阅读说明：本技术 一种聚天冬氨酸-多巴胺/聚乙二醇聚合物及其制备造影剂的用途 (Polyaspartic acid-dopamine/polyethylene glycol polymer and application thereof in preparation of contrast agent ) 是由 吴昌强 于 2020-06-04 设计创作，主要内容包括：本发明公开了一种聚天冬氨酸-多巴胺/聚乙二醇聚合物及其制备造影剂的用途,该聚合物为聚天冬氨酸-多巴胺/聚乙二醇接枝共聚物,以及将该共聚物与Fe<Sup>3+</Sup>螯合制备纳米颗粒,和用该共聚物包裹四氧化三铁纳米晶体颗粒,用于核磁共振造影剂。(The invention discloses a polyaspartic acid-dopamine/polyethylene glycol polymer and application thereof in preparing a contrast agent, wherein the polymer is a polyaspartic acid-dopamine/polyethylene glycol graft copolymer, and the copolymer and Fe are mixed 3+ Chelating to prepare nano particles, and coating ferroferric oxide nano crystal particles with the copolymer for a nuclear magnetic resonance contrast agent.)

1. A polyaspartic acid-dopamine/polyethylene glycol polymer shown in formula I,

wherein R is-CH₃、H；

x is 0 to 500, and y, z and m are independently 1 to 500.

2. Chelated Fe shown as formula II³⁺The number of the nano-particles,

wherein x is 0 to 500, and y, z and m are independently 1 to 500.

3. A superparamagnetic nanoparticle coated with a polymer shown in formula I is a coated ferroferric oxide nanoparticle shown in formula III, wherein x is 0-500, y, z and m are independently 1-500,

4. a method of making a polymer of formula I, comprising:

placing polysuccinimide and amino-terminated polyethylene glycol into a reaction bottle, adding dimethyl sulfoxide, stirring and dissolving, dissolving dopamine hydrochloride by using dimethyl sulfoxide and triethylamine, adding the dissolved dopamine hydrochloride into the reaction bottle together under the protection of argon gas, reacting at 80 ℃, adding a sodium hydroxide solution, continuing to react, after the reaction is finished, adjusting the pH value to 6 by using a hydrochloric acid solution, placing the reaction solution into a dialysis bag, dialyzing for 24 hours in an aqueous solution, collecting the solution in the dialysis bag, and freeze-drying to obtain the product.

5. Preparation of chelated Fe shown in formula II³⁺Nanoparticles are prepared by dissolving polyaspartic acid-dopamine/polyethylene glycol polymer of formula I with ultrapure water, and dropping FeCl under stirring₃Reacting the solution at room temperature for 30min, adjusting the pH of the solution to 7 with NaOH, and dialyzing with distilled water for three days to obtain chelated Fe³⁺An aqueous solution of nanoparticles.

6. A method for preparing coated ferroferric oxide nanoparticles shown in a formula III, comprising the following steps: dissolving the polyaspartic acid-dopamine/polyethylene glycol polymer shown in the formula I in ultrapure water, dripping aqueous solution of superparamagnetic iron oxide nanocrystal particles wrapped by citric acid while stirring, reacting at room temperature for 4 hours, adjusting the pH of the solution to 7 by NaOH, and dialyzing by distilled water for three days to obtain aqueous solution coated with ferroferric oxide nanoparticles.

7. The method of claim 6, wherein the citric acid-coated superparamagnetic iron oxide nanocrystal particle is SPIO @ CA.

8. Chelated Fe of formula II according to claim 2³⁺The nanoparticles are useful in magnetic resonance contrast agents.

9. The coated ferroferric oxide nanoparticles of formula III according to claim 3 for use in a magnetic resonance contrast agent.

10. Polyaspartic acid-dopamine/polyethylene glycol polymer of formula I according to claim 1, having an average molecular weight of about 15000 Da.

Technical Field

The invention relates to the field of nanochemistry and magnetic resonance contrast agents, in particular to a ligand polymer for modifying magnetic nanoparticles, magnetic nanoparticles modified by the ligand polymer and application of the ligand polymer as a magnetic resonance contrast agent.

