Ultrasonic drug delivery system based on cellulose nanocrystals and preparation method and application thereof

Abstract

The invention belongs to the technical field of ultrasonic molecular imaging and biomedical engineering, and particularly relates to an ultrasonic drug delivery system based on cellulose nanocrystals as well as a preparation method and application of the ultrasonic drug delivery system. The cellulose nanocrystal-based ultrasonic drug delivery system provided by the invention is a novel ultrasonic drug delivery system constructed by taking the cellulose nanocrystal as a base material and loading a chemotherapeutic drug, a target head molecule and an ultrasonic contrast agent through an electrostatic layer-by-layer self-assembly technology. The system can realize tumor extravascular field imaging and rapid and accurate drug delivery of a directional tumor area under the guidance of external ultrasound, and effectively solves the problems of low mechanical tolerance, poor ultrasonic imaging effect, poor chemotherapeutic drug targeting, high toxic and side effects, incapability of in-vitro regulation and control and the like of an existing ultrasonic contrast agent; therefore, integration of tumor diagnosis and immunotherapy under ultrasonic guidance is realized, and the method has important significance in tumor diagnosis and treatment application.

Description

Technical Field

[0001] The present invention belongs to the field of ultrasonic molecular imaging and biomedical engineering technology, and specifically relates to an ultrasonic drug delivery system based on cellulose nanocrystals and a preparation method and application thereof. Background Art

[0002] Cancer is a complex disease involving multiple pathogenesis mechanisms. As one of the main causes of human death, it has become a major threat to human life and public health. The occurrence and development of cancer is related to a series of continuous mutations in cells. These mutations are the therapeutic targets of most chemotherapeutic drugs, but a major challenge in tumor treatment is the inherent and acquired resistance of tumors to chemotherapeutic drugs. Therefore, constructing a new drug delivery system to reduce the dosage of chemotherapeutic drugs, reduce their toxic side effects and thus improve the efficacy, and achieve efficient treatment of cancer can provide a new treatment and diagnosis method for cancer research.

[0003] The emergence of ultrasound contrast agents (UCA) as a major advancement in the field of ultrasound diagnosis in recent years has provided a very favorable basis for the identification and diagnosis of various diseases, especially tumor diseases. Through intravenous injection of ultrasound contrast agents, the perfusion information of blood flow is used to distinguish normal tissues from diseased tissues, which effectively enhances the sensitivity and specificity of disease diagnosis. However, contrast agents are limited by shortcomings such as short circulation time in the body, too fast metabolism time, and low mechanical tolerance, and are at a bottleneck stage of development. At the same time, single-function contrast agents can no longer meet the diverse needs of medicine, and research on multifunctional ultrasound contrast agents has entered the field of vision of researchers, such as multimodal ultrasound contrast agents (contrast agents used in multiple imaging modes) and multifunctional ultrasound contrast agents (not only suitable for imaging, but also used in drug delivery, gene transfection, etc.). At this stage, although multimodal contrast agents can be used to improve diagnostic accuracy, treatment after diagnosis is also a major problem.

[0004] How to develop a new ultrasonic drug delivery system to perform diagnosis and treatment simultaneously, and treat the patient's diseased area in a timely manner while obtaining the diagnosis results, can not only shorten the patient's pain of taking the medicine twice and the possible side effects of the medicine, but also help shorten the diagnosis and treatment time, improve the disease treatment effect, and realize the integration of diagnosis and treatment. It is of great significance in the diagnosis and treatment of cancer. Summary of the invention

[0005] In order to solve the problems of the above-mentioned prior art, the first purpose of the present invention is to provide an ultrasonic drug delivery system based on cellulose nanocrystals, which has the comprehensive characteristics of high biosafety, good drug penetration, strong targeting, high utilization rate, low toxic and side effects, and good imaging effect in the extravascular area of ​​tumors. It can improve the delivery efficiency of tumor chemotherapy drugs while realizing the integration of tumor diagnosis and chemotherapy under ultrasound guidance.

[0006] The second object of the present invention is to provide a method for preparing an ultrasonic drug delivery system based on cellulose nanocrystals.

