David Arazawa

Faculty Mentor: William Federspiel

Research:The future development of artificial lungs is pushing for increased gas exchange rates across a smaller surface area with greater biocompatibility for long term use. To be realized advancements in biomaterials, micro-fabrication manufacturing and bioengineering will all need to play together into developing the next generation devices. Mr. Arazawa's work has already taken the first steps in this direction by examining the challenges of insufficient carbon dioxide (CO2) removal due to limited diffusion in artificial lungs and respiratory assist devices. In blood CO2 is predominantly (greater than 90%) transported in a bicarbonate ion form. The enzyme carbonic anhydrase directly catalyzes this reaction inter-converting CO2 between its hydrated and non hydrated forms. By immobilizing this enzyme on the outer surface of the hollow fiber membranes, local concentration gradient of CO2 gas can be significantly increased improving diffusional gradients and thereby enhancing CO2 removal, by as much as 36% in preliminary blood experiments. Furthermore this enzymatic coating has demonstrated an improvement overall biocompatibility. A second technology currently being developed is the use of impeller devices to provide active blood mixing, minimizing diffusional boundary layers. Both techniques have independently demonstrated success in more efficient CO2 gas exchange, but when mutually employed active mixing shear forces significantly decrease enzyme activity as a result of denaturation. Moreover the activity of enzymatic coatings is susceptible to variables such as time, pH and temperature. Therefore while current carbonic anhydrase immobilization techniques have demonstrated a proof of principle, long term success will require more resilient bioactive coatings capable of providing continued activity with resistance to denaturation.

Publications:

• Arazawa DT, Oh HI, Federspiel WJ . " Carbonic Anhydrase Immobilized Bioactive Hollow Fibers Accelerate CO2 Removal for Artificial Lung Applications ". ASAIO Conference2010 , 2010
• Arazawa DT, Federspiel WJ . " Immobilized Carbonic Anhydrase on Hollow Fibers Accelerates CO2 From Blood ". ASAIO Journal57 ( 2 ): 110 , 2011

Conferences:

• Bioengineering Graduate Student Research Symposium, Pittsburgh, PA, United States of America, 5/1/2007
• MIRM Scientific Retreat , Pittsburgh , PA , United States of America , 03/2010
• ASAIO Conference , Baltimore , MD , United States of America , 05/2010

• ASAIO Conference , Washington DC , , United States of America , 06/2011

• MIRM Scientific Retreat , Pittsburgh , PA , United States of America , 03/2011

• MIRM Scientific Retreat , Pittsburgh , PA , United States of America , 03/2013

David is developing enzymatic coatings to increase the CO2 removal efficiency of artificial lungs and respiratory assist devices.