a silica particle, and b is an iron-resveratrol network coating silica particle;

[0024] Figure 2 The element distribution image of the iron-resveratrol network coating silica particles prepared in Example 1 of the present application;

[0025] Figure 3 The zeta potential images of the metal-phenolic network coating silica particles prepared in Example 1 and Example 3 of the present application, wherein the polyphenol ligands are resveratrol, rutin, naringin, and curcumin, respectively;

[0026] Figure 4 The contact angles of the metal-phenolic network coating prepared in Example 1 and Example 3 of the present application, wherein the polyphenol ligands are resveratrol, rutin, naringin, and curcumin, respectively;

[0027] Figure 5 The antioxidant trend image of the iron-resveratrol network coating silica particles prepared in Example 1 of the present application;

[0028] Figure 6 The optical microscope image of the sample after ultrasonic emulsification in Comparative Example 1 of the present application;

[0029] Figure 7 The optical microscope images of the Pickering emulsion prepared in Example 4 of the present application, wherein a is just prepared, and b is after the Pickering emulsion is placed for 30 days;

[0030] Figure 8Pickering emulsion type verification image of the Pickering emulsion prepared for the present application embodiment 4;

[0031] Figure 9 Pickering emulsion pH response performance prepared for the present application embodiment 4;

[0032] Figure 10 Optical microscopic image of the Pickering emulsion prepared for the present application embodiment 7, respectively, iron-rutin network coating silica particle prepared emulsion; iron-naringin network coating silica particle prepared emulsion; iron-curry network coating silica particle prepared emulsion. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed description is exemplary, and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0034] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific embodiments.

[0035] Embodiment 1

[0036] The preparation method of metal-phenolic coating particles comprises the following steps:

[0037] 5mg of nanosilica particles were added to 1mL of water, then 0.3mg of resveratrol (RES) and 4mg of ferrous chloride were added, and ultrasonic dispersion was carried out for 2min to dissolve resveratrol and ferrous chloride; high-frequency ultrasonic dispersion was carried out for 2h, the ultrasonic frequency was 412kHz, the power was 40W, and the temperature was set to 40℃; after three times of water washing and centrifugation, iron-resveratrol network coating silica particles were obtained.

[0038] Embodiment 2

[0039] A kind of metal-phenolic network coating particles, which is different from embodiment 1 in that the particles are replaced by polystyrene microspheres, ZIF-8 nanoparticles and mesoporous silica particles respectively. Other steps and conditions are consistent with embodiment 1, and iron-resveratrol network coating polystyrene particles, iron-resveratrol network coating ZIF-8 particles and iron-resveratrol network coating mesoporous silica particles are prepared.

[0040] Embodiment 3

[0041] A metal-phenolic network coating particle, which is different from example 1 in that resveratrol is replaced by rutin, naringin, curcumin respectively, the concentration in the mixed solution is 1 mg / mL, 1 mg / mL, 0.3 mg / mL respectively. Other steps and conditions are consistent with example 1, iron-rutin network coating silica particles, iron-naringin network coating silica particles, iron-curcumin network coating silica particles are prepared.

[0042] Example 4

[0043] The preparation method of the Pickering emulsion comprises the following steps:

[0044] Take 6 mg of iron-resveratrol network coating silica particles prepared in example 1 and disperse them in 2.4 mL of water, add them to a 5 mL glass bottle, then add 0.6 mL of medium-chain triglyceride, and ultrasonic treatment, the power is 200 W, the ultrasonic time is 2 min, to obtain a Pickering emulsion.

[0045] Example 5

[0046] The preparation method of the Pickering emulsion comprises the following steps:

[0047] Take 12 mg of iron-resveratrol network coating silica particles prepared in example 1 and disperse them in 2.4 mL of water, add them to a 5 mL glass bottle, then add 0.6 mL of medium-chain triglyceride, and ultrasonic treatment, the power is 200 W, the ultrasonic time is 2 min, to obtain a Pickering emulsion.

[0048] Example 6

[0049] The preparation method of the Pickering emulsion comprises the following steps:

[0050] Take 6 mg of iron-resveratrol network coating polystyrene particles, iron-resveratrol network coating ZIF-8 particles, and iron-resveratrol network coating mesoporous silica particles prepared in example 2 respectively and disperse them in 2.4 mL of water, add them to a 5 mL glass bottle respectively, then add 0.6 mL of medium-chain triglyceride respectively, and ultrasonic treatment, the power is 200 W, the ultrasonic time is 2 min, to obtain a Pickering emulsion.

[0051] Example 7

[0052] The preparation method of the Pickering emulsion comprises the following steps:

[0053] 6 mg of the iron-rutin network coated silica particles, iron-naringin network coated silica particles, iron-curcumin network coated silica particles prepared in Example 3 were dispersed into 2.4 mL water, respectively, and were added into 5 mL glass bottles, respectively, then 0.6 mL medium chain triglyceride was added, respectively, and were treated by ultrasonic, power was 200 W, ultrasonic time was 2 min, to obtain Pickering emulsion, respectively.

[0054] Comparative Example 1

[0055] In order to compare the influence of particles without metal-phenolic network coating on the particle emulsification performance, comparative example 1 was set. The difference between comparative example 1 and example 4 was that the particles were nano-silica particles without metal-phenolic network coating on the surface, and other steps and conditions were consistent with example 4.

