Surface grafting of artificial joints with a biocompatible polymer for preventing periprosthetic osteolysis

Abstract

Periprosthetic osteolysis-bone loss in the vicinity of a prosthesis-is the most serious problem limiting the longevity of artificial joints. It is caused by bone-resorptive responses to wear particles originating from the articulating surface. This study investigated the effects of graft polymerization of our original biocompatible phospholipid polymer 2-methacryloyloxyethyl phosphorylcholine (MPC) onto the polyethylene surface. Mechanical studies using a hip-joint simulator revealed that the MPC grafting markedly decreased the friction and the amount of wear. Osteoclastic bone resorption induced by subperiosteal injection of particles onto mouse calvariae was abolished by the MPC grafting on particles. MPC-grafted particles were shown to be biologically inert by culture systems with respect to phagocytosis and resorptive cytokine secretion by macrophages, subsequent expression of receptor activator of NF-kappaB ligand in osteoblasts, and osteoclastogenesis from bone marrow cells. From the mechanical and biological advantages, we believe that our approach will make a major improvement in artificial joints by preventing periprosthetic osteolysis.

Large enhancement in neurite outgrowth on a cell membrane-mimicking conducting polymer

“…1b). Starting from hydroxymethyl-functionalized EDOT (EDOT-OH), we introduced a zwitterionic phosphorylcholine functional group, simulating a phospholipid, onto EDOT (giving the new monomer EDOT-PC), using a procedure similar to those reported previously for the preparation of phosphorylcholinefunctionalized polyacrylates and self-assembled monolayers [54][55][56][57] . EDOT-OH was first reacted with 2-chloro-2-oxo-1,3,2-dioxaphospholane (COP); the dioxaphospholane ring was subsequently opened in the presence of trimethylamine to yield the phosphorylcholine functional group.…”

“…In vivo applications of these materials may suffer, however, from the unwanted nonspecific binding of cells and biomacromolecules, leading to severe insulating scar formation and failure of electrical communication with living tissues. Previous investigations of non-conductive materials have concluded that the presence of phosphorylcholine side chains can prevent microphages from recognizing artificial implants as foreign bodies, leading to diminution/eradication of the inflammatory response 55 . We expected the biomimetic PEDOTs developed herein to interact specifically with targeted cells and prevent nonspecific binding.…”

Structures and Synthesis of Zwitterionic Polymers

“…In particular, the latter profits from the facile incorporation of reactive groups in special positions, e.g., in the center or at the ends of the polymers, that enable efficient attachment of the macromolecules onto the substrates. Still, classical grafting-from [318][319][320][321][322][323][324][325][326][327][328][329][330][331][332][333][334][335], grafting-to [336][337][338][339][340][341][342][343][344][345][346], and grafting-through [316,347] procedures are of course continuously in use, especially in industrial applications, where the activation of the surfaces for the grafting process by physical means or by simple, "unpretentious" chemistry is preferred for reasons of experience, cost and high-throughput.…”

Precise surface structure control of inorganic solid and metal oxide nanoparticles through surface-initiated radical polymerization

“…Water lubrication systems have attracted much attention due to their applications as medical implant devices [33] such as artificial joints for the human hip [34] as well as other environmentally friendly technologies. The surface grafting of polymers in general has been studied intensively to improve the lubrication properties of solid surfaces.…”