Biomimetic Lubricant Containing Grafted MPDSAH Lubricin Mimetic

In this paper,the structure and lubrication principle of lubricin in human synovial fluid were studied.By simulating its key structural features,the special structure and lubrication of the N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propane sulfonate inner salt(MPDSAH)zwitterionic polymer brush synthesizes a lubricity mimetic with good lubricity.A simulated lubricant structure of p AA-g-PEG and grafted MPDSAH zwitterionic side chains was synthesized.To mimic the brush-like mucin domain,a hydrophilic polyethylene glycol(PEG)brush was grafted onto polyacrylic acid(p AA).In addition,polyacrylic acid is the main chain,MPDSAH is a zwitterionic polyelectrolyte grafting side chain,4-(4,6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride(DMTMM)It is a graft intermediate prepared by reversible addition-fragmentation chain transfer and atom transfer radical polymerization.The synthesized products were verified by molecular weight,AFM and infrared spectroscopy characterization experiments.The effect of the size of the p AA-g-PEG configuration on the friction and the effect of the graft concentration of MPDSAH on the lubrication condition during the synthesis were investigated.In the friction test,cobalt chromium molybdenum alloy,ultra-high molecular weight polyethylene(UHMWPE)and in vitro cartilage sections were used as friction substrates.For p AA-g-PEG simulated lubricants,the larger polymer in the solution forms a smoother and more complete aqueous lubricant film on the friction surface,enhancing the lubrication effect and different graft ratios(p AA: MPDSAH is(a)2 :1(82 mg: 10 mg);(b)3:2(61.5 mg: 10 mg);(c)1:1(41 mg: 10 mg);(d)1:2(20.5 mg: 10 mg))In the lubricant environment,the coefficients of friction exhibited on in vitro cartilage sections were:(a)0.093 ± 0.012;(b)0.098 ± 0.021;(c)0.087 ± 0.007;(d)0.102 ± 0.016.The specific lubrication effect is affected by the different grafting concentrations of the zwitterionic monomers during the synthesis.The experimental study on the water absorption rate and the surface wear morphology of the alloyed luster analogs was carried out to further explore its hydrophilicity and its influence on the surface wear of the alloy in sliding.The effect of the EDC/NHS activation process on the grafted MPDSAH lubricin mimetic was explored.The specific cross-linking principle was expounded,and its effectiveness was verified by controlling the time of the cross-linking process.This process can effectively extend the residence time of the zwitterionic polymer brush in the cartilage surface area.The control group was set to observe the hydrolysis effect of the protease on whether or not to carry out cross-linking treatment,thereby verifying its antiproteolytic ability.The cartilage surface contact angle indicates a good hydrophilicity of the lubricin mimetic on the cartilage.The biocompatibility of the synthesized lupus mimics was examined by MTT cell colorimetry and hemolysis rate,respectively.The specific results showed that it has good biocompatibility.