Vliv proteinů a rychlosti na tření a adsorpci kontaktního páru Kov/UHMWPE

The Influence of Proteins and Speed on Friction and Adsorption of Metal/UHMWPE Contact Pair

journal article in Scopus

en

It was reported in several studies that friction and wear of joint prosthesis are apparently influenced by the proteins contained in the synovial fluid. However, detailed mechanisms of these tribological processes have not been clarified yet. The present study aims on the effect of adsorbed protein film on frictional behaviour of metal/polyethylene contact pair. Reciprocating pin-on-plate test was conducted, while the CoCrMo pin was sliding against UHMWPE plate. The contact was lubricated by various solutions of albumin and γ-globulin solved in PBS. After the friction test, the thickness of adsorbed film was evaluated using spectroscopic ellipsometry. Structure of the adsorbed proteins was later examined by FT-IR. The results showed that at low sliding speed equal to 10 mm/s, there was a linear correlation between the friction coefficient and the thickness of the adsorbed protein film. An increase of friction was thus accompanied by the evolution of protein film. In that case, both proteins undergone substantial conformational changes, losing their original structure. On the contrary, proteins could sustain their secondary structure to some extent at higher sliding speed (50 mm/s), when different behaviour of the both proteins could be observed. This phenomenon was attributed to different structure of albumin and γ-globulin in its native state. It might be concluded that friction coefficient of metal-on-polyethylene joint prosthesis is influenced by protein content, as well as kinematic conditions, since the sliding conditions have a certain effect on both the adsorbed film formation and structure of the adsorbed molecules.

V několika předchozích studiích bylo poukázáno na fakt, že tření a opotřebení kloubních náhrad je ovlivněno proteiny obsaženými v synoviální kapalině. Nicméně, detailní mechanismy těchto tribologických procesů nebyly doposud dostatečně objasněny. Předkládaná studie se zaměřuje na vliv adsorbovaného proteinového filmu na třecí vlastnosti kontaktního páru kov/UHMWPE. Byly realizovány testy v konfiguraci pin-on-plate, kdy byl CoCrMo pin přitlačován na UHMWPE destičku, která vykonávala reciproční pohyb. Kontakt byl mazán různými roztoky albuminu a γ-globulinu rozpuštěnými v PBS. Po třecím testu byla s využitím spektroskopické elipsometrie měřena tloušťka adsorbovaného filmu. Následně byla s využitím FT-IR hodnocena struktura adsorbovaných proteinů. Výsledky ukázaly, že za nízké kluzné rychlosti rovné 10 mm/s je závislost koeficientu tření na tloušťce adsorbované vrstvy lineární. Nárůst tření byl tak doprovázen nárůstem proteinového filmu. Za těchto podmínek došlo u obou proteinů ke konformačním změnám, kdy ztratily svoji původní strukturu. Naopak, proteiny si do určitého rozsahu uchovaly svoji strukturu za vyšší kluzné rychlosti (50 mm/s), kdy bylo pozorováno jejich vzájemně odlišné chování. Tento fakt je připisován odlišné struktuře albuminu a γ-globulinu v jejich nativním stavu. Lze konstatovat, že tření kloubního páru kov-polyetylen je ovlivněno obsahem proteinů, stejně jako kinematickými podmínkami, které mají zřejmý vliv jak na formování adsorbovaného filmu, tak na strukturu adsorbovaných molekul.

It was reported in several studies that friction and wear of joint prosthesis are apparently influenced by the proteins contained in the synovial fluid. However, detailed mechanisms of these tribological processes have not been clarified yet. The present study aims on the effect of adsorbed protein film on frictional behaviour of metal/polyethylene contact pair. Reciprocating pin-on-plate test was conducted, while the CoCrMo pin was sliding against UHMWPE plate. The contact was lubricated by various solutions of albumin and γ-globulin solved in PBS. After the friction test, the thickness of adsorbed film was evaluated using spectroscopic ellipsometry. Structure of the adsorbed proteins was later examined by FT-IR. The results showed that at low sliding speed equal to 10 mm/s, there was a linear correlation between the friction coefficient and the thickness of the adsorbed protein film. An increase of friction was thus accompanied by the evolution of protein film. In that case, both proteins undergone substantial conformational changes, losing their original structure. On the contrary, proteins could sustain their secondary structure to some extent at higher sliding speed (50 mm/s), when different behaviour of the both proteins could be observed. This phenomenon was attributed to different structure of albumin and γ-globulin in its native state. It might be concluded that friction coefficient of metal-on-polyethylene joint prosthesis is influenced by protein content, as well as kinematic conditions, since the sliding conditions have a certain effect on both the adsorbed film formation and structure of the adsorbed molecules.

Kloubní náhrada; proteiny; tření; UHMWPE; adsorpce

Joint prosthesis; proteins; friction; UHMWPE; adsorption

01.09.2017

Elsevier

United Kingdom

2352-5738

11

2017

51–59

9