title: Microphase separation in bioerodible copolymers for drug delivery.
abstract: This research examines the microstructure of bioerodible polyanhydrides with an eye towards precise design of drug delivery devices. Our main hypothesis is that the bioerodible copolymer poly(1,6-bis-p-carboxyphenoxyhexane-co-sebacic anhydride) (CPH : SA) undergoes micro-phase separation at certain copolymer compositions due to differences in relative hydrophobicity of the co-monomers, resulting in thermodynamic partitioning of drugs incorporated into these copolymers. We investigate the thermal properties, degree of crystallinity, and surface microstructure of several compositions of CPH : SA using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and atomic force microscopy (AFM). We observe that the degree of crystallinity decreases, while the crystal lamellar thickness increases with CPH content. Phase-imaging using AFM indicates the presence of micro-domains in 20 : 80 and 80 : 20 CPH : SA, while poly(SA) and 50 : 50 CPH : SA show no micro-phase separation. Finally, drug-polymer interactions are studied by loading the polymers with different amounts of brilliant blue (hydrophilic) and p-nitroaniline (hydrophobic). DSC and WAXD analysis shows that loading hydrophobic drugs into relatively hydrophobic polymers (poly(SA)) lowers melting point that becomes more pronounced with increased drug loading.
authors.affiliation: Department of Chemical & Biochemical Engineering, Rutgers, The State University of New Jersey, Piscatawaay 08854-8058, USA.
authors.forename: E
authors.initials: E
authors.lastname: Shen
authors.forename: R
authors.initials: R
authors.lastname: Pizsczek
authors.forename: B
authors.initials: B
authors.lastname: Dziadul
authors.forename: B
authors.initials: B
authors.lastname: Narasimhan
mesh_terms: D001673:Biodegradation, Environmental; D002152:Calorimetry, Differential Scanning; D016503:Drug Delivery Systems; D018625:Microscopy, Atomic Force; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D011108:Polymers