High-load curcumin water-soluble nanocrystal prepared by using microfluidic device and method for preparing high-load curcumin water-soluble nanocrystal

Abstract

The invention discloses a high-load curcumin water-soluble nanocrystal prepared by a microfluidic device and a method thereof, and relates to the technical field of nanocrystal processing, the microfluidic device comprises a molecule assembly section and a nanocrystal assembly section, the molecule assembly section comprises a feeding micro-channel and a molecule assembly channel, and the nanocrystal assembly section comprises a nanocrystal assembly channel. The nanocrystal assembling section comprises at least one nanocrystal assembling channel of a spiral backflow structure. The method comprises the following steps: S1, preparing a soybean protein isolate solution, a rhamnolipid solution and a curcumin solution; s2, respectively introducing the materials into a feeding micro-channel, firstly mixing the soybean protein isolate solution and the rhamnolipid solution, then enabling the mixture and the curcumin solution to enter a molecular assembly channel together, and mixing for molecular assembly; and S3, continuing to enter the nanocrystal assembly channel for nanocrystal assembly to obtain the nanocrystal. According to the invention, a microfluidic technology is combined with a pH driving method, so that highly accurate control on the size of the nanocrystal is successfully realized, and the encapsulation efficiency, the loading capacity and the water solubility of the nanocrystal are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of nanocrystal processing, and in particular to a microfluidic device for preparing water-soluble nanocrystals with high curcumin loading and a method thereof. Background Art

[0002] Curcumin is a curcuminoid hydrophobic bioactive substance extracted from the rhizomes of plants in the Zingiberaceae and Araceae families. As a rare natural orange-yellow colorant with a diketone structure in nature, it has low toxicity and a broad spectrum of biological and pharmacological activities, such as antioxidant, anti-inflammatory, anticancer and antibacterial activities. Therefore, curcumin shows great application potential. However, curcumin has extremely low solubility and bioavailability in acidic environments, and is easily degraded under light or high temperature conditions. These defects seriously limit its application. Therefore, how to improve the solubility and stability of curcumin is an urgent problem to be solved.

[0003] Nanocrystals refer to tiny particles with a diameter in the nanometer range. Compared with ordinary micron-sized particles, nanocrystals have unique characteristics such as small size and large specific surface area. Therefore, they are widely used to encapsulate fat-soluble bioactive substances to improve their water solubility and bioavailability. This makes nanocrystals have broad application prospects in many fields, especially in the delivery of functional bioactive substances. As the application prospects of nanocrystals continue to broaden, various methods for preparing nanocrystals emerge in an endless stream. However, most of the existing methods for preparing nanocrystals use organic solvents, which may cause certain biological toxic effects, thereby affecting their biosafety. In addition, nanocrystals prepared by existing methods also have problems with low encapsulation efficiency and loading capacity.

[0004] The pH-driven method is a method that controls the formation and assembly of nanoparticles by adjusting the pH of the solution. This method uses the property that the solubility and charge of the solute change with pH, ​​so that the solute undergoes molecular interactions and spontaneously assembles into stable nanocrystals during the pH change. Compared with traditional chemical methods, pH-driven methods are simple and efficient, do not require organic solvents, and have good application potential in large-scale production in the food industry. However, as a thermodynamic self-assembly method, the nanoparticles prepared by the pH-driven method are not stable enough in mass production and are prone to aggregation or precipitation. In addition, the encapsulation efficiency and loading capacity of the nanocrystals are low, affecting their controlled release effect.

[0005] Microfluidics is an emerging interdisciplinary subject involving chemistry, fluid physics, new materials and biomedical engineering. Compared with the traditional thermodynamically controlled nanocrystal preparation process, the kinetic regulation of microfluidics has the advantages of strong controllability, efficient reaction, high throughput, high integration and strong repeatability. However, the microfluidic devices in the prior art have a general effect on the assembly of nanocrystals. This may be because the structure of the microfluidic devices in the prior art is unreasonable, resulting in uncontrollable precipitation due to excessively high or low local pH in the channel, and unable to ensure the uniform embedding of bioactive substances and biopolymers, thereby failing to obtain nanocrystals with uniform distribution and stable structure. Summary of the invention

[0006] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art. In view of the problems that curcumin crystals or curcumin complexes have "extremely low solubility and bioavailability, low encapsulation efficiency and loading capacity, easy degradation under light or high temperature conditions, and potential biological toxicity of organic solvents", a microfluidic device is provided to prepare water-soluble nanocrystals with high curcumin loading and a method thereof.

[0007] The present invention designs a microfluidic device, and the microchannel design of the microfluidic device of the present invention can shorten the mixing length and mixing time of the self-assembly of nanocrystals, and prevent the nanocrystals from excessively aggregating or precipitating. In this process, curcumin is dissolved in an alkaline solution, and the biopolymer is dissolved in an acidic solution. By adjusting the parameters such as the inner diameter of the pipeline and the fluid flow rate of the microfluidic chip, rapid material exchange is achieved, so that curcumin and the biopolymer are controllably assembled into nanocrystals under non-covalent action, and the use of organic solvents is avoided in the entire preparation process. The present invention uses soy protein isolate / rhamnolipid nanocrystals as a water-soluble biopolymer carrier of curcumin, wherein the soy protein isolate is mainly responsible for providing a stable carrier environment and improving bioavailability, and rhamnolipid is used as an effective surfactant to enhance the solubility of curcumin and the absorption efficiency in the body. The ternary complex nanocrystals prepared by the present invention are assembled by hydrogen bonds and hydrophobic interactions, and the preparation process is simple, fast, safe and efficient, and has broad application prospects in the fields of food, cosmetics and medicine.

[0008] The technical solution of the present invention is as follows:

[0009] The first aspect of the present invention provides a method for preparing water-soluble nanocrystals with high curcumin loading using a microfluidic device.

[0010] The microfluidic device comprises a molecular assembly section and a nanocrystal assembly section, wherein the molecular assembly section comprises a feed microchannel and a molecular assembly channel, and the nanocrystal assembly section comprises at least one nanocrystal assembly channel in a spiral reflux structure; the feed microchannel, the molecular assembly channel and the nanocrystal assembly channel are connected in sequence, the feed microchannel has a feed port, and the nanocrystal assembly channel has a discharge port;

[0011] The method for preparing water-soluble nanocrystals with high curcumin loading using the microfluidic device comprises the following steps:

[0012] S1, dissolving soy protein isolate in an aqueous solution, refrigerating, and obtaining a soy protein isolate solution; dissolving rhamnolipid in an aqueous solution, obtaining a rhamnolipid solution; dissolving curcumin in an aqueous solution, and ultrasonicating to obtain a curcumin solution;

[0013] S2, introducing the soy protein isolate solution, the rhamnolipid solution and the curcumin solution into the feed microchannel through the feed port, respectively, wherein the soy protein isolate solution and the rhamnolipid solution are first mixed, and then enter the molecular assembly channel together with the curcumin solution to mix and perform molecular assembly;

[0014] S3, continuing to enter the nanocrystal assembly channel to assemble nanocrystals to obtain water-soluble nanocrystals with high curcumin loading.

