Polymeric carriers of vanadyl ions based on copolymers of N-vinylpyrrolidone with vinylimines

Abstract

In this study, a series of new chelating copolymers containing 20% azomethine groups, poly(N-vinylpyrrolidone-co-vinylsalicylideneimine) (poly[VP-co-VSalI]), poly(N-vinylpyrrolidone-co-vinylpicolinideneimine) (poly[VP-co-VPicI]), poly(N-vinylpyrrolidone-co-vinylpyridoxylideneimine) (poly[VP-co-VPyrI]) with M = 63000 Da and their vanadium(IV) complexes – poly(VP-co-VSalI)-VO, poly(VP-co-VPicI)-VO, poly(VP-co-VPyrI)-VO, were designed and synthesized. These are intended for the delivery and pH-dependent release of vanadium species in the intestine environment. The chelating polymers were obtained from poly(N-vinylpyrrolidone-co-N-vinylamine) (poly[VP-VAm]) by polymer-analogous transformations with the corresponding aldehydes. The vanadium content, determined by ICP-AES and spectrophotometric methods, was 5.36%, 4.99%, and 9.1% of the dry mass for poly(VP-co-VSalI)-VO, poly(VP-co-VPyrI)-VO, and poly(VP-co-VPicI)-VO, respectively. XPS data confirmed that only vanadium(IV) is presented in the complexes. All complexes demonstrated a pH-dependent release of low molecular weight vanadium species, making them promising candidates for the development of vanadium-containing systems for oral administration. These systems protect the main vanadium content in the stomach but can release biologically active ions in the intestine.