Microfluidic nanosphere embedding system, active grease nanosphere and preparation method of active grease nanosphere

Abstract

The invention discloses a micro-fluidic nanosphere embedding system, an active grease nanosphere and a preparation method of the active grease nanosphere, and relates to the technical field of grease processing, the embedding system comprises a micro-channel compounding mixed flow module, a core-shell structure nanoparticle generation module and a nanosphere assembly module; the preparation method comprises the following steps: dissolving shellac and soya bean lecithin or rhamnolipid or sophorolipid with a solvent, and mixing with active grease to obtain an alcohol-soluble mixed solution; carrying out primary nano-assembly on the nano-particles and water in a micro-channel to generate a micro nano-particle suspension with a shell-core structure; after air is injected, continuous sectional type flowing bubbles are generated in the snakelike micro-channel, and secondary assembly of active grease nanoparticles is generated in micro-liquid cavities spaced by the bubbles to generate nanosphere suspension; and removing the solvent to obtain the active grease nanosphere. In the process of forming the nanoparticles, the alcohol-soluble wall material can be well clung to the outside of the active grease, so that the grease is prevented from being contacted with the outside, and the spherical nanoparticles are formed and assembled into a more stable nanosphere structure under the driving of gas.

Description

Technical Field

[0001] The invention relates to the technical field of oil processing, and in particular to a microfluidic nanosphere embedding system, active oil nanospheres and a preparation method thereof. Background Art

[0002] Natural active oil is a hot topic in food science and nutrition research. The solubility of natural active oil in water medium is low, and it is difficult to be directly added to food matrix, and it is very susceptible to the influence of environmental conditions such as light, heat, oxygen and produces hydroperoxide and unpleasant taste and smell during production, processing, transportation and storage. At present, in order to solve these problems, the wide application of algae oil in the food industry is realized, and its bad flavor is generally covered by embedding technology or adding antioxidants to improve its solubility and oxidative stability. For example, Chinese patent application CN114712328B discloses a method for preparing slow-release propolis saccule based on natural shellac composite wall material, and the method process needs to be extracted and filtered many times, and the process flow is complicated, and the production process has multiple requirements for temperature, and the production process consumes energy. Therefore, how to improve and simplify the embedding process conditions of natural active oil to improve the stability of active oil is a problem that needs to be solved urgently.

[0003] Nanospheres are spherical microparticles with diameters ranging from nanometers to hundreds of nanometers. They have unique micro-surface effects, small size effects, and quantum size effects, and can be used to stably embed active oils. Natural active oils embedded in nanosphere structures are generally prepared by methods such as spray drying, which have problems such as high energy consumption and poor uniformity of prepared particle size and structure, which limits their fine application in the food or cosmetics industry. Microfluidic technology has the advantages of automation, low energy consumption, high repeatability, and easy operation. The special structural characteristics of microchannels based on microfluidic technology can achieve precise control of the mixing process, thereby realizing low-cost and continuous preparation of special nanostructured particles with low energy consumption and extremely short reaction time. Therefore, how to achieve efficient and rapid preparation of stable and uniformly structured nanospheres through microchannel design is a problem that needs to be solved. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide a microfluidic nanosphere encapsulation system and active oil nanospheres prepared by the system and a method thereof. Specifically, in order to solve the problem that active oils are easily oxidized, and the existing encapsulation technology process is complicated and cannot produce active oil nanospheres with stable and uniform structure, the present invention provides a low-energy green method based on microfluidic technology, which can simply prepare nanospheres with stable and uniform structure by adjusting the assembly of nanoparticles through high-pressure micro-air cavities in microchannels.

[0005] The technical solution of the present invention is as follows:

[0006] The first aspect of the present invention provides a microfluidic nanosphere embedding system, comprising:

[0007] A microchannel composite mixed flow module, comprising a first flow channel, a second flow channel and a mixing flow channel, wherein the feed ends of the first flow channel and the second flow channel respectively have a mixed wall material inlet and an active oil inlet, and the discharge ends are both connected to the mixing flow channel;

[0008] A core-shell structure nanoparticle generation module, comprising a third flow channel and a fourth flow channel connected to the side wall of the third flow channel, wherein the feed end of the fourth flow channel is connected to the mixing flow channel, and the discharge end is connected to the third flow channel, a plurality of micro-pillars arranged in an array are arranged in the discharge end of the fourth flow channel, and the feed end of the third flow channel has a water phase inlet;

[0009] A nanosphere assembly module comprises a gas injection pipeline, a fifth flow channel and a sixth flow channel, wherein the feed end of the fifth flow channel is connected to the discharge end of the third flow channel, the discharge end is connected to the sixth flow channel, the sixth flow channel has a discharge port, and the gas injection pipeline has a gas input port and a gas output port connected to the fifth flow channel.

[0010] Preferably, the mixing channel includes at least one pipe with a U-shaped cross-section, the first channel and the second channel are both connected to the feed end of the U-shaped pipe, and the discharge end of the U-shaped pipe is connected to the feed end of the fourth channel through a connecting pipe.

[0011] Preferably, the inner diameter of the fourth flow channel gradually increases from the feed end to the discharge end, and the spacing between the plurality of micro-pillars is 50-100 microns.

[0012] Preferably, the gas input port is arranged at both ends of the gas injection pipeline, the gas output port is arranged at the middle end of the gas injection pipeline, the diameter of the gas output port is smaller than the diameter of the gas input port, and the gas output port is embedded in the fifth flow channel and located at the center of the fifth flow channel.

[0013] Preferably, the sixth flow channel includes a plurality of linear pipelines and curved pipelines connected in sequence.

[0014] The second aspect of the present invention provides a method for preparing active lipid nanospheres, which is prepared using the above-mentioned microfluidic nanosphere embedding system, and the preparation method comprises the following steps:

[0015] S1, dissolving shellac and soybean lecithin or rhamnolipid or sophorolipid in a solvent, stirring, and centrifuging to obtain a mixed solution of a good solvent;

[0016] Preferably, when soybean lecithin is selected as the biosurfactant in step S1, the assembled nanospheres have the smallest nanosphere particle size and the best clarification properties of the actual product.