[0015] Preferably, in step S1, the mass ratio of curcumin to soy protein isolate and rhamnolipid is 1:2-8:2-8.

[0016] Preferably, in step S1,

[0017] Weighing soy protein isolate with a purity of more than 90% and dissolving it in an aqueous solution, refrigerating it at 0-4°C for 8-24 hours after it is fully dissolved, and adjusting the pH to 2-3 with 0.1-2 mol / L HCl to obtain a soy protein isolate solution with a concentration of 7-9%;

[0018] Weigh rhamnolipid with a purity of more than 95% and dissolve it in an aqueous solution, and use 0.1-2 mol / L HCl to adjust the pH to 2-3 to obtain a rhamnolipid solution with a concentration of 7-9%;

[0019] Curcumin with a purity of more than 95% is weighed and dissolved in an aqueous solution with a pH of 11 to 12, and ultrasonicated for 4 to 6 minutes to prepare a 3.0 to 5.0 mg / mL curcumin solution.

[0020] Preferably, the inner diameters of the feed microchannel, the molecular assembly channel and the nanocrystal assembly channel are all 0.5-1.2 mm, and the flow rates of the soy protein isolate solution, rhamnolipid solution and curcumin solution in the molecular assembly channel and the nanocrystal assembly channel are all 0.7-0.9 m / s.

[0021] Preferably, the feed microchannel comprises a first feed microchannel and a second feed microchannel, the feed end of the first feed microchannel has a first feed port; the feed end of the second feed microchannel has a second feed port and a third feed port, and the discharge end of the first feed microchannel and the discharge end of the second feed microchannel are both connected to the feed end of the molecular assembly channel;

[0022] In step S2, the curcumin solution is introduced into the first feed microchannel through the first feed port, and the soy protein isolate solution and the rhamnolipid solution are respectively introduced into the second feed microchannel through the second feed port and the third feed port, the soy protein isolate solution and the rhamnolipid solution are first mixed in the second feed microchannel, and then enter the molecular assembly channel together with the curcumin solution in the first feed microchannel for mixing and molecular assembly.

[0023] Preferably, the first feed microchannel is circular or arc-shaped, the first feed port and the molecular assembly channel are respectively arranged at both ends of the first feed microchannel, and the second feed microchannel includes two feed channels and a mixing channel, the two feed channels and the mixing channel are arranged at an angle, and the mixing channel and the molecular assembly channel are arranged in a straight line.

[0024] Preferably, the nanocrystal assembly channel includes a first arc, a second arc, a third arc, a fourth arc and a fifth arc connected in sequence, the openings of the first arc, the third arc and the fifth arc are facing upward, the openings of the second arc and the fourth arc are facing downward, the first arc, the second arc and the fifth arc all extend in a direction away from the molecular assembly section, and the third arc and the fourth arc both extend in a direction close to the molecular assembly section to form a spiral reflux structure, and the sum of the diameters of the third arc and the fourth arc is smaller than the diameter of the second arc.

[0025] Preferably, the radii of the first arc, the second arc, the third arc, the fourth arc and the fifth arc are 7-8 cm, 12-13 cm, 3-4 cm, 3-4 cm and 7-8 cm respectively.

[0026] Preferably, the number of the nanocrystal assembly channels is 2 to 6, and the 2 to 6 nanocrystal assembly channels are sequentially connected to form the nanocrystal assembly section.

[0027] The second aspect of the present invention provides a water-soluble nanocrystal with high curcumin loading, which is prepared by the above method.

[0028] The particle size of the nanocrystal of the invention is 50-160nm, the encapsulation rate of curcumin is greater than 90%, and the loading capacity of curcumin is greater than 7%.

[0029] The present invention has at least one of the following beneficial effects:

[0030] 1. The present invention innovatively adopts microfluidic technology combined with pH driving method, successfully realizes highly accurate control of nanocrystal size, and significantly improves the encapsulation rate, loading capacity and water solubility of nanocrystals. The present invention prepares nanocrystals with high consistency and good stability based on spiral reflux microfluidic chips. By using specific biopolymers as wall materials, hydrophobic bioactive substances such as curcumin can be efficiently encapsulated, thereby significantly improving the encapsulation rate, loading capacity, stability, solubility and bioaccessibility of hydrophobic bioactive substances. Microfluidic technology itself has the advantages of simple operation and low energy consumption, and no organic solvents are used in the entire preparation process, making this technology particularly suitable for application in food, cosmetics and pharmaceutical industries. Compared with the traditional pH-driven method, the innovative preparation method of the present invention can produce curcumin nanocrystals with higher encapsulation rate and loading capacity, significantly improving the bioavailability and stability of curcumin. This technological breakthrough has laid the foundation for the wide application of curcumin in the fields of food and medicine.

[0031] 2. In the preparation method of the present invention, rhamnolipid is first inserted into the hydrophobic pocket of soy protein isolate, and linked with the amino acid residues of soy protein isolate through hydrogen bonds and hydrophobic interactions to form a binary complex. The binary complex is further combined with curcumin through hydrogen bonds and hydrophobic interactions to form a ternary complex. These non-covalent interactions not only stabilize the structure of the complex, but also improve the water solubility of curcumin and enhance its biocompatibility.

[0032] 3. The present invention systematically characterizes and compares the effects of the combined application of microfluidic technology and pH-driven method and the use of pH-driven method alone on the nano-delivery system, laying a theoretical foundation for the development of more efficient nano-drug delivery systems.

[0033] 4. The present invention innovates a method for preparing nanocrystals. The method is simple and efficient to operate, does not require organic solvents, and uses a carrier with good biocompatibility. These advantages make the method have significant economic and environmental benefits and is very conducive to commercial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the structure of the microfluidic device in Example 1 of the present invention;

[0035] Figure 2 It is a schematic diagram of a part of the structure of the microfluidic device in Example 1 of the present invention;

[0036] Figure 3Schematic diagrams of the structures of the microfluidic devices in Comparative Examples 4 to 6 of the present invention, wherein A is a schematic diagram of the structure of the microfluidic device in Comparative Example 4, B is a schematic diagram of the structure of the microfluidic device in Comparative Example 5, and C is a schematic diagram of the structure of the microfluidic device in Comparative Example 6;

[0037] Reference numerals:

[0038] 1. Molecular assembly section; 11. First feed microchannel; 12. Second feed microchannel; 13. Molecular assembly channel; 14. First feed inlet; 15. Second feed inlet; 16. Third feed inlet;

[0039] 2. Nanocrystal assembly section; 21. Nanocrystal assembly channel; 22. First circular arc; 23. Second circular arc; 24. Third circular arc; 25. Fourth circular arc; 26. Fifth circular arc; 27. Discharge port.

