Sterically blocking adhesion of cells to biological surfaces with a surface-active copolymer containing poly(ethylene glycol) and phenylboronic acid

Graft copolymers were designed that could spontaneously bind to biological surfaces and block subsequent recognition and adhesion at those surfaces. Phenylboronic acid (PBA) moieties in the polymer backbone provided binding to surfaces, forming reversible covalent complexes with cis-diols found in many biological molecules. Pendant poly(ethylene glycol) (PEG) side chains sterically protected those surfaces from subsequent interactions with other proteins and cells. The PEG and PBA grafting ratios on these poly-L-lysine-graft-(PEG;PBA) copolymers [PLL-g-(PEG;PBA)] were varied, and the polymers were tested in models relevant to undesirable wound-healing responses such as peritoneal adhesion formation and posterior capsule opacification. PLL-g-(PEG;PBA) polymers spontaneously coated tissue culture polystyrene and completely blocked rabbit lens epithelial cell adhesion to the surface over a wide range of PEG grafting ratios. PLL-g-(PEG;PBA)s with optimal grafting ratios were able to coat adsorbed serum proteins or extracellular matrices and block cell spreading on the surfaces at 4 h, although the effect was lost within 24 h. The polymer also enhanced the efficacy of surgical lysis of peritoneal adhesions in rats. The reversible covalent complexes formed by the PBA moieties on the copolymer backbone were more effective at binding biological surfaces than electrostatic interactions formed via a copolymer lacking the PBA moieties, that is, PLL-g-PEG.