CN113926401A

CN113926401A - Organic-inorganic composite microcapsule and preparation method thereof

Info

Publication number: CN113926401A
Application number: CN202111224194.XA
Authority: CN
Inventors: 肖作兵; 严吉晨; 张雅琪; 寇兴然; 牛云蔚
Original assignee: Shanghai Institute of Technology
Current assignee: Shanghai Institute of Technology
Priority date: 2021-10-20
Filing date: 2021-10-20
Publication date: 2022-01-14

Abstract

The invention discloses an organic-inorganic composite microcapsule and a preparation method thereof. The organic-inorganic composite microcapsule comprises protamine, sodium alginate, Sodium Dodecyl Sulfate (SDS), thymol, sodium silicate solution and deionized water. The invention takes protamine and sodium alginate as wall materials and thymol as core materials, and prepares an organic-inorganic composite microcapsule by an emulsion template-layer-by-layer self-assembly method. The invention is inspired by biological cell structure, and develops a method for preparing organic-inorganic composite microcapsules through the synergistic effect of layer-by-layer self-assembly and biomimetic mineralization. In addition, the preparation method has mild conditions, simple and easily-controlled process, and the prepared microcapsule has uniform particle size and strong stability. Compared with the traditional microcapsule wall material, the wall material adopted by the invention is safer and more environment-friendly, has better biocompatibility and is more widely applied.

Description

Organic-inorganic composite microcapsule and preparation method thereof

Technical Field

The invention relates to an organic-inorganic composite microcapsule and a preparation method thereof, belonging to the technical field of microcapsule preparation.

Background

Thymol is a monoterpene phenol compound extracted from various essential oils of flowers and plants, has good antiseptic property, natural antibacterial, insecticidal, antimicrobial, antioxidant and other properties, and is mainly applied to the fields of medicine, food, agriculture, veterinarian, pest control and the like at present. The natural food additive has the characteristics of greenness, safety, high efficiency and the like, is a natural food additive and a medicinal component approved by FDA, and can partially or completely replace the traditional chemical preservative. However, the practical use of thymol is hampered by the problems of poor stability, low water solubility, and low bioavailability. Microencapsulation is an effective way to solve this problem, and the release of thymol can be effectively controlled by microencapsulation. In recent decades, tween 80, liposomes, polylactic-co-glycolic acid (PLGA) and polylactic acid (PLA) have been used as a carrier for loading thymol, significantly improving the physicochemical properties of thymol. However, these carrier materials are either costly or poorly biocompatible and unstable. Bio-based polyelectrolytes are a new generation of materials that are gaining increasing attention as carriers. Sodium alginate is polyanionic natural polysaccharide biomacromolecule, protamine is polycationic natural polypeptide, and the 2 polyelectrolytes have the advantages of biodegradability, biocompatibility and the like.

Disclosure of Invention

The technical problem solved by the invention is as follows: the application of thymol is limited due to the problems of poor stability, low water solubility, low bioavailability and the like of the thymol, and the problems of high cost, poor biocompatibility of a carrier material, instability and the like exist in a preparation method of the microcapsule of the thymol.

In order to solve the technical problems, the invention provides an organic-inorganic composite microcapsule, which comprises a core material and a wall material, wherein the core material is thymol, and the wall material is protamine and sodium alginate; the organic-inorganic composite microcapsule is prepared by taking protamine and sodium alginate as wall materials and thymol as a core material through an emulsion template-layer-by-layer self-assembly method, and the preparation raw materials comprise protamine, sodium alginate, sodium dodecyl sulfate, thymol, a sodium silicate solution and deionized water. Wherein the mass ratio of protamine, sodium alginate, sodium dodecyl sulfate, thymol, sodium silicate solution and deionized water is 0.2-0.3: 0.2-0.3: 2-2.5: 0.5-1.5: 14-15: 16.5 to 17.

The invention also provides a preparation method of the organic-inorganic composite microcapsule, which comprises the following steps:

step 1): mixing and stirring a surfactant lauryl sodium sulfate and deionized water; adding thymol, continuously stirring, standing and defoaming to obtain microemulsion;

step 2): respectively preparing a protamine solution and a sodium alginate solution;

step 3): taking the microemulsion prepared in the step 1), injecting the protamine solution into the microemulsion by using an injection pump and stirring the solution; then injecting the sodium alginate solution by using an injection pump and stirring;

step 4): continuously injecting the protamine solution with the same volume as the volume in the step 3) by using an injection pump and stirring to obtain a mixed solution;

step 5): and (4) taking the mixed solution obtained in the step 4), injecting a sodium silicate solution into the mixed solution by using an injection pump, and stirring the mixed solution.

