CN108938593B

CN108938593B - Preparation method of lipid-coated solid drug nanoparticles

Info

Publication number: CN108938593B
Application number: CN201810778725.1A
Authority: CN
Inventors: 曾志鹏; 陈永明; 刘利新; 赵鹏飞
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2018-07-16
Filing date: 2018-07-16
Publication date: 2021-06-08
Anticipated expiration: 2038-07-16
Also published as: CN108938593A

Abstract

The invention discloses a preparation method of lipid-coated solid drug nanoparticles. The method comprises the following steps: firstly, amphiphilic micromolecular drugs are subjected to a rapid nano-precipitation method under the condition that no stabilizer is added to obtain a drug nanoparticle solution; then the lipid solution is extruded with the lipid solution to prepare the lipid-coated solid drug nano-particles. Compared with the traditional medicine nano-particles, the lipid-coated solid medicine nano-particles prepared by the invention have ultrahigh drug loading capacity which can reach more than 60 percent and are remarkably higher than the traditional medicine nano-particles; the preparation method can realize continuous production, has small difference among batches, and is suitable for industrial production; in addition, the surface of the drug particles is coated with lipid, and the protective layer endows the drug nanoparticles with long-term storage stability, active targeting property of tumor tissues and pH responsiveness, and has a larger application prospect in the aspect of drug delivery.

Description

Preparation method of lipid-coated solid drug nanoparticles

Technical Field

The invention belongs to the field of biomedicine, and particularly relates to a preparation method of lipid-coated solid drug nanoparticles.

Background

Although the nano-chemotherapy drug delivery system improves the curative effect to a certain extent and prolongs the survival time of patients, the cancer still is one of the diseases which have the greatest threat to human health at present. Although nano-drug formulations are being developed and manufactured, and even approved for clinical use, most nano-drugs have a fatal drawback in that the drug loading is low, usually less than 10%; in addition, some carriers adopted in the nano-medicament have no medicament effect and even can generate toxic or side effect; and the preparation process of the nano-drug usually involves a complicated process or complex chemical synthesis, so that the repeatability of different batches is poor, and the large-scale industrial production is difficult.

Rapid nano-precipitation is a microfluidic technique that allows continuous production of drug nanoparticles by kinetically controlled molecular aggregation processes. The nano particles prepared by the rapid nano precipitation method have controllable particle size, narrow dispersion and good repeatability, can be produced continuously in large scale and are suitable for industrial production. The main mechanism is to realize the fast exchange between solvent (containing medicine) and non-solvent (containing stabilizer) by means of high-turbulence mixer (such as coaxial turbulence mixer, four-channel vortex mixer, etc.), and to control the grain size and dispersivity of nanometer grains by regulating the nucleation and growth rate of solute. However, the nano-drug prepared by the rapid nano-precipitation method also has the defect of low drug loading.

Therefore, the large-scale production, the reduction of the production cost, the improvement of the drug loading rate, the reduction of the toxic and side effects and the intelligent drug release are the problems which are urgently needed to be solved by the clinical transformation of the nano-medicament at present.

Disclosure of Invention

The invention aims to provide a preparation method of lipid-coated solid drug nanoparticles aiming at the defects and shortcomings in the prior art. According to the method, by combining a rapid nano-precipitation method and a lipid extrusion technology, firstly, an amphiphilic small-molecule drug is prepared into nanoparticles under the condition of not using a stabilizer, and then the drug nanoparticles are wrapped by the lipid extrusion technology, so that the method has no adverse effect on the anticancer effect of the drug, and the prepared lipid-wrapped solid drug nanoparticles are high in drug loading, small in particle size, narrow in dispersion, good in stability and small in toxic and side effects.

The above object of the present invention is achieved by the following scheme:

a method for preparing lipid-coated solid drug nanoparticles comprises firstly obtaining drug nanoparticle solution from amphiphilic micromolecular drug by rapid nano-precipitation method without using stabilizer; then the lipid-coated solid drug nano-particles are prepared by the method of extrusion with lipid.

