Dozens of microfluidic devices have been developed over the years that filter circulating tumor cells (CTC) from whole blood. Once inside the device, though, the cells end up stuck to the mechanism that captured them, making it difficult to quickly study them without causing damage.
Scientists from the RIKEN Advanced Science Institute in Japan and University of California Los Angeles have developed a new mechanism using polymer grafted silicon nanowires that capture CTC’s at body temperature (37°C, 99°F) and release them when cooled to close to freezing (4°C, 39°F).
Blood is passed through the device like a filter that contains a molecule capable of adhering to tumor cells like Velcro and separating them with efficiency ranging from 40% to 70%. The cancer cells are retained by tiny temperature-responsive polymer brushes inside the device. At 37 degrees Celsius, these polymer brushes stick to the tumor cells, but when cooled to 4 degrees Celsius, they release them, allowing scientists to examine the cells.
“Until now, most devices have demonstrated the ability to capture circulating tumor cells with high efficiency. However, it is equally important to release these captured cells, to preserve and study them in order to obtain insightful information about them. This is the big difference with our device.” Explains Hsiao-hua Yu, who led the team that developed the technique to coat the device with polymer brushes.
Abstract in Advanced Materials: Capture and Stimulated Release of Circulating Tumor Cells on Polymer-Grafted Silicon Nanostructures