[0017] S2, mixing the mixed solution of the good solvent in step S1 with the active oil to form a stable alcohol-soluble mixed solution;

[0018] S3, mixing the alcohol-soluble mixed solution in step S2 with water to perform preliminary nano-assembly to generate a suspension of tiny nanoparticles with a core-shell structure;

[0019] S4, passing the tiny nanoparticle suspension in step S3 into a microchannel, and passing air into the microchannel, wherein the air generates continuous segmented bubbles in the microchannel, so that the continuous tiny nanoparticle suspension in the microchannel is divided into multiple segments;

[0020] S5, controlling the flow rate of the air to adjust the interval and flow speed of the bubbles in the microchannel, so that the tiny nanoparticle suspension is assembled into nanospheres to obtain a uniform nanosphere suspension;

[0021] S6, removing the solvent in the uniform nanosphere suspension in step S5 to obtain active lipid nanospheres.

[0022] Preferably, in step S2, the mixed solution of the good solvent and the active oil are respectively injected into the mixed wall material inlet and the active oil inlet, and the mixed solution of the good solvent and the active oil enter the mixing flow channel through the first flow channel and the second flow channel respectively, and are uniformly mixed in the mixing flow channel to form a stable alcohol-soluble mixed solution;

[0023] In step S3, water is introduced into the third flow channel through the aqueous phase inlet, the alcohol-soluble mixed solution enters the third flow channel through the fourth flow channel and mixes with the water, the alcohol-soluble mixed solution and the water undergo preliminary nano-assembly, and a tiny nanoparticle suspension with a core-shell structure is generated in the third flow channel.

[0024] Preferably, in step S4, the micro-nano particle suspension enters the fifth flow channel, air is introduced into the gas injection pipe through the gas input port, the air enters the fifth flow channel through the gas output port, and the air generates continuous segmented bubbles in the fifth flow channel, so that the continuous micro-nano particle suspension in the fifth flow channel is divided into multiple segments;

[0025] In step S5, the tiny nanoparticle suspension enters the sixth flow channel, and the flow rate of the introduced air is controlled to regulate the spacing and flow speed of the bubbles in the microchannel, so that the tiny nanoparticle suspension generates axial flow in the sixth flow channel and generates high-speed reflux at the air-liquid interface to assemble nanospheres, thereby obtaining a uniform nanosphere suspension.

[0026] Preferably, in step S5, the ratio of the air flow rate to the liquid flow rate introduced into the sixth flow channel is controlled to be maintained at 1:1, and the total flow rate of the liquid and air in the sixth flow channel is regulated to be 20-150 mL / min.

[0027] More preferably, the ratio of air and liquid flow rates in the sixth flow channel is controlled to be 1:1, and the total flow rate of the gas-liquid two phases is 100 mL / min, so as to regulate the interval and generation frequency of bubbles in the microchannel to obtain the optimal nanosphere assembly conditions. The nanospheres generated under this condition have the highest stability and the smallest particle size.

[0028] The third aspect of the present invention provides an active oil nanosphere obtained by the method described above.

[0029] The average particle size of the nanoparticles prepared by the method of the invention is within 10 nanometers, and the size of the nanospheres is within 200 nanometers.

[0030] The present invention has at least one of the following beneficial effects:

[0031] 1. The structure of the microfluidic nanosphere embedding system of the present invention is conducive to the high-throughput rapid preparation of nanospheres. Specifically, under the controlled laminar mixing of the microchannel, the wall material phase liquid and the active grease phase form a stable and uniform alcohol-soluble mixed solution in the microchannel, and after passing through the microcolumn array, the water phase is mixed in the pipeline to form a nanoparticle suspension with stable size. Through the gas injection pipeline, multiple air bubbles can be controllably formed in the pipeline, and then through the serpentine long flow channel of the microchannel, the nanoparticle suspension can be fully dispersed during the flow process, and the nanoparticles can not only be mixed axially in the microfluid cavity separated by the bubbles, but also produce fluid circulation near the interface, which is conducive to the assembly of nanosphere particles, and forms a firm and uniform nanosphere structure. The microfluidic system of the present invention is simple in structure, easy to use, conducive to the high-throughput formation and assembly of nanoparticles and nanospheres, and ensures that the nanoparticles can be assembled to form a firm and uniform nanosphere structure.

[0032] 2. The present invention utilizes a microfluidic nanosphere embedding system to complete the preparation of core-shell nanoparticles and the assembly of nanospheres. Soy lecithin or rhamnolipid or sophorolipid and shellac are dissolved in ethanol to obtain a wall material alcohol solution, which then flows evenly and quickly with active oil in a microchannel of a zigzag structure to form an alcohol-soluble mixed solution; the nanoparticles are prepared using microfluidic technology, and the two solvents are quickly and evenly mixed in a microfluidic device. Compared with a simple nanoprecipitation method, the properties of the nanostructure, such as size, surface properties, and loading capacity for active substances, can be better controlled; when there is a microscale transport phenomenon in the microfluidic platform, the mixing time is shorter than the time for nucleation and growth of the nanoparticles, and the uniform mixing environment hinders the aggregation and agglomeration of the nanoparticles, which is conducive to the preparation of smaller nanoparticles with uniform size distribution. Therefore, in the process of forming nanoparticles in the microchannel, the alcohol-soluble wall material can be well attached to the outside of the active oil to protect the oil from external contact, and can especially embed easily oxidized unsaturated fatty acid oils to form spherical nanoparticles and assemble into a more stable nanosphere structure. The average particle size of the nanoparticles prepared by the method of the invention is within 10 nanometers, and the size of the nanospheres is within 200 nanometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of the microfluidic nanosphere embedding system in Example 1 of the present invention;

[0034] Reference numerals:

[0035] 1. Microchannel compound mixed flow module, 11. First flow channel, 12. Second flow channel, 13. Mixing flow channel, 14. Mixed wall material inlet, 15. Active oil inlet;

[0036] 2. a core-shell structure nanoparticle generation module, 21. a third flow channel, 22. a fourth flow channel, 23. a water phase inlet, 24. a microcolumn, 25. a microchannel liquid one-way valve;

[0037] 3. Nanosphere assembly module, 31. Gas injection pipeline, 32. Fifth flow channel, 33. Sixth flow channel, 34. Gas input port, 35. Gas output port, 36. Discharge port.

