Hydrodynamic Cell