Characterization and optimization of a novel design to increase the haemocompatibility of biomaterials

Previously, our group has developed a novel design that can inhibit platelet deposition on biomedical polymers by exploiting endogenous nitric oxide (NO) and several naturally occurring mechanisms in the body. L-cysteine residues are covalently attached to the surface of the polymer in order to promote NO transfer from high molecular weight thiol-containing proteins, such as serum albumin, to the thiol group of the attached L-cysteine. NO is then released from the attached L-cysteine and available to inhibit platelet deposition. The present study involves the characterization and optimization of the L-cysteine-modified polymers. The modified polymers are characterized by several methods, including a method developed by our group, x-ray photoelectron spectroscopy, and fluorescence microscopy. The modified polymers are optimized by using a factorial design and varying the concentrations and reaction times of the species involved in the modification process. In addition to the L-cysteine residues, a L-cysteine analogue and a L-cysteine polypeptide are attached to the polymer. The optimization process was used to determine the best method to attach the most L-cysteine residues to the polymer that will result in the most free thiol groups available to transfer NO to and from the surface to prevent platelet deposition.