Background

The nano magnetic material is a novel material appearing in the 8O age of the 2O century. The application of magnetic microspheres formed by coating small molecules or high molecular substances on the surfaces of nano magnetic particles in biomedicine aspects such as drug loading, medical diagnosis and the like draws more and more attention. Among the reported magnetic nanoparticles, studies on the preparation of superparamagnetic nano iron oxide (SPIO) and its application in Magnetic Resonance Imaging (MRI) diagnosis are particularly emphasized. MRI has the advantages of no wound, good safety, no ionizing radiation, multi-parameter imaging and the like, and can rapidly provide high-resolution anatomical images of any part, any direction (sagittal plane, coronal plane and transverse plane) and any fault of the whole body of a patient. MRI is applied to brain, nervous system, abdomen and cardiovascular angiography of human body, is particularly effective for detecting tissue necrosis, ischemia and a plurality of malignant tumors, can meet the requirement of early diagnosis of lesions, is regarded as a potential diagnosis method, and is rapidly and widely applied to clinical medical imaging diagnosis. MRI contrast agents can be classified into paramagnetic contrast agents and superparamagnetic contrast agents according to the magnetization characteristics of a substance.Paramagnetic contrast agents are typically paramagnetic metal ions (Fe)³⁺、Mn²⁺Or Gd³⁺Etc.) or chelates thereof, the superparamagnetic contrast agent is typically a magnetic nanocrystalline particle. Paramagnetic contrast agents, such as gadolinium (Gd) amine carboxylate MRI contrast agents, primarily shorten the longitudinal relaxation time T adjacent to the hydrogen protons₁At magnetic resonance T₁The signal increase is present on the weighted image, which is a positive contrast agent. The superparamagnetic contrast agent is a special ferromagnetic substance, and the main component of the superparamagnetic contrast agent is Fe with a unique crystal structure₃O₄The composite material comprises subminiature superparamagnetic iron oxide, monocrystal ferric oxide micro-polymer, liposome-coated superparamagnetic iron oxide, subminiature superparamagnetic iron oxide coated by albumin, dextran, polystyrene, monoclonal antibody and the like. The iron oxide nanoparticles can simultaneously shorten the longitudinal relaxation time T of adjacent hydrogen protons₁And transverse relaxation time T₂By optimizing the parameters of the magnetic resonance series, the magnetic resonance imaging method can be used at T₁Obtaining a high signal on the weighted image, at T₂The weighted image has low signal, so the MRI contrast performance is more excellent.

The SPIOs are mutually attracted and subjected to van der Waals force to generate coagulation, and in order to effectively stabilize the SPIOs, the surface energy of the nanoparticles can be reduced through surface copolymerization and surface modification, so that the nanoparticles with good dispersibility can be obtained. Biocompatible organic polymer materials are widely used as stabilizers for nanoparticles, and the biocompatible polymers can be classified into natural biological macromolecules and synthetic macromolecules. Common natural biological macromolecules include amino acid polymers (e.g., gelatin, polypeptides, proteins, and polysaccharide polymers). Typical synthetic polymers are: polymethacrylic acid, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polylactic acid, thermosensitive polymer poly-N-isopropylacryloyl and copolymers thereof. The organic polymer can be coated on the surface of the magnetic nanoparticles by an in-situ method (coating with a polymer during the synthesis of the magnetic nanoparticles) and a post-synthesis coating method (grafting a polymer to the surface of the magnetic nanoparticles after they are formed).

CN102579336A discloses an MRI-visible ultra-stable adriamycin nano-micelle drug delivery system, which is a spherical nano-composite particle under a transmission electron microscope and comprises a carrier and adriamycin physically wrapped by the carrier; the structure of the carrier is shown as the following formula (IV), and the carrier takes nano ferroferric oxide as a core, adriamycin as an anticancer drug, polyethylene glycol monomethyl ether cystamine derivatives as hydrophilic groups, dopamine as a ligand for connecting the nano ferroferric oxide, and polyaspartic acid as a connecting arm between the polyethylene glycol monomethyl ether cystamine derivatives and the dopamine.

Since the nanomicelle drug delivery system of CN102579336 is of the multi-coating type (multiple iron oxide nanocrystals are contained in one nanoparticle), at T₂Very high relaxation rate, up to 99.7mM^-1s^-1Can be used for magnetic resonance T₂Contrast agents, but not both for use as magnetic resonance T₁A contrast agent.

Currently in clinical use₁The contrast agent is primarily a gadolinium agent, which has recently been found to produce nephrogenic systemic fibrotic diseases and residual risk to the brain.

Disclosure of Invention

The invention aims to provide a polyaspartic acid-dopamine/polyethylene glycol graft copolymer and application of the polymer in preparing a magnetic resonance contrast agent.

In one embodiment, the invention relates to a polyaspartic acid-dopamine/polyethylene glycol graft polymer (hereinafter also referred to as "polyaspartic acid-dopamine/polyethylene glycol copolymer") shown in formula I,

wherein R is-CH₃H; x is 0 to 500, and y, z and m are independently 1 to 500.

Preferably, the polyaspartic acid-dopamine/polyethylene glycol polymer of formula I above has an average molecular weight of about 15000 Da.

In another embodiment, a chelated Fe of formula II of the present invention³⁺The number of the nano-particles,

wherein x is 0 to 500, and y, z and m are independently 1 to 500.

In another embodiment, the superparamagnetic nanoparticle coated by the polymer shown in the formula I is a coated ferroferric oxide nanoparticle shown in a formula III,

wherein x is 0 to 500, and y, z and m are independently 1 to 500.

