Ionic Cross-Linkable Alendronate-Conjugated Biodegradable Polyurethane Films for Potential Guided Bone Regeneration

Biodegradable and hydrophilic poly(ε-caprolactone) (PCL)-based polyurethane (PU) dispersion was synthesized using PCL diol as the first polyol by a pre-polymer method. Dimethylol propionic acid (DMPA) was used as the polyol to provide carboxyl groups in PU and enhance the hydrophilicity of the resultant PU film. The carboxyl groups of the waterborne PU were utilized for the conjugation with alendronate (Alen) and the ionic cross-linking among PU polymers by calcium chloride. Both the Alen conjugation and ionic cross-linking significantly reduced the water contact angle. The Alen-conjugated PU (Alen-PU) film without ionic cross-linking exhibited a ductile characteristic with high elongation at break. The ionic cross-linking of the Alen-PU film resulted in the enhancement of Young’s modulus and tensile strength. In addition, the ionic cross-linking increased the biodegradation time of the PU-based films. The employment of Alen in PU film led to the lower proliferation and higher differentiation of pre-osteoblastic cells (MC3T3-E1) than PU film. We believed that the Alen-PU films have the potential for widespread application in tissue engineering, especially for guided bone regeneration.