阅读说明：本技术 一种基于双水相体系的聚电解质微囊一步制备法 (Polyelectrolyte microcapsule one-step preparation method based on aqueous two-phase system ) 是由 秦建华 刘海涛 王慧 于 2019-11-28 设计创作，主要内容包括：本发明提供了一种基于双水相体系的聚电解质微囊一步制备法。该方法包括微流控芯片的制备、双水相溶液的准备、微流体的操控、聚电解质微囊的形成和鉴定等。本发明以集成了常开气动泵阀的微流控芯片为技术平台,以水包水液滴为成型模板,通过一步法将分子表面具有相反电荷的两种聚电解质分子精准可控地制备为微囊。该微囊可用于生物活性物质的负载与运输,如蛋白类药物、核酸和细胞等,在合成生物学、生物工程和再生医学等领域发挥巨大作用。(The invention provides a one-step preparation method of polyelectrolyte microcapsules based on a two-aqueous-phase system. The method comprises the steps of preparing a microfluidic chip, preparing a two-aqueous-phase solution, controlling microfluid, forming and identifying polyelectrolyte microcapsules and the like. The invention takes a micro-fluidic chip integrated with a normally open pneumatic pump valve as a technical platform, takes water-in-water droplets as a forming template, and prepares two polyelectrolyte molecules with opposite charges on the molecular surfaces into a microcapsule in a precise and controllable manner by a one-step method. The microcapsule can be used for loading and transporting bioactive substances, such as protein drugs, nucleic acids, cells and the like, and plays a great role in the fields of synthetic biology, bioengineering, regenerative medicine and the like.)

1. A preparation method of polyelectrolyte microcapsules based on a two-aqueous phase system is characterized by comprising the following steps: the method is based on a double-aqueous-phase system, takes a micro-fluidic chip integrated with a normally open pneumatic pump valve as a technical platform, takes water-in-water droplets as a forming template, and prepares two polyelectrolyte molecules with opposite charges on the molecular surfaces into the polyelectrolyte microcapsules in a precise and controllable manner through a one-step method.

2. The method for preparing polyelectrolyte microcapsules based on aqueous two-phase system according to claim 1, characterized in that: the micro-fluidic chip is specifically as follows:

preparing a Polydimethylsiloxane (PDMS) chip integrated with a normally open pneumatic pump valve by using a conventional soft lithography method; the chip is used for generating a double-aqueous-phase liquid drop template and preparing a polyelectrolyte microcapsule, and the structure of the chip comprises an upper layer and a lower layer: the upper layer is a liquid path part and consists of a reaction phase inlet (1) containing polyelectrolyte 1, a reaction phase channel (2), a continuous phase inlet (3), a continuous phase channel (4), an upper layer compressed air inlet (5), a dispersed phase inlet (6) containing polyelectrolyte 2, a dispersed phase channel (7), a pneumatic valve action area (8), a droplet transportation channel (9), a microcapsule forming channel (10), a microcapsule outlet (11), an intersection A (12) and an intersection B (13); the lower layer is a gas path part and consists of a lower layer compressed air inlet (14), a gas channel (15) and a normally open pneumatic pump valve (16).

3. The method for preparing polyelectrolyte microcapsules based on aqueous two-phase system according to claim 1, characterized in that: the aqueous two-phase system is specifically prepared as follows:

dissolving polyelectrolyte I in polyethylene glycol (PEG) aqueous solution, taking the mixed solution as a reaction phase, taking pure PEG aqueous solution as a continuous phase, and dissolving polyelectrolyte II in dextran aqueous solution, taking the mixed solution as a dispersion phase; wherein the polyelectrolyte I and the polyelectrolyte II are high molecules with opposite charges.

4. The method for preparing polyelectrolyte microcapsules based on aqueous two-phase system according to claim 3, characterized in that:

the polyelectrolyte with positive charges is one of chitosan, polylysine, polydienedimethylammonium chloride, polyallylamine and polyethyleneimine, and can be used as polyelectrolyte I or II.

5. The method for preparing polyelectrolyte microcapsules based on aqueous two-phase system according to claim 3, characterized in that:

the polyelectrolyte with negative charges is one of sodium alginate, pectin, hyaluronic acid, polyacrylic acid, polymethacrylic acid, carboxymethyl cellulose, gelatin, polyglycolic acid, sodium polystyrene sulfonate and sodium polyvinyl sulfonate, and can be used as polyelectrolyte I or II.

