This research proposes to exploit a special physical phenomenon, ultrasonic cavitation and implosion, to fabricate open cell biodegradable polymer foams with controlled size and structure for tissue engineering scaffolds. Existing scaffold fabrication methods involve the use of either organic solvents or a leaching step, both of which are undesirable for tissue engineering applications. Conventional gas foaming techniques have limitations in creating open cell polymer foams. The study explores gas-polymer-ultrasound interactions, gas solubility and diffusivity, ultrasonic cavitation and implosion, bubble dynamics and disruption, The research will first explore the effects of foaming temperature and time on the structures of closed cell PLGA (poly(DL-lactic-co-glycolic acid)) foams. Then, the cell rupture behavior under ultrasonic energy will be studied for different frequencies and amplitudes. The created open cell structures will be characterized in terms of their morphology, density, porosity, and mechanical properties. Using CO2 as a blowing agent and the ultrasonic vibration to create open cell structures, the proposed process is biocompatible, environmentally benign, and easy to scale up. The new processing technology will result in not only a family of novel biomaterials that will find wide applications in tissue engineering, but also other open-cell polymeric materials that can be used in many applications such as micro filtration. Collaboration with medical researchers from the Fred Hutchinson Cancer Research Center (U. Washington) and the Integra Lifesciences Corporation, which specializes in medical devices, implants, and biomaterials should lead to a faster technology transfer and an education interdisciplinary experience for the students involved.
The proposed research will address the feasibility of a solvent and leach free open-cell polymer foaming process that represents a quantum leap forward from the capability of the current technology. It could change the way the tissue engineering community processes synthetic degradables into scaffolds and revolutionize the field of ex vivo expanded cell therapy.
