CN110229368B - Janus particle with biocompatibility and preparation method thereof - Google Patents

Abstract

The invention discloses a Janus particle with biocompatibility and a preparation method thereof. The method adopts a biocompatible material, purple gum and a polylactic acid material are dissolved in a common good solvent, then a mixed solution is quickly injected into an aqueous solution containing a surfactant at a certain temperature, and the purple gum-polylactic acid Janus nano-particles with one end of the purple gum and the other end of the polylactic acid are obtained based on a coprecipitation and phase separation mechanism. The size of Janus nano-particles can be regulated and controlled by regulating the concentration of the shellac and the polylactic acid in the good solvent; the proportion of the lac hemisphere to the polylactic acid hemisphere in the Janus nano-particles can be regulated and controlled by regulating the proportion of the lac to the polylactic acid in the good solvent. And then, polylysine with biocompatibility is modified on the surface of the lac hemisphere through the interaction of positive and negative charges, so that the hydrophilicity of the lac hemisphere is improved. The Janus nano-particles with biocompatibility have amphipathy, and can well stabilize the emulsion of oil in water as a particle surfactant.

Description

Janus particle with biocompatibility and preparation method thereof

Technical Field

The invention relates to the field of particle materials, in particular to a Janus particle with biocompatibility and a preparation method thereof.

Background

The emulsion has wide application prospect in the fields of food, cosmetics and the like. Emulsions include water-in-oil emulsions in which the aqueous phase is dispersed in the oil phase and oil-in-water emulsions in which the oil phase is dispersed in the aqueous phase. The stabilization of emulsions generally requires the addition of surfactants. The traditional surfactant is an amphiphilic molecule which has both hydrophilic groups and hydrophobic groups, and can effectively reduce the tension of a water/oil interface. However, the traditional molecular surfactant is in a dynamic equilibrium of adsorption and desorption at an interface due to thermal motion, and liquid drops are easy to fuse. On the other hand, under the influence of Ostwald ripping, small droplets will gradually become smaller and large droplets will gradually become larger, eventually leading to phase separation. The amphiphilic solid particles may effectively replace molecular surfactants. The solid particles can not be desorbed at a water/oil interface due to thermal motion, and the stable Pickering emulsion can be stable for a long time. However, no biocompatible Janus particles exist at present, which greatly limits the application of the particles in the fields of food, cosmetics and the like.

The invention adopts biocompatible materials to prepare the lac-polylactic acid Janus nano-particles with adjustable properties through coprecipitation and phase separation. Polylysine is further surface modified through the interaction of positive and negative charges, and the hydrophilicity of the lac hemisphere is improved. The prepared Janus nano-particles with biocompatibility have amphipathy, and can well stabilize the emulsion of oil in water as a particle surfactant.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a Janus particle of lac-polylactic acid with biocompatibility and a preparation method thereof. The preparation method adopts biocompatible materials, such as lac, polylactic acid, polylysine and the like, and the materials have good biocompatibility and biodegradability, are green and pollution-free, and have edibility. The method is simple and easy to implement, the size, the composition and the morphology of the prepared Janus particles can be accurately regulated, and based on the amphiphilic structure of the Janus particles, the Janus nanoparticles with biocompatibility can be used as food-grade particle surfactants to well stabilize the emulsion of oil in water.

To achieve the above object, the present invention provides a solution comprising the steps of:

(1) dissolving lac in tetrahydrofuran, and stirring until the lac is completely dissolved to obtain a lac solution; adding polylactic acid to obtain a mixed solution of shellac and polylactic acid; adding tween 80 into deionized water, and performing ultrasonic dispersion to obtain a tween 80 aqueous solution;

(2) heating the mixed solution prepared in the step (1) and a tween 80 aqueous solution, injecting the mixed solution into the tween 80 aqueous solution, shaking and mixing uniformly to obtain a uniform dispersion of biocompatible Janus particles of lac-polylactic acid in the tween 80 aqueous solution;

(3) standing the Janus particles of the lac-polylactic acid with biocompatibility, which are prepared in the step (2), in the uniform dispersion liquid of the Tween 80 solution at room temperature, then taking the solution, centrifuging the solution in a high-speed centrifuge, removing supernatant after centrifugation, then adding deionized water, and re-dispersing the particles in the water uniformly; and repeating the centrifugal dispersion process to remove the surfactant Tween 80, and finishing the washing of the Janus particles to obtain the uniform dispersion liquid of the Janus particles with biocompatibility in the deionized water.

