Progress towards development of a photolytic artificial lung

While most chronic diseases are on the decline, medical pulmonary disease is on the increase. The unrelenting nature of chronic lung disease has long energized the pulmonary community to seek technologies to replicate the capacity of the lungs to exchange oxygen for carbon dioxide. While most such artificial lung technologies work by delivering oxygen to the blood through a system of hollow fibers or tubes, our approach employs photolytic energy to generate oxygen from the water already present in blood, thus eliminating the need for gas delivery. To this end, progress in the development of a photolytic artificial lung (PAL) is reported. The device provides photolytically driven electrochemistry for blood oxygenation or for maintenance of breathing air in confined spaces. The device is based on the catalyzed photoactivity of a transition metal oxide such as titanium dioxide (TiO2). Photoactive anatase TiO2 films have been developed for use in a photolytic artificial lung. The PAL is capable of facilitating gas exchange in the blood, thereby bypassing alveolar-capillary interfaces. The device will eventually be used in ex-vitro and in-vitro devices. The direct photolytic process, using UV laser radiation, converts water to liquid phase oxygen (dissolved oxygen), with commensurate reduction of carbon dioxide. The test cell consisted of an indium tin oxide coating, an anatase TiO2 coating (∼2 μm thick), and a MnO2 overcoat deposited on fused silica by reactive magnetron sputtering. Blood flowed over the coated side and oxygen exchange occurred at the MnO2 interface. Three hundred and fifty-four nanometers UV radiation was incident on the silica/indium tin oxide (ITO) side. Electron-hole pairs were generated in the TiO2 layer by the laser radiation, which catalyzed a redox reaction with water in the blood. The MnO2 was also used as a catalyst to dissolve oxygen in the blood. Oxyhemoglobin increased as much as 90% with this process. The maximum rate of oxygen generation was 1.08 ml O2/(m2 min), thus projecting an alveolar surface area of 75 m2. We conclude that it is feasible to photolytically oxygenate the hemoglobin contained in whole blood with oxygen derived from the blood's own water content.