The method is suitable for amphiphilic micromolecular drugs, when the drugs are completely hydrophobic drugs, the drug nanoparticle solution prepared by the rapid nano-precipitation method can quickly separate out macroscopic precipitates within a few seconds, and the lipid extrusion treatment step of the second step cannot be carried out; however, when the drug is completely hydrophilic, the drug is not present in the solution in the form of nanoparticles but dissolved in the solution prepared by the rapid nano-precipitation method, and thus the lipid extrusion treatment cannot be performed.

Preferably, the amphiphilic small molecule drug is methotrexate, chlorambucil or adriamycin.

Preferably, the specific process of rapid nano-precipitation comprises: respectively introducing the solution dissolved with the amphiphilic micromolecular drug and water into different channels of a four-channel vortex mixer according to the volume ratio of 1: 3-11, and mixing through high-speed turbulence to obtain the drug nanoparticle solution. Specifically, an organic solution of amphiphilic micromolecular medicine and ultrapure water are respectively introduced into the 1 st channel, the 2 nd channel, the 3 rd channel and the 4 th channel of a four-channel vortex mixer, and are subjected to high-speed turbulent mixing in the vortex mixer to quickly form a medicine nanoparticle solution.

In the rapid nano-precipitation process, a stabilizing agent is not added, the amphiphilic micromolecular drug is directly prepared into a drug nano-particle solution, and the drug nano-particles in the solution are completely 100% of the drug due to the fact that the stabilizing agent is not added, so that the high drug-loading rate of the finally prepared lipid-coated solid drug nano-particles is guaranteed.

Preferably, the solvent for dissolving the amphiphilic small molecule drug comprises but is not limited to one, two or more mixed solution of N, N-dimethylformamide, N-methylpyrrolidone or dimethyl sulfoxide; the flow rate of the solution dissolved with the amphiphilic micromolecular medicine in the high-speed turbulent mixing process is 1 mL/min-20 mL/min.

Preferably, when the amphiphilic small molecule drug is methotrexate, chlorambucil or adriamycin, the concentration of the drug in the drug-dissolved solution is 1-6 mg/mL, 0.5-4 mg/mL or 0.1-2 mg/mL. When the concentration of the drug in the solution is too high, a macroscopic precipitate can be separated out from the solution treated by the rapid nano-precipitation method instead of forming nano-particles; however, when the concentration is too low, it is difficult to form nanoparticles from the drug molecules.

Preferably, when the amphiphilic small molecule drug is methotrexate, chlorambucil or adriamycin, the concentration of the drug in the drug-dissolved solution is 3-5 mg/mL, 0.5-2 mg/mL or 0.3-1 mg/mL.

More preferably, when the amphiphilic small molecule drug is methotrexate, chlorambucil, or doxorubicin, respectively, the concentration of the drug in the drug-dissolved solution is 4mg/mL, 1 mg/mL, or 0.5 mg/mL, respectively.

Preferably, the specific process of the extrusion comprises: mixing the ethanol solution dissolved with the lipid with the drug nanoparticle solution, and repeatedly extruding the mixture for at least 7 times through a polyvinylidene fluoride membrane with the pore diameter of 50-200 nm to obtain the lipid-coated solid drug nanoparticle. More preferably, the polyvinylidene fluoride membrane has a pore diameter of 100nm, and ethanol with a mass concentration of 4% is used for dissolving the lipid.

Preferably, the lipid includes, but is not limited to, at least two of 1, 2-dioleoyl-SN-glycerol-3-phosphorylethanolamine, cholesterol succinate monoester, 1, 2-distearoyl-SN-glycerol-3-phosphorylethanolamine-polyethylene glycol (2000) DSPE-PEG or 1, 2-distearoyl-SN-glycerol-3-phosphorylethanolamine-polyethylene glycol-folate.

