Knowledge Bank

Low-cost velocity dependent cell sorting in 2D is a currently nonexistent technology for cancer research. The development of such a device would enable further research on the treatment of various deleterious cancers, such as Glioblastoma Multiforme (GBM), which metastasize based off the high motility of a single cell. Here we present a low-cost device capable of sorting these cells. Separation would enable development of highly specific therapeutic agents to limit cancer metastasis in patients. This device consists of microfluidics channels situated under microtextured Polydimethylsiloxane (PDMS) coated with the thermoresponsive polymer Poly(N-isopropylacrylamide) (PNIPAM). Cells are seeded on one end of the device and orient themselves parallel to the striations patterned into the PDMS; traveling further across the device over time. At a specific location (determined by velocity of target cells and time passed), low-temperature fluid can be passed through the microfluidic channel below which triggers a selective conformational change in the PNIPAM. This change shifts PNIPAM from nonpolar to polar, causing the polymer to release previously-adhered cells into solution in favor of binding to media. Establishing the PNIPAM layer capable of releasing cells while allowing them to adhere to microtextures on the PDMS involved a multi-step process. First, PDMS stamps are made of varying thickness, then they were placed in a plasma cleaner and exposed to Argon for 1,3, and 5 minutes at 30 Watts, 8-10 MHz, and ~1000microTorr. Then, samples were exposed to N-isopropylacrylamide (NIPAM) via immersion into a polymer solution and via dropping that solution onto samples and baked at 3 hours or 5 hours. Cell detachment analysis, goniometer experimentation, and SEM images showed that a 1 minute Argon gas exposure, with 1 minute of NIPAM immersion and a 3 hour bake yielded the most successful layer that lifted cells without inhibiting the PDMS microtexture. Future work involves optimizing the device to lift all cells exposed to the channel, as well as further corroborating its efficacy.