[0007] The third object of the present invention is to provide application of the above-mentioned cellulose nanocrystal-based ultrasonic drug delivery system.

[0008] One of the purposes of the present invention is to adopt the technical solution:

[0009] A cellulose nanocrystal-based ultrasonic drug delivery system, comprising: a nanocarrier, a chemotherapeutic drug, a target head molecule and an ultrasonic contrast agent;

[0010] Wherein, the nanocarrier is cellulose nanocrystal; the chemotherapy drug is one or more of doxorubicin, paclitaxel, and gemcitabine; the target head molecule is hyaluronic acid; and the ultrasound contrast agent is SonoVue or Sildenafil.

[0011] Cellulose nanocrystal (CNC) is a biorenewable nano-scale material, which is a cellulose crystal retained after cellulose is degraded by strong acid or strong alkali, and lignin and amorphous regions are removed. In the present invention, CNC is used as a nanocarrier, which can produce a strong echo intensity under ultrasonic irradiation, and the nanomedicine based on CNC shows a long circulation time. At the same time, the present invention experiments confirm that CNC has good compatibility with amphiphilic polymers, target molecules and chemotherapeutic drugs, improves the inhibitory effect on cancer cell proliferation, and is a good carrier and modified microbubble material. In addition, the present invention carries a specific target molecule hyaluronic acid (HA) in the drug-loaded ultrasound contrast agent. HA is a widely distributed acidic mucopolysaccharide with good biocompatibility and low immunogenicity, and binds with high affinity to the N-terminal peptide chain of CD44. HA binds to the CD44 receptor on the surface of tumor cells, and receptor-mediated endocytosis can be achieved, thereby targeting tumor cells and achieving the purpose of improving drug delivery efficiency.

[0012] The above-mentioned ultrasonic drug delivery system based on cellulose nanocrystals provided by the present invention is not only simple to prepare and highly safe, but also has strong tumor targeting and a long circulation time in the body. It can achieve imaging of the extravascular area of ​​the tumor and rapid and accurate drug delivery to the targeted tumor area under the guidance of external ultrasonic contrast imaging conditions, effectively solving the current problems of poor utilization of tumor chemotherapy drugs, strong toxic side effects, weak targeting and inability to integrate diagnosis and treatment.

[0013] As a preferred solution, the cellulose nanocrystals are selected from one or more of rod-shaped cellulose nanocrystals, TEMPO-modified cellulose nanocrystals, mechanically prepared cellulose nanocrystals, and cellulose nano whiskers.

[0014] As a preferred solution, the chemotherapy drug is doxorubicin.

[0015] The second object of the present invention is to adopt the following technical solution:

[0016] The preparation method of the above-mentioned cellulose nanocrystal-based ultrasonic drug delivery system comprises the following steps:

[0017] S1, dissolving the nanocarrier in ultrapure water and stirring evenly to obtain a nanocarrier suspension;

[0018] S2, adding a polyethyleneimine solution dissolved in ultrapure water and stirred evenly to the stirring nanocarrier suspension, stirring continuously, then centrifuging, washing and resuspending the precipitate to obtain a mixed solution A;

[0019] S3, adding the chemotherapeutic drug solution dissolved in ultrapure water and stirred evenly to the stirring mixed solution A, continuing stirring, then centrifuging, washing and resuspending the precipitate to obtain a mixed solution B;

[0020] S4, adding the target head molecule solution dissolved in ultrapure water and stirred evenly into the stirring mixed solution B, stirring continuously, then centrifuging, washing and resuspending the precipitate to obtain a mixed solution C;

[0021] S5. Evenly mix the ultrasound contrast agent solution dissolved in physiological saline and stirred evenly with the mixed solution C to obtain the cellulose nanocrystal-based ultrasound drug delivery system.

[0022] The preparation method of the ultrasonic drug delivery system based on cellulose nanocrystals provided by the present invention loads chemotherapeutic drugs through electrostatic layer-by-layer self-assembly technology, has a simple preparation process, mild conditions, and is easy to realize industrial production.