[0040] Figure 4 This is a scanning electron microscope image of the nanocrystal prepared in Example 1 of the present invention;

[0041] Figure 5 This is a scanning electron microscope image of the nanocrystal prepared in Example 2 of the present invention;

[0042] Figure 6 This is a scanning electron microscope image of the nanocrystal prepared in Example 3 of the present invention;

[0043] Figure 7 This is a scanning electron microscope image of the nanocrystal prepared in Comparative Example 1 of the present invention;

[0044] Figure 8 This is a scanning electron microscope image of the nanocrystal prepared in Comparative Example 2 of the present invention;

[0045] Fig. 9 This is a scanning electron microscope image of the nanocrystal prepared in Comparative Example 3 of the present invention;

[0046] Fig.10 This is a scanning electron microscope image of the nanocrystal prepared in Comparative Example 4 of the present invention;

[0047] Fig.11 This is a scanning electron microscope image of the nanocrystal prepared in Comparative Example 5 of the present invention;

[0048] Fig.12 This is a scanning electron microscope image of the nanocrystal prepared in Comparative Example 6 of the present invention;

[0049] Fig.13 This is a scanning electron microscope image of the nanocrystals prepared in Comparative Example 7 of the present invention. DETAILED DESCRIPTION

[0050] 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.

[0051] One embodiment of the present invention provides a method for preparing water-soluble nanocrystals with high curcumin loading using a microfluidic device.

[0052] like Figures 1-2 As shown, the microfluidic device includes a molecular assembly section 1 and a nanocrystal assembly section 2, the molecular assembly section 1 includes a feed microchannel and a molecular assembly channel 13, and the nanocrystal assembly section 2 includes at least one nanocrystal assembly channel 21; the feed microchannel, the molecular assembly channel 13 and the nanocrystal assembly channel 21 are connected in sequence, the feed microchannel has a feed port, the nanocrystal assembly channel 21 has a discharge port 27, and the nanocrystal assembly channel 21 has a spiral reflux structure;

[0053] The method for preparing water-soluble nanocrystals with high curcumin loading using the microfluidic device comprises the following steps:

[0054] S1, dissolving soy protein isolate in an aqueous solution, refrigerating, and obtaining a soy protein isolate solution; dissolving rhamnolipid in an aqueous solution, obtaining a rhamnolipid solution; dissolving curcumin in an aqueous solution, and ultrasonicating to obtain a curcumin solution;

[0055] S2, respectively introducing the soy protein isolate solution, the rhamnolipid solution and the curcumin solution into the feed microchannel through the feed port, wherein the soy protein isolate solution and the rhamnolipid solution are first mixed, and then enter the molecular assembly channel 13 together with the curcumin solution to mix and perform molecular assembly;

[0056] S3, continue entering the nanocrystal assembly channel 21 to assemble nanocrystals to obtain water-soluble nanocrystals with high curcumin loading.

[0057] Figure 1 This is a schematic diagram of the structure of the microfluidic device with a spiral reflux structure used in the present invention. When the three-phase solution intersects, although the flow resistance is large, due to the physical property differences (density, viscosity, surface tension, etc.) between the three phases and the existence of obstacles, the speed may be locally accelerated or slowed down near the confluence point, forming two different flow modes: laminar flow and turbulent flow. This change in flow behavior is conducive to improving the mass transfer efficiency between fluids, reducing mixing time, and improving fluid mixing effects. The specific principles are as follows:

[0058] Molecular assembly stage: The main function of this stage is to ensure the uniform distribution of different molecules. Through the precise control of the microfluidic chip, efficient mixing of fluids in tiny channels can be achieved. At this stage, the mixed molecules begin to undergo preliminary chemical reactions, such as coordination, ionic bond formation, or the formation of other chemical bonds. In addition, the reaction conditions can be optimized by controlling parameters such as pH, concentration, and flow rate to create ideal conditions for the subsequent assembly process and ensure that it can proceed smoothly. During the molecular assembly process, rhamnolipids first insert into the hydrophobic pocket of soy protein isolate and bind to the amino acid residues of soy protein isolate through hydrogen bonds and hydrophobic interactions to form a binary complex. This binding order causes the binary complex to provide more binding sites for curcumin, which helps to form a stable ternary complex. The binary complex then binds to curcumin through hydrogen bonds and hydrophobic interactions to form a ternary complex. These non-covalent interactions not only stabilize the structure of the complex, but also improve the water solubility and bioavailability of curcumin.

[0059] Nanocrystal assembly stage: This stage mainly uses the precise control ability of microfluidics to achieve the orderly assembly and precise positioning of nanocrystals in a microscale environment. This process begins with the nucleation stage of the nanocrystals in the solution, where the initial core gradually grows and eventually evolves into a stable nanocrystal structure. Microfluidics technology achieves precise control of molecular movement and positioning by precisely controlling the flow conditions such as the flow rate and flow rate of the fluid, enabling it to be precisely assembled into nanostructures with specific sizes and functions, while ensuring that the nanocrystals are evenly dispersed in the solution to prevent them from agglomerating.

[0060] In some specific embodiments of the present invention, in step S1, the mass ratio of curcumin to soy protein isolate and rhamnolipid is 1:2-8:2-8, preferably 1:3-7:3-7, and more preferably 1:4-6:4-6.

[0061] In some specific embodiments of the present invention, in step S1,

[0062] Weighing soy protein isolate with a purity of more than 90% and dissolving it in an aqueous solution, refrigerating it at 0-4°C for 8-24 hours after it is fully dissolved, and adjusting the pH to 2-3 with 0.1-2 mol / L HCl to obtain a soy protein isolate solution with a concentration of 7-9%;

[0063] Preferably, after being fully dissolved, the mixture is refrigerated at 1 to 4° C. for 12 to 24 hours, and the pH is adjusted to 2.2 to 2.8 using 1 to 2 mol / L HCl to obtain a soy protein isolate solution with a concentration of 7.5 to 8.5%;

[0064] More preferably, after being fully dissolved, the solution is refrigerated at 3-4° C. for 16-24 hours, and the pH is adjusted to 2.4-2.6 using 1-2 mol / L HCl to obtain a soy protein isolate solution with a concentration of 7.7-8.3%.

[0065] In some specific embodiments of the present invention, in step S1,

[0066] Weigh rhamnolipid with a purity of more than 95% and dissolve it in an aqueous solution, and use 0.1-2 mol / L HCl to adjust the pH to 2-3 to obtain a rhamnolipid solution with a concentration of 7-9%;

[0067] Preferably, rhamnolipid with a purity of >95% is weighed and dissolved in an aqueous solution, and the pH is adjusted to 2.2-2.8 using 1-2 mol / L HCl to obtain a rhamnolipid solution with a concentration of 7.5-8.5%;

[0068] More preferably, rhamnolipid with a purity of >95% is weighed and dissolved in an aqueous solution, and the pH is adjusted to 2.4-2.6 using 1-2 mol / L HCl to obtain a rhamnolipid solution with a concentration of 7.7-8.3%;

[0069] In some specific embodiments of the present invention, in step S1,

[0070] Curcumin with a purity of more than 95% is weighed and dissolved in an aqueous solution with a pH of 11 to 12, and ultrasonicated for 4 to 6 minutes to prepare a 3.0 to 5.0 mg / mL curcumin solution.

