title: Correlation between heparin release and polymerization degree of organically modified silica xerogels from 3-methacryloxypropylpolysilsesquioxane.
abstract: This work aimed to investigate the use of an organically modified porous silica matrix (poly(methacryloxypropyl)-poly(silsesquioxane); P-MA-PS) as a release system for heparin. The matrices were obtained from methacryloxypropyltrimethoxysilane (MAS) via the sol-gel process under acidic conditions following photochemical polymerization and cross-linking of the organic matrix. Modulation of the polymerization degree of the organic matrix in the range 0-71% allowed adjusting the release kinetics of heparin according to therapeutic needs. It was demonstrated that higher drug loads and a decreasing polymerization degree resulted in a faster release profile of heparin, which followed a square root of time kinetic according to the Higuchi model. The hydrolytic degradation of hybrid xerogel was found to follow a zero-order kinetic whereas the heparin concentration did not show an influence on the degradation rate of the matrix. Since the released heparin retained its biological activity, the P-MA-PS matrices are of clinically interest, e.g. as coating on drug eluting coronary stents.
authors.affiliation: Department for Functional Materials in Medicine and Dentistry, University of Würzburg, Pleicherwall 2, D-97070 Würzburg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Tebbe
authors.forename: Roger
authors.initials: R
authors.lastname: Thull
authors.forename: Uwe
authors.initials: U
authors.lastname: Gbureck
mesh_terms: D005782:Gels / Q000737:chemistry; D006493:Heparin / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry*; D015394:Molecular Structure; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D012821:Silanes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014466:Ultraviolet Rays
chemical_list: D005782:Gels; D008689:Methacrylates; D011108:Polymers; D012821:Silanes; C017492:methacryloxypropyltrimethoxysilane; D012822:Silicon Dioxide; D006493:Heparin