[0023] The present invention adopts the above method to prepare the obtained ultrasonic drug delivery system based on cellulose nanocrystals. The cellulose nanocrystals used are a kind of biorenewable nanomaterials, which are not easy to deform and have good biocompatibility. Combined with the target head molecule HA, it can specifically target the CD44 receptor highly expressed on the surface of tumor cells, and construct a stable and efficient delivery carrier for chemotherapy drugs.

[0024] Furthermore, the present invention introduces polyethyleneimine to prepare an ultrasonic drug delivery system, and utilizes the "proton sponge effect" of polyethyleneimine (PEI) to promote the release of drugs from endosomes and prevent them from being degraded by lysosomal enzymes. The released chemotherapy drugs are embedded between double-stranded DNA bases to form a stable complex, inhibiting DNA replication and transcription, while destroying the DNA structure, causing cell damage and further inducing cell apoptosis, thereby achieving efficient delivery of chemotherapy drugs.

[0025] In addition, the ultrasonic drug delivery system of the present invention has long-acting circulation performance in the body. Its biological source characteristics and target head molecular specificity ensure the efficient exertion of the efficacy of the drugs carried. After the drugs have exerted their functions, they can be quickly and safely degraded in the body, which not only ensures its safe and efficient delivery of drugs, but also guarantees safe degradation in the body.

[0026] In addition, the present invention uses cellulose nanocrystals in the form of solid nanoparticles, which can produce strong echo intensity under ultrasonic irradiation. Combined with ultrasound contrast agents, the mechanical index tolerance and ultrasound enhancement effect of the new ultrasound drug delivery system in vivo and in vitro can be enhanced. During drug delivery, in vitro ultrasound can be performed at the tumor site to achieve active and passive targeting of tumor lesions under ultrasound guidance. Combined with ultrasound targeted microbubble rupture (UTMD), microbubble enrichment at the tumor site can be achieved to achieve targeted drug delivery, and drug delivery and treatment effects can be monitored in real time. In this way, drug delivery and ultrasound imaging are cleverly combined to achieve integrated cancer diagnosis and treatment.

[0027] As a preferred solution, the concentration of the nanocarrier suspension is 5-10 mg / mL; the concentration of the polyethyleneimine solution is 5-15 mg / mL; the concentration of the chemotherapy drug solution is 1-5 mg / mL; and the concentration of the target head molecule solution is 0.05-0.1 mg / mL.

[0028] As a preferred embodiment, the molecular weight of polyethyleneimine is 2,000 to 3,000, more preferably 2,500.

[0029] As a preferred solution, in steps S2, S3, and S4, the stirring speed is 200 to 350 rpm, and the continuous stirring time is 0.5 to 1.0 h.

[0030] As a preferred solution, in steps S2, S3, and S4, the centrifugal speed is 10000-14000 rpm, and the centrifugal time is 10-15 min.

[0031] As a preferred scheme, in steps S2, S3, and S4, the washing is performed using ultrapure water, and the number of washing times is 2 to 5 times; the resuspension is performed using ultrapure water; the volume of ultrapure water added during the resuspension is the same as the volume of ultrapure water used in the nanocarrier suspension, polyethyleneimine solution, chemotherapeutic drug solution, and target head molecule solution.

[0032] As a preferred solution, in steps S1 to S4, the dosage ratio of the solute in the nanocarrier solution, polyethyleneimine solution, chemotherapy drug solution, and target molecule solution is (5-10) mg: (5-15) mg: (1-5) mg: (0.05-0.1) mg.

[0033] As a preferred solution, in step S5, the mixing ratio of the ultrasound contrast agent solution and the mixed solution C is 1 mL:1 mL.

[0034] The third object of the present invention is to adopt the following technical solution:

[0035] The above-mentioned cellulose nanocrystal-based ultrasonic drug delivery system is used in the preparation of diagnostic reagents for ultrasonic diagnosis of tumors and / or pharmaceutical preparations for tumor immunotherapy.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) In view of the poor tolerance of the mechanical index of ultrasound contrast agents currently on the market, the present invention utilizes the high biocompatibility of cellulose nanocrystals and their strong ultrasonic rebound intensity under ultrasonic irradiation to construct a new ultrasonic drug delivery system with strong stability, high safety and strong targeting, and the system can load a variety of chemotherapeutic drugs to meet the needs of ultrasonic diagnosis and / or chemotherapy of various tumors;