[0038] Figure 1-1 and Figure 1-2 This is a schematic diagram of the principle of preparing active lipid nanospheres by the microfluidic nanosphere embedding system in Example 1 of the present invention;

[0039] Figure 2 is a scanning electron microscope image of the nanospheres prepared in Examples 1 to 4 of the present invention and Comparative Example 2;

[0040] Figure 3 1 is an example diagram of nanospheres prepared in Examples 1 to 4 of the present invention and Comparative Example 2;

[0041] Figure 4 This is a test chart of the oxidation stability of the nanospheres prepared in Examples 1 to 4 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] One embodiment of the present invention provides Figure 1 A microfluidic nanosphere embedding system is shown, comprising:

[0044] The microchannel composite mixed flow module 1 comprises a first flow channel 11, a second flow channel 12 and a mixing flow channel 13, wherein the feed ends of the first flow channel 11 and the second flow channel 12 respectively have a mixed wall material inlet 14 and an active oil inlet 15, and the discharge ends are both connected to the mixing flow channel 13;

[0045] The core-shell structure nanoparticle generation module 2 comprises a third flow channel 21 and a fourth flow channel 22 connected to the side wall of the third flow channel 21, wherein the feed end of the fourth flow channel 22 is connected to the mixing flow channel 13, and the discharge end is connected to the third flow channel 21, and a plurality of micro-pillars arranged in an array are arranged in the discharge end of the fourth flow channel, and the feed end of the third flow channel 21 has an aqueous phase inlet 23;

[0046] The nanosphere assembly module 3 includes a gas injection pipeline 31, a fifth flow channel 32 and a sixth flow channel 33. The feed end of the fifth flow channel 32 is connected to the discharge end of the third flow channel 21, and the discharge end is connected to the sixth flow channel 33. The sixth flow channel 33 has a discharge port 36. The gas injection pipeline 31 has a gas input port 34 and a gas output port 35 connected to the fifth flow channel 32.

[0047] The structure of the microfluidic nanosphere embedding system of the present invention is conducive to the high-throughput rapid preparation of nanospheres. Under the controllable laminar flow mixing of the microchannel, the wall material phase liquid and the active oil phase form a stable and uniform alcohol-soluble mixed liquid in the microchannel, and after passing through the microcolumn array, the mixed liquid and the water phase are mixed in the pipeline to form a nanoparticle suspension with stable size. By injecting gas into the pipeline, multiple sections of air bubbles can be controllably formed in the pipeline, which is conducive to the assembly of nanosphere particles.

[0048] In some embodiments, the mixing channel 13 includes at least one pipe with a U-shaped cross-section, the first channel 11 and the second channel 12 are both connected to the feed end of the U-shaped pipe, and the discharge end of the U-shaped pipe is connected to the feed end of the fourth channel 22 through a connecting pipe.

[0049] In some embodiments, the number of the first flow channel 11, the second flow channel 12 and the mixing flow channel 13 are all 2, the two first flow channels 11 and the two second flow channels 12 are arranged at an angle, the feed ends of the two first flow channels 11 are connected to each other and the mixed wall material inlet 14 is arranged at the connection, and the feed ends of the two second flow channels 12 are connected to each other and the active oil inlet 15 is arranged at the connection.

[0050] In some embodiments, the inner diameter of the fourth flow channel 22 gradually increases from the feed end to the discharge end. A plurality of micropillars 24 arranged in an array are disposed in the discharge end of the fourth flow channel 22. The spacing between the plurality of micropillars 24 is 50-100 microns.

[0051] In some embodiments, the micro-pillars 24 are square, cylindrical or triangular in shape.

[0052] The micro-pillars 24 arranged in an array are arranged at the discharge end of the fourth flow channel 22, and the "capillary phenomenon" effect similar to the transpiration of plants is utilized to achieve efficient, rapid and uniform mixing between the solvents.

[0053] In some embodiments, the cross section of the fourth flow channel 22 is a right-angle trapezoid, and a microchannel liquid one-way valve 25 is provided at the connection between the third flow channel 21 and the fifth flow channel 32 .

[0054] In some embodiments, the gas input port 34 is arranged at both ends of the gas injection pipe 31, and the gas output port 35 is arranged at the middle end of the gas injection pipe 31. The diameter of the gas output port 35 is smaller than the diameter of the gas input port 34. The gas output port 35 is embedded in the fifth flow channel 32 and is located at the center of the fifth flow channel 32.

[0055] In some embodiments, the sixth flow channel 33 includes a plurality of linear pipelines and curved pipelines connected in sequence.

[0056] Another embodiment of the present invention provides a method for preparing active lipid nanospheres, comprising the following steps:

[0057] S1, dissolving shellac and soybean lecithin in a solvent, stirring, and centrifuging to obtain a mixed solution of a good solvent;

[0058] S2, mixing the mixed solution of the good solvent in step S1 with the active oil to form a stable alcohol-soluble mixed solution;

[0059] S3, mixing the alcohol-soluble mixed solution in step S2 with water to perform preliminary nano-assembly to generate a suspension of tiny nanoparticles with a core-shell structure;

[0060] S4, passing the tiny nanoparticle suspension in step S3 into a microchannel, and passing air into the microchannel, wherein the air generates continuous segmented bubbles in the microchannel, so that the continuous tiny nanoparticle suspension in the microchannel is divided into multiple segments;

[0061] S5, controlling the flow rate of the air to adjust the interval and flow speed of the bubbles in the microchannel, so that the tiny nanoparticle suspension is assembled into nanospheres to obtain a uniform nanosphere suspension;

[0062] S6, removing the solvent in the uniform nanosphere suspension in step S5 to obtain active lipid nanospheres.

[0063] The preparation method of the present invention can protect the oil from external contact, and can especially embed unsaturated fatty acid oil that is easily oxidized to form spherical nanoparticles and assemble them into a more stable nanosphere structure.