[0071] Preferably, curcumin with a purity of >95% is weighed and dissolved in an aqueous solution with a pH of 11.4 to 12, and ultrasonicated for 4.5 to 5.5 minutes to obtain a 3.5 to 4.5 mg / mL curcumin solution.

[0072] Preferably, curcumin with a purity of >95% is weighed and dissolved in an aqueous solution with a pH of 11.6 to 12, and ultrasonicated for 4.8 to 5.2 minutes to obtain a 3.7 to 4.3 mg / mL curcumin solution.

[0073] In some specific embodiments of the present invention, the inner diameters of the feed microchannel, the molecular assembly channel 13, and the nanocrystal assembly channel 21 are all 0.5-1.2 mm, and the flow rates of the soy protein isolate solution, rhamnolipid solution, and curcumin solution in the molecular assembly channel 13 and the nanocrystal assembly channel 21 are all 0.7-0.9 m / s.

[0074] Another embodiment of the present invention is a water-soluble nanocrystal with high curcumin loading prepared by the above method, wherein the particle size of the nanocrystal is 50-160 nm, the encapsulation efficiency of curcumin is greater than 90%, and the loading capacity of curcumin is greater than 7%.

[0075] The present invention is further described in detail below with specific examples, but the present invention is not limited to the following specific examples.

[0076] Example 1

[0077] like Figures 1-2 The structure diagram of the microfluidic device in this embodiment is shown, which includes two parts: molecular assembly section 1 and nanocrystal assembly section 2. The main function of molecular assembly section 1 is to ensure the uniform distribution of different molecules. Through the precise control of the microfluidic chip, efficient mixing of fluids in microchannels can be achieved; nanocrystal assembly stage 2 uses the precise control capability of microfluidic technology to achieve orderly assembly and precise positioning of nanocrystals in a microscale environment. The specific structure is as follows:

[0078] The molecular assembly section 1 includes a feed microchannel and a molecular assembly channel 13. In this embodiment, the feed microchannel includes a first feed microchannel 11 and a second feed microchannel 12. The feed end of the first feed microchannel 11 has a first feed port 14; the feed end of the second feed microchannel 12 has a second feed port 15 and a third feed port 16. The discharge end of the first feed microchannel 11 and the discharge end of the second feed microchannel 12 are both connected to the feed end of the molecular assembly channel 13.

[0079] The first feed microchannel 11 is circular or arc-shaped, and is circular in the present embodiment. The first feed port 14 and the molecular assembly channel 13 are respectively arranged at both ends of the first feed microchannel 11. The second feed microchannel 12 includes two feed channels and a mixing channel. The two feed channels and the mixing channel are arranged at an angle, and the mixing channel and the molecular assembly channel 13 are arranged in a straight line.

[0080] The nanocrystal assembly section 2 includes a nanocrystal assembly channel 21, which is connected to the molecular assembly channel 13. The nanocrystal assembly channel 21 has a discharge port 27, and the nanocrystal assembly channel 21 has a spiral reflux structure; specifically, the structure of the nanocrystal assembly channel 21 is as follows:

[0081] The nanocrystal assembly channel 21 includes a first arc 22, a second arc 23, a third arc 24, a fourth arc 25 and a fifth arc 26 connected in sequence, wherein the openings of the first arc 22, the third arc 24 and the fifth arc 26 face upward, and the openings of the second arc 23 and the fourth arc 25 face downward. In this embodiment, “opening upward” and “opening downward” refer to the Figure 1The horizontal direction is a horizontal line, the opening is upward toward the top of the horizontal line, and the opening is downward toward the bottom of the horizontal line. The first arc 22, the second arc 23 and the fifth arc 26 all extend in a direction away from the molecular assembly section 1, and the third arc 24 and the fourth arc 25 all extend in a direction close to the molecular assembly section 1 to form a spiral reflux structure, and the sum of the diameters of the third arc 24 and the fourth arc 25 is smaller than the diameter of the second arc 23, so that the third arc 24 and the fourth arc 25 present a spiral reflux structure.

[0082] like Figure 2 As shown, the radii of the first arc 22, the second arc 23, the third arc 24, the fourth arc 25 and the fifth arc 26 are 7 to 8 cm respectively. Figure 2 R1 in), 12~13cm( Figure 2 R2 in), 3~4cm( Figure 2 R3 in), 3~4cm( Figure 2 R4) and 7-8cm ( Figure 2 In this embodiment, the radii of the first arc 22, the second arc 23, the third arc 24, the fourth arc 25 and the fifth arc 26 are 8 cm, 13 cm, 4 cm, 4 cm and 8 cm respectively.

[0083] The number of nanocrystal assembly channels 21 can be multiple, such as 2 to 6, and the 2 to 6 nanocrystal assembly channels 21 are connected in sequence. In this embodiment, the number of nanocrystal assembly channels 21 is 4, and the 4 nanocrystal assembly channels 21 are connected in sequence to form a nanocrystal assembly section 2, which helps the material to assemble nanocrystals therein to form water-soluble nanocrystals.

[0084] The inner diameters of the feed microchannel, the molecular assembly channel 13, and the nanocrystal assembly channel 21 are adjustable between 0.5 and 1.2 mm. In this embodiment, the inner diameters of the feed microchannel, the molecular assembly channel 13, and the nanocrystal assembly channel 21 are 1 mm, which can be selected according to actual conditions.

[0085] The method for preparing water-soluble nanocrystals with high curcumin loading using the microfluidic device comprises the following steps:

[0086] Step 1: Weigh soy protein isolate with a purity of more than 90% and dissolve it in an aqueous solution to prepare a soy protein isolate solution with a concentration of 8%. After the soy protein isolate solution is fully dissolved, refrigerate it at 4° C. overnight to fully hydrate it, thereby obtaining a soy protein isolate solution.

[0087] Step 2: Take rhamnolipid with a purity of >95% and dissolve it in an aqueous solution to prepare a rhamnolipid solution with a concentration of 8%.

[0088] Step 3: Weigh curcumin with a purity of >95% and dissolve it in an aqueous solution with a pH of 12, and ultrasonicate for five minutes to dissolve all the curcumin to prepare a 4.0 mg / mL curcumin solution.

[0089] Step 4: Dilute the soy protein isolate solution and rhamnolipid solution respectively before use and adjust the pH to 2. The final mass ratio of curcumin to soy protein isolate and rhamnolipid is 1:8:2.

