Construction And Tribological Study Of Drug-loading-Lubricating System Of Degradable Mesoporous Silicon Ball

Osteoarthritis is a major cause of pain,disability and increased medical costsworldwide.The epidemiological point of view about osteoarthritis is that the etiology is complex and multifactorial.For advanced osteoarthritis,joint replacement is an effective treatment.However,the performance of artificial joints after surgery may not be as good as the original joints,and the life of the prosthesis is limited.Today,research focus has shifted to the prevention and treatment of early osteoarthritis.Therefore,the content of this study is based on the medicinal silica nano-particles（MSNs）’s high-efficiency drug-loading performance,and its surface is specifically functionalized to make the modified MSNs have a hydration lubrication function.MSNs with lubricating function are injected into diseased joints after being loaded with drugs,and drug treatment is performed while improving the lubrication of the articular cartilage contact surface,so that early osteoarthritis can achieve the effect of comprehensive treatment.Aiming at this goal,we used UV photopolymerization to chemically graft polyelectrolyte molecular brushes with hydration and lubricating effects on the surface of MSNs:polymethacryl ethylsulfobetaine to prepare injectable superlubricating nanomedicines carrier and loaded with cargos（Rhodamine B）.The injectable MSNs@p SBMA not only improves the lubricating performance of the sliding contact surface through the p SBMA zwitterionic polyelectrolyte molecular brush,but also continuously releases the drug through the mesoporous channels of a large number of drug-loaded MSNs to treat inflammation.In the lubrication test,the Coefficient of friction（COF）of MSNs@p SBMA-1,MSNs@p SBMA-2 and MSNs@p SBMA-3（"1,2 and 3"represent the thickness of the MSNs surface grafted p SBMA polyelectrolyte molecular brush）are at 0.087,0.071,and 0.045,and there is a significant improvement over the COF of MSNs（0.221）.In addition,the drug release rates of Rh B-loaded three MSNs@p SBMA within 54 hours were 49.93%,42.41%,and 39.33%,respectively.And further verified its hydration lubrication mechanism.After the lubrication test,the SEM surface morphology analysis of the sliding contact surface showed that MSNs@p SBMA can adhere to its surface and protect it from severe wear.In addition,further research has shown that MSNs are hardly degraded in the body within a short period of time,resulting in toxic effects of bioaccumulation.Therefore,we went one step further and prepared biodegradable mesoporous silica nanoparticles（b MSNs）with a low cross-linked silicate skeleton by an oil-water biphasic layering method.Then,by photopolymerization,a 2-methacryloyloxyethyl phosphate choline（PMPC）was grafted onto the surface of b MSNs to synthesize a biodegradable superlubricated nanoparticle（b MSNs-NH₂@PMPC）.Vitro degradation experiments show that the degradation cycle of b MSNs and b MSNs-NH₂@PMPC is about 7 days,which can effectively avoid the toxic effects of bioaccumulation in previous studies.Tribological tests show that the COF of b MSNs-NH₂@PMPC is about 0.088,which is50%lower than the COF of b MSNs.This is due to the hydration lubrication mechanism caused by the positive and negative charges on the PMPC polyelectrolyte molecular brush grafted on the surface of b MSNs.At the same time,the release experiments of b MSNs-NH₂@PMPC showed that the sustained release effect was very obvious.The b MSNs-NH₂@PMPC has broad application prospects in the clinical treatment of osteoarthritis.