[0064] The invention provides a high-throughput microfluidic preparation method of nanospheres with highly controllable particle size and stable structure. Shellac and soybean lecithin or rhamnolipid or sophorolipid are used as nanoparticles as the basic wall material of nanoparticles, dissolved and blended under mechanical stirring to form an ethanol mixed solution, which is injected into a microfluidic reaction chip after filtration, and forms nanospheres through a series of reactions with active oils and fats that are controllably injected in a microchannel. In the process, no high energy input or a large amount of harmful solvents are required, and a preliminary nano-assembly occurs with the solvent through the transpiration-like effect of the capillary microporous structure, and small-diameter nanoparticles are made in the nanoparticle generation module of the chip, and then flow-assembled in a multi-stage separated microfluid cavity generated by high-pressure gas to obtain a nanosphere suspension, and finally the ethanol solution is removed and recovered to obtain a highly concentrated suspension of nanospheres. In this process, the structure of the nanospheres remains intact and stable. And due to the high-speed reflux and axial mixing generated by the gas-liquid interface in the microchannel, the nanospheres can be controlled to be assembled into uniform nanospheres, and the consistency and stability of the nanosphere particles are high.

[0065] In some embodiments, the solvent in step S1 is ethanol.

[0066] In some embodiments, the water in step S3 is purified water.

[0067] In some embodiments, the microfluidic nanosphere embedding system is used for preparation.

[0068] In step S2, the mixed solution of the good solvent and the active oil are respectively injected into the mixed wall material inlet 14 and the active oil inlet 15, and the mixed solution of the good solvent and the active oil enter the mixing flow channel 13 through the first flow channel 11 and the second flow channel 12 respectively, and are uniformly mixed in the mixing flow channel 13 to form a stable alcohol-soluble mixed solution;

[0069] In step S3, pure water is introduced into the third flow channel 21 through the aqueous phase inlet 23, the alcohol-soluble mixed solution enters the third flow channel 21 through the fourth flow channel 22 and mixes with the pure water, the alcohol-soluble mixed solution and the pure water undergo preliminary nano-assembly, and a tiny nanoparticle suspension with a core-shell structure is generated in the third flow channel 21.

[0070] In some embodiments, in step S4, the micro-nanoparticle suspension enters the fifth flow channel 32, air is introduced into the gas injection pipe 31 through the gas input port 34, and the air enters the fifth flow channel 32 through the gas output port 35, and the air generates continuous segmented bubbles in the fifth flow channel 32, so that the continuous micro-nanoparticle suspension in the fifth flow channel 32 is divided into multiple segments;

[0071] In step S5, the tiny nanoparticle suspension enters the sixth flow channel 33, and the flow rate of the introduced air is controlled to regulate the spacing and flow speed of the bubbles in the microchannel, so that the tiny nanoparticle suspension generates axial flow in the sixth flow channel 33 and generates high-speed reflux at the air-liquid interface to assemble nanospheres, thereby obtaining a uniform nanosphere suspension.

[0072] In some embodiments, in step S5, the ratio of the air flow rate to the liquid flow rate is controlled to be 1:1, and the total flow rate of the gas-liquid two phases is 100 (mL / min) to regulate the spacing and generation frequency of the bubbles in the microchannel to obtain the optimal nanosphere assembly conditions. The nanospheres generated under this condition have the highest stability and the smallest particle size.

[0073] In certain embodiments, in step S6, the method for removing the ethanol in the uniform nanosphere suspension in step S5 can be distillation, such as molecular distillation, or RO membrane filtration. Since a certain amount of ethanol will remain in the nanoparticle formation and nanosphere assembly process, it is necessary to remove ethanol. Since molecular distillation and RO membrane filtration are prior art, their technical means and principles are well known to those skilled in the art, and are not repeated in the present embodiment.

[0074] Another embodiment of the present invention provides an active lipid nanosphere obtained by the above method.

[0075] The average particle size of the nanoparticles prepared by the method of the invention is within 10 nanometers, and the size of the nanospheres is within 200 nanometers.

[0076] The preparation process of oil nanospheres in the prior art is mostly prepared by physical methods and chemical methods, such as ultrasonic dispersion method, high pressure homogenization method, emulsification-solvent volatilization method, these conventional processes are complicated, time-consuming and labor-intensive, resulting in high cost of large-scale production, and the obtained nanospheres are uneven in size, unstable in structure and particle distribution, and uneven in product quality. The present invention directly passes the prepared alcohol-soluble wall material, pure water, and active oil three fluids into three pipes of the microchannel, the three pass through the microchannel composite mixed flow module, the nanoparticle generation module quickly embeds the active oil, and forms small-sized nanoparticles, and then a certain flow of air is passed into the gas channel to control the stable assembly of the special structure of the nanospheres, realizes the simplification of the conventional process multi-process, and the obtained nanosphere suspension is of high quality, with a stable and uniform structure, providing a technical basis for the rapid preparation of high-quality active oil nanosphere droplets.

[0077] The principle of the present invention is:

[0078] like Figure 1-1 As shown, shellac and soybean lecithin or rhamnolipid or sophorolipid are dissolved in ethanol to form an alcohol-soluble wall material phase; the alcohol-soluble wall material phase and the active oil phase are added to the microchannel compounding mixed flow module 1, and the two are continuously mixed in a plurality of approximately zigzag mixing channels 13 to obtain an alcohol-soluble mixed phase; then, the alcohol-soluble mixed phase enters the nanoparticle generation module 2, and undergoes preliminary nanoassembly with pure water in a specially designed microchannel to generate a tiny nanoparticle suspension with a shell-core structure; by rapidly mixing the active oil, shellac, soybean lecithin or rhamnolipid or sophorolipid in a microfluidic nanosphere embedding system, preliminary nanoassembly occurs, and the active oil first aggregates to form oil droplets, and then the shellac polymer and soybean lecithin or rhamnolipid or sophorolipid are precipitated at the oil-water interface through the action of the capillary nanoparticle generation module designed based on transpiration, so as to minimize the total free energy, and form core-shell nanoparticles with active oil as the core and shellac and soybean lecithin or rhamnolipid or sophorolipid as the wall material. Furthermore, the uneven mixing during the nanosphere assembly process is the main reason for the poor structural and size uniformity. Figure 1-2As shown, a tiny nanoparticle suspension with a core-shell structure is introduced into the nanosphere assembly module 3. After air is injected into the channel, a continuous segmented flow of bubbles is generated in the serpentine microchannel, and secondary assembly of active oil nanoparticles occurs in the microfluidic cavity between the bubbles to generate a nanosphere suspension; ethanol in the suspension is removed to obtain high-purity active oil nanospheres. The present invention utilizes the improved heat and mass transfer in the microfluidic channel. The relative values ​​of the kinetic rate and mixing rate of the fluid on a micrometer scale, as well as the axial dispersion in the single-phase flow, determine the degree of aggregation and assembly of the resulting nanoparticle size. The fluid in the segmented microfluidic cavity generated by gas injection has rapid circulation mixing and efficient mass transfer of the liquid, so that the core-shell nanoparticles in the flow segmented microfluidic cavity can be further controlled to assemble into active oil nanospheres of uniform size.