[0038] (2) The ultrasonic drug delivery system based on cellulose nanocrystals prepared by the present invention can perform fixed-point imaging and targeted drug delivery at the lesion site under the guidance of ultrasound imaging, and can be regulated in vitro to enrich the drug at the lesion site for precise delivery, thereby maximizing the drug utilization rate and realizing the integration of tumor diagnosis and treatment under ultrasound guidance;

[0039] (3) The ultrasonic drug delivery system prepared by the present invention can not only actively target tumor cells using the target head molecule, but also passively target using the UTMD effect of ultrasound under ultrasonic conditions, thereby achieving active and passive synergistic targeting of tumor sites and significantly improving the anti-tumor effect of chemotherapeutic drugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings used in the embodiments; it should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope of protection;

[0041] Figure 1 is a TEM image of the ultrasonic drug delivery system based on cellulose nanocrystals in Example 1 of the present invention;

[0042] Figure 2 It is an in vitro ultrasound contrast imaging diagram of the ultrasound drug delivery system based on cellulose nanocrystals in Example 1 of the present invention at different MI values ​​in B mode and contrast mode;

[0043] Figure 3 is an ultraviolet absorption spectrum of the ultrasonic drug delivery system based on cellulose nanocrystals in Example 2 of the present invention;

[0044] Figure 4This is a cytotoxicity study diagram of the cell colony experiment of the ultrasonic drug delivery system based on cellulose nanocrystals and 4T1 cells at different concentrations in Example 3 of the present invention;

[0045] Figure 5 These are ultrasound images of the liver and kidneys in B mode and contrast mode at different times of tail vein injection of the cellulose nanocrystal-based ultrasound drug delivery system in Example 4 of the present invention. DETAILED DESCRIPTION

[0046] In order to make the technical purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and Examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of protection of the present invention. In the following examples, the raw materials or reagents involved are conventional materials or reagents that can be obtained through commercial channels unless otherwise specified.

[0047] In the following examples, the polyethyleneimine solution used has a molecular weight of 2500.

[0048] The present invention does not specifically limit the cellulose nanocrystals used in the following embodiments, and the technician can select them according to the needs, and they only need to ensure the delivery requirements of the drug. Preferably, the cellulose nanocrystals are selected from one or more of rod-shaped cellulose nanocrystals, TEMPO-modified cellulose nanocrystals, mechanically prepared cellulose nanocrystals, and cellulose nano whiskers. In particular, in the following embodiments, mechanically prepared cellulose nanocrystals, TEMPO-modified cellulose nanocrystals, rod-shaped cellulose nanocrystals, and cellulose nano whiskers are all purchased from ScienceK Co., Ltd.

[0049] The ultrasound contrast agent used in the present invention is SonoVue or Sezoan, both of which are conventional commercial products. Commercially available SonoVue is a white powder, and each commercially available SonoVue contains 59mg SF6 gas and 25mg lyophilized powder (lyophilized powder composition: polyethylene glycol 4000, distearyl phosphatidylcholine, dipalmitoyl phosphatidylglycerol sodium, palmitic acid); each commercially available Sezoan contains 16uL perfluorobutane microspheres. When used, according to the standard preparation method of ultrasound contrast agents specified in the instructions, a SonoVue or Sezoan is mixed with 5mL of normal saline to prepare an ultrasound contrast agent solution, and then the ultrasound contrast agent solution is mixed with mixed solution C to prepare an ultrasound drug delivery system.

[0050] Example 1

[0051] This embodiment provides an ultrasonic drug delivery system based on cellulose nanocrystals, comprising: a nanocarrier, a chemotherapeutic drug, a target head molecule and an ultrasonic contrast agent; wherein the nanocarrier is cellulose nanocrystals; the chemotherapeutic drug is doxorubicin; the target head molecule is hyaluronic acid; and the ultrasonic contrast agent is SonoVue. The cellulose nanocrystals are specifically mechanically prepared cellulose nanocrystals (CNCs-M).