[0056] Characterization of metal-phenolic network coated particles

[0057] (1) The morphology of the iron-resveratrol network coated silica particles in example 1 was characterized. From Figure 1 it can be seen that the surface roughness of the silica particles increased after the metal-phenolic network functional coating on the surface of the particles. And the uniform distribution of C and Fe elements on the particles was confirmed by STEM-EDX mapping Figure 2 ). These results showed the formation of iron-resveratrol network coating on the surface of the silica particles.

[0058] (2) The zeta potential and wettability of the iron-resveratrol network coated silica particles in example 1 and the iron-rutin network coated silica particles, iron-naringin network coated silica particles, iron-curcumin network coated silica particles in example 3 were tested. From Figure 3 it can be seen that the metal-phenolic network coating can change the surface charge of the silica particles; at the same time, it can change the surface wettability of the particles, and the wettability is different with the change of the hydrophobicity of the phenolic compound Figure 4 .

[0059] Performance characterization of metal-phenolic network coated particles

[0060] The antioxidant performance of the iron-resveratrol network coated silica particles in example 1 was tested. Different concentrations of iron-resveratrol network coated silica particles were respectively incubated with 0.2 mM DPPH solution in the dark for 30 min, and the ultraviolet absorption at 517 nm was tested by ultraviolet spectrophotometer. As shown in Figure 5 , the prepared iron-resveratrol network coated silica particles had good antioxidant performance, which was concentration-dependent, and the antioxidant capacity could reach 71% when the concentration of the iron-resveratrol network coated silica particles was 5 mg / mL.

[0061] Stability and microstructure analysis of the Pickering emulsion prepared by the present application

[0062] Microstructure analysis of the sample after ultrasonic emulsification of the present application comparative example 1: the sample after ultrasonic emulsification of comparative example 1 was taken with a pipette gun, dropped on a glass slide, and observed under an optical microscope. The results are shown in Figure 6 There were no obvious emulsion droplets, indicating that the silica particles did not have emulsifying ability.

[0063] Storage stability test of the Pickering emulsion prepared by the present application example 4: the Pickering emulsion prepared by example 4 was taken with a pipette gun, dropped on a glass slide, and observed under an optical microscope. The results are shown in Figure 7 The droplet size of the Pickering emulsion prepared by example 4 was uniform and did not change significantly after 30 days, indicating that it had excellent storage stability.

[0064] Verification of the type of the Pickering emulsion prepared by the present application example 4: the upper Pickering emulsion was taken and added to water and medium-chain triglyceride, respectively. The results are shown in Figure 8 The droplets dispersed in water and aggregated in oil, indicating that an O / W Pickering emulsion was formed.

[0065] pH response test of the Pickering emulsion prepared by the present application example 4: 300 μL of the upper emulsion was added to a water solution with pH 1, and after 5 h, the emulsion was taken with a pipette gun, dropped on a glass slide, and observed under an optical microscope. The results are shown in Figure 9 The emulsion broke, indicating that the metal-phenolic network coating particles had pH responsiveness, and at low pH, the metal-phenolic network coating decomposed. It was proved that the strategy of the present application could make the emulsion have pH responsiveness by changing the wettability of the particle surface.

[0066] Microstructure analysis of the Pickering emulsion prepared by the present application example 7: the Pickering emulsion prepared by example 7 was taken with a pipette gun, dropped on a glass slide, and observed under an optical microscope. The results are shown in Figure 10 The metal-phenolic network coating silica particles stabilized by different polyphenol ligands formed emulsions with different emulsion droplet sizes, indicating that different metal-phenolic network coatings gave the particles different surface properties and different emulsifying ability.

[0067] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing Pickering emulsion from metal-phenolic network coated particles, characterized in that: The process includes the following steps: adding the metal-phenolic network coating particles to water and dispersing them evenly to obtain a dispersion; adding an oil phase to the dispersion and ultrasonically emulsifying it; the concentration of the metal-phenolic network coating particles in the oil-water mixture is 0.2~6 mg / mL. The metal-phenolic network coating particles are obtained by ultrasonic reaction of nanoparticles, soluble metal salts and hydrophobic phenolic compounds in water. The ultrasonic reaction time is 0.5-4 h and the power is 30-60 W. The hydrophobic phenolic compound is selected from one or a combination of astragaloside, quercetin, hesperidin, silagetin, resveratrol, rutin, naringin or curcumin. The mass ratio of the soluble metal salt to the hydrophobic phenolic compound is 2:1 to 5:

1.

2. The method for preparing Pickering emulsion from metal-phenolic network coated particles according to claim 1, characterized in that: The volume percentage of the oil phase in the oil-water mixture is 5-60%, v / v.

3. The method for preparing Pickering emulsion from metal-phenolic network coated particles according to claim 1, characterized in that: The power of ultrasonic emulsification is 50~400 W, and the ultrasonic emulsification time is 1~10 min.

4. The method for preparing Pickering emulsion from metal-phenolic network coated particles according to claim 3, characterized in that: The power of ultrasonic emulsification is 100~200 W, and the ultrasonic emulsification time is 1~2 min.

5. The method for preparing Pickering emulsion from metal-phenolic network coated particles according to claim 1, characterized in that: The concentration of the hydrophobic phenolic compound is 0.2~10 mg / mL.

6. The method for preparing Pickering emulsion from metal-phenolic network coated particles according to claim 1, characterized in that: The nanoparticles are selected from one or a combination of polystyrene microspheres, calcium carbonate particles, ZIF-8 nanoparticles, and silica particles.

7. The method for preparing Pickering emulsion from metal-phenolic network coated particles according to claim 1, characterized in that, The nanoparticles are silicon dioxide nanoparticles.

8. A Pickering emulsion, characterized in that: It is prepared by any of the preparation methods described in claims 1-7.

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