(4) And (3) dissolving polylysine in deionized water, adding the homogeneous dispersion liquid of the Janus particles prepared in the step (3) in the deionized water, standing, and obtaining the homogeneous dispersion liquid of the amphiphilic Janus particles of the polylysine modified lac hemisphere in water through the interaction of positive and negative charges between the positively charged polylysine and the negatively charged lac hemisphere.

Preferably, in the present invention, in the step (1),

the weight range of the lac added in 1mL tetrahydrofuran is 2-100 mg; further preferably, the weight range of the lac added in 1mL tetrahydrofuran is 2-50mg, and the lac is a natural wrapping material, is easily soluble in organic solvents such as ethanol and the like and alkaline solutions, but is difficultly soluble in neutral or acidic solutions.

The mass range of the polylactic acid added into 1mL of water is 2-100 mg; further preferably, the mass range of the polylactic acid added in 1mL of tetrahydrofuran is 2-50mg, and the polylactic acid is a synthetic polymer material which is easily soluble in tetrahydrofuran but hardly soluble in ethanol.

The molecular weight range of the polylactic acid is 2000-; more preferably, the molecular weight of the polylactic acid is 3000.

The volume fraction range of the tween 80 added into 1mL of water is 0.5 to 5 percent; further preferably, the tween 80 is added in a volume fraction range of 0.8% to 2% in 1mL of water.

Preferably, in the present invention, in the step (2),

the preparation process needs to be carried out in a water bath at 65-90 ℃, and the generated particles can be stable for a long time at room temperature. Further preferably, the bath temperature is 70 ℃.

The injection speed of the mixed solution into the Tween 80 aqueous solution is 5ml/h-30 ml/h; further preferably, the injection rate is 15ml/h to 20 ml/h.

The volume percentage range of the mixed solution and the Tween 80 aqueous solution is 1.67-6.67%; further preferably, the volume fraction of the mixed solution and the tween 80 aqueous solution ranges from 1.67% to 3.33%.

Preferably, in the present invention, in the step (3),

the standing time range at room temperature is 4-12 h; further preferably, the time range of standing and storing at room temperature is 6 h.

The centrifugal dispersion frequency range is 3-10 times; further preferably, the number of centrifugal washing is 5.

Preferably, in the present invention, in the step (4),

the mass ratio of the polylysine to the Janus particles is in a range of 2: 1-5: 1; further preferably, the mass ratio of polylysine to Janus particles is in the range of 3: 1-4: 1.

on the other hand, the Janus particles with biocompatibility prepared by the method are disclosed, the size and the appearance of the Janus particles are controllable, and the proportion of lac hemispheres and polylactic acid hemispheres in the Janus particles is controllable.

The invention also discloses a preparation method of the oil-in-water emulsion with stable amphiphilic Janus particles of the polylysine modified lac hemisphere, which comprises the following steps:

taking a uniform dispersion of amphiphilic Janus particles of polylysine modified shellac hemisphere prepared in claim 1 in water, adding silk oil, wherein the volume ratio of oil phase to uniform dispersion is 1: and 5, mixing the oil phase and the water phase for 1-8min to obtain the oil-in-water emulsion with stable amphiphilic Janus particles of the polylysine modified lac hemisphere.

The invention has the beneficial effects that:

(1) the Janus particles prepared from the biocompatible material have good biocompatibility and biodegradability, are non-toxic and non-irritant to human bodies, and have edibility. Meanwhile, two hemispheres of the Janus particle are made of different materials, so that one Janus particle has the properties of the two materials, and the advantages of the lac and the polylactic acid are taken into consideration.