[0090] Step 5: Inject the curcumin solution, soy protein isolate solution, and rhamnolipid solution into the microfluidic device through a syringe pump, and set the flow rate to 0.8 m / s. The specific method is as follows:

[0091] The curcumin solution is introduced into the first feeding microchannel 11 through the first feeding port 14, and the curcumin solution is divided into two in the first feeding microchannel 11 and enters through the half arc respectively;

[0092] The soy protein isolate solution and the rhamnolipid solution are introduced into the second feed microchannel 12 through the second feed port 15 and the third feed port 16 respectively; the soy protein isolate solution and the rhamnolipid solution are first mixed in the second feed microchannel 12;

[0093] The mixed soy protein isolate solution and rhamnolipid solution enter the molecular assembly channel 13 together with the curcumin solution to be mixed and molecularly assembled;

[0094] The molecularly assembled curcumin, soybean protein isolate and rhamnolipid continue to enter the nanocrystal assembly channel 21. Since the nanocrystal assembly channel 21 presents a spiral reflux structure, the molecularly assembled curcumin, soybean protein isolate and rhamnolipid continue to assemble nanocrystals through non-covalent interactions in the nanocrystal assembly channel 21, and finally obtain water-soluble nanocrystals with high curcumin loading.

[0095] Example 2

[0096] Step 1: Weigh soy protein isolate with a purity of more than 90% and dissolve it in an aqueous solution to prepare a soy protein isolate solution with a concentration of 8%. After the soy protein isolate solution is fully dissolved, refrigerate it at 4° C. overnight to fully hydrate it, thereby obtaining a soy protein isolate solution.

[0097] Step 2: Take rhamnolipid with a purity of >95% and dissolve it in an aqueous solution to prepare a rhamnolipid solution with a concentration of 8%.

[0098] Step 3: Weigh curcumin with a purity of >95% and dissolve it in an aqueous solution with a pH of 12, and ultrasonicate for five minutes to dissolve all the curcumin to prepare a 4.0 mg / mL curcumin solution.

[0099] Step 4: Dilute the soy protein isolate solution and rhamnolipid solution respectively before use and adjust the pH to 2. The final mass ratio of curcumin to soy protein isolate and rhamnolipid is 1:5:5.

[0100] Step 5: The curcumin solution, the soy protein isolate solution, and the rhamnolipid solution were respectively injected into the microfluidic device in Example 1 by a syringe pump, and the flow rate was set to 0.8 m / s. The specific method is as follows:

[0101] The curcumin solution is introduced into the first feeding microchannel 11 through the first feeding port 14, and the curcumin solution is divided into two in the first feeding microchannel 11 and enters through the half arc respectively;

[0102] The soy protein isolate solution and the rhamnolipid solution are introduced into the second feed microchannel 12 through the second feed port 15 and the third feed port 16 respectively; the soy protein isolate solution and the rhamnolipid solution are first mixed in the second feed microchannel 12;

[0103] The mixed soy protein isolate solution and rhamnolipid solution enter the molecular assembly channel 13 together with the curcumin solution to be mixed and molecularly assembled;

[0104] The molecularly assembled curcumin, soybean protein isolate and rhamnolipid continue to enter the nanocrystal assembly channel 21. Since the nanocrystal assembly channel 21 presents a spiral reflux structure, the molecularly assembled curcumin, soybean protein isolate and rhamnolipid continue to assemble nanocrystals through non-covalent interactions in the nanocrystal assembly channel 21, and finally obtain water-soluble nanocrystals with high curcumin loading.

[0105] The curcumin phase, protein phase and lipid phase were introduced into inlets 1, 2 and 3 of the microfluidic chip respectively, and the fluid flow rate was adjusted to 0.8 m / s. The solutions were quickly mixed and diffused in the microchannel, so that curcumin, soy protein isolate and rhamnolipid were assembled into nanocrystals through non-covalent interactions.

[0106] Example 3

[0107] Step 1: Weigh soy protein isolate with a purity of more than 90% and dissolve it in an aqueous solution to prepare a soy protein isolate solution with a concentration of 8%. After the soy protein isolate solution is fully dissolved, refrigerate it at 4° C. overnight to fully hydrate it, thereby obtaining a soy protein isolate solution.

[0108] Step 2: Take rhamnolipid with a purity of >95% and dissolve it in an aqueous solution to prepare a rhamnolipid solution with a concentration of 8%.

[0109] Step 3: Weigh curcumin with a purity of >95% and dissolve it in an aqueous solution with a pH of 12, and ultrasonicate for five minutes to dissolve all the curcumin to prepare a 4.0 mg / mL curcumin solution.

[0110] Step 4: Dilute the soy protein isolate solution and rhamnolipid solution respectively before use and adjust the pH to 2. The final mass ratio of curcumin to soy protein isolate and rhamnolipid is 1:2:8.

[0111] Step 5: The curcumin solution, the soy protein isolate solution, and the rhamnolipid solution were respectively injected into the microfluidic device in Example 1 by a syringe pump, and the flow rate was set to 0.8 m / s. The specific method is as follows:

[0112] The curcumin solution is introduced into the first feeding microchannel 11 through the first feeding port 14, and the curcumin solution is divided into two in the first feeding microchannel 11 and enters through the half arc respectively;

[0113] The soy protein isolate solution and the rhamnolipid solution are introduced into the second feed microchannel 12 through the second feed port 15 and the third feed port 16 respectively; the soy protein isolate solution and the rhamnolipid solution are first mixed in the second feed microchannel 12;

[0114] The mixed soy protein isolate solution and rhamnolipid solution enter the molecular assembly channel 13 together with the curcumin solution to be mixed and molecularly assembled;

[0115] The molecularly assembled curcumin, soybean protein isolate and rhamnolipid continue to enter the nanocrystal assembly channel 21. Since the nanocrystal assembly channel 21 presents a spiral reflux structure, the molecularly assembled curcumin, soybean protein isolate and rhamnolipid continue to assemble nanocrystals through non-covalent interactions in the nanocrystal assembly channel 21, and finally obtain water-soluble nanocrystals with high curcumin loading.

[0116] Comparative Example 1

[0117] The difference from Example 1 is that the microfluidic device in Example 1 is not used, that is, in step 5, curcumin, soy protein isolate and rhamnolipid are assembled by stirring, and the specific method is as follows:

[0118] Step 1: Weigh soy protein isolate with a purity of more than 90% and dissolve it in an aqueous solution to prepare a soy protein isolate solution with a concentration of 8%. After the soy protein isolate solution is fully dissolved, refrigerate it at 4° C. overnight to fully hydrate it, thereby obtaining a soy protein isolate solution.

[0119] Step 2: Take rhamnolipid with a purity of >95% and dissolve it in an aqueous solution to prepare a rhamnolipid solution with a concentration of 8%.

[0120] Step 3: Weigh curcumin with a purity of >95% and dissolve it in an aqueous solution with a pH of 12, and ultrasonicate for five minutes to dissolve all the curcumin to prepare a 4.0 mg / mL curcumin solution.