[0079] The present invention is further described in detail below with specific examples, but the present invention is not limited to the following specific examples.

[0080] Example 1

[0081] like Figure 1 The microfluidic nanosphere embedding system in this embodiment is shown, which includes a microchannel compounding and mixing module 1, a core-shell structure nanoparticle generation module 2 and a nanosphere assembly module 3 connected in sequence. The specific structure is as follows:

[0082] The microchannel composite mixing flow module 1 comprises a first flow channel 11 , a second flow channel 12 and a mixing flow channel 13 . The feed ends of the first flow channel 11 and the second flow channel 12 respectively have a mixed wall material inlet 14 and an active oil inlet 15 , and the discharge ends are both connected to the mixing flow channel 13 .

[0083] In this embodiment, the number of the first flow channel 11, the second flow channel 12 and the mixing flow channel 13 are all 2, and the first flow channel 11 and the second flow channel 12 are all inclined relative to the horizontal direction. The two first flow channels 11 and the two second flow channels 12 are set at an angle, which can be 60° or 45°. The first flow channel 11 and the second flow channel 12 located on the same side are arranged in parallel, and the first flow channel 11 is located on the outside of the second flow channel 12. The feed ends of the two first flow channels 11 are connected to each other and the mixed wall material inlet 14 is set at the connection, and the feed ends of the two second flow channels 12 are connected to each other and the active oil inlet 15 is set at the connection, so that the materials entering from the mixed wall material inlet 14 and the active oil inlet 15 are divided into two and flow into the two first flow channels 11 and the two second flow channels 12.

[0084] In this embodiment, the mixing channel 13 includes three pipes with U-shaped cross-sections, and the three pipes are connected in sequence. The first channel 11 and the second channel 12 are both connected to the feed end of the first U-shaped pipe. Specifically, the discharge ends of the first channel 11 and the second channel 12 are arranged at right angles and enter the U-shaped pipe through the same feed port, that is, the materials entering from the first channel 11 and the second channel 12 are first mixed at the feed end of the U-shaped pipe to obtain a preliminary mixed material, and the preliminary mixed material is divided into two and flows to the two side channels of the U-shaped pipe; then enter the next U-shaped pipe, first mix again at the feed end, and then divide into two and flow to the two side channels of the U-shaped pipe, until all the U-shaped pipes are passed through, and the discharge end of the U-shaped pipe is connected to the feed end of the fourth channel 22 through a connecting pipe. In this embodiment, it is connected to the feed end of the fourth channel 22 through a right-angle elbow. The use of a U-shaped pipe is conducive to uniform mixing of materials.

[0085] The inner diameters of the first flow channel 11, the second flow channel 12, the mixing flow channel 13 and the right-angle elbow in the microchannel compounding and mixing module 1 are all kept consistent, and the preliminary dissolved liquid of the raw materials is finely remixed in this module to ensure the uniformity of the nanoparticles when they are formed in the next module.

[0086] The core-shell structure nanoparticle generation module 2 includes a third flow channel 21 and a fourth flow channel 22 connected to the side wall of the third flow channel 21, the feed end of the fourth flow channel 22 is connected to the mixing flow channel 13, and the discharge end is connected to the third flow channel 21, and a plurality of micro-columns 24 arranged in an array are arranged in the discharge end of the fourth flow channel 22, and the feed end of the third flow channel 21 has a water phase inlet 23.

[0087] In this embodiment, the inner diameter of the fourth flow channel 22 gradually increases from the feed end to the discharge end. Specifically, the cross section of the fourth flow channel 22 is a right-angle trapezoid, the mixing flow channel 13 is connected to the upper base of the trapezoid, and the third flow channel 21 is connected to the lower base of the trapezoid. A plurality of micro-pillars 24 arranged in an array are arranged in the discharge end of the fourth flow channel 22, and the spacing between the plurality of micro-pillars 24 is 50-100 microns. The micro-pillars 24 in this embodiment are cylindrical, and the "capillary phenomenon" effect similar to the transpiration of plants is used to achieve efficient, rapid and uniform mixing between solvents.

[0088] In this embodiment, a microchannel liquid one-way valve 25 is provided at the connection between the third flow channel 21 and the fifth flow channel 32 to ensure that the liquid does not flow back after the high-pressure gas is introduced.

[0089] The nanosphere assembly module 3 includes a gas injection pipeline 31, a fifth flow channel 32 and a sixth flow channel 33. The gas injection pipeline 31 is a T-shaped structure, including a gas input pipe with at least two gas input ports 34 connected on both sides, and a gas output port 35 connected in the middle. The diameter of the gas output port 35 is slightly smaller than the diameter of the gas input pipe 34. The gas input pipe is vertically arranged to the fifth flow channel 32, the gas injection pipeline 31 is embedded in the fifth flow channel 32, and the gas output port 35 is located at the center of the fifth flow channel 32. The feed end of the fifth flow channel 32 is connected to the discharge end of the third flow channel 21, and the discharge end is connected to the sixth flow channel 33. The sixth flow channel 33 has a discharge port 36. In this embodiment, the sixth flow channel 33 is serpentine, including 8 semicircular pipes and 10 straight pipes. The semicircular pipes and the straight pipes are connected in sequence, which ensures that the gas-propelled nanospheres can be stably assembled in the separated micro-liquid chambers with high efficiency. During the assembly process, the nanoparticles generate high-speed reflux in the axial direction of the liquid flow and between the gas-liquid interface, which is a necessary condition for the generation of nanospheres. On the other hand, the separated gas chambers ensure that the generated nanospheres will not be stacked, aggregated and assembled indefinitely, which is a necessary condition for size control.