Preferably, the lipid is 1, 2-dioleoyl-SN-glycerol-3-phosphorylethanolamine and cholesterol succinate monoester, and 1, 2-distearoyl-SN-glycerol-3-phosphorylethanolamine-polyethylene glycol (2000) or 1, 2-distearoyl-SN-glycerol-3-phosphorylethanolamine-polyethylene glycol-folic acid, and the molar ratio of the 1, 2-dioleoyl-SN-glycerol-3-phosphorylethanolamine to the polyethylene glycol-folic acid is 10-15: 4-9: 1-5; more preferably, the molar ratio of the three is 10:9: 1.

Preferably, after the ethanol solution dissolved with lipid is mixed with the drug nanoparticle solution, the mass ratio of the amphiphilic micromolecular drug to the lipid in the solution is 1-4: 1; more preferably, the mass ratio of amphiphilic small molecule drug to lipid is 4: 1.

When the lipid is used in a small amount, the stability of the drug nanoparticles will be significantly reduced although the drug loading of the finally prepared drug nanoparticles is higher.

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

compared with the traditional medicine nano-particles, the lipid-coated solid medicine nano-particles prepared by the method have the greatest advantage of ultrahigh drug loading capacity which can reach more than 60 percent and is remarkably higher than the traditional medicine nano-particles; in addition, the rapid nano-precipitation method can be used for continuous production, has small difference among batches, and is suitable for industrial production; the surface of the drug particles is wrapped with lipid, and the protective layer endows the drug nanoparticles with long-term storage stability, active targeting property of tumor tissues and pH responsiveness. The lipid-coated solid drug nanoparticles prepared by the method have a wide application prospect in the aspect of drug delivery.

Drawings

Figure 1 is a graph of the effect of organic phase/aqueous phase ratio on particle size and particle size distribution of methotrexate nanoparticles.

FIG. 2 shows the particle size and surface potential changes of methotrexate nanoparticles before and after lipid encapsulation.

FIG. 3 is a transmission electron micrograph of methotrexate drug nanoparticles before and after lipid encapsulation.

FIG. 4 shows the effect of the particle size (graph A) and particle size distribution (graph B) of chlorambucil and adriamycin drug nanoparticles in organic phase/aqueous phase ratio, and the change of particle size and surface potential before and after lipid encapsulation of chlorambucil (graph C) and adriamycin (graph D) drug nanoparticles.

Figure 5 is the in vitro stability of methotrexate drug nanoparticles before and after lipid encapsulation.

Figure 6 is the in vitro toxicity of methotrexate, lipid-encapsulated methotrexate nanoparticles.

FIG. 7 shows the results of the experiment of inhibiting tumor in nude mice by methotrexate and lipid-encapsulated methotrexate nanoparticles.

Detailed Description

The invention is further described with reference to the drawings and the following detailed description, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Unless otherwise indicated, reagents and materials used in the following examples are commercially available. .

Example 1 preparation of methotrexate nanoparticle solution

Methotrexate is weighed and dissolved in a mixed solvent (volume ratio is 7: 3) of N, N-dimethylformamide and N-methylpyrrolidone to prepare a 4mg/mL methotrexate organic solution, the methotrexate organic solution is introduced into the 1 st channel of a four-channel vortex mixer, and ultrapure water is introduced into the other three channels, so that the methotrexate nanoparticle solution is prepared by rapid turbulent mixing. The volume ratio of the methotrexate organic solution to the water phase is 1: 3-9, and the flow rate of the organic phase is 6 mL/min.

When the volume ratio of the organic solution (organic phase) to the aqueous phase of methotrexate is changed, methotrexate nanoparticles having different particle sizes can be prepared, and the specific ratio and particle size relationship are shown in fig. 1.

When the volume ratio of the organic phase to the aqueous phase is 1: 3-9, the particle size of the prepared methotrexate nanoparticles ranges from 49 nm to 384 nm, the particle size distribution ranges from 0.1 to 0.2, and the particle size distribution of the methotrexate nanoparticles in the methotrexate nanoparticle solution is very uniform.