6. The method for preparing polyelectrolyte microcapsules based on aqueous two-phase system according to claim 1, characterized in that: the specific regulation and control of the microfluidic chip are as follows:

a reaction phase containing polyelectrolyte I enters the microfluidic chip through a reaction phase inlet (1) and then reaches an intersection B (13) along a reaction phase channel (2); the continuous phase enters the micro-fluidic chip through the continuous phase inlet (3) and sequentially passes through the continuous phase channel (4), the intersection A (12) and the liquid drop transport channel (9) to reach the intersection B (13); the dispersed phase containing the polyelectrolyte II enters the micro-fluidic chip through a dispersed phase inlet (6) and sequentially passes through a dispersed phase channel (7), a pneumatic pump valve action area (8), an intersection A (12) and a droplet transport channel (9) to reach an intersection B (13); compressed air enters the microfluidic chip through the upper layer compressed air inlet (5), sequentially passes through the lower layer compressed air inlet (14) and the gas channel (15) to reach the normally open pneumatic pump valve (16), and periodically drives the pneumatic pump valve to expand, so that the action area of the pneumatic pump valve is extruded, and the formation of dispersed phase droplets containing polyelectrolyte II is promoted.

7. The method for preparing polyelectrolyte microcapsules based on aqueous two-phase system according to claim 6, characterized in that: the formation and identification of the polyelectrolyte microcapsules are specifically as follows:

the dispersed phase droplet containing the polyelectrolyte II and the reaction phase containing the polyelectrolyte I are arranged at a crossing B

(13) When the two phases meet each other, the polyelectrolyte II on the surface of the liquid drop and the polyelectrolyte I in the reaction phase pass through the middle continuous phase to contact each other due to free diffusion movement, and the complex reaction between positive and negative charges is instantly generated to form the polyelectrolyte microcapsule taking the dispersed phase water-in-water liquid drop as the template.

8. The method for preparing polyelectrolyte microcapsules based on aqueous two-phase system according to claim 2, characterized in that: the width of the upper chip reaction phase channel (2) and the microcapsule forming channel (10) is 100-400 μm, and the length of the microcapsule forming channel (10) is 1-4 cm; the widths of the continuous phase channel (4), the disperse phase channel (7) and the droplet transport channel (9) are 50-250 μm, and the heights of all upper chip channels are 100-300 μm; the height and width of the lower chip channel are as follows: 50-300 μm.

9. The method for preparing polyelectrolyte microcapsules based on aqueous two-phase system according to claim 3, characterized in that: the molecular weight of the PEG is 4000-20000Da, and the concentration range is 5-50% (w/v); the dextran has molecular weight of 70k-500kDa and concentration range of 5-30% (w/v); the molecular weight of the polyelectrolyte I and the molecular weight of the polyelectrolyte II are both 40k-1000kDa, and the concentration is 0.25-4% (w/v).

10. The method for preparing polyelectrolyte microcapsules based on aqueous two-phase system according to claim 6, characterized in that: flow rate range of reaction phase containing polyelectrolyte I: 1-8 ul/min; continuous phase flow rate range: 1-6 ul/min; compressed air pressure range: 10-60 kPa; range of flow rate of dispersed phase containing polyelectrolyte II: 0.05-0.6 ul/min; the operation cycle range of the pneumatic pump valve is as follows: 0.1-1 s.

Technical Field

The invention belongs to the fields of micro-fluidic technology, material chemistry and the like, and particularly relates to a one-step preparation method of a polyelectrolyte microcapsule based on a two-aqueous-phase system.

Background

Polyelectrolyte microcapsules are spherical particles with an aqueous phase lumen and a shell formed by the solidification of oppositely charged polymers by electrostatic attraction, and have diameters in the micrometer to millimeter scale. Because of good biocompatibility, mild gelling conditions and proper space core-shell structure, the polyelectrolyte microcapsules are widely applied to the fields of biology, medicine, pharmacy, food and the like. However, conventional methods for fabricating polyelectrolyte microcapsules often involve multiple steps, wherein solid microspheroidal particles are first prepared as a template for the formation of the templated microcapsules, and then the layer-by-layer assembly method is used to alternately deposit oppositely charged polyelectrolytes on the surface of the microspheroidal particles, and then the template material is decomposed into accessible single molecules, thereby obtaining the final hollow microcapsules. The preparation process is complicated and time-consuming, has large damage to the loaded substance and low loading efficiency, and is not beneficial to the popularization and application of the polyelectrolyte microcapsules.

In recent years, droplet microfluidic technology has been developed greatly, and functionalized microspheres and microcapsules of various materials and different shapes can be prepared accurately, and the micron-sized products make great contribution in the fields of materials science, biology, pharmacy and the like. The aqueous two-phase emulsification system consisting of two polymer solutions or one polymer solution and one salt solution is introduced into the field of droplet microfluidics, so that the process for producing microspheres and microcapsules is milder, and the possibility of in-situ assembly and synthesis of polyelectrolyte microcapsules in a microfluidic channel is provided. And the possibility of industrialization of the prepared polyelectrolyte microcapsules is greatly increased due to the advantages of accurate controllability, high flux and the like of the microfluidic technology. According to the invention, the polyelectrolyte microcapsules with controllable appearance and high yield and made of different materials are prepared in the microfluidic chip by a one-step method by utilizing the microfluidic chip integrated with the normally open pneumatic pump valve and a two-water-phase emulsification system.

Disclosure of Invention

The invention aims to provide a one-step preparation method of polyelectrolyte microcapsules based on an aqueous two-phase system, which aims to provide early-stage technical support for the development of pharmacy, regenerative medicine, food industry and the like.

The invention provides a preparation method of a polyelectrolyte microcapsule based on a two-aqueous-phase system, which is based on the two-aqueous-phase system, takes a micro-fluidic chip integrated with a normally-open pneumatic pump valve as a technical platform, takes water-in-water droplets as a forming template, and prepares two polyelectrolyte molecules with opposite charges on the molecular surfaces into the polyelectrolyte microcapsule in a precise and controllable manner through a one-step method.

The micro-fluidic chip is specifically as follows:

preparing a Polydimethylsiloxane (PDMS) chip integrated with a normally open pneumatic pump valve by using a conventional soft lithography method; the chip is used for generating a double-aqueous-phase liquid drop template and preparing a polyelectrolyte microcapsule, and the structure of the chip comprises an upper layer and a lower layer: the upper layer is a liquid path part and consists of a reaction phase inlet 1 containing polyelectrolyte 1, a reaction phase channel 2, a continuous phase inlet 3, a continuous phase channel 4, an upper layer compressed air inlet 5, a dispersed phase inlet 6 containing polyelectrolyte 2, a dispersed phase channel 7, a pneumatic valve action area 8, a droplet transportation channel 9, a microcapsule forming channel 10, a microcapsule outlet 11, an intersection A12 and an intersection B13; the lower layer is a gas path part and consists of a lower layer compressed air inlet 14, a gas channel 15 and a normally open pneumatic pump valve 16.

The aqueous two-phase system is specifically prepared as follows:

dissolving polyelectrolyte I in polyethylene glycol (PEG) aqueous solution, taking the mixed solution as a reaction phase, taking pure PEG aqueous solution as a continuous phase, and dissolving polyelectrolyte II in dextran aqueous solution, taking the mixed solution as a dispersion phase; wherein the polyelectrolyte I and the polyelectrolyte II are high molecules with opposite charges.

The polyelectrolyte with positive charges is one of chitosan, polylysine, polydienedimethylammonium chloride, polyallylamine and polyethyleneimine, and can be used as polyelectrolyte I or II.

The polyelectrolyte with negative charges is one of sodium alginate, pectin, hyaluronic acid, polyacrylic acid, polymethacrylic acid, carboxymethyl cellulose, gelatin, polyglycolic acid, sodium polystyrene sulfonate and sodium polyvinyl sulfonate, and can be used as polyelectrolyte I or II.

The specific regulation and control of the microfluidic chip are as follows:

a reaction phase containing polyelectrolyte I enters the microfluidic chip through a reaction phase inlet 1 and then reaches an intersection B13 along a reaction phase channel 2; the continuous phase enters the microfluidic chip through the continuous phase inlet 3 and sequentially passes through the continuous phase channel 4, the intersection A12 and the liquid drop transport channel 9 to reach the intersection B13; the dispersed phase containing the polyelectrolyte II enters the microfluidic chip through a dispersed phase inlet 6 and reaches an intersection B13 through a dispersed phase channel 7, a pneumatic pump valve action area 8, an intersection A12 and a droplet transport channel 9 in sequence; compressed air enters the microfluidic chip through the upper compressed air inlet 5, sequentially passes through the lower compressed air inlet 14 and the gas channel 15 to reach the normally open pneumatic pump valve 16, and periodically drives the pneumatic pump valve to expand, so that the action area of the pneumatic pump valve is extruded, and the formation of dispersed phase droplets containing polyelectrolyte II is promoted. Flow rate range of reaction phase containing polyelectrolyte I: 1-8 ul/min; continuous phase flow rate range: 1-6 ul/min; compressed air pressure range: 10-60 kPa; range of flow rate of dispersed phase containing polyelectrolyte II: 0.05-0.6 ul/min; the operation cycle range of the pneumatic pump valve is as follows: 0.1-1 s.

The formation and identification of the polyelectrolyte microcapsules are specifically as follows:

the dispersed phase liquid drop containing the polyelectrolyte II meets the reaction phase containing the polyelectrolyte I at the intersection B13, the polyelectrolyte II on the surface of the liquid drop and the polyelectrolyte I in the reaction phase pass through the middle continuous phase to be contacted with each other due to free diffusion movement, and the complex reaction between positive and negative charges is instantaneously generated, so that the polyelectrolyte microcapsule taking the dispersed phase water-in-water liquid drop as the template is formed.

The width of the upper chip reaction phase channel 2 and the microcapsule forming channel 10 is 100-400 μm, and the length of the microcapsule forming channel 10 is 1-4 cm; the widths of the continuous phase channel 4, the disperse phase channel 7 and the droplet transport channel 9 are 50-250 μm, and the heights of all the upper chip channels are 100-300 μm; the height and width of the lower chip channel are as follows:

50-300μm。

the molecular weight of the PEG is 4000-20000Da, and the concentration range is 5-50% (w/v); the dextran has molecular weight of 70k-500kDa and concentration range of 5-30% (w/v); the molecular weight of the polyelectrolyte I and the molecular weight of the polyelectrolyte II are both 40k-1000kDa, and the concentration is 0.25-4% (w/v).

The invention has the beneficial effects that:

the method can greatly reduce the procedure for preparing the polyelectrolyte microcapsule and improve the production efficiency; the whole preparation process is simple, mild and controllable, and damage to a load in the microcapsule can be effectively avoided; the prepared microcapsule is very suitable for the loading and transportation of bioactive substances, such as protein drugs, nucleic acid, cells and the like, and plays a great role in the fields of synthetic biology, bioengineering, regenerative medicine and the like

Drawings

FIG. 1 is a schematic view of a microfluidic chip;

wherein: a upper layer liquid path chip; b, a lower layer gas circuit chip; c, combining two layers of chips into a general graph;

the device comprises a reaction phase inlet 1 containing polyelectrolyte I, a reaction phase channel 2, a continuous phase inlet 3, a continuous phase channel 4, an upper layer compressed air inlet 5, a dispersed phase inlet 6 containing polyelectrolyte II, a dispersed phase channel 7, a pneumatic valve action area 8, a droplet transport channel 9, a microcapsule forming channel 10, a microcapsule outlet 11, a crossing A12, a crossing B13, a lower layer compressed air inlet 14, a gas channel 15 and a normally open pneumatic pump valve 16.

FIG. 2 is a schematic of two aqueous phase droplet and polyelectrolyte microcapsule formation at an intersection in a chip, wherein: a schematic diagram of the formation of aqueous two-phase droplets at intersection a; b schematic diagram of polyelectrolyte microcapsule formation at intersection B.

FIG. 3 is an optical microscopic characterization of polyelectrolyte microcapsules of example 1, wherein: a low power representation of polyelectrolyte microcapsules (scale: 100 μm); b high power characterization of polyelectrolyte microcapsules (Scale: 20 μm)

FIG. 4 is a representation of polyelectrolyte microcapsules in example 2, wherein: a optical microscope characterization (scale: 100 μm); b fluorescence microscopy characterization (ruler: 100 μm).

FIG. 5 is a scanning electron microscopy characterization of polyelectrolyte microcapsules in example 3 (scale: 500 μm).

Detailed Description

In the micro-fluidic chip prepared by the micro-processing technology, a plurality of fluids of a double-aqueous phase system are sequentially introduced, and the controllable one-step preparation of the polyelectrolyte microcapsules is realized by controlling a normally open pneumatic pump valve. The prepared microcapsule can be characterized by using an optical microscope, an electron microscope and the like. The invention is further illustrated by the following figures and examples.

Example 1

A one-step preparation method of polyelectrolyte microcapsules based on an aqueous two-phase system comprises the following steps:

(1) preparing a micro-fluidic chip: preparing a PDMS chip integrated with a normally open pneumatic pump valve by using a conventional soft lithography method; the chip is used for generating a double-aqueous-phase liquid drop template and preparing polyelectrolyte microcapsules, and as shown in figure 1, the structure of the chip comprises an upper layer and a lower layer: the upper layer is a liquid path part and consists of a polylysine-containing reaction phase inlet 1, a reaction phase channel 2, a continuous phase inlet 3, a continuous phase channel 4, an upper layer compressed air inlet 5, a hyaluronic acid-containing dispersed phase inlet 6, a dispersed phase channel 7, a pneumatic valve action area 8, a droplet transportation channel 9, a microcapsule forming channel 10, a microcapsule outlet 11, an intersection A12 and an intersection B13; the lower layer is a gas path part and consists of a lower layer compressed air inlet 14, a gas channel 15 and a normally open pneumatic pump valve 16. Wherein, the width of the upper layer reaction phase channel 2 and the microcapsule forming channel 10 is 150 μm, and the length of the microcapsule forming channel 10 is 1.5 cm; the continuous phase channel 4, the dispersed phase channel 7 and the droplet transport channel 9 have a width of 100 μm and all the upper chip channels have a height of 150 μm. The height and width of the lower chip channel are as follows: 100 μm.

(2) Preparing aqueous two-phase solution: dissolving polylysine in PEG aqueous solution, taking the mixed solution as a reaction phase, taking pure PEG aqueous solution as a continuous phase, dissolving hyaluronic acid in dextran aqueous solution, and taking the mixed solution as a dispersion phase. The PEG used has a molecular weight of 8000Da and a concentration of 10% (w/v); dextran molecular weight 70kDa, concentration 10% (w/v); polylysine has a molecular weight of 70kDa and a concentration of 0.5% (w/v); hyaluronic acid has a molecular weight of 80kDa and a concentration of 0.5% (w/v).

(3) Controlling the microfluidic chip: the polylysine-containing reaction phase enters the microfluidic chip through the reaction phase inlet 1 and then reaches the intersection B13 along the reaction phase channel 2; the continuous phase enters the microfluidic chip through the continuous phase inlet 3 and sequentially passes through the continuous phase channel 4, the intersection A12 and the liquid drop transport channel 9 to reach the intersection B13; the dispersed phase containing hyaluronic acid enters the microfluidic chip through the dispersed phase inlet 6, and reaches the intersection B13 through the dispersed phase channel 7, the pneumatic pump valve action area 8, the intersection A12 and the droplet transport channel 9 in sequence; compressed air enters the microfluidic chip through the upper layer compressed air inlet 5, sequentially passes through the lower layer compressed air inlet 14 and the gas channel 15 to reach the normally open pneumatic pump valve 16, and periodically drives the pneumatic pump valve to expand, so that the action area of the pneumatic pump valve is extruded, and the formation of dispersed phase liquid drops containing hyaluronic acid is promoted. Wherein, the flow rate of the reaction phase containing polylysine is as follows: 2 ul/min; continuous phase flow rate: 2 ul/min; air pressure of compressed air: 15 kPa; flow rate of dispersed phase containing hyaluronic acid: 0.1 ul/min; the operation cycle range of the pneumatic pump valve is as follows: 0.6 s.

(4) Formation and characterization of polyelectrolyte microcapsules: the dispersed phase water-in-water droplet containing hyaluronic acid formed in step 3 meets the reaction phase containing polylysine at the intersection B13, the hyaluronic acid on the surface of the droplet and the polylysine in the reaction phase pass through the middle continuous phase to contact with each other due to free diffusion movement, and the complexation reaction between positive and negative charges is instantaneously generated, so that the polyelectrolyte microcapsule taking the dispersed phase droplet as the template is formed. The microcapsules were characterized by light microscopy to determine their morphology and size, as shown in fig. 2 and 3.

Example 2

A one-step preparation method of polyelectrolyte microcapsules based on an aqueous two-phase system comprises the following steps:

(1) preparing a micro-fluidic chip: preparing a PDMS chip integrated with a normally open pneumatic pump valve by using a conventional soft lithography method; the chip is used for generating a double-aqueous-phase liquid drop template and preparing a polyelectrolyte microcapsule, and the structure of the chip comprises an upper layer and a lower layer: the upper layer is a liquid path part and consists of a chitosan-containing reaction phase inlet 1, a reaction phase channel 2, a continuous phase inlet 3, a continuous phase channel 4, an upper layer compressed air inlet 5, a sodium alginate-containing dispersed phase inlet 6, a dispersed phase channel 7, a pneumatic valve action area 8, a droplet transportation channel 9, a microcapsule forming channel 10, a microcapsule outlet 11, an intersection A12 and an intersection B13; the lower layer is a gas path part and consists of a lower layer compressed air inlet 14, a gas channel 15 and a normally open pneumatic pump valve 16. Wherein, the width of the upper layer reaction phase channel 2 and the microcapsule forming channel 10 is 250 μm, and the length of the microcapsule forming channel 10 is 2.5 cm; the continuous phase channel 4, the dispersed phase channel 7 and the droplet transport channel 9 have a width of 150 μm and all upper chip channels have a height of 200 μm. The height and width of the lower chip channel are as follows: 200 μm.

(2) Preparing aqueous two-phase solution: dissolving fluorescein isothiocyanate labeled chitosan in a PEG aqueous solution, taking the mixed solution as a reaction phase, taking a pure PEG aqueous solution as a continuous phase, dissolving sodium alginate in a glucan aqueous solution, and taking the mixed solution as a dispersion phase. The PEG used has a molecular weight of 10kDa and a concentration of 20% (w/v); dextran molecular weight of 250kDa and concentration of 15% (w/v); the chitosan has molecular weight of 200kDa and concentration of 1.5% (w/v); the molecular weight of the sodium alginate is 100kDa, and the concentration is 1% (w/v).

(3) Controlling the microfluidic chip: the chitosan-containing reaction phase enters the microfluidic chip through the reaction phase inlet 1 and then reaches the intersection B13 along the reaction phase channel 2; the continuous phase enters the microfluidic chip through the continuous phase inlet 3 and sequentially passes through the continuous phase channel 4, the intersection A12 and the liquid drop transport channel 9 to reach the intersection B13; the dispersed phase containing sodium alginate enters the micro-fluidic chip through the dispersed phase inlet 6, and reaches the intersection B13 through the dispersed phase channel 7, the pneumatic pump valve action area 8, the intersection A12 and the droplet transport channel 9 in sequence; compressed air enters the microfluidic chip through the upper layer compressed air inlet 5, sequentially passes through the lower layer compressed air inlet 14 and the gas channel 15 to reach the normally open pneumatic pump valve 16, and periodically drives the pneumatic pump valve to expand, so that the action area of the pneumatic pump valve is extruded, and the formation of dispersed phase liquid drops containing sodium alginate is promoted. Wherein, the flow rate of the reaction phase containing chitosan is as follows: 4 ul/min; continuous phase flow rate: 3 ul/min; air pressure of compressed air: 30 kPa; flow rate of dispersed phase containing sodium alginate: 0.3 ul/min; the operation cycle range of the pneumatic pump valve is as follows: 0.2 s.

(4) Formation and characterization of polyelectrolyte microcapsules: (3) the dispersed phase water-in-water droplet containing sodium alginate formed in the step (A) meets a reaction phase containing chitosan at a crossing B13, the sodium alginate on the surface of the droplet and the chitosan in the reaction phase pass through the middle continuous phase to contact with each other due to free diffusion movement, and the complexation reaction between positive charges and negative charges is instantaneously generated, so that the polyelectrolyte microcapsule taking the dispersed phase droplet as a template is formed. The microcapsules were characterized by light and fluorescence microscopy to determine their morphology and size, as shown in figure 4.

Example 3

A one-step preparation method of polyelectrolyte microcapsules based on an aqueous two-phase system comprises the following steps:

(1) preparing a micro-fluidic chip: preparing a PDMS chip integrated with a normally open pneumatic pump valve by using a conventional soft lithography method; the chip is used for generating a double-aqueous-phase liquid drop template and preparing a polyelectrolyte microcapsule, and the structure of the chip comprises an upper layer and a lower layer: the upper layer is a liquid path part and consists of a reaction phase inlet 1 containing sodium polystyrene sulfate (PSS), a reaction phase channel 2, a continuous phase inlet 3, a continuous phase channel 4, an upper layer compressed air inlet 5, a dispersed phase inlet 6 containing polydiene dimethyl ammonium chloride (PDDA), a dispersed phase channel 7, a pneumatic valve action area 8, a droplet transportation channel 9, a microcapsule forming channel 10, a microcapsule outlet 11, a crossing A12 and a crossing B13; the lower layer is a gas path part and consists of a lower layer compressed air inlet 14, a gas channel 15 and a normally open pneumatic pump valve 16. Wherein, the width of the upper layer reaction phase channel 2 and the microcapsule forming channel 10 is 350 μm, and the length of the microcapsule forming channel 10 is 3.5 cm; the continuous phase channel 4, the dispersed phase channel 7 and the droplet transport channel 9 have a width of 200 μm and all the upper chip channels have a height of 250 μm. The height and width of the lower chip channel are as follows: 250 μm.

(2) Preparing aqueous two-phase solution: PSS is dissolved in PEG aqueous solution, the mixed solution is used as a reaction phase, pure PEG aqueous solution is used as a continuous phase, PDDA is dissolved in glucan aqueous solution, and the mixed solution is used as a disperse phase. The PEG used has a molecular weight of 20kDa and a concentration of 40% (w/v); dextran molecular weight is 500kDa, concentration is 30% (w/v); PSS has a molecular weight of 1000kDa and a concentration of 4% (w/v); the molecular weight of PDDA was 500kDa and the concentration was 2% (w/v).

(3) Controlling the microfluidic chip: the PSS-containing reaction phase enters the microfluidic chip through a reaction phase inlet 1 and then reaches an intersection B13 along a reaction phase channel 2; the continuous phase enters the microfluidic chip through the continuous phase inlet 3 and sequentially passes through the continuous phase channel 4, the intersection A12 and the liquid drop transport channel 9 to reach the intersection B13; the PDDA-containing dispersed phase enters the microfluidic chip through a dispersed phase inlet 6 and sequentially passes through a dispersed phase channel 7, a pneumatic pump valve action area 8, an intersection A12 and a droplet transport channel 9 to reach an intersection B13; compressed air enters the microfluidic chip through the upper layer compressed air inlet 5, sequentially passes through the lower layer compressed air inlet 14 and the gas channel 15, reaches the normally open pneumatic pump valve 16, and periodically drives the pneumatic pump valve to expand, so that the action area of the pneumatic pump valve is extruded, and the formation of dispersed phase liquid drops containing PDDA is promoted. Wherein, the flow rate of the reaction phase containing PSS is as follows: 8 ul/min; continuous phase flow rate: 4 ul/min; air pressure of compressed air: 50 kPa; PDDA containing dispersed phase flow rate: 0.5 ul/min; the operation cycle range of the pneumatic pump valve is as follows: 0.8 s.

(4) Formation and characterization of polyelectrolyte microcapsules: (3) the PDDA-containing dispersed phase water-in-water droplets formed in the step (1) meet with the PSS-containing reaction phase at a crossing B13, the PDDA on the surface of the droplets and the PSS in the reaction phase pass through the middle continuous phase to contact with each other due to free diffusion movement, and the complex reaction between positive charges and negative charges is instantaneously generated to form the polyelectrolyte microcapsule taking the dispersed phase droplets as a template. The microcapsules were characterized by scanning electron microscopy to determine their morphology and size, as shown in figure 5.