[0090] This embodiment also provides a method for preparing nanospheres encapsulating active oils, which is specifically prepared by the above-mentioned microfluidic nanosphere encapsulation system, comprising:

[0091] Step 1: Weigh the shellac and soybean lecithin, dissolve them in anhydrous ethanol, and prepare a mixed alcohol-soluble wall material solution. The solution contains 4% shellac and 1% soybean lecithin, and centrifuges at 3000 rpm for 10 minutes to remove insoluble impurities and obtain the supernatant to obtain a wall material phase alcohol solution. The injection amounts of the wall material phase alcohol solution, algae oil, and purified water are 7mL / min, 7mL / min, and 35mL / min, respectively, and the mass ratio of the three is about 1:1:5. They are respectively introduced into the microfluidic nanosphere embedding system through the mixed wall material inlet 14, the active oil inlet 15, and the aqueous phase inlet 23. At this time, no air is introduced into it, and a continuous nanoparticle suspension is collected at the liquid outlet.

[0092] Step 2: After the liquid output is stable, continuous air is introduced into the microfluidic nanosphere embedding system through the gas input port 34, and the ratio of the air flow to the liquid flow is controlled to be 1:1, and the total flow of the gas-liquid two phases is 100 (mL / min) calculated according to a single microfluidic chip set, so that a microfluidic cavity separated by multiple sections of air bubbles is formed in the microchannel, and the flow is stable. When the air flow is adjusted to 1:1 with the total liquid flow, the nanoparticles are assembled in the microfluidic cavity under the circulation of axial and non-axial fluids, and nanospheres are formed.

[0093] Step 3: The emulsion of the formed nanospheres is subjected to molecular distillation to obtain a high-purity suspension of nanospheres free of ethanol.

[0094] Example 2

[0095] Step 1: The weighed shellac and soybean lecithin are dissolved in anhydrous ethanol to prepare a mixed alcohol-soluble wall material solution. The solution contains 4% shellac and 1% soybean lecithin, and is centrifuged at 3000 rpm for 10 minutes to remove insoluble impurities and obtain the supernatant to obtain a wall material phase alcohol solution. The injection amounts of the wall material phase alcohol solution, algae oil, and purified water are 1.4 mL / min, 1.4 mL / min, and 7 mL / min, respectively, and the mass ratio of the three is about 1:1:5. They are respectively introduced into the microfluidic nanosphere embedding system through the mixed wall material inlet 14, the active oil inlet 15, and the aqueous phase inlet 23. At this time, no air is introduced into it, and a continuous nanoparticle suspension is collected at the liquid outlet.

[0096] Step 2: After the liquid output is stable, continuous air is introduced into the microfluidic nanosphere embedding system through the gas input port 34, and the ratio of the air flow to the liquid flow is controlled to be 1:1, and the total flow of the gas-liquid two phases is 20 (mL / min) calculated according to a single microfluidic chip set, so that a microfluidic cavity separated by multiple air bubbles is formed in the microchannel, and the flow is stable. When the air flow is adjusted to 1:1 with the total liquid flow, the nanoparticles are assembled in the microfluidic cavity under the circulation of axial and non-axial fluids, and nanospheres are formed.

[0097] Step 3: The emulsion of the formed nanospheres is subjected to molecular distillation to obtain a high-purity suspension of nanospheres free of ethanol.

[0098] Example 3

[0099] Step 1: The weighed shellac and rhamnolipid are dissolved in anhydrous ethanol to prepare a mixed alcohol-soluble wall material solution. The solution contains 4% shellac and 1% soybean lecithin, and is centrifuged at 3000 rpm for 10 minutes to remove insoluble impurities and obtain the supernatant to obtain a wall material phase alcohol solution. The injection amounts of the wall material phase alcohol solution, algae oil, and purified water are 7mL / min, 7mL / min, and 35mL / min, respectively, and the mass ratio of the three is about 1:1:5. They are respectively introduced into the microfluidic nanosphere embedding system through the mixed wall material inlet 14, the active oil inlet 15, and the aqueous phase inlet 23. At this time, no air is introduced into it, and a continuous nanoparticle suspension is collected at the liquid outlet.

[0100] Step 2: After the liquid output is stable, continuous air is introduced into the microfluidic nanosphere embedding system through the gas input port 34, and the ratio of the air flow to the liquid flow is controlled to be 1:1, and the total flow of the gas-liquid two phases is 100 (mL / min) calculated according to a single microfluidic chip set, so that a microfluidic cavity separated by multiple sections of air bubbles is formed in the microchannel, and the flow is stable. When the air flow is adjusted to 1:1 with the total liquid flow, the nanoparticles are assembled in the microfluidic cavity under the circulation of axial and non-axial fluids, and nanospheres are formed.

[0101] Step 3: The emulsion of the formed nanospheres is subjected to molecular distillation to obtain a high-purity suspension of nanospheres free of ethanol.

[0102] Example 4

[0103] Step 1: The weighed shellac and sophorolipids are dissolved in anhydrous ethanol to prepare a mixed alcohol-soluble wall material solution. The solution contains 4% shellac and 1% soybean lecithin, and is centrifuged at 3000 rpm for 10 minutes to remove insoluble impurities and obtain the supernatant to obtain a wall material phase alcohol solution. The injection amounts of the wall material phase alcohol solution, algae oil, and purified water are 7mL / min, 7mL / min, and 35mL / min, respectively, and the mass ratio of the three is about 1:1:5. They are respectively introduced into the microfluidic nanosphere embedding system through the mixed wall material inlet 14, the active oil inlet 15, and the aqueous phase inlet 23. At this time, no air is introduced into it, and a continuous nanoparticle suspension is collected at the liquid outlet.