Because the EPR effect and tissue penetrability of the nanoparticles with the particle size of about 50 nm at a tumor site are good, methotrexate nanoparticles prepared by using an organic phase and an aqueous phase in a volume ratio of 1:9 are selected, and the particle size of the methotrexate nanoparticles is 49.1 nm.

Example 2 preparation of nanoparticles of lipid-encapsulated methotrexate

Weighing 1, 2-dioleoyl-SN-glycerol-3-phosphorylethanolamine (DOPE), cholesterol succinic acid monoester (CHEMS), 1, 2-distearoyl-SN-glycerol-3-phosphorylethanolamine-polyethylene glycol (2000) (DSPE-PEG), preparing a mixture according to a molar ratio of 10:9:1, and dissolving in dichloromethane to prepare a 10 mg/mL mixed lipid solution for later use. The pipette is used to quantitatively pipette 0.1 mL of mixed lipid dichloromethane solution into 10 mL of 4% ethanol solution, and the solution is sonicated by a probe sonicator until clear for use. After the lipid ethanol solution with the same volume and the methotrexate nanoparticle solution with the particle size of 49.1nm prepared in example 1 were mixed, the mass ratio of methotrexate to the mixed lipid in the mixed solution was 4:1, and the mixed solution was repeatedly extruded through a 100nm polyvinylidene fluoride membrane for 7 times to obtain lipid-encapsulated methotrexate nanoparticles MTX NP @ lipid.

The preparation process is also adopted, the lipid is replaced by mixed lipid of 1, 2-dioleoyl-SN-glycerol-3-phosphorylethanolamine (DOPE), cholesterol succinic acid monoester (CHEMS) and 1, 2-distearoyl-SN-glycerol-3-phosphorylethanolamine-polyethylene glycol-folic acid (DSPE-PEG-FA) according to the molar ratio of 10:9:1, and the folate-encapsulated methotrexate nanoparticle MTX NP @ lipid-FA is prepared

The particle size of 3 methotrexate nanoparticles was examined and their morphology was observed. The results are shown in FIGS. 2 and 3, where MTX NP is a methotrexate nanoparticle, and MTX NP @ lipid-FA are 2 lipid-encapsulated methotrexate nanoparticles using different lipids.

As can be seen from fig. 2, the particle size of the lipid-encapsulated methotrexate nanoparticles was increased to 56 nm and the surface potential was changed from neutrality to about-10 mV, which was more advantageous than the methotrexate nanoparticles in improving the in vivo stability of the lipid-encapsulated methotrexate nanoparticles.

As can be seen from FIG. 3, there are aggregates between methotrexate nanoparticles (MTX NP), while 2 lipid-encapsulated methotrexate nanoparticles (MTX NP @ lipid and MTX NP @ lipid-FA) were well dispersed, demonstrating good stability.

The particle size of the prepared lipid-encapsulated methotrexate nanoparticles is 56 nm, the dispersity is 0.187, the encapsulation efficiency is 84.5%, and the drug loading rate is 62.3%.

The drug loading of the lipid-coated methotrexate nanoparticles prepared by the method is as high as 62.3%, which is 2 times of the drug loading of the nanoparticles prepared by a rapid nano-precipitation method, and the method provided by the invention obviously improves the drug loading of the methotrexate nanoparticles.

Example 3 preparation of lipid-coated chlorambucil or doxorubicin nanoparticles

Weighing chlorambucil or adriamycin, respectively dissolving the chlorambucil or adriamycin in dimethyl sulfoxide or N, N-dimethylformamide to respectively prepare 1 mg/mL or 0.5 mg/mL organic solutions, respectively introducing the organic solutions into the 1 st channel of the four-channel vortex mixer, and introducing ultrapure water into the other three channels to realize rapid turbulent mixing so as to prepare chlorambucil nanoparticle solution and adriamycin nanoparticle solution. The volume ratio of the chlorambucil nanoparticle solution (organic phase) or the adriamycin nanoparticle solution (organic phase) to the water phase is set to be 1: 3-11, the flow rate of the organic phase is 10 mL/min, and the chlorambucil nanoparticle solution and the adriamycin nanoparticle solution are prepared.