[0052] The preparation method of the above-mentioned cellulose nanocrystal-based ultrasonic drug delivery system comprises the following steps:

[0053] (1) 5 mg of mechanically prepared cellulose nanocrystals (CNCs-M) were placed in 1 mL of ultrapure water to prepare a 5 mg / mL CNC suspension and stirred evenly;

[0054] (2) Weigh 5 mg of polyethyleneimine (PEI) and dissolve it in 1 mL of ultrapure water to prepare a 5 mg / mL PEI solution; slowly add the PEI solution dropwise to the CNC suspension obtained in step (1) stirred at 200 rpm, stir together for 30 min, centrifuge at 12000 rpm for 10 min, discard the supernatant, resuspend the precipitate with ultrapure water and wash it three times, and then resuspend the precipitate with 1 mL of ultrapure water to obtain a mixed solution A;

[0055] (3) 1 mg of doxorubicin (DOX) was dissolved in 1 mL of ultrapure water to prepare a 1 mg / mL DOX solution; the DOX solution was slowly added dropwise to the mixed solution A stirred at 200 rpm, and the mixture was stirred for 30 min. The mixture was centrifuged at 12,000 rpm for 10 min, the supernatant was discarded, the precipitate was resuspended and washed three times with ultrapure water, and then the precipitate was resuspended with 1 mL of ultrapure water to obtain a mixed solution B;

[0056] (4) 50 μg of hyaluronic acid (HA) was dissolved in 1 mL of ultrapure water to prepare a 0.05 mg / mL HA solution; the HA solution was slowly added dropwise to the mixed solution B stirred at 200 rpm, and the mixture was stirred for 30 min, and then centrifuged at 12,000 rpm for 10 min, the supernatant was discarded, and the precipitate was resuspended and washed with ultrapure water for 3 times, and then the precipitate was resuspended with 1 mL of ultrapure water to obtain a mixed solution C;

[0057] (5) A tube of SonoVue ultrasound contrast agent (SV MBs) was dissolved in 5 mL of normal saline, and then mixed evenly with mixed solution C at a ratio of 1 mL:1 mL to obtain the cellulose nanocrystal-based ultrasound drug delivery system of Example 1, which was recorded as SV@CPDA-M.

[0058] Example 1 The transmission electron microscopy (TEM) image of the ultrasonic drug delivery system based on cellulose nanocrystals prepared is as follows: Figure 1 As shown. Figure 1It can be seen that the ultrasonic drug delivery system of Example 1 is a rod-shaped structure, the ultrasonic contrast agent (SVMBs) is a micron-sized spherical bubble, and the rod-shaped drug delivery system is dispersed in the shell layer of the ultrasonic contrast agent, forming a new type of ultrasonic drug delivery system.

[0059] Further, the ultrasonic drug delivery system prepared in Example 1 was injected into the small capsule at the head of the rubber-tipped dropper, and ultrapure water was used as the background. In vitro ultrasound detection was performed using a Doppler color ultrasound diagnostic instrument (HITACHI, Japan) in B mode and contrast mode, and the ultrasound contrast enhancement effect under different mechanical indexes (MI was 0.08, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00 and 1.05, respectively) was studied. The in vitro ultrasound contrast imaging of the ultrasonic drug delivery system of this embodiment is shown in FIG. Figure 2 As shown. Figure 2 It can be seen that in B mode and contrast mode, the ultrasound image enhancement effect becomes brighter in color and clearer in image layer details as MI increases, indicating that the ultrasound drug delivery system has good imaging effect under ultrasound and the ultrasound echo intensity is MI-dependent.

[0060] Example 2

[0061] This embodiment provides an ultrasonic drug delivery system based on cellulose nanocrystals, comprising: a nanocarrier, a chemotherapeutic drug, and a target head molecule; wherein the nanocarrier is cellulose nanocrystals; the chemotherapeutic drug is doxorubicin; and the target head molecule is hyaluronic acid. The cellulose nanocrystals are specifically TEMPO-modified cellulose nanocrystals (TEMPO-CNCs).