(2) The size, the composition and the appearance of the Janus particles can be accurately regulated, for example, the size of the Janus nano particles can be regulated by regulating the concentration of the shellac and the polylactic acid in a good solvent; the proportion of the lac hemisphere to the polylactic acid hemisphere in the Janus nano-particles can be regulated and controlled by regulating the proportion of the lac to the polylactic acid in the good solvent.

(3) The amphiphilic Janus particles of the polylysine modified lac hemisphere, which are prepared by the invention, can be used as a particle surfactant, so that the stability of an emulsion of oil in water is improved.

Drawings

The invention is further described below with reference to the figures and examples.

FIG. 1(a) is a schematic diagram of the preparation of biocompatible Janus particles;

FIG. 1(b) is a schematic representation of Janus particles prepared in example 1;

FIG. 1(c) is a scanning electron micrograph of Janus particles prepared in example 1;

FIG. 2 is an optical image of the morphology change of Janus particles of example 2 in an alkaline solution;

FIG. 3 is a scanning electron microscope image of Janus particles of different particle size prepared in example 3;

FIG. 4 is a scanning electron microscope image of Janus particles of different morphologies prepared in example 4;

FIG. 5(a) is a schematic representation of amphiphilic Janus particles of polylysine-modified shellac hemisphere, as prepared in example 5;

FIG. 5(b) is a schematic representation of oil droplets stabilized in water by amphiphilic Janus particles of polylysine-modified shellac hemisphere prepared in example 5;

fig. 5(c) is an optical image of oil droplets in an oil-in-water emulsion stabilized by amphiphilic Janus particles of polylysine-modified shellac hemisphere prepared in example 5;

fig. 6 is an image of an oil-in-water emulsion in which amphiphilic Janus particles of polylysine-modified shellac hemispheres prepared in example 5 are stabilized and an image of an oil-in-water emulsion in which Janus particles prepared in example 1 are stabilized;

FIG. 7(a) potentiometric measurements of homogeneous dispersions of amphiphilic Janus particles of hemispheres of polylysine-modified shellac prepared in example 5 in water;

fig. 7(b) measurement of interfacial tension between oil and homogeneous dispersion of amphiphilic Janus particles of polylysine-modified shellac hemisphere prepared in example 5 in water.

FIG. 8 is a scanning electron microscope image of the particles prepared in comparative example 1;

FIG. 9 is a scanning electron microscope image of the particles prepared in comparative example 2;

fig. 10 is a scanning electron microscope image of the particles prepared in comparative example 3.

Detailed Description

Example 1: preparing Janus particles with biocompatibility and particle size of about 400nm

Referring to the attached fig. 1(a), the method of the present invention is used to prepare the biologically compatible Janus particles, and the specific steps are as follows:

(1) dissolving 120mg of lac in 5ml of tetrahydrofuran, putting the lac into a rotor, and stirring the lac on a magnetic stirring table until the lac is completely dissolved to obtain a lac solution with the concentration of 24 mg/ml; and dissolving 120mg of polylactic acid in the lac solution, and performing ultrasonic dispersion to obtain a mixed solution with the lac concentration of 24mg/ml and the polylactic acid concentration of 24 mg/ml. Adding 1ml of Tween 80 into 100ml of deionized water, ultrasonically dispersing in an ultrasonic cleaning instrument, and filtering with a disposable needle filter (specification: phi 25mm x 0.45 μm) to obtain Tween 80 aqueous solution.

(2) And (2) heating the mixed solution prepared in the step (1) and 3ml of Tween 80 aqueous solution in a constant-temperature water bath kettle, setting the water bath temperature at 70 ℃, heating for 15min, taking 100 mu l of the mixed solution prepared in the step (1), injecting the mixed solution into 3ml of the Tween 80 aqueous solution prepared in the step (1) at the flow rate of 20ml/h, and uniformly mixing by shaking to obtain the uniform dispersion of the biocompatible shellac-polylactic acid Janus particles in the Tween 80 solution.