Referring to the steps in example 2, lipid-coated chlorambucil nanoparticles and lipid-coated doxorubicin nanoparticles were prepared, respectively.

The effect of the volume ratio of the organic phase to the aqueous phase on the particle size and dispersion of the 2 nanoparticles prepared was tested and the results are shown in fig. 4. As can be seen from FIGS. 4A and 4B, the particle sizes of the chlorambucil particles and the doxorubicin nanoparticles both decreased as the volume ratio of the organic phase to the aqueous phase decreased. When the volume ratio of the organic phase to the aqueous phase is 1: 3-11, the particle size range of the chlorambucil rice particles is 48-263 nm, and the particle size distribution is 0.06-0.18; the particle size range of the adriamycin particles is 65-258 nm, and the particle size distribution is 0.06-0.15. The nanoparticle size distribution of both drugs was very uniform.

When the volume ratio of the organic phase to the aqueous phase is 1:9, the particle size of the chlorambucil and adriamycin nanoparticles is closest to 50 nm, and is 48 nm and 65 nm respectively. The chlorambucil and adriamycin nanoparticles with the particle sizes of 48 nm and 65 nm are respectively selected, so that the mass ratio of the medicine to the mixed lipid is ensured to be 4:1, the chlorambucil and doxorubicin nanoparticles were encapsulated according to the procedure of example 2 to prepare lipid-encapsulated chlorambucil nanoparticles and lipid-encapsulated doxorubicin nanoparticles.

The changes of the particle size and surface potential of the drug nanoparticles in 2 before and after encapsulation of lipid are shown in fig. 4C and 4D. As can be seen from FIGS. 4C and 4D, the particle size of the drug nanoparticles increases by about 10 nm after lipid encapsulation, and the surface potential changes from neutral to about-10 mV, thus proving that lipid encapsulation is successfully completed on the drug nanoparticles.

The particle size of the prepared lipid-coated adriamycin nano particles is 66 nm, the dispersion degree is 0.124, the encapsulation rate is 89.4%, and the drug-loading rate is 66.4%.

The particle size of the prepared lipid-coated chlorambucil nanoparticles is 55 nm, the dispersion degree is 0.145, the encapsulation rate is 87.4%, and the drug loading rate is 63.7%.

Similarly, the drug loading rates of the lipid-coated adriamycin nanoparticles and the lipid-coated chlorambucil nanoparticles prepared by the method are respectively as high as 66.4% and 63.7%, which are remarkably higher than those of the conventional drug nanoparticles.

Example 4 in vitro stability of lipid-encapsulated drug nanoparticles

The in vitro stability of 2 nanoparticles was tested using the methotrexate nanoparticles (MTX NP) and lipid-encapsulated methotrexate nanoparticles (MTX NP @ lipid) prepared in example 1 as test subjects.

The test procedure was as follows: PBS solutions of group A (MTX NP particle), group B (MTX NP @ lipid particle), and group C (MTX NP @ lipid particle after dialysis) were allowed to stand at room temperature for one week, and changes in the particle size of the three groups were recorded for a predetermined period of time.

The recorded results are shown in FIG. 5. As can be seen from fig. 5, the MTX NP particles gradually increased in particle size with increasing resting time, and the increase in particle size was significantly increased when resting time exceeded 4 days; the MTX NP @ lipid particles in the groups B and C have no obvious change in particle size after standing in a PBS buffer solution for a period of time, so that the MTX NP @ lipid particles are known to have good in vitro stability.

