Controlled release of moxifloxacin from intraocular lenses modified by Ar plasma-assisted grafting with AMPS or SBMA: An in vitro study.

Intraocular lenses (IOLs) present an alternative for extended, local drug delivery in the prevention of post-operative acute endophthalmitis. In the present work, we modified the surface of a hydrophilic acrylic material, used for manufacturing of IOLs, through plasma-assisted grafting copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) or [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), with the aim of achieving a controlled and effective drug release. The material was loaded with moxifloxacin (MFX), a commonly used antibiotic for endophthalmitis prevention. The characterization of the modified material showed that relevant properties, like swelling capacity, wettability, refractive index and transmittance, were not affected by the surface modification. Concerning the drug release profiles, the most promising result was obtained when AMPS grafting was done in the presence of MFX. This modification led to a higher amount of drug being released for a longer period of time, which is a requirement for the prevention of endophthalmitis. The material was found to be non-cytotoxic for rabbit corneal endothelial cells. In a second step, prototype IOLs were modified with AMPS and loaded with MFX as previously and, after sterilization and storage (30days), they were tested under dynamic conditions, in a microfluidic cell with volume and renovation rate similar to the eye aqueous humour. MFX solutions collected in this assay were tested against Staphylococcus aureus and Staphylococcus epidermidis and the released antibiotic proved to be effective against both bacteria until the 12th day of release.

Surface and hemocompatibility studies of bi-soft segment polyurethane membranes.

Cross-linked urethane/urea membranes with two soft segments were prepared by extending a poly(propylene oxide) based tri-isocyanate-terminated prepolymer (PUR) with polybutadiene diol (PBDO). The ratio of prepolymer and polybutadiene diol was varied to yield cross-linked membranes with different compositions, exhibiting different degrees of phase-separation of the PBDO segments in the bulk and of surface enrichment in PUR. In this work, surface energy and hemocompatibility aspects (hemolysis and thrombosis) of the PUR/PBDO membranes were evaluated. The results showed that the membrane surface energy increased with the PBDO content until 25% of PBDO, and decreased thereafter. The introduction of the second, more hydrophobic, soft segment (PBDO) in the PUR membranes turned hemolytic into non-hemolytic membranes and, for a blood-material contact time of 10 minutes, decreased the thrombogenicity significantly. The 10% PBDO membrane was the least thrombogenic and was also non-hemolytic. The hemolysis degree did not vary significantly with the PBDO content while, for blood-material contact times of 10 minutes, the thrombogenicity increased with an increase in PBDO content above 10%. Membrane thrombogenicity varied with the blood-material contact time. For blood contact times of 10 minutes, all membranes tested were less thrombogenic than glass.