(3) Standing the Janus particles of the lac-polylactic acid with biocompatibility, which are prepared in the step (2), at the temperature of a uniform dispersion liquid of a Tween 80 solution for 6 hours, then taking the solution, centrifuging the solution in a high-speed centrifuge at the set rotating speed of 10000rpm for 8min, removing supernatant after centrifugation, then adding deionized water, and re-dispersing the particles in water uniformly; and repeating the centrifugal dispersion process for 5 times to remove the surfactant Tween 80, and finishing the washing of the Janus particles to obtain a uniform dispersion liquid (shown in figure 1 (b)) of the biocompatible Janus particles in the deionized water, wherein the scanning electron microscope image of the Janus particles is shown in figure 1(c), and the average particle size of the Janus particles is about 400 nm.

Example 2: particle morphology change process of Janus particles in alkaline solution

(1) Dissolving 150mg of lac in 5ml of tetrahydrofuran, placing the lac into a rotor, and stirring the lac on a magnetic stirring table until the lac is completely dissolved to obtain a lac solution with the concentration of 30 mg/ml; and dissolving 150mg of polylactic acid in the lac solution, and performing ultrasonic dispersion to obtain a mixed solution with the lac concentration of 30mg/ml and the polylactic acid concentration of 30 mg/ml. Adding 1ml of Tween 80 into 100ml of deionized water, ultrasonically dispersing in an ultrasonic cleaning instrument, and filtering with a disposable needle filter (specification: phi 25mm x 0.45 μm) to obtain Tween 80 aqueous solution.

(2) And (2) heating the mixed solution prepared in the step (1) and 3ml of Tween 80 aqueous solution in a constant-temperature water bath kettle, setting the water bath temperature at 70 ℃, heating for 15min, taking 100 mu l of the mixed solution prepared in the step (1), injecting the mixed solution into 3ml of the Tween 80 aqueous solution prepared in the step (1) at the flow rate of 20ml/h, and uniformly mixing by shaking to obtain the uniform dispersion of the biocompatible shellac-polylactic acid Janus particles in the Tween 80 solution.

(3) Standing the Janus particles of the lac-polylactic acid with biocompatibility, which are prepared in the step (2), at the temperature of a uniform dispersion liquid of a Tween 80 solution for 6 hours, then taking the solution, centrifuging the solution in a high-speed centrifuge at the set rotating speed of 10000rpm for 8min, removing supernatant after centrifugation, then adding deionized water, and re-dispersing the particles in water uniformly; and repeating the centrifugal dispersion process for 5 times to remove the surfactant Tween 80, and finishing the washing of the Janus particles to obtain the uniform dispersion liquid of the biocompatible Janus particles in the deionized water.

(4) 4g of sodium hydroxide was dissolved in 50ml of deionized water, the dissolved sodium hydroxide solution was cooled to room temperature, and deionized water was added to a solution volume of 100ml, to obtain a 0.1mol/L pH 13 sodium hydroxide solution.

(5) Taking the homogeneous dispersion liquid of the biocompatible Janus particles prepared in the step (3) in deionized water, adding deionized water for dilution to obtain the homogeneous dispersion liquid with the concentration of the Janus particles being 2mg/mL, taking 100 mu L of the solution, dropwise adding the solution onto a glass slide, covering the glass slide with a cover glass, taking 20 mu L of the sodium hydroxide solution prepared in the step (4), slowly adding the sodium hydroxide solution to the edge of the glass slide, observing the change of the appearance of a certain Janus particle along with time under an optical microscope, as shown in figure 2, one hemisphere of the Janus particles undergoes a process of swelling and enlarging and then gradually dissolving, while the other hemisphere does not swell and dissolve, and finally, only one hemisphere exists in an alkaline solution because shellac can be gradually dissolved in an alkaline environment, and polylactic acid is not influenced by the alkaline environment, thereby proving that half of the Janus particles are shellac materials, half of the polylactic acid material.