Example 5 in vitro cytotoxicity of lipid-encapsulated drug nanoparticles

The CCK8 method was used to evaluate the cytotoxicity of methotrexate nanoparticles in vitro. The method comprises the following specific steps: MCF-7 cells at 1X 10⁴The density of each well is planted in a 96-well plate, after the cells grow overnight and adhere to the wall, 100 mu L of complete culture medium containing different MTX (group A), MTX NP @ lipid (group B) and MTX NP @ lipid-FA (group C) is taken to replace the original medium. After 48h of co-incubation, the viability of the corresponding cells was determined using CCK8 reagent.

The experimental result is shown in FIG. 6, MTX NP @ lipid and MTX NP @ lipid-FA all show drug concentration dependence, the sequence of killing power of the 3 groups on MCF-7 cells is MTX NP @ lipid-FA > MTX NP @ lipid > MTX, namely the MTX NP @ lipid-FA has the strongest inhibition effect on the MCF-7 cells; the MTX NP @ lipid-FA targeting was also the most preferred.

Example 6 experiment of lipid-encapsulated drug nanoparticles for inhibiting tumor in nude mice

MCF-7 cell-inoculated nude mice were used to evaluate in vivo anti-tumor experiments for methotrexate nanoparticles. When the tumor volume of the nude mice reaches 100mm³The treatment was performed in 4 groups of 6 individuals, each group was administered intravenously with physiological saline (group A), methotrexate (group B), MTX NP @ lipid (group C) and MTX NP @ lipid-FA (group D), wherein the administration dose of methotrexate was 10 mg/kg. Each group of nude mice was dosed once in three days for 6 times in the test period, and the length and length of tumor was measured with vernier caliper every two days to calculate the tumor volume.

The experimental results are shown in fig. 7, and it can be seen that B, C, D groups all have inhibitory effects on tumors in nude mice, and the inhibitory effects are more significant than those in group a; however, compared among B, C, D, the inhibition effect of the group D on the tumor of the nude mice is the best, and the inhibition effect of the group C and the group D on the tumor of the nude mice is the significance of the group B; namely, the inhibition effect of the lipid-coated methotrexate drug nanoparticles on the tumor of a nude mouse is obviously superior to that of the methotrexate small molecule drug.

The lipid-coated drug nanoparticles prepared by the method not only remarkably improve the drug loading capacity of the drug, but also have no influence on the performance and the effect of the drug, and the effect of the drug is remarkably improved due to the improvement of the drug loading capacity.

Comparative example 1

In the experimental process, in addition to 3 drugs of methotrexate, chlorambucil or adriamycin, various other drugs have been tested, but not all of them can be successfully prepared into lipid-encapsulated drug nanoparticles, wherein the specific preparation process is as follows, taking hydrophobic drugs of curcumin and paclitaxel as examples:

1. curcumin is weighed and dissolved in ethanol to prepare 1 mg/mL curcumin organic solution, the curcumin organic solution is introduced into the 1 st channel of the four-channel vortex mixer, and ultrapure water is introduced into the other three channels to prepare curcumin nano particles. The volume ratio of the curcumin organic solution to the water phase is 1: 3-9, and the flow rate of the organic phase is 10 mL/min. However, the curcumin nanoparticle solution precipitates visible to the naked eye within a few seconds, and the second-step lipid extrusion operation cannot be carried out.

2. Weighing paclitaxel, dissolving in dimethyl sulfoxide to obtain 1 mg/mL paclitaxel organic solution, introducing into channel 1 of the four-channel vortex mixer, and introducing ultrapure water into the other three channels to prepare paclitaxel nanoparticles. The volume ratio of the paclitaxel organic solution to the water phase is 1: 3-9, and the flow rate of the organic phase is 10 mL/min. However, the paclitaxel nanoparticle solution precipitates visible to the naked eye within a few seconds, and the second lipid extrusion operation cannot be performed.

Through analysis of the reasons of the failure of the tests, the reason that the curcumin and the paclitaxel cannot be successfully prepared into the lipid-coated drug nanoparticles is that the drug has too strong hydrophobicity, and the nanoparticles formed after the rapid nano-precipitation treatment are aggregated and precipitated due to the Ostwald curing process, so that the lipid extrusion operation cannot be carried out.