[0104] Step 2: After the liquid output is stable, continuous air is introduced into the microfluidic nanosphere embedding system through the gas input port 34, and the ratio of the air flow to the liquid flow is controlled to be 1:1, and the total flow of the gas-liquid two phases is 100 (mL / min) calculated according to a single microfluidic chip set, so that a microfluidic cavity separated by multiple sections of air bubbles is formed in the microchannel, and the flow is stable. When the air flow is adjusted to 1:1 with the total liquid flow, the nanoparticles are assembled in the microfluidic cavity under the circulation of axial and non-axial fluids, and nanospheres are formed.

[0105] Step 3: The emulsion of the formed nanospheres is subjected to molecular distillation to obtain a high-purity suspension of nanospheres free of ethanol.

[0106] Comparative Example 1

[0107] This embodiment provides a method for preparing nanospheres encapsulating active oils. The difference from Example 1 is that Comparative Example 2 does not use the above-mentioned microfluidic nanosphere encapsulation system, but uses a direct mixing method, which specifically includes:

[0108] Step 1: Weigh the shellac and active oils and dissolve them in ethanol solution and centrifuge at 3000 rpm for 10 minutes.

[0109] In Comparative Example 1, soybean lecithin was used as an emulsifier to emulsify the alcohol-soluble mixture under strong stirring. It was found that the oil phase and the water phase were separated and large particles were precipitated. Almost no nanospheres were produced in the solution, and subsequent operations could not be performed.

[0110] Comparative Example 2

[0111] This embodiment provides a method for preparing nanospheres encapsulating active oils. The difference from Example 1 is that Comparative Example 2 does not use the above-mentioned microfluidic nanosphere encapsulation system, but uses a disperser, specifically comprising:

[0112] Step 1: Weigh the shellac and soybean lecithin, dissolve them in anhydrous ethanol to prepare a mixed alcohol-soluble wall material solution. The solution contains 4% shellac, 1% soybean lecithin, and 4% algae oil, and centrifuge at 3000 rpm for 10 minutes to remove insoluble impurities and obtain the alcohol-soluble mixed solution. Mix with pure water and pass it into the liquid inlet of the disperser, and collect the continuous nanosphere suspension at the liquid outlet.

[0113] Step 2: The nanosphere emulsion is subjected to molecular distillation to obtain a high-purity suspension of nanospheres that does not contain ethanol.

[0114] Results test:

[0115] The nanospheres prepared in Examples 1 to 4 and Comparative Example 2 were observed under a scanning electron microscope, and the oxidation stability of the nanospheres prepared in Examples 1 to 4 and Comparative Example 2 was tested. The test method is as follows:

[0116] Oxidation stability test

[0117] Determination method of primary oxidation products (POV value): The primary oxidation product of oil oxidation, hydroperoxide, is characterized by POV value. Take 0.3mL of sample solution and mix it with 1.5mL of isooctane / isopropanol (3:1, v / v), shake it thoroughly, and centrifuge it at 1000g centrifugal force at room temperature for 2min. Then, take 0.2mL of the organic layer after centrifugation and mix it with 2.8mL of methanol / n-butanol (2:1, v / v), and then add 15μL NH4SCN (3.94mol / L) and 15μL Fe 2+ Mix the two solutions (prepared before use), react for 20 minutes in a dark environment, measure the absorbance at a wavelength of 510 nm, and use cumene hydroperoxide to make a standard curve to calculate the POV value.

[0118] Determination method of secondary oxidation products (TBARS value): Malondialdehyde (MDA) is the main secondary oxidation product of lipid oxidation. Under heating conditions, 2-thiobarbituric acid (TBA) reacts with MDA to generate a red substance, which can be used to measure the content of MDA to evaluate the degree of secondary oxidation. Take 1mL of sample solution and mix it with 2mL TBA solution (15% trichloroacetic acid + 0.375% TBA dissolved in 0.25mol / L HCl solution), shake it thoroughly, heat it in a 95℃ water bath for 15min, cool it to room temperature, centrifuge it at 1000g centrifugal force and room temperature for 10min, take the supernatant and measure the absorbance at a wavelength of 532nm, and use 1,1,3,3-tetraethoxypropane to make a standard curve to calculate the TBARS value.

[0119] The scanning electron microscopy images of the nanospheres prepared in Examples 1 to 4 and Comparative Example 2 are as follows: Figure 2 As shown by Figure 2 It can be seen that the nanospheres prepared in Examples 1 to 4 have a pollen-like structure that aggregates into balls, that is, large-particle nanospheres are assembled from small-particle nanoparticles. Compared with Examples 1 to 4, the nanospheres obtained in Comparative Example 2 have no characteristic structure and large particles and heavy adhesion. This shows that the use of the microfluidic nanosphere embedding system of the present invention is conducive to ensuring the consistency and stability of the formation of nanospheres, and Example 1 in the comparative example has the smallest nanosphere particle size, indicating that different biosurfactants and the total flow rate in the chip after air is introduced will affect the assembly process and final particle size of the prepared nanospheres. When the total flow rate is 100 (mL / min) for a single microfluidic chip and soybean lecithin is used as a biosurfactant, the preparation effect is best.

[0120] The actual product of the nanosphere suspension prepared in Examples 1 to 4 and Comparative Example 2 is as follows: Figure 3 As shown, among the appearances presented in Examples 1 to 4, Example 1 has the best light transmittance, is stable and has no precipitation, and is clear and transparent in appearance compared to Comparative Example 2. Nanospheres with small particle sizes generally have a clearer appearance, which is consistent with the microstructure diagram of the nanospheres. This shows that the microfluidic nanosphere embedding system of the present invention is conducive to the production of a single emulsion of nanospheres with a pollen-like aggregation structure, and the obtained nanosphere droplets have high quality and good particle size controllability.

