Control of vitamin B12 release from poly(ethylene glycol)/poly(butylene terephthalate) multiblock copolymers

R. van Dijkhuizen-Radersma, F.L.A.M.A. Peters, N.A. Stienstra, Dirk W. Grijpma, Jan Feijen, K. de Groot, J.M. Bezemer

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45 Citations (Scopus)


The release of vitamin B12 (1355 Da) from matrices based on multiblock copolymers was studied. The copolymers were composed of hydrophilic poly(ethylene glycol)-terephthalate (PEGT) blocks and hydrophobic poly(butylene terephthalate) (PBT) blocks. Vitamin B12 loaded films were prepared by using a water-in-oil emulsion method. The copolymer properties, like permeability, could be varied by increasing the PEG-segment length from 300 up to 4000 g/mol and by changing the wt% of PEGT. From permeation and release experiments, the diffusion coefficient of vitamin B12 through PEGT/PBT films of different compositions was determined. The diffusion coefficient of vitamin B12 was strongly dependent on the composition of the copolymers. Although an increased wt% of PEGT (at a constant PEG-segment length) resulted in a higher diffusion coefficient, a major effect was observed at increasing PEG-segment length. By varying the copolymer composition, a complete release of vitamin B12 in 1 day up to a constant release for over 12 weeks was obtained. The release rate could be effectively tailored by blending copolymers with different PEG-segment lengths. The swelling and the crystallinity of the matrix could explain the effect of the matrix composition on the release behavior.
Original languageUndefined
Pages (from-to)1527-1536
Issue number6
Publication statusPublished - 2002


  • Crystallinity
  • Controlled release
  • Peptides
  • IR-74795
  • Poly(ether ester)
  • METIS-223605
  • Swelling

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