[0121] Step 4: Dilute the soy protein isolate solution and rhamnolipid solution respectively before use and adjust the pH to 2. The final mass ratio of curcumin to soy protein isolate and rhamnolipid is 1:8:2.

[0122] Step 5: The rhamnolipid solution was slowly added to the soy protein isolate solution, and stirred at 400 rpm for 3 minutes to obtain a soy protein isolate-rhamnolipid mixed solution. Subsequently, the curcumin solution was slowly added to the mixed solution, and stirred at room temperature in the dark for 30 minutes (400 rpm) to promote the assembly of curcumin, soy protein isolate and rhamnolipid into nanocrystals.

[0123] Comparative Example 2

[0124] The difference from Example 2 is that the microfluidic device in Example 1 is not used, that is, in step 5, curcumin, soy protein isolate and rhamnolipid are assembled by stirring, and the specific method is as follows:

[0125] Step 1: Weigh soy protein isolate with a purity of more than 90% and dissolve it in an aqueous solution to prepare a soy protein isolate solution with a concentration of 8%. After the soy protein isolate solution is fully dissolved, refrigerate it at 4° C. overnight to fully hydrate it, thereby obtaining a soy protein isolate solution.

[0126] Step 2: Take rhamnolipid with a purity of >95% and dissolve it in an aqueous solution to prepare a rhamnolipid solution with a concentration of 8%.

[0127] Step 3: Weigh curcumin with a purity of >95% and dissolve it in an aqueous solution with a pH of 12, and ultrasonicate for five minutes to dissolve all the curcumin to prepare a 4.0 mg / mL curcumin solution.

[0128] Step 4: Dilute the soy protein isolate solution and rhamnolipid solution respectively before use and adjust the pH to 2. The final mass ratio of curcumin to soy protein isolate and rhamnolipid is 1:5:5.

[0129] Step 5: The rhamnolipid solution was slowly added to the soy protein isolate solution, and stirred at 400 rpm for 3 minutes to obtain a soy protein isolate-rhamnolipid mixed solution. Subsequently, the curcumin solution was slowly added to the mixed solution, and stirred at room temperature in the dark for 30 minutes (400 rpm) to promote the assembly of curcumin, soy protein isolate and rhamnolipid into nanocrystals.

[0130] Comparative Example 3

[0131] The difference from Example 3 is that the microfluidic device in Example 1 is not used, that is, in step 5, curcumin, soy protein isolate and rhamnolipid are assembled by stirring, and the specific method is as follows:

[0132] Step 1: Weigh soy protein isolate with a purity of more than 90% and dissolve it in an aqueous solution to prepare a soy protein isolate solution with a concentration of 8%. After the soy protein isolate solution is fully dissolved, refrigerate it at 4° C. overnight to fully hydrate it, thereby obtaining a soy protein isolate solution.

[0133] Step 2: Take rhamnolipid with a purity of >95% and dissolve it in an aqueous solution to prepare a rhamnolipid solution with a concentration of 8%.

[0134] Step 3: Weigh curcumin with a purity of >95% and dissolve it in an aqueous solution with a pH of 12, and ultrasonicate for five minutes to dissolve all the curcumin to prepare a 4.0 mg / mL curcumin solution.

[0135] Step 4: Dilute the soy protein isolate solution and rhamnolipid solution respectively before use and adjust the pH to 2. The final mass ratio of curcumin to soy protein isolate and rhamnolipid is 1:2:8.

[0136] Step 5: The rhamnolipid solution was slowly added to the soy protein isolate solution, and stirred at 400 rpm for 3 minutes to obtain a soy protein isolate-rhamnolipid mixed solution. Subsequently, the curcumin solution was slowly added to the mixed solution, and stirred at room temperature in the dark for 30 minutes (400 rpm) to promote the assembly of curcumin, soy protein isolate and rhamnolipid into nanocrystals.

[0137] Comparative Example 4

[0138] The difference from Example 1 is that the microfluidic device in Example 1 is not used, but Figure 3 The microfluidic device shown in A. Figure 3 The difference between the microfluidic device shown in A and the microfluidic device of Example 1 is that the nanocrystal assembly channel 21 does not include the third arc 24 and the fourth arc 25, and the other structures are the same as the microfluidic device in Example 1.

[0139] The preparation method is the same as that in Example 1.

[0140] Comparative Example 5

[0141] The difference from Example 1 is that the microfluidic device in Example 1 is not used, but Figure 3 The microfluidic device shown in B. Figure 3 The difference between the microfluidic device shown in B and the microfluidic device of Example 1 is that the radius of the third arc 24 in the nanocrystal assembly channel 21 is reduced to 2 cm, and the other structures are the same as the microfluidic device in Example 1.

[0142] The preparation method is the same as that in Example 1.

[0143] Comparative Example 6

[0144] The difference from Example 1 is that the microfluidic device in Example 1 is not used, but Figure 3 The microfluidic device shown in C. Figure 3 The difference between the microfluidic device shown in C and the microfluidic device in Example 1 is that the radius of the third arc 24 in the nanocrystal assembly channel 21 is increased to 8 cm, and the other structures are the same as the microfluidic device in Example 1.

[0145] The preparation method is the same as that in Example 1.

[0146] Comparative Example 7

[0147] The microfluidic device in Example 1 is used, but the difference from Example 1 is that the curcumin solution and the soy protein isolate solution are first mixed, and then mixed with the rhamnolipid solution. The specific method is as follows:

[0148] The rhamnolipid solution is introduced into the first feeding microchannel 11 through the first feeding port 14. The rhamnolipid solution is divided into two in the first feeding microchannel 11 and enters through the half arc respectively;

[0149] The soy protein isolate solution and the curcumin solution are introduced into the second feed microchannel 12 through the second feed port 15 and the third feed port 16 respectively; the soy protein isolate solution and the curcumin solution are first mixed in the second feed microchannel 12;

[0150] The mixed soy protein isolate solution, curcumin solution and rhamnolipid solution enter the molecular assembly channel 13 for mixing and molecular assembly;

[0151] The other steps are the same as those in Example 1.

[0152] Test Results and Characterization

[0153] The nanocrystals prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were tested using the following test methods:

[0154] 1. The nanocrystals prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were observed under an electron microscope. The results are as follows: Figures 4 to 13 shown.

[0155] 2. Particle size results of different nanoparticles

[0156] Test method: The prepared soy protein isolate-rhamnolipid nanocrystal dispersions loaded with curcumin in different proportions were pretreated and measured by a nanoparticle size analyzer. The measurement results are shown in Table 1.