[0121] Oxidation stability test structure see Figure 4 ,Depend on Figure 4It can be seen that the production of primary oxidation products (POV) and secondary oxidation products (TBARS) in Examples 1-4 are less than that in Comparative Example 2, indicating that the oxidative stability of the nanospheres prepared in Examples 1 to 4 is better than that in Comparative Example 2. And when the ratio of shellac to soybean lecithin is 4:1, and the total flow rate of the gas-liquid two phases is 100 (mL / min) for a single microfluidic chip, the oxidative stability of the active oil nanospheres is the best. Different lipid biosurfactants will affect the oxidative stability of the prepared nanospheres. When soybean lecithin is used as the biosurfactant, the oxidative stability of the nanospheres is the best.

[0122] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A microfluidic nanosphere embedding system, characterized in that: include: A microchannel composite mixed flow module (1), comprising a first flow channel (11), a second flow channel (12) and a mixing flow channel (13), wherein the feed ends of the first flow channel (11) and the second flow channel (12) are respectively provided with a mixed wall material inlet (14) and an active oil inlet (15), and the discharge ends are both connected to the mixing flow channel (13); A core-shell structure nanoparticle generation module (2), comprising a third flow channel (21) and a fourth flow channel (22) connected to the side wall of the third flow channel (21), wherein the feed end of the fourth flow channel (22) is connected to the mixing flow channel (13), and the discharge end is connected to the third flow channel (21), a plurality of micro-pillars (24) arranged in an array are arranged in the discharge end of the fourth flow channel (22), and the feed end of the third flow channel (21) has a water phase inlet (23); A nanosphere assembly module (3) comprises a gas injection pipeline (31), a fifth flow channel (32) and a sixth flow channel (33), wherein the feed end of the fifth flow channel (32) is connected to the discharge end of the third flow channel (21), and the discharge end is connected to the sixth flow channel (33), the sixth flow channel (33) is provided with a discharge port (36), and the gas injection pipeline (31) is provided with a gas input port (34) and a gas output port (35) connected to the fifth flow channel (32).

2. The microfluidic nanosphere embedding system according to claim 1, characterized in that: The mixing channel (13) comprises at least one pipe with a U-shaped cross section, the first channel (11) and the second channel (12) are both connected to the feed end of the U-shaped pipe, and the discharge end of the U-shaped pipe is connected to the feed end of the fourth channel (22) via a connecting pipe.

3. The microfluidic nanosphere embedding system according to claim 1, characterized in that: The inner diameter of the fourth flow channel (22) gradually increases from the feed end to the discharge end, and the spacing between the plurality of micro-pillars (24) is 50-100 microns.

4. The microfluidic nanosphere embedding system according to claim 1, characterized in that: The gas input port (34) is arranged at both ends of the gas injection pipeline (31), and the gas output port (35) is arranged at the middle end of the gas injection pipeline (31); the diameter of the gas output port (35) is smaller than the diameter of the gas input port (34); and the gas output port (35) is embedded in the fifth flow channel (32) and is located at the center of the fifth flow channel (32).

5. The microfluidic nanosphere embedding system according to claim 1, characterized in that: The sixth flow channel (33) comprises a plurality of linear pipelines and curved pipelines connected in sequence.

6. A method for preparing active oil nanospheres, characterized in that: The preparation is carried out using the microfluidic nanosphere embedding system as described in any one of claims 1 to 5, and the preparation method comprises the following steps: S1, dissolving shellac and soybean lecithin or rhamnolipid or sophorolipid in a solvent, stirring, and centrifuging to obtain a mixed solution of a good solvent; S2, mixing the mixed solution of the good solvent in step S1 with the active oil to form a stable alcohol-soluble mixed solution; S3, mixing the alcohol-soluble mixed solution in step S2 with water to perform preliminary nano-assembly to generate a suspension of tiny nanoparticles with a core-shell structure; S4, passing the tiny nanoparticle suspension in step S3 into a microchannel, and passing air into the microchannel, wherein the air generates continuous segmented bubbles in the microchannel, so that the continuous tiny nanoparticle suspension in the microchannel is divided into multiple segments; S5, controlling the flow rate of the air to adjust the interval and flow speed of the bubbles in the microchannel, so that the tiny nanoparticle suspension is assembled into nanospheres to obtain a uniform nanosphere suspension; S6, removing the solvent in the uniform nanosphere suspension in step S5 to obtain active lipid nanospheres.

7. The preparation method according to claim 6, characterized in that: In step S2, the mixed solution of the good solvent and the active oil are respectively injected into the mixed wall material inlet (14) and the active oil inlet (15), and the mixed solution of the good solvent and the active oil enter the mixing flow channel (13) through the first flow channel (11) and the second flow channel (12) respectively, and are uniformly mixed in the mixing flow channel (13) to form a stable alcohol-soluble mixed solution; In step S3, water is introduced into the third flow channel (21) through the aqueous phase inlet (23), the alcohol-soluble mixed solution enters the third flow channel (21) through the fourth flow channel (22) and mixes with the water, the alcohol-soluble mixed solution and the water undergo preliminary nano-assembly, and a tiny nanoparticle suspension with a core-shell structure is generated in the third flow channel (21).

8. The preparation method according to claim 7, characterized in that: In step S4, the micro-nano particle suspension enters the fifth flow channel (32), air is introduced into the gas injection pipe (31) through the gas input port (34), and the air enters the fifth flow channel (32) through the gas output port (35), and the air generates continuous segmented bubbles in the fifth flow channel (32), so that the continuous micro-nano particle suspension in the fifth flow channel (32) is divided into multiple segments; In step S5, the micro-nanoparticle suspension enters the sixth flow channel (33), and the flow rate of the introduced air is controlled to regulate the spacing and flow speed of the bubbles in the microchannel, so that the micro-nanoparticle suspension generates an axial flow in the sixth flow channel (33) and generates a high-speed reflux at the air-liquid interface to assemble nanospheres, thereby obtaining a uniform nanosphere suspension.

9. The preparation method according to claim 8, characterized in that: In step S5, the ratio of the air flow rate to the liquid flow rate introduced into the sixth flow channel is controlled to be maintained at 1:1, and the total flow rate of the liquid and air in the sixth flow channel is adjusted to be 20-150 mL / min.

10. An active oil nanosphere, characterized in that: The active oil nanospheres obtained by the method described in any one of claims 6 to 9 have a size within 200 nanometers, a uniform particle size distribution, a clear and transparent appearance, and stable oil antioxidant properties.

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