Biomedical Sensors and Subsystems

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High-Throughput Photodynamic Therapy (PDT) Screening Chip with Oxygen, Photosensitizer and Light Exposure Controls
Xia Lou, Gwangseong Kim, Yong-Eun Lee Koo, Raoul Kopelman, and Euisik Yoon
(a) PDT chip outlook and (b) typical high-throughput photosensitizer efficacy test result showing cell viability change under different PDT conditions
(a) PDT chip outlook and (b) typical high-throughput photosensitizer efficacy test result showing cell viability change under different PDT conditions

Photodynamic therapy (PDT) has emerged as a promising treatment for cancer since 1980s, especially with the advancement of new-generation photosensitizers (PS) and various PS delivery strategies. However, the experimental technologies for PDT lag behind to meet the need of huge number of screening tests for numerous photosensitizers developed recently in terms of specificity for target cancer cells and activating light delivery. In this project we developed a microfluidic chip that can provide the control of all these three crucial parameters in photodynamic therapy including the concentration of photosensitizers, oxygen levels and activating light intensity. By using the microfluidic gradient-generating networks, we can simultaneously provide nine different concentrations of photosensitizer. Also by imposing an extra gas layer in the top channel, we can provide different oxygen levels for each flow layer through molecular diffusion across the thin PDMS membrane which separates the two layers. Also exposure dose can be controlled by an LED light source. Methyleneblue (MB), which has been used for a variety of applications as photosensitizer, and rat C6 glioma tumor cells are adopted for PDT efficiency test. We observed distinctive viability for various Methyleneblue concentrations, oxygen levels and exposure doses. From this, we could determine the minimum (threshold) level of these parameters required for reaching certain effectiveness.

Updated 03/27/2012