Eric C. Burckle

Development of a photolytic artificial lung: preliminary concept validation.

There is an established need for pulmonary technology capable of facilitated gas exchange in the blood, thereby bypassing the alveolar-capillary interface. To address this need, we emulated one of the best-known photolytic reactions in nature, photosynthesis, in which green plants use sunlight to drive the exchange of oxygen for carbon dioxide. Our goal in the current study was to demonstrate the feasibility of direct photolytic conversion of water to liquid phase oxygen (dissolved oxygen [DO]) in synthetic serum. To this end, we constructed a test flow cell consisting of a conductive coating of vacuum-deposited titanium (Ti) metal, adherent TiO2 (anatase), and MnO2, applied as a laminate to a glass substrate, and then immersed the device in Locke’s-Ringer solution (synthetic blood serum). Long wavelength (low energy) ultraviolet A laser light, directed to the transparent glass slide, reproducibly resulted in the generation of an active form of oxygen (AO), which was subsequently converted directly by the catalytic action of MnO2 to DO. The absence of light activation provided an entirely null response. We conclude that the photolytic production of DO from water in a blood serum surrogate, with commensurate CO2 clearance, is feasible. A prototype photolytic module is proposed, which uses multiple parallel photolytic surfaces to improve system production capacity and CO2 clearance through selective gas–liquid separation from the oxygen-enriched fluid.

Photolytically driven generation of dissolved oxygen and increased oxyhemoglobin in whole blood.

The severely debilitating nature of chronic lung disease has long provided the impetus for the development of technologies to supplement the respiratory capacity of the human lung. Although conventional artificial lung technologies function by delivering pressurized oxygen to the blood through a system of hollow fibers or tubes, our approach uses photolytic energy to generate dissolved oxygen (DO) from the water already present in blood, thus eliminating the need for gas delivery. We have previously demonstrated that it is feasible to generate dissolved oxygen from water based on UVA illumination of a highly absorbent TiO2 thin film. In the current study, we extend this work by using photolytic energy to generate DO from whole blood, thus resulting in an increase of oxyhemoglobin as a function of back side TiO2 surface film illumination. Initial experiments, performed with Lockes Ringer solution, demonstrated effective film thickness and material selection for the conductive layer. The application of a small bias voltage was used to conduct photogenerated electrons from the aqueous phase to minimize electron recombination with the DO. Mixed arterial-venous bovine blood was flowed in a recirculating loop over TiO2 nanocrystalline films illuminated on the side opposite the blood (or “back side”) to eliminate the possibility of any direct exposure of blood to light. After light exposure of the TiO2 film, the fraction of oxyhemoglobin in the blood rapidly increased to near saturation and remained stable throughout the trial period. Last, we evaluated potential biofouling of the DO generating surface by scanning electron microscopy, after photolytically energized DO generation in whole blood, and observed no white or red blood cell surface deposition, nor the accumulation of any other material at this magnification. We conclude that it is feasible to photolytically oxygenate the hemoglobin contained in whole blood with oxygen derived from the bloods own water content without involving a gaseous phase