It should be finally noted that the above examples are only intended to illustrate the technical solutions of the present invention, and not to limit the scope of the present invention, and that other variations and modifications based on the above description and thought may be made by those skilled in the art, and that all embodiments need not be exhaustive. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing lipid-coated solid drug nanoparticles is characterized in that amphiphilic micromolecular drugs are prepared into drug nanoparticle solution by a rapid nano-precipitation method under the condition of not using a stabilizer; then preparing the lipid-coated solid drug nanoparticles by extruding the lipid-coated solid drug nanoparticles and lipid;

the amphiphilic small molecule drug is methotrexate, chlorambucil or adriamycin.

2. The method for preparing lipid-coated solid drug nanoparticles according to claim 1, wherein the specific process of rapid nano-precipitation comprises: respectively introducing the solution dissolved with the amphiphilic micromolecular drug and water into different channels of a four-channel vortex mixer according to the volume ratio of 1: 3-11, and mixing through high-speed turbulence to obtain the drug nanoparticle solution.

3. The method for preparing lipid-coated solid drug nanoparticles according to claim 2, wherein the solvent of the solution dissolved with the amphiphilic small molecule drug comprises one or more of N, N-dimethylformamide, N-methylpyrrolidone or dimethyl sulfoxide.

4. The method for preparing lipid-coated solid drug nanoparticles according to claim 2, wherein the flow rate of the solution dissolved with the amphiphilic small molecule drug during the high-speed turbulent mixing is 1-20 mL/min.

5. The method for preparing lipid-coated solid drug nanoparticles according to claim 2, wherein when the amphiphilic small molecule drug is methotrexate, chlorambucil or adriamycin, the concentration of the drug in the drug-dissolved solution is 1-6 mg/mL, 0.5-4 mg/mL or 0.1-2 mg/mL, respectively.

6. The method for preparing lipid-coated solid drug nanoparticles according to claim 1, wherein the extrusion comprises the following specific processes: mixing the ethanol solution dissolved with the lipid with the drug nanoparticle solution, and repeatedly extruding the mixture for at least 7 times through a polyvinylidene fluoride membrane with the pore diameter of 50-200 nm to obtain the lipid-coated solid drug nanoparticle.

7. The method of claim 6, wherein the lipid comprises at least two of 1, 2-dioleoyl-SN-glycero-3-phosphoethanolamine, cholesterol succinate monoester, 1, 2-distearoyl-SN-glycero-3-phosphoethanolamine-polyethylene glycol (2000), or 1, 2-distearoyl-SN-glycero-3-phosphoethanolamine-polyethylene glycol-folate.

8. The method for preparing lipid-encapsulated solid drug nanoparticles according to claim 7, wherein the lipid is 1, 2-dioleoyl-SN-glycerol-3-phosphoethanolamine and cholesterol succinate monoester, and 1, 2-distearoyl-SN-glycerol-3-phosphoethanolamine-polyethylene glycol (2000) or 1, 2-distearoyl-SN-glycerol-3-phosphoethanolamine-polyethylene glycol-folic acid;

the molar ratio of the 1, 2-dioleoyl-SN-glycerin-3-phosphorylethanolamine, cholesterol succinic acid monoester, 1, 2-distearoyl-SN-glycerin-3-phosphorylethanolamine-polyethylene glycol (2000) or 1, 2-distearoyl-SN-glycerin-3-phosphorylethanolamine-polyethylene glycol-folic acid is 10-15: 4-9: 1-5.

9. The preparation method of the lipid-coated solid drug nanoparticle as claimed in claim 6, wherein the mass ratio of the amphiphilic small molecule drug to the lipid in the solution is 1-4: 1 after the ethanol solution in which the lipid is dissolved is mixed with the drug nanoparticle solution.