[0062] The preparation method of the ultrasonic drug delivery system based on cellulose nanocrystals in this embodiment is basically the same as that in Example 1, except that TEMPO-modified cellulose nanocrystals are used instead of mechanically prepared cellulose nanocrystals, and step (5) is omitted, i.e., the mixing step of the ultrasonic contrast agent is omitted. The ultraviolet absorption spectrum of the ultrasonic drug delivery system based on cellulose nanocrystals obtained in this embodiment is shown in FIG. Figure 3 As shown. Figure 3 It can be seen that the drug delivery system of Example 2 has a characteristic absorption peak of doxorubicin (DOX) at around 480 nm, indicating that the chemotherapy drug has been successfully loaded therein.

[0063] Example 3

[0064] This embodiment provides an ultrasonic drug delivery system based on cellulose nanocrystals, comprising: a nanocarrier, a chemotherapeutic drug, and a target head molecule; wherein the nanocarrier is cellulose nanocrystals; the chemotherapeutic drug is doxorubicin; and the target head molecule is hyaluronic acid. The cellulose nanocrystals are specifically rod-shaped cellulose nanocrystals (CNCs).

[0065] The preparation method of the ultrasonic drug delivery system based on cellulose nanocrystals in this embodiment is basically the same as that in Example 1, except that rod-shaped cellulose nanocrystals are used instead of mechanically prepared cellulose nanocrystals, and step (5), i.e., the mixing step of the ultrasonic contrast agent, is omitted. According to this preparation method, drug delivery systems with different concentrations are prepared.

[0066] Using the cell colony assay, different concentrations of drug delivery systems (0, 2, 4, 8ug / mL) were co-incubated with 4T1 cells (mouse breast cancer cells). The drug-containing culture medium was replaced every 48 hours for a total of 3 times. After fixation with tissue cell fixative and staining with crystal violet dye, the cells were washed clean and the results of each well were photographed and recorded. Figure 4 As shown. Figure 4 It can be seen that as the drug concentration increases, the number of cell colonies gradually decreases, that is, the cellulose nanocrystal-based drug delivery system of the present invention has good chemotherapy drug delivery efficiency and concentration-dependent cytotoxicity.

[0067] Example 4

[0068] This embodiment provides an ultrasonic drug delivery system based on cellulose nanocrystals, comprising: a nanocarrier, a chemotherapeutic drug, a target head molecule and an ultrasonic contrast agent; wherein the nanocarrier is cellulose nanocrystals; the chemotherapeutic drug is doxorubicin; the target head molecule is hyaluronic acid; and the ultrasonic contrast agent is sildenafil. The cellulose nanocrystals are specifically cellulose nanowhiskers (CN-Ws).

[0069] The preparation method of the cellulose nanocrystal-based ultrasonic drug delivery system of this embodiment is basically the same as that of Example 1, except that cellulose nanowhiskers are used instead of cellulose nanocrystals prepared by mechanical method, and Cetrolan is used instead of SonoVue as the ultrasonic contrast agent to prepare the ultrasonic drug delivery system of Example 4.

[0070] Balb / c mice were selected, and 100uL of the ultrasonic drug delivery system prepared in Example 4 was injected from the tail vein of the mice. The real-time liver and kidney ultrasound imaging enhancement effect of the ultrasonic drug delivery system injected into the tail vein of the Balb / c mice was studied in the B mode and contrast mode when the MI was 0.19 at 0s, 5s and 10s after injection when the MI was 0.19. The in vivo ultrasound imaging of the liver and kidney at different times in this example is shown in FIG. Figure 5 As shown. Figure 5 It can be seen that after the tail vein injection of the ultrasound drug delivery system, it has a good ultrasound imaging effect in the liver and kidneys of mice. At the same time, the ultrasound echo intensity in the liver and kidneys gradually increases with time.

[0071] In summary, the ultrasonic drug delivery system based on cellulose nanocrystals provided by the present invention is not only simple to prepare and highly safe, but also has strong tumor targeting and a long circulation time in the body. It can achieve imaging of the extravascular area of ​​the tumor and rapid and accurate drug delivery to the targeted tumor area under the guidance of external ultrasonic contrast imaging conditions, effectively solving the current problems of poor utilization of tumor chemotherapy drugs, strong toxic side effects, weak targeting and inability to integrate diagnosis and treatment.

