Crystalline phase composition of thin film determined by GIXRD. The crystal structure of the film was evaluated by GIXRD. A four-circle x-ray diffractometer, Philips X'Pert MRD PRO system with a horizontal, high-resolution goniometer (320 mm radius), was used in the grazing incidence geometry. Based on the strong 2Theta peaks at 25°, 37°, 48°, and 54°, the primary crystal phase of the thin film was anatase with a probable rutile secondary phase (see inset). The average anatase and rutile phase crystallite sizes, determined from the width of the (101) and (110) diffraction peaks, were and , respectively.
Assessment of surface properties of thin film by atomic force microscopy. Surface topology and roughness were determined with a Veeco Nanoscope III atomic force microscope, employing a standard silicon nitride tip in contact mode, with a scan rate of 3 Hz. (a) wide view normal to the surface demonstrating a relatively uniform array of nanocrystals ( diameter) constituting the photoactive thin film. The 2D rms roughness was 13–15 nm. (b) Surface perspective of the plan view in image A. (c) Higher resolution scan obtained near the center of the image depicted in image B, confirming the relative uniformity of the nanocrystallites. A ring-like ordering is also observed in the lower half of the image. The vertical color scale in images A–C is 400 nm black-to-white. (d) Cross-section surface profile from image A, showing a peak-to-valley height of 70 nm (red triangles) on a vertical scale of . Overall, these results demonstrate that this method of crystal deposition results in a stochastically uniform array of nanocrystallites on the surface.
Photolytic generation of oxyhemoglobin formation in whole blood. These results demonstrate rapid generation of DO sufficient to provide complete oxygenation of hemoglobin in a single pass. (a) Linear relationship between (percent hemoglobin saturation with oxygen) and the log of the anodic compartment residence time, indicating the nature of the DO diffusion process from the photocatalyst to the flowing blood volume. (b) Blood shown before and after photoactivation (all trials), demonstrating that photoactivation has no effect on .
Hemocompatibility of photolytic oxyhemoglobin formation. Hematological parameters were assessed following single pass photolytic generation of DO and formation of oxyhemoglobin. Blood smears are shown both before (a) and after (b) photolysis, demonstrating no apparent hemolysis. (c) Rate of hemolysis before and after treatment depicted as spun Hct pre- and post-treatment, showing no significant change (mean of all trials, error bars omitted). (d) Percent F-met-hemoglobin before and after photolysis for each trial, showing no significant change in any instance.
Diagram showing the mechanism underlying photocatalytic DO generation and oxyhemoglobin formation. Photocatalytic oxygen generation is based on the capacity of , thin films to convert light energy to electric current; with the resulting charge separation is used to generate oxygen from adjacent (nondiffusion) water molecules. The photochemical materials are designed to produce DO directly in an aqueous fluid (blood) which is then available to bind with hemoglobin. As shown here, UV light interacts with the metal oxide to photolytically generate DO (and oxyhemoglobin, ), hydrogen and free electrons. In the proposed device, hydrogen ions and electrons may then migrate to the cathode to facilitate chemical reduction of circulating carbon dioxide.
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