Preferably, the mass ratio of the sodium dodecyl sulfate to the deionized water to the thymol in the step 1) is 2-2.5: 16.5-17: 0.5 to 1.5.

Preferably, the stirring speed in the step 1) is 400-600 rpm, the temperature is 40-60 ℃, and the time is 20-40 min.

Preferably, the concentration of the protamine solution prepared in the step 2) is 2-4 mg/mL, and the concentration of the sodium alginate solution is 2-4 mg/mL.

Preferably, the proportion of the microemulsion, the protamine solution and the sodium alginate solution in the step 3) is 2-4 g: 5-7 mL: 5-7 mL.

Preferably, the dropping speed of the injection pump in the step 3) and the step 4) is 0.2-0.4 mL/min, the stirring speed is 800-1000 rpm, the temperature is 20-30 ℃, and the time is 30-40 min.

Preferably, the volume ratio of the mixed solution to the sodium silicate solution in the step 5) is 2: 1; the concentration of the sodium silicate solution is 0.04 mol/L.

Preferably, the dropping speed of the injection pump in the step 5) is 0.1-0.2 mL/min, the stirring speed is 800-1000 rpm, the temperature is 20-30 ℃, and the time is 30-40 min.

The principle of the invention is as follows:

the invention is inspired by biological cell structure, utilizes the electrostatic attraction between 2 polyelectrolytes with opposite charges as a driving force to carry out layer-by-layer self-assembly and the synergistic action with biomimetic mineralization, and develops a novel and simple method for preparing the organic-inorganic composite microcapsule. Layer-by-layer self-assembled (LBL) microcapsules are made by assembling the positively charged biomacromolecule protamine (Pro) and negatively charged polyelectrolyte sodium Alginate (ALG) onto an emulsion template. Then an inorganic silicon dioxide layer is constructed through a biomimetic mineralization process induced by an external protamine layer, and thymol is encapsulated in the composite microcapsule. Compared with Pro/ALG, the LBL microcapsule has obviously improved storage stability due to the shielding effect of the inorganic shell.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the organic-inorganic composite microcapsule prepared by the invention, thymol is taken as a core material, protamine and sodium alginate are taken as wall materials, and the microcapsule can be formed through the synergistic effect of layer-by-layer self-assembly and biomimetic mineralization; microencapsulation can reduce the loss of thymol through the physical barrier effect of the wall material, cover unpleasant odor, realize the controllable release of the core material at the same time, maintain or improve the biological activity of the core material in an application system, and improve the utilization efficiency; the microcapsule has uniform size, no toxicity, good biocompatibility and high bioavailability, and can realize the slow release of the thymol; the stability of the microcapsule is enhanced, and the influence of light, heat and the like on thymol is reduced to a certain extent; the microcapsule has simple preparation process, does not need or rarely introduces other chemical reagents, has no danger of solvent residue, and is suitable for application in the fields of food and the like;

2. according to the preparation method of the organic-inorganic composite essence microcapsule provided by the invention, thymol is coated in the capsule and sustained release is realized, long-acting bacteriostasis is carried out, the stability of the product is improved, and a new idea is provided for the actual application and market development of plant essential oil.

Drawings

Fig. 1 is a distribution diagram of particle sizes of organic-inorganic composite microcapsules prepared in example 1;

FIG. 2 is a transmission electron microscope image of the organic-inorganic composite microcapsule prepared in example 1;

fig. 3 is a distribution diagram of particle sizes of organic-inorganic composite microcapsules prepared in example 2;

fig. 4 is a transmission electron microscope image of the organic-inorganic composite microcapsule prepared in example 2.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

Example 1

A preparation method of an organic-inorganic composite microcapsule comprises the following steps:

mixing 2.25g of surfactant Sodium Dodecyl Sulfate (SDS) and 16.75g of deionized water in a glass bottle at 50 ℃, and stirring at 500rpm for 30 min; then adding 1g of thymol, stirring at 50 ℃ and 500rpm for 30 min; standing and defoaming to obtain the microemulsion. Taking 3g of microemulsion, adding 6mL of protamine solution (3mg/mL) into an injection pump (0.3mL/min), and stirring at 800rpm for 30 min; adding 6mL sodium alginate solution (3mg/mL) into the syringe pump (0.3mL/min), and stirring at 800rpm for 30 min; adding 6mL protamine solution (3mg/mL) with syringe pump (0.3mL/min), stirring at 800rpm for 30 min; adding 6mL sodium alginate solution (3mg/mL) into the syringe pump (0.3mL/min), and stirring at 800rpm for 30 min; 6mL of the above mixture was taken, and 3mL of 0.04mol/L sodium silicate solution was added by a syringe pump (0.15mL/min) and stirred at 800rpm for 30 min.

