阅读说明：本技术 仿生边界润滑剂及其制备方法 (Bionic boundary lubricant and preparation method thereof ) 是由 熊党生 田朔 时志兵 于 2019-04-17 设计创作，主要内容包括：本发明公开了一种仿生边界润滑剂及其制备方法。所述的仿生边界润滑剂以聚丙烯酸作为接枝主链的单体,N,N-二甲基-N-甲基丙烯酰胺基丙基-N,N-二甲基-N-丙烷磺酸内盐作为两性离子聚电解质接枝侧链,4-(4,6-二甲氧基三嗪-2-基)-4-甲基吗啉盐酸盐作为引发剂,通过可逆加成-断裂链转移和原子转移自由基聚合形成具有瓶刷结构的高分子聚合物。后期应用中,可以通过1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐和N-羟基琥珀酰亚胺偶联反应使聚丙烯酸的羧酸基团与软骨表面氨基基团结合以形成固定位点,从而锚定在关节软骨表面起边界润滑作用,减轻关节软骨的摩擦磨损,对关节软骨损伤及关节炎起到防护和治疗作用。(The invention discloses a bionic boundary lubricant and a preparation method thereof. The bionic boundary lubricant takes polyacrylic acid as a monomer of a grafting main chain, N, N-dimethyl-N-methylacrylamidopropyl-N, N-dimethyl-N-propanesulfonic acid inner salt as a zwitterionic polyelectrolyte grafting side chain, and 4- (4, 6-dimethoxytriazine-2-yl) -4-methylmorpholine hydrochloride as an initiator, and forms a high polymer with a bottle brush structure through reversible addition-fragmentation chain transfer and atom transfer radical polymerization. In later-period application, carboxylic acid groups of polyacrylic acid and amino groups on the surface of the cartilage are combined to form fixing points through the coupling reaction of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide so as to be anchored on the surface of the articular cartilage to play a role in boundary lubrication, reduce friction and abrasion of the articular cartilage and play a role in protection and treatment of articular cartilage damage and arthritis.)

1. The bionic boundary lubricant is characterized in that polyacrylic acid is used as a main chain, N, N-dimethyl-N-methylacrylamidopropyl-N, N-dimethyl-N-propanesulfonic acid inner salt is used as a zwitterionic polyelectrolyte grafting side chain, and 4- (4, 6-dimethoxytriazine-2-yl) -4-methylmorpholine hydrochloride is used as a grafting intermediate, and the bionic boundary lubricant is prepared by reversible addition-fragmentation chain transfer and atom transfer radical polymerization.

2. The preparation method of the biomimetic boundary lubricant according to claim 1, characterized by comprising the following specific steps:

step 1, adding a free radical initiator 4, 4-azobis (cyanovaleric acid) and a chain transfer agent 4-cyano-4- (thiobenzoyl) valeric acid into acrylic acid in a dark, anhydrous and anaerobic environment, stirring and reacting at 50-60 ℃, dialyzing after the reaction is finished, and freeze-drying to obtain polyacrylic acid with the molecular weight of 60-100 kDa;

and 2, adding DMMPPS into a borate buffer solution of polyacrylic acid according to the molar ratio of the polyacrylic acid to the DMMPPS of 3: 2-1: 1, uniformly mixing, dropwise adding the borate buffer solution of DMTMM, adjusting the pH value to 6-7, stirring for reaction, dialyzing after the reaction is finished, and freeze-drying to obtain the bionic boundary lubricant.

3. The production method according to claim 2, wherein in step 1, the acrylic acid: chain transfer agent: the molar ratio of the free radical initiator was 762:1: 0.25.

4. The preparation method according to claim 2, wherein in the step 1, the reaction time is 48-72 hours.

5. The method according to claim 2, wherein in steps 1 and 2, the dialysis is performed with water, the molecular weight of the dialysis bag is 5kDa or more, and the dialysis time is 3 days or more.

6. The method of claim 2, wherein in step 2, the borate buffer has a pH of 8.5.

7. The preparation method according to claim 2, wherein in the step 2, the reaction time is 24-48 h.

Technical Field

The invention belongs to the technical field of biomedical materials, and relates to a bionic boundary lubricant for protecting articular cartilage and a preparation method thereof.

Background

Osteoarthritis (OA) is a common disease with reduced lubricating and drag-reducing abilities of the joint surfaces, and may eventually further lead to joint movement disorders, and eventually joint necrosis, which seriously affects the quality of life of patients. The major lubricating component in synovial fluid is lubricin. Lubricin, a high molecular weight glycoprotein, reduces the coefficient of friction in boundary mode lubrication [ Swann et al (1972) J.biol.chem.247: 8069-73; jay et al (1998) J.biomed.Mat.Res.40: 414-8; chawla et al (2013) Acta Biomat.6:3388-94 ]. During the progression of osteoarthritis, the major macromolecular aggrecan in cartilage may protect the degradation of the extracellular matrix. The interaction of lubricin with type II collagen and hydroxyapatite helps to maintain a thin film of lubricin protein molecules on the articular surface. This protective lubricant layer is often destroyed after injury and disease, and the cartilage itself cannot rapidly recover the thin film on the surface to retard cartilage degradation. Numerous experiments have shown that delayed lubricant expression and secretion in the surface region is associated with impaired healing [ Elsaid et al (2012) Osteohrthritis Cartilage 20: 940-.