[0157] 3. Encapsulation efficiency and loading capacity of different nanoparticles

[0158] Test method: Take 2 mL of the prepared soy protein isolate-rhamnolipid nanocrystal dispersion with different ratios of curcumin, centrifuge the dispersion at 10,000 rpm for 5 minutes to remove the unencapsulated curcumin, take 100 μL of the supernatant to dilute and measure the absorbance at 424 nm by UV spectrophotometer. The encapsulation efficiency and loading capacity of curcumin nanocrystals are calculated from the standard curve (R 2 >0.999). The calculation formula is as follows:

[0159] Encapsulation efficiency (%) = curcumin content in nanocrystals / total curcumin added amount × 100

[0160] Loading capacity (%) = curcumin content in nanocrystals / total weight of nanocrystals × 100

[0161] The measurement results are shown in Table 1.

[0162] 4. Solubility of different nanoparticles

[0163] Test method: The freshly prepared soy protein isolate-rhamnolipid nanocrystal dispersions loaded with curcumin in different proportions were vacuum freeze-dried to obtain nanocrystal powders. The excess nanocrystal powder was weighed and then dispersed in a sealed glass bottle containing 5 ml of distilled water (pH 6.8). These dispersions were incubated in a water bath (100 rpm, 25°C) and the dispersions were collected after incubation until they could not be dissolved. The dispersions were centrifuged at 10,000 rpm for 5 minutes to remove the undissolved nanocrystal powder, and the supernatant was collected and filtered with a 0.45 μm microporous filter. The absorbance was measured at 424 nm using a UV-visible spectrophotometer. The solubility of curcumin was calculated from the standard curve, and the results are shown in Table 1.

[0164] Figure 4 This is a scanning electron microscope image of the nanocrystals prepared in Example 1. Figure 5 is a scanning electron microscope image of the nanocrystal of Example 2, Figure 6 The scanning electron microscope image of the nanocrystal of Example 3 is shown in FIG. Figures 4 to 6 It can be seen that with the increase of rhamnolipid content, the particle size of nanocrystals decreased significantly and showed obvious single particle shape. This is because curcumin changes the scope and degree of interaction between attractive and repulsive forces between nanocrystals. In addition, the presence of a small amount of rhamnolipid can reduce the interfacial tension between liquids and form a three-dimensional rigid layer around the molecules, thereby preventing molecular aggregation and precipitation. With the increase of rhamnolipid concentration, curcumin complex nanocrystals have stronger repulsion, which helps to form a more uniform structure.

[0165] Figures 7 to 13 The SEM images of the nanocrystals prepared in Comparative Examples 1 to 7 are as follows: Figures 7 to 13It can be seen that the particle size of the nanocrystals in the comparative example is significantly larger than that of the nanocrystals in the embodiment, and the particle size distribution is relatively wide. The reason for this phenomenon in comparative examples 1 to 3 may be that the reaction is carried out in a larger container, the mixing process relies on magnetic stirring, and the diffusion rate of the reactants is slow, resulting in instability in the nucleation and growth stages, thereby generating larger and more widely distributed nanocrystals. The particle size distribution of the nanocrystals in comparative example 4 is uneven and irregular, which may be because the microfluidic chip lacks a spiral reflux structure and a complex flow path, the fluid resistance is small, and the shear force is small when the crystal is formed, resulting in the formation of larger nanocrystals. The particle size of the nanocrystals in comparative examples 5 to 6 is slightly larger than that in embodiment 1, which may be due to the difference in the spiral reflux structure in the microfluidic chip. The nanocrystal particle size of comparative example 7 is the largest and the distribution is the widest, which may be due to the different molecular binding order. The curcumin-soy protein isolate binary complex formed first is saturated when it binds to rhamnolipid, resulting in rhamnolipid forming a coating layer on the outer layer of the binary complex, thereby forming larger nanocrystals.

[0166] Table 1 Particle size, encapsulation efficiency, loading capacity and solubility of powder after rehydration of different nanocrystals

[0167]

[0168] Table 1 lists the particle size, encapsulation efficiency, loading capacity and solubility of the nanocrystals prepared by Examples 1-3 and Comparative Examples 1-7. The experimental results show that as the content of rhamnolipid increases, the particle size of the nanocrystals decreases significantly. This may be because rhamnolipid, as an amphipathic lipid, can effectively reduce surface tension and promote the formation of small-diameter nanocrystals through steric hindrance effect. Among them, Example 2 performs the most outstanding, with the highest encapsulation efficiency and loading capacity. This may be because the hydrogen bonds and hydrophobic interactions between the soy protein isolate and rhamnolipid in Example 2 reach an optimal balance, thereby forming a more stable nanostructure. The solubility of the nanocrystals also presents the same trend, which is because rhamnolipid, as a surfactant, reduces the surface tension of the system and improves solubility.

[0169] The nanocrystal encapsulation efficiency and loading capacity of Examples 1-3 are significantly higher than those of Comparative Examples 1-3, indicating that compared with conventional stirring assembly, the microfluidic device in Example 1 can better assemble curcumin, soy protein isolate and rhamnolipid into nanocrystals, thereby achieving a high loading of curcumin.

[0170] The nanocrystal encapsulation efficiency and loading capacity of Example 1 are significantly higher than those of Comparative Examples 4-6, indicating that the microfluidic device in Example 1 can better assemble curcumin, soy protein isolate and rhamnolipid into nanocrystals and achieve a high loading of curcumin, which may be due to Figure 1The nanocrystal assembly channel 21 includes a spiral reflux structure, and its smaller arc radius can generate a greater centrifugal force when the fluid passes through the curved part, thereby causing a stronger radial velocity change and fluid disturbance, which can not only break the laminar state of the fluid and enhance local convection mixing, but also form a complex flow pattern through a continuous arc design, so that the components in the fluid can be effectively mixed in a shorter time and smaller space, so that the prepared nanocrystals are more evenly distributed, with smaller particle size, better encapsulation rate and load capacity. In contrast, Figure 3 The nanocrystal assembly channel 21 in the structure A does not include the third arc 24 and the fourth arc 25, and cannot form a spiral reflux structure; Figure 3 Although structures B and C in the figure also have spiral reflux structures, the smaller arc radius in the spiral reflux structure of B leads to uneven distribution of fluid velocity. In laminar flow, the fluid dynamic instability caused by this uneven velocity distribution is often insufficient to promote effective mixing of the fluid, thus affecting the mixing effect. The larger arc radius in the C structure makes the centrifugal force generated by the fluid through the curved part smaller, resulting in less vortex in the fluid flow. Fluid mixing mainly relies on laminar diffusion, and the mixing effect is poor.

[0171] The nanocrystal encapsulation efficiency and loading capacity of Example 1 are significantly higher than those of Comparative Example 7, indicating that the mixing order of curcumin, soy protein isolate and rhamnolipid will also affect the assembly effect of the nanocrystals.

[0172] Therefore, whether the nanocrystal assembly channel 21 has a spiral reflux structure, the radius of the spiral reflux structure, and the mixing order of curcumin, soy protein isolate, and rhamnolipid will affect the assembly effect of the microfluidic device on curcumin, soy protein isolate, and rhamnolipid, indicating that the microfluidic device and method in Example 1 have a good assembly effect on curcumin, soy protein isolate, and rhamnolipid.

