Effects of molecular weight of grafted hyaluronic acid on wear initiation.
Hyaluronic acid (HA) of different molecular weights (Mw) was grafted onto mica surfaces to study the effects of Mw on the conformation and wear protection properties of a grafted HA (gHA) layer in lubricin (LUB) and bovine synovial fluid (BSF) using a surface forces apparatus. The Mw of gHA had significant effects on the wear pressure (Pw), at which point the wear initiates. Increasing the gHA Mw from 51 to 2590kDa increased Pw from 4 to 8MPa in LUB and from 15 to 31MPa in BSF. The 2590kDa gHA in BSF had the best wear protection (Pw∼31MPa), even though it exhibited the highest friction coefficient (μ∼0.35), indicating that a low μ does not necessarily result in good wear protection, as is often assumed. The normal force profile indicated that BSF confines the gHA structure, making it polymer brush-like, commonly considered as an excellent structure for boundary lubrication.
Chemical Engineering Department, University of California at Santa Barbara, Santa Barbara, CA, USA.
Dong Woog
DW
Lee
Chemical Engineering Department, University of California at Santa Barbara, Santa Barbara, CA, USA; Faculty of Pharmacy, Universite de Montreal, Succursale Centre Ville Montreal, Quebec H3C 3J7, Canada.
Xavier
X
Banquy
Chemical Engineering Department, University of California at Santa Barbara, Santa Barbara, CA, USA.
Saurabh
S
Das
Chemical Engineering Department, University of California at Santa Barbara, Santa Barbara, CA, USA.
Nicholas
N
Cadirov
Department of Emergency Medicine and School of Engineering, Brown University, Providence, RI, USA.
Gregory
G
Jay
Chemical Engineering Department, University of California at Santa Barbara, Santa Barbara, CA, USA; Materials Department, University of California at Santa Barbara, Santa Barbara, CA, USA. Electronic address: Jacob@engr.ucsb.edu.
Jacob
J
Israelachvili
D000818:Animals; D001696:Biomechanical Phenomena / Q000187:drug effects; D002417:Cattle; D017276:Friction / Q000187:drug effects; D006023:Glycoproteins / Q000494:pharmacology; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry* / Q000494:pharmacology*; D008970:Molecular Weight; D012996:Solutions; D013582:Synovial Fluid / Q000737:chemistry / Q000187:drug effects; D000099158:Proteoglycan 4
D006023:Glycoproteins; D006820:Hyaluronic Acid; D012996:Solutions; D000099158:Proteoglycan 4
Hyaluronic acid; Lubricin; Synergistic lubrication; Wear initiation; Wear protection