title: Characteristics of vitamin C encapsulated tripolyphosphate-chitosan microspheres as affected by chitosan molecular weight.
abstract: In this paper, the effect of chitosan molecular weight on the characteristics (size, encapsulation efficiency, zeta potential, surface morphology and release rate) of vitamin C encapsulated tripolyphosphate cross-linked chitosan (TPP-chitosan) microspheres. The molecular weight of chitosan had a noticeable influence on the size, encapsulation efficiency, zeta potential, surface morphology and controlled release behaviour of the vitamin C encapsulated TPP-chitosan microspheres. The mean particle size and encapsulation efficiencies of TPP-chitosan microspheres were 3.1, 4.9 and 6.7 microm and 67.25, 60.43 and 52.74% for the microspheres prepared using low, medium and high molecular weight chitosan, respectively. All the TPP-chitosan microspheres (low, medium and high molecular weight) had positive charge on their surface. The zeta potential of the TPP-chitosan microspheres prepared using low, medium and high molecular weight chitosan was 41.25, 40.84 and 39.13 mV, respectively. The particle sizes of TPP-chitosan microspheres increased with increases in chitosan molecular weight. Molecular weight of chitosan did not affect significantly the % yield of TPP-chitosan microspheres prepared by spray-drying. The influence of chitosan molecular weight on the surface morphology of vitamin C encapsulated TPP-chitosan microspheres was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was observed that, as the molecular weight of chitosan increases, TPP-chitosan microspheres with uniform spherical shape could be obtained. The physical state of vitamin C (amorphous or crystalline) in TPP-chitosan matrix was studied by X-ray diffraction (XRD) and it was found that vitamin C is dispersed at the molecular level (amorphous) in the TPP-chitosan matrix. Release rate of the vitamin C from TPP-chitosan microspheres was significantly affected by the chitosan molecular weight. The release rate decreased with increase in the chitosan molecular weight. The release of vitamin C from TPP-chitosan microspheres followed Fick's law of diffusion.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University, Seoul, South Korea.
authors.forename: K G
authors.initials: KG
authors.lastname: Desai
authors.forename: C
authors.initials: C
authors.lastname: Liu
authors.forename: H J
authors.initials: HJ
authors.lastname: Park
mesh_terms: D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000493:pharmacokinetics; D048271:Chitosan / Q000737:chemistry*; D003692:Delayed-Action Preparations / Q000737:chemistry; D004339:Drug Compounding / Q000379:methods*; D016503:Drug Delivery Systems / Q000379:methods*; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D008970:Molecular Weight; D010316:Particle Size; D011122:Polyphosphates; D013499:Surface Properties
chemical_list: D003692:Delayed-Action Preparations; D011122:Polyphosphates; D048271:Chitosan; C005692:triphosphoric acid; D001205:Ascorbic Acid