In one aspect, the present invention provides a method of preparing a polymer of formula I, comprising:

placing polysuccinimide and amino-terminated polyethylene glycol into a reaction bottle, adding dimethyl sulfoxide, stirring and dissolving, dissolving dopamine hydrochloride by using dimethyl sulfoxide and triethylamine, adding the dissolved dopamine hydrochloride into the reaction bottle under the protection of argon gas, reacting at 80 ℃, adding a sodium hydroxide solution, continuing to react, adjusting the pH value to 6 by using a hydrochloric acid solution after the reaction is finished, placing the reaction solution into a dialysis bag, and dialyzing the solution for 24 hours. And collecting the solution in the dialysis bag, and freeze-drying to obtain the product.

In another aspect, the present invention provides a method for preparing chelated Fe of formula II³⁺Nanoparticles are prepared by dissolving polyaspartic acid-dopamine/polyethylene glycol copolymer of formula I with ultrapure water, and dropping FeCl under stirring₃Reacting the solution at room temperature for 30min, adjusting the pH of the solution to 7 with NaOH, and dialyzing with distilled water for three days to obtain chelated Fe³⁺An aqueous solution of nanoparticles.

In another aspect, the present invention provides a method for preparing a coated ferroferric oxide nanoparticle represented by formula III, including: dissolving the polyaspartic acid-dopamine/polyethylene glycol copolymer shown in the formula I in ultrapure water, dripping the superparamagnetic iron oxide nanoparticle aqueous solution wrapped by citric acid while stirring, reacting at room temperature for 4 hours, adjusting the pH of the solution to 7 by using NaOH, and dialyzing by using distilled water for three days to obtain the coated ferroferric oxide nanoparticle aqueous solution. The citric acid-coated superparamagnetic iron oxide nanocrystal particle is SPIO @ CA (English abbreviation of citric acid-coated superparamagnetic iron oxide nanoparticle).

The polyaspartic acid-dopamine/polyethylene glycol copolymer shown in the formula I is used for chelating Fe³⁺Form a chelate Fe as shown in formula II³⁺Nanoparticles for use as magnetic resonance contrast agents.

The polyaspartic acid-dopamine/polyethylene glycol copolymer shown in the formula I is used for wrapping ferroferric oxide nanocrystal particles to prepare nanoparticles shown in a formula III: the nanoparticles are useful as magnetic resonance contrast agents.

The polymer of the invention chelates Fe³⁺Type, has better T₁Relaxation efficiency (2.76 mM)^-1s^-1To T₁Well behaved by contrast agents) useful for magnetic resonance T₁A contrast agent. When the iron oxide nanoparticles are wrapped by the polymer, the iron oxide nanoparticles are of a single wrapping type (one nanoparticle comprises one iron oxide nanocrystal), the relaxation efficiency of the iron oxide nanoparticles is related to the particle size of the iron oxide nanocrystals, and the currently used iron oxide nanoparticles have T₁、T₂Relaxation rates are respectively r₁＝ 6.78mM^-1s^-1，r₂＝11.43mM^-1s^-1，r₂/r₁1.69(0.5T), with good T at both clinical 1.5T and 3.0T magnetic resonances₁And T₂Enhancement effect, which can be used for magnetic resonance T₁-T₂Bifunctional contrast agents. So the iron oxide nanoparticles of the present invention can be used as T₁-T₂Bifunctional contrast agents, iron oxide nanoparticles of the multiple-coating type (capable of being used only as T) with CN102579336₂Contrast agents) have a wider use than in imaging and are more effective in imaging.

Drawings

FIG. 1 preparation of the polyaspartic acid-dopamine/polyethylene glycol graft copolymer of example 1¹H NMR spectrum;

FIG. 2 the polyaspartic acid-dopamine/polyethylene glycol graft copolymer of example 3 chelated Fe³⁺Dynamic light scattering particle size distribution of the nanoparticles;

FIG. 3 the polyaspartic acid-dopamine/polyethylene glycol graft copolymer of example 3 chelates Fe³⁺T of nanoparticles₁And T₂Relaxation efficiency;

FIG. 4 shows the dynamic light scattering particle size distribution of the poly (aspartic acid-dopamine/polyethylene glycol) graft copolymer coated ferroferric oxide nanoparticles of example 3;

FIG. 5T of the poly (aspartic acid-dopamine/polyethylene glycol) graft copolymer coated ferroferric oxide nanoparticles of example 3₁And T₂Relaxation efficiency;

FIG. 6 shows T of different concentrations of aqueous solutions of nanoparticles at 1.5T₁And T₂Weighting the imaging effect;

FIG. 7 shows T of different concentrations of aqueous solutions of nanoparticles at 3.0T₁And T₂The imaging effect is weighted.

Detailed Description

The following examples are merely representative for further understanding of the spirit of the present invention, and are not intended to limit the scope of the present invention.