The current reports on lubricating polymers grafted with other polymers for the treatment of osteoarthritis focus mostly on the modeling of structure and its function, the effect is not retained long even after injection, and the injected material gradually disappears in the joint synovial fluid over time. For example, Samaroo grafted polyethylene glycol (PEG) onto a polyacrylic acid (pAA) core to mimic the hydrophilic mucin-like domain of lubricin, Lubrication and binding of lubricin mimetics depends on the structural parameters of the copolymer with a coefficient of friction in the range of 0.140 ± 0.024 to 0.248 ± 0.030, higher [ kirkj.samaro, et al. binding and Lubrication of biomedical Boundary Lubricants on aromatic vehicle, j ournalof ororaltho aedic RESEARCH march.2017doi 10.1002/jor.23370 ]. Chinese patent application CN 104870020 a discloses a method for preparing a bionic lubricant, which uses polyacrylic acid PAA as a main chain and polyethylene glycol PEG as a grafted side chain, wherein the PEG side chain is only used as a simple hydrophilic group, so as to endow biological tissues with proper level of lubricity, and the prepared bionic lubricant has insufficient friction performance.

Disclosure of Invention

The invention aims to provide a bionic boundary lubricant with good biocompatibility and biological friction performance for protecting articular cartilage and a preparation method thereof.

The technical scheme for realizing the purpose of the invention is as follows:

the bionic boundary lubricant is prepared by reversible addition-fragmentation chain transfer (RAFT) and Atom Transfer Radical Polymerization (ATRP) by using polyacrylic acid (pAA) as a main chain, N, N-dimethyl-N-methylacrylamidopropyl-N, N-dimethyl-N-propanesulfonic acid inner salt (DMMPPS) as a zwitterionic polyelectrolyte grafted side chain and 4- (4, 6-dimethoxytriazine-2-yl) -4-methylmorpholine hydrochloride (DMTMM) as a grafted intermediate.

The preparation method of the bionic boundary lubricant comprises the following specific steps:

step 1, adding a free radical initiator 4, 4-azobis (cyanovaleric acid) (4, 4' -azobis4-cyanopentanoic acid, A-CPA) and a chain transfer agent 4-cyano-4- (thiobenzoyl) valeric acid (4-cyanophthalate, CPA-DB) into acrylic acid in a dark, anhydrous and anaerobic environment, stirring for reaction at 50-60 ℃, dialyzing after the reaction is finished, and freeze-drying to obtain polyacrylic acid (pAA) with the molecular weight of 60-100 kDa;

and 2, adding DMMPPS into a borate buffer solution of polyacrylic acid according to the molar ratio of the polyacrylic acid to the DMMPPS of 3: 2-1: 1, uniformly mixing, dropwise adding the borate buffer solution of DMTMM, adjusting the pH value to 6-7, stirring for reaction, dialyzing after the reaction is finished, and freeze-drying to obtain the bionic boundary lubricant.

Preferably, in step 1, the acrylic acid: chain transfer agent: the molar ratio of the free radical initiator was 762:1: 0.25.

Preferably, in the step 1, the reaction time is 48-72 h.

Preferably, in steps 1 and 2, the dialysis is performed by water dialysis, the molecular weight of the dialysis bag is above 5kDa, and the dialysis time is above 3 days.

Preferably, in step 2, the pH of the borate buffer is 8.5.

Preferably, in the step 2, the reaction time is 24-48 h.

Compared with the prior art, the invention has the following advantages:

(1) the novel zwitterion bottle brush polymer is prepared by utilizing an atom transfer radical polymerization method, and the reaction condition is mild;

(2) DMMPPS with good biocompatibility is adopted as a grafting side chain monomer, and a zwitterionic polymer brush segment ionizes anions and cations in water, and the zwitter-ionic polymer brush segment is firmly combined with hydrated anions and cations in synovial fluid to form a hydrated sheath and a surface hydrated layer on the surface of a biological tissue, so that a lubricating boundary layer of the biological tissue has higher friction bearing capacity and excellent lubricating performance, the friction coefficient is kept at 0.096 +/-0.021 in a cartilage friction experiment, and the friction coefficient is obviously reduced in a range of 0.140 +/-0.024 to 0.248 +/-0.030 when the biological tissue is grafted to polyacrylic acid pAA by PEG;

(3) in later-period application, carboxylic acid groups of PAA and ammonia groups on the surface of cartilage can be combined to form fixing points through coupling reaction of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), so that the PAA is anchored on the surface of the articular cartilage to play a role in boundary lubrication, the frictional wear of the articular cartilage is reduced, and the application prospect of the PAA in osteoarthritis and cartilage injury treatment and protection is wide.

Drawings

FIG. 1 is a schematic representation of the formation of a hydrated layer on the cartilage surface by zwitterions.

FIG. 2 is a molecular reaction scheme for grafting on the backbone of pAA of the present invention.

FIG. 3 is a schematic view of a biomimetic lubricin in accordance with the present invention.

FIG. 4 is an AFM image of a biomimetic boundary lubricant of the present invention.

FIG. 5 is an infrared image of zwitterionic monomer before and after grafting.

FIG. 6 is a graph of the friction of biomimetic boundary lubricants prepared with different grafting ratios.

FIG. 7 is the water contact angle of the biomimetic boundary lubricant of the present invention before and after use on cartilage surface.

Detailed Description

The present invention will be described in more detail with reference to the following examples and the accompanying drawings.