Study on the preparation of novel functional poly(dioxanone) and for the controlled release of protein

Abstract

This paper describes the synthesis and ring-opening polymerization of a new functional dioxanone monomer 5-benzyloxymethyl-1,4-dioxan-2-one (BDON) in bulk using stannous octoate [Sn(Oct) 2], aluminium isopropoxide [Al(O i Pr) 3] or aluminium isobutoxide [Al(O i Bu) 3] as an initiator. The influences of reaction conditions such as polymerization temperature, polymerization time, initiator and initiator concentration on the monomer conversion and molecular weight have been investigated. The protecting benzyl groups of poly(5-benzyloxymethyl-1,4-dioxan-2-one) (PBDON) were subsequently removed by catalytic hydrogenation to give poly(5-hydroxymethyl-1,4-dioxan-2-one) (PHDON) with pendant hydroxyl groups. The polymers obtained were characterized by FTIR, 1H NMR, 13C NMR, GPC and DSC. In vitro degradation rates of the three poly(dioxanone) PHDON, PBDON and PDON under different conditions were also investigated. On the other hand, several copolymers P(BDON- co-DON)s were also synthesized. Deprotection of the benzyl groups in the copolymers afforded the corresponding hydroxyl-containing P(HDON- co-DON)s. Bovine serum albumin (BSA), a model protein drug, was encapsulated with PDON, PBDON or P(HDON- co-DON) to form microparticles and release behavior of these microparticles were studied.