Example 3: controlling Janus particle size by varying initial concentration of material

(1) Following the procedure of example 1, the concentrations of shellac and polylactic acid in tetrahydrofuran were varied, but keeping the shellac concentration the same as the polylactic acid concentration, the following sets of concentrations were set: 2mg/ml, 6mg/ml, 12mg/ml, 18mg/ml, 24mg/ml and 30mg/ml, respectively, to obtain Janus particles with the same volume of lac hemisphere and polylactic acid hemisphere, but the whole size of the particles is changed within a range of hundreds of nanometers, as shown in figure 3.

(2) The particle size distribution of the Janus particles with different sizes prepared in the step (1) is measured by a DLS method, and the results are as follows:

when the concentration of the lac and the PLA are both 2mg/ml, the average particle size of the Janus particles is about 230 nm;

when the concentration of the lac and the concentration of the PLA are both 6mg/ml, the average particle size of the Janus particles is about 270 nm;

when the concentration of the shellac and the PLA are both 12mg/ml, the average particle size of the Janus particles is about 300 nm;

when the concentration of the lac and the PLA are both 18mg/ml, the average particle size of the Janus particles is about 350 nm;

when the concentration of the shellac and the PLA are both 24mg/ml, the average particle size of the Janus particles is about 400 nm;

when the shellac and PLA concentrations were both 30mg/ml, the average particle size of the Janus particles was about 700 nm.

Example 4: volume ratio of two hemispheres of Janus particles is adjusted and controlled by changing initial concentration ratio of materials

(1) Following the procedure of example 1, keeping the concentration of PLA in tetrahydrofuran at 12mg/ml, the shellac concentration was varied and the following sets of shellac concentrations were set: 4mg/ml, 8mg/ml, 12mg/ml, 16mg/ml, 20mg/ml, 24mg/ml, 28mg/ml and 32mg/ml, respectively, to prepare Janus particles with gradually changing volume ratio of two hemispheres in the particles, as shown in figure 4.

(2) The particle size distribution of the Janus particles prepared in the step (1) is measured by a DLS method, and the result is as follows:

when the shellac is 4mg/ml and the PLA concentration is 12mg/ml, the average particle size of the Janus particles is about 300 nm;

when the shellac is 8mg/ml and the PLA concentration is 12mg/ml, the average particle size of the Janus particles is about 330 nm;

when the lac is 12mg/ml and the PLA concentration is 12mg/ml, the average particle size of the Janus particles is about 340 nm;

when the lac is 16mg/ml and the PLA concentration is 12mg/ml, the average particle size of the Janus particles is about 380 nm;

when the lac is 20mg/ml and the PLA concentration is 12mg/ml, the average particle size of the Janus particles is about 390 nm;

when the lac is 24mg/ml and the PLA concentration is 12mg/ml, the average particle size of the Janus particles is about 400 nm;

when the lac is 28mg/ml and the PLA concentration is 12mg/ml, the average particle size of the Janus particles is about 450 nm;

when the shellac is 32mg/ml and the PLA concentration is 12mg/ml, the average particle size of the Janus particles is about 5000 nm.

Example 5: oil-in-water emulsion with stable amphiphilic Janus particles of polylysine modified lac hemisphere

(1) And (3) dissolving 170mg of polylysine in 4mL of deionized water, adding 1mL of the homogeneous dispersion of the Janus particles in the deionized water, which is prepared in the step (3) in the example 1, wherein the concentration of the Janus particles is 48mg/mL, standing for 4h, and allowing the positively charged polylysine and the negatively charged shellac hemisphere to interact through positive and negative charges to obtain the homogeneous dispersion of the amphiphilic Janus particles of the polylysine modified shellac hemisphere in the water (as shown in the attached figure 5 (a)).

(2) Adding 50mg of Sudan II dye into 10ml of silk oil, mixing thoroughly, and filtering with disposable needle filter (specification: phi 25mm × 0.45 μm) to obtain Sudan II dye-dyed silk oil.