The obtained organic-inorganic composite microcapsule has particle size distribution of 204.41nm and zeta potential of-50.33 mV, as shown in figure 1, by observation of particle sizer, which indicates that the microcapsule has uniform particle size distribution and strong stability.

Example 2

mixing 2.25g of surfactant Sodium Dodecyl Sulfate (SDS) and 16.75g of deionized water in a glass bottle at 50 ℃, and stirring at 500rpm for 30 min; then adding 1g of thymol, stirring at 50 ℃ and 500rpm for 30 min; standing and defoaming to obtain the microemulsion. Taking 3g of microemulsion, adding 6mL of protamine solution (3mg/mL) into an injection pump (0.3mL/min), and stirring at 800rpm for 30 min; adding 6mL sodium alginate solution (3mg/mL) into the syringe pump (0.3mL/min), and stirring at 800rpm for 30 min; continuing to inject (0.3mL/min), adding 6mL protamine solution (3mg/mL), stirring at 800rpm for 30 min; 6mL of the above mixture was taken, and 3mL of 0.04mol/L sodium silicate solution was added by a syringe pump (0.15mL/min) and stirred at 800rpm for 30 min.

The particle size distribution of the obtained organic-inorganic composite microcapsule is observed by a particle sizer and is shown in figure 2, the particle size is 199.69nm, the zeta potential is-70.42 mV, and the particle size distribution of the microcapsule is uniform and the stability is enhanced.

While the invention has been described with respect to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

1. An organic-inorganic composite microcapsule is characterized by comprising a core material and a wall material, wherein the core material is thymol, and the wall material is protamine and sodium alginate; the organic-inorganic composite microcapsule is prepared by taking protamine and sodium alginate as wall materials and thymol as a core material through an emulsion template-layer-by-layer self-assembly method, and the preparation raw materials comprise protamine, sodium alginate, sodium dodecyl sulfate, thymol, a sodium silicate solution and deionized water.

2. The method for preparing an organic-inorganic composite microcapsule according to claim 1, comprising the steps of:

3. The preparation method of the organic-inorganic composite microcapsule according to claim 2, wherein the mass ratio of the sodium dodecyl sulfate, the deionized water and the thymol in the step 1) is 2-2.5: 16.5-17: 0.5 to 1.5.

4. The method for preparing organic-inorganic composite microcapsules according to claim 2, wherein the stirring speed in the step 1) is 400-600 rpm, the temperature is 40-60 ℃, and the time is 20-40 min.

5. The preparation method of the organic-inorganic composite microcapsule according to claim 2, wherein the concentration of the protamine solution prepared in the step 2) is 2-4 mg/mL, and the concentration of the sodium alginate solution is 2-4 mg/mL.

6. The preparation method of the organic-inorganic composite microcapsule according to claim 2, wherein the proportion of the microemulsion, the protamine solution and the sodium alginate solution in the step 3) is 2-4 g: 5-7 mL: 5-7 mL.

7. The method for preparing organic-inorganic composite microcapsules according to claim 2, wherein the dropping speed of the injection pump in the step 3) and the step 4) is 0.2-0.4 mL/min, the stirring speed is 800-1000 rpm, the temperature is 20-30 ℃, and the time is 30-40 min.

8. The method for preparing organic-inorganic composite microcapsules according to claim 2, wherein the volume ratio of the mixed solution to the sodium silicate solution in the step 5) is 2: 1; the concentration of the sodium silicate solution is 0.04 mol/L.

9. The method for preparing organic-inorganic composite microcapsules according to claim 2, wherein the dropping speed of the injection pump in the step 5) is 0.1-0.2 mL/min, the stirring speed is 800-1000 rpm, the temperature is 20-30 ℃, and the time is 30-40 min.