ABSTRACT
Polyethylene (PE) and polypropylene (PP) were surface functionalized with beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) with the aim of providing PE and PP with the capability of behaving as drug delivery systems. Functionalization was carried out according to a two-step procedure: (i) glycidyl methacrylate (GMA) was grafted by means of gamma radiation and (ii) the epoxy groups of GMA reacted with the hydroxyl groups of CDs forming ether bonds. For a fix radiation dose and GMA concentration, grafting yield (ranging from 1 to 100 micromol GMA cm(-2)) depended on the time during which the preirradiated PE and PP films and slabs were immersed in the GMA solution. CD grafting (from 0.013 to 0.734 micromol cm(-2)) was confirmed by infrared analysis, DSC and the organic compound approach (using 3-methylbenzoic acid as a probe). Functionalization with CDs rendered as highly cytocompatible materials as the starting ones, did not cause relevant changes in the water contact angle and the friction coefficient of PE and PP, but remarkably improved their capability to uptake diclofenac through formation of inclusion complexes with the CDs. Furthermore, the functionalized materials released the drug for 1 h, which could be useful for management of initial pain, inflammation at the insertion site as well as adhesion of certain microorganisms if these materials are used as medicated medical devices.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemistry , Coated Materials, Biocompatible , Diclofenac/chemistry , Drug Carriers , Polyethylene/chemistry , Polypropylenes/chemistry , beta-Cyclodextrins/chemistry , 2-Hydroxypropyl-beta-cyclodextrin , Animals , BALB 3T3 Cells , Calorimetry, Differential Scanning , Cell Survival/drug effects , Chemistry, Pharmaceutical , Drug Compounding , Epoxy Compounds/chemistry , Fibroblasts/drug effects , Friction , Gamma Rays , Kinetics , Methacrylates/chemistry , Mice , Microscopy, Electron, Scanning , Polyethylene/radiation effects , Polyethylene/toxicity , Polypropylenes/radiation effects , Polypropylenes/toxicity , Solubility , Spectroscopy, Fourier Transform Infrared , Surface Properties , Technology, Pharmaceutical/methods , Temperature , Wettability , beta-Cyclodextrins/toxicityABSTRACT
The polyethylene used in total hip arthroplasty has gone through many changes over the past several decades, including consolidation processes, resin types, method of sterilization, packaging, and the extent of crosslinking. To isolate the in vivo performance of material changes from implant system design changes, we assessed the postretrieval surface wear and damage of components made from three different polyethylene types used in a single implant system. The polyethylene types investigated are representative of the sequentially available bearing materials that have dominated use in total hip arthroplasty over the last several decades. Forty-six components with implantation durations of 12 to 96 months were assessed for surface wear and damage and for socket wear and creep volume change. Acetabular components made from highly crosslinked polyethylene had a 50% lower total damage score than components made from polyethylene that was either gamma-sterilized in air or in nitrogen. The wear and creep socket volume change was 80% and 90% lower for the highly crosslinked components compared with the gamma-sterilized in air and nitrogen groups, respectively. These data of direct component measurement are consistent with earlier predictions that recent changes in polyethylene material processing can lead to clinically improved bearing performance.