(3) And (3) taking 5ml of the uniform dispersion liquid of the amphiphilic Janus particles of the polylysine modified lac hemisphere prepared in the step (1) in water, adding 1ml of silk oil dyed by Sudan II dye obtained in the step (2), mixing the oil phase and the water phase for 1min by using a vortex mixer to obtain an oil-in-water emulsion with stable amphiphilic Janus particles of the polylysine modified lac hemisphere, wherein the amphiphilic Janus particles are adsorbed on the surface of oil drops, and the method is shown in the attached drawing 5 (b). The oil droplets dispersed in water were observed under a microscope as shown in FIG. 5 (c).

(4) Taking the homogeneous dispersion of the Janus particles prepared in the step (3) in the example 1 in deionized water to obtain 1mL of homogeneous dispersion with Janus particle concentration of 48mg/mL, adding 4mL of deionized water and 1mL of silk oil dyed by Sudan II dye obtained in the step (1), mixing the oil phase and the water phase for 1min by using a Vortex Mixer to obtain an oil-in-water emulsion with stabilized Janus particles, and observing a graph comparing the change of oil drops in the oil-in-water emulsion with stabilized Janus particles and the change of oil drops in the oil-in-water emulsion with stabilized amphiphilic Janus particles of the polylysine modified shellac hemisphere prepared in the step (3), as shown in the attached figure 6.

Because the carboxyl part of the shellac hemisphere in the Janus particle is ionized, the shellac surface is negatively charged, and the polylysine has positively charged amino groups, the positively charged polylysine is adsorbed on the shellac hemisphere surface through the electrostatic interaction of positive and negative charges. Because polylysine has hydrophilicity, the lac hemisphere modified by polylysine also has hydrophilicity, and meanwhile, the polylactic acid hemisphere has hydrophobicity, so that the Janus particles have amphipathy, the lac hemisphere is hydrophilic, and the polylactic acid hemisphere is hydrophobic. The experimental results in fig. 7(a) show that the potential of amphiphilic Janus particles of the polylysine-modified shellac hemisphere is significantly reduced, i.e. the negative charge in the Janus particles is neutralized with the positive charge in polylysine, and the two undergo electrostatic adsorption reaction. The experimental results in fig. 7(b) show that the interface tension between the uniform dispersion of unmodified Janus particles in water and the silk oil is large, and the amphiphilic Janus particles of the polylysine modified shellac hemisphere can significantly reduce the interface tension between oil and water, thereby realizing the function of stabilizing the oil and water phases.

Comparative example 1: effect of organic solvents on Janus particle formation

The procedure of example 1 was followed except for step (1), in which 120mg of shellac was dissolved in 5ml of acetone. FIG. 8 is a scanning electron microscope image of the particles prepared in comparative example 1. Comparative example 1, in which irregularly shaped particles were prepared without forming dumbbell-shaped Janus particles, and example 1, in which dumbbell-shaped Janus particles having a shellac material at one end and a polylactic acid material at the other end were prepared, illustrates that the use of different organic solvents has an important effect on the formation of Janus particles.

Comparative example 2: effect of temperature on Janus particle formation

The procedure of example 1 was followed, except for the step (2), wherein 100. mu.l of the mixed solution prepared in the step (1) was taken, the mixed solution was injected into 3ml of the aqueous Tween 80 solution prepared in the step (1) at a flow rate of 20ml/h, and mixed by shaking to obtain a Tween 80 solution containing Janus particles. FIG. 9 is a SEM image of particles prepared in comparative example 2, where it can be seen that there are some dumbbell-shaped particles, but most of the particles are ellipsoidal, and that the particles prepared in comparative example 2 are only partially dumbbell-shaped Janus particles as compared to example 1, which illustrates the temperature that has a significant effect on the formation of Janus particles.

