Improving biomaterial properties of collagen films by chemical modification

Films of bovine collagen were chemically modified with the goal of improvin g their biomaterial properties. The modified films were investigated with r espect to their affinity to fibroblast and endothelial cells, as well as th eir antibacterial properties tested by adhesion of Staphylococcus aureus. M odifications that only change the net charge of collagen, such as acetylati on, succinylation, and treatment with glutaraldehyde tall increase the nega tive charge), and amination with ethylenediamine (EDA), N,N-dimethyl-EDA (D MEDA), or butylamine tall increase the positive charge), did not dramatical ly alter the mammalian cell attachment to the film. In contrast, derivatiza tion of collagen using methoxypoly(ethylene glycol) (PEG] diminished the at tachment of fibroblasts by 98 +/- 1% and of endothelial cells by more than 99% compared to unmodified collagen. Moreover, the rate of growth of fibrob lasts dropped by 97 +/- 1% and that of endothelial cells by 88 +/- 3% as a result of PEGylation of collagen. Adhesion of S. aureus cells also plummete d by 93 +/- 2% as a result of this PEGylation. With these antifouling prope rties, PEG-collagen may be a promising coating material for coronary stents . Subsequent derivatization of PEG-collagen with EDA or DMEDA abolished its mammalian cell-repelling ability, whereas bacterial cell repulsion was par tially retained: for example, DMEDA-modified PEG-collagen exhibits up to a 5-fold lower bacterial adhesion than collagen. It is worth noting that a ma terial that allows mammalian cell attachment but reduces bacterial adhesion could be useful as an implant or coating. (C) 2001 John Wiley & Sons, Inc.