[0173] The nanocrystal preparation method combined with microfluidic technology of the present invention significantly improves the physical and chemical properties of the nanocrystals. The precise control capability of microfluidic technology at a microscale enables curcumin to precisely bind to the binding sites of soy protein isolate and rhamnolipid, and curcumin is linked to soy protein isolate and rhamnolipid through hydrogen bonds and hydrophobic interactions, which is crucial for optimizing the physical and chemical properties of the nanocrystals.

[0174] 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 method for preparing water-soluble nanocrystals with high curcumin loading using a microfluidic device, characterized in that: The microfluidic device comprises a molecular assembly section (1) and a nanocrystal assembly section (2), the molecular assembly section (1) comprises a feed microchannel and a molecular assembly channel (13), and the nanocrystal assembly section (2) comprises at least one nanocrystal assembly channel (21) in a spiral reflux structure; the feed microchannel, the molecular assembly channel (13) and the nanocrystal assembly channel (21) are connected in sequence, the feed microchannel is provided with a feed inlet, and the nanocrystal assembly channel (21) is provided with a discharge outlet (27); The method for preparing water-soluble nanocrystals with high curcumin loading using the microfluidic device comprises the following steps: S1, dissolving soy protein isolate in an aqueous solution, refrigerating, and obtaining a soy protein isolate solution; dissolving rhamnolipid in an aqueous solution, obtaining a rhamnolipid solution; dissolving curcumin in an aqueous solution, and ultrasonicating to obtain a curcumin solution; S2, introducing the soy protein isolate solution, the rhamnolipid solution and the curcumin solution into the feed microchannel through the feed port, respectively, wherein the soy protein isolate solution and the rhamnolipid solution are first mixed, and then enter the molecular assembly channel (13) together with the curcumin solution to mix and perform molecular assembly; S3, continuing to enter the nanocrystal assembly channel (21) to assemble nanocrystals to obtain water-soluble nanocrystals with high curcumin loading.

2. The method for preparing water-soluble nanocrystals with high curcumin loading by a microfluidic device according to claim 1, characterized in that: In step S1, the mass ratio of curcumin to soy protein isolate and rhamnolipid is 1:2-8:2-8.

3. The method for preparing water-soluble nanocrystals with high curcumin loading by a microfluidic device according to claim 1, characterized in that: In step S1, Weighing soy protein isolate with a purity of more than 90% and dissolving it in an aqueous solution, refrigerating it at 0-4°C for 8-24 hours after it is fully dissolved, and adjusting the pH to 2-3 with 0.1-2 mol / L HCl to obtain a soy protein isolate solution with a concentration of 7-9%; Weigh rhamnolipid with a purity of more than 95% and dissolve it in an aqueous solution, and use 0.1-2 mol / L HCl to adjust the pH to 2-3 to obtain a rhamnolipid solution with a concentration of 7-9%; Curcumin with a purity of more than 95% is weighed and dissolved in an aqueous solution with a pH of 11 to 12, and ultrasonicated for 4 to 6 minutes to prepare a 3.0 to 5.0 mg / mL curcumin solution.

4. The method for preparing water-soluble nanocrystals with high curcumin loading by a microfluidic device according to claim 1, characterized in that: The inner diameters of the feed microchannel, the molecular assembly channel (13), and the nanocrystal assembly channel (21) are all 0.5 to 1.2 mm, and the flow rates of the soy protein isolate solution, the rhamnolipid solution, and the curcumin solution in the molecular assembly channel (13) and the nanocrystal assembly channel (21) are all 0.7 to 0.9 m / s.

5. The method for preparing water-soluble nanocrystals with high curcumin loading by a microfluidic device according to claim 1, characterized in that: The feed microchannel comprises a first feed microchannel (11) and a second feed microchannel (12); the feed end of the first feed microchannel (11) has a first feed port (14); the feed end of the second feed microchannel (12) has a second feed port (15) and a third feed port (16); the discharge end of the first feed microchannel (11) and the discharge end of the second feed microchannel (12) are both connected to the feed end of the molecular assembly channel (13); In step S2, the curcumin solution is introduced into the first feed microchannel (11) through the first feed port (14), and the soy protein isolate solution and the rhamnolipid solution are introduced into the second feed microchannel (12) through the second feed port (15) and the third feed port (16), respectively. The soy protein isolate solution and the rhamnolipid solution are first mixed in the second feed microchannel (12), and then enter the molecular assembly channel (13) together with the curcumin solution in the first feed microchannel (11) to mix and perform molecular assembly.

6. The method for preparing water-soluble nanocrystals with high curcumin loading by a microfluidic device according to claim 5, characterized in that: The first feed microchannel (11) is circular or arc-shaped, the first feed port (14) and the molecular assembly channel (13) are respectively arranged at two ends of the first feed microchannel (11), and the second feed microchannel (12) includes two feed channels and a mixing channel, the two feed channels and the mixing channel are arranged at an angle, and the mixing channel and the molecular assembly channel (13) are arranged in a straight line.

7. The method for preparing water-soluble nanocrystals with high curcumin loading by a microfluidic device according to claim 1, characterized in that: The nanocrystal assembly channel (21) comprises a first circular arc (22), a second circular arc (23), a third circular arc (24), a fourth circular arc (25) and a fifth circular arc (26) which are connected in sequence; the openings of the first circular arc (22), the third circular arc (24) and the fifth circular arc (26) face upward, and the openings of the second circular arc (23) and the fourth circular arc (25) face downward; the first circular arc (22), the second circular arc (23) and the fifth circular arc (26) all extend in a direction away from the molecular assembly section (1), and the third circular arc (24) and the fourth circular arc (25) all extend in a direction close to the molecular assembly section (1) to form a spiral reflux structure; and the sum of the diameters of the third circular arc (24) and the fourth circular arc (25) is smaller than the diameter of the second circular arc (23).

8. The method for preparing water-soluble nanocrystals with high curcumin loading by a microfluidic device according to claim 7, characterized in that: The radii of the first circular arc (22), the second circular arc (23), the third circular arc (24), the fourth circular arc (25) and the fifth circular arc (26) are 7-8 cm, 12-13 cm, 3-4 cm, 3-4 cm and 7-8 cm respectively.

9. The method for preparing water-soluble nanocrystals with high curcumin loading by a microfluidic device according to claim 8, characterized in that: The number of the nanocrystal assembly channels (21) is 2 to 6, and the 2 to 6 nanocrystal assembly channels (21) are sequentially connected to form the nanocrystal assembly section (2).

10. A water-soluble nanocrystal with high curcumin loading prepared by the method according to any one of claims 1 to 9, characterized in that: The particle size of the nanocrystal is 50-160nm, the encapsulation rate of curcumin is greater than 90%, and the loading capacity of curcumin is greater than 7%.

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