Claims

1. An ultrasonic drug delivery system based on cellulose nanocrystals, characterized in that: The ultrasonic drug delivery system based on cellulose nanocrystals comprises: a nanocarrier, a chemotherapeutic drug, a target head molecule and an ultrasonic contrast agent; Wherein, the nanocarrier is cellulose nanocrystal; the chemotherapy drug is one or more of doxorubicin, paclitaxel, and gemcitabine; the target head molecule is hyaluronic acid; and the ultrasound contrast agent is SonoVue or Sildenafil.

2. The ultrasonic drug delivery system based on cellulose nanocrystals according to claim 1, characterized in that: The cellulose nanocrystals are selected from one or more of rod-shaped cellulose nanocrystals, TEMPO-modified cellulose nanocrystals, mechanically prepared cellulose nanocrystals, and cellulose nano whiskers.

3. The method for preparing the ultrasonic drug delivery system based on cellulose nanocrystals according to claim 1, characterized in that: The following steps are involved: S1, dissolving the nanocarrier in ultrapure water and stirring evenly to obtain a nanocarrier suspension; S2, adding a polyethyleneimine solution dissolved in ultrapure water and stirred evenly to the stirring nanocarrier suspension, stirring continuously, then centrifuging, washing and resuspending the precipitate to obtain a mixed solution A; S3, adding the chemotherapeutic drug solution dissolved in ultrapure water and stirred evenly to the stirring mixed solution A, stirring continuously, then centrifuging, washing and resuspending the precipitate to obtain a mixed solution B; S4, adding the target head molecule solution dissolved in ultrapure water and stirred evenly into the stirring mixed solution B, stirring continuously, then centrifuging, washing and resuspending the precipitate to obtain a mixed solution C; S5. Evenly mix the ultrasound contrast agent solution dissolved in physiological saline and stirred evenly with the mixed solution C to obtain the cellulose nanocrystal-based ultrasound drug delivery system.

4. The method for preparing the ultrasonic drug delivery system based on cellulose nanocrystals according to claim 3, characterized in that: The concentration of the nanocarrier suspension is 5-10 mg / mL; the concentration of the polyethyleneimine solution is 5-15 mg / mL; the concentration of the chemotherapeutic drug solution is 1-5 mg / mL; and the concentration of the target head molecule solution is 0.05-0.1 mg / mL.

5. The method for preparing the ultrasonic drug delivery system based on cellulose nanocrystals according to claim 3, characterized in that: In steps S2, S3 and S4, the stirring speed is 200-350 rpm, and the continuous stirring time is 0.5-1.0 h.

6. The method for preparing the ultrasonic drug delivery system based on cellulose nanocrystals according to claim 3, characterized in that: In steps S2, S3 and S4, the centrifugal speed is 10000-14000 rpm, and the centrifugal time is 10-15 min.

7. The method for preparing the ultrasonic drug delivery system based on cellulose nanocrystals according to claim 3, characterized in that: In steps S2, S3, and S4, the washing is performed with ultrapure water for 2 to 5 times; the resuspension is performed with ultrapure water; the volume of ultrapure water added during the resuspension is the same as the volume of ultrapure water used in the nanocarrier suspension, polyethyleneimine solution, chemotherapeutic drug solution, and target head molecule solution.

8. The method for preparing the ultrasonic drug delivery system based on cellulose nanocrystals according to claim 3, characterized in that: In steps S1 to S4, the dosage ratio of the solute in the nanocarrier suspension, the polyethyleneimine solution, the chemotherapeutic drug solution, and the target head molecule solution is (5-10) mg: (5-15) mg: (1-5) mg: (0.05-0.1) mg.

9. The method for preparing the ultrasonic drug delivery system based on cellulose nanocrystals according to claim 3, characterized in that: In step S5, the mixing ratio of the ultrasound contrast agent solution and the mixed solution C is 1 mL:1 mL.

10. An application of the cellulose nanocrystal-based ultrasonic drug delivery system according to claim 1 or 2 or the cellulose nanocrystal-based ultrasonic drug delivery system prepared by the preparation method according to any one of claims 3 to 9, characterized in that: Application in the preparation of diagnostic reagents for tumor ultrasound diagnosis and / or pharmaceutical preparations for tumor immunotherapy.

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