POLY(ETHYLENE OXIDE)-MODIFIED POLYASPARTAMIDE-FERROCENE CONJUGATES

In continuation of earlier investigations of polymer-ferrocene conjuga tes for biomedical applications, this article deals with conjugates pr epared by N-acylation of linear, amine-functionalized polyaspartamide carriers with 4-ferrocenyl-butanoic acid. Acylation is brought about b oth by mediation of HBTU coupling agent and by the N-hydroxysuccinimid e active ester method. The polymeric carriers contain oligo- or poly(e thylene oxide)side chains introduced here for enhancement of water sol ubility. The longer side chains, in addition, are to impart such biome dically important properties as increased resistance to uptake by the reticuloendothelial system and to protein binding, extended circulatio n life time, and lowered immunogenicity. The conjugates comprise from 10 to 25 mol% ferrocenylated subunits, corresponding to ca. 2-5% Fe by mass. Freshly prepared and isolated in the solid state, they dissolve smoothly in aqueous media, with upper concentration limit; (>0.2 g/ml ) dictated solely by their viscosity behavior. The conjugates are of i nterest in biomedical applications.