Comparative example 3: effect of surfactants on Janus particle formation

The procedure of example 1 was followed except that no tween 80 surfactant was added and the aqueous tween 80 solution was replaced with deionized water. FIG. 10 is a scanning electron micrograph of the particles prepared in comparative example 3. Comparative example 3, in which particles having an ellipsoidal shape were prepared and dumbbell-shaped Janus particles were not prepared, and example 1, in which dumbbell-shaped Janus particles having a shellac material at one end and a polylactic acid material at the other end were prepared, illustrates that the presence of a surfactant has an important effect on the formation of Janus particles.

Claims (5)

1. A method for preparing Janus particles with biocompatibility is characterized by comprising the following steps:

(1) dissolving lac in tetrahydrofuran, wherein the concentration range of the lac in the tetrahydrofuran is 2-100mg/ml, and stirring until the lac is completely dissolved to obtain a lac solution; adding polylactic acid, wherein the concentration range of the polylactic acid in tetrahydrofuran is 2-100mg/ml, and obtaining a mixed solution of the shellac and the polylactic acid; adding tween 80 into deionized water, wherein the volume fraction range of the tween 80 in the deionized water is 0.5% -5%, and performing ultrasonic dispersion to obtain a tween 80 aqueous solution;

(2) respectively heating the mixed solution prepared in the step (1) and a Tween 80 aqueous solution to 65-90 ℃, injecting the mixed solution into the Tween 80 aqueous solution at the speed of 5-30 ml/h at the temperature, wherein the volume percentage range of the mixed solution and the Tween 80 aqueous solution is 1.67-6.67%, and uniformly mixing by shaking to obtain a uniform dispersion of the Janus particles of the biocompatible shellac-polylactic acid in the Tween 80 solution;

(3) standing the Janus particles of the lac-polylactic acid with biocompatibility, which are prepared in the step (2), in the uniform dispersion liquid of the Tween 80 solution at room temperature, then taking the solution, centrifuging the solution in a high-speed centrifuge, removing supernatant after centrifugation, then adding deionized water, and re-dispersing the particles in the water uniformly; repeating the centrifugal dispersion process to remove the surfactant Tween 80, and finishing the washing of the Janus particles to obtain the uniform dispersion liquid of the Janus particles with biocompatibility in the deionized water;

(4) dissolving polylysine in deionized water, and adding the uniform dispersion liquid of the Janus particles prepared in the step (3) in the deionized water, wherein the concentration range of the polylysine in the water is 24-400mg/mL, the concentration range of the Janus particles dispersed in the water is 12-100mg/mL, and the mass ratio of the polylysine to the Janus particles is 2: 1-5: and 1, standing for 1-8h, and obtaining the uniform dispersion liquid of the amphiphilic Janus particles of the polylysine modified lac hemisphere in water through the interaction of positive charges and negative charges between the polylysine with positive charges and the lac hemisphere with negative charges.

2. The method for preparing biocompatible Janus particles as claimed in claim 1, wherein, in step (1),

the weight range of the lac added in 1mL tetrahydrofuran is 2-100 mg;

the mass range of the polylactic acid added into 1mL of water is 2-100 mg;

the molecular weight range of the polylactic acid is 1000-5000;

the volume fraction range of the tween 80 added in 1mL of water is 0.5 to 5 percent.

3. The method of claim 1, wherein in step (3),

the standing time range at room temperature is 4-12 h;

the centrifugal dispersion times range from 3 times to 10 times.

4. Janus particles with biocompatibility prepared according to the method of any one of claims 1-3.

5. A preparation method of an oil-in-water emulsion with stable amphiphilic Janus particles of polylysine modified lac hemispheres is characterized by comprising the following steps:

taking a uniform dispersion of amphiphilic Janus particles of polylysine modified shellac hemisphere prepared in claim 1 in water, adding silk oil, wherein the volume ratio of oil phase to uniform dispersion is 1: and 5, mixing the oil phase and the water phase for 1-8min to obtain the oil-in-water emulsion with stable amphiphilic Janus particles of the polylysine modified lac hemisphere.

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