title: Loading dependent swelling and release properties of novel biodegradable, elastic and environmental stimuli-sensitive polyurethanes.
abstract: A novel degradable, elastic, anionic, and linear polyurethane was synthesized from hexamethylene diisocyanate, polycaprolactone diol, and a bicine chain extender. The chemical structure, mechanical properties, degradation rate, and swelling ratio were characterized by comparing the polymer with a polyurethane containing a 2,2-(methylimino) diethanol chain extender. Due to the incorporation of negatively charged carboxyl side groups, the bicine extended polymers exhibited higher micro-phase separation, better mechanical properties in dry condition, and better sensitivity to environmental stimuli than controls, as demonstrated by its high swelling ratio at elevated pH, lower ionic strength, or higher temperature. The swelling ratio of membranes showed reversible change as the function of pH at 37 degrees C, the membranes becoming fully water soluble at pH above 8.3. Nile blue chloride and lysozyme were selected to study their release from this polymer. The release rates of both compounds were significantly influenced by the pH and ionic strength. The swelling ratios were also influenced by lysozyme loading at low pH. The pH dependent properties were used to fabricate scaffolds by drop-on-demand printing. Bicine extended polyurethanes may be of interest for possible drug delivery applications, customizable scaffold fabrication and other potential biomedical applications.
authors.affiliation: Department of Bioengineering, Clemson University, Clemson, SC 29634, USA.
authors.forename: Changhong
authors.initials: C
authors.lastname: Zhang
authors.forename: Kejia
authors.initials: K
authors.lastname: Zhao
authors.forename: Tianyi
authors.initials: T
authors.lastname: Hu
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Cui
authors.forename: Nathan
authors.initials: N
authors.lastname: Brown
authors.forename: Thomas
authors.initials: T
authors.lastname: Boland
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry; D004337:Drug Carriers / Q000138:chemical synthesis / Q000737:chemistry; D004548:Elasticity; D006863:Hydrogen-Ion Concentration; D007281:Ink; D008422:Materials Testing; D008567:Membranes, Artificial; D008970:Molecular Weight; D009113:Muramidase / Q000737:chemistry; D011140:Polyurethanes / Q000138:chemical synthesis / Q000737:chemistry; D011327:Printing; D012995:Solubility; D013718:Tensile Strength; D054457:Tissue Scaffolds
chemical_list: D001672:Biocompatible Materials; D004337:Drug Carriers; D008567:Membranes, Artificial; D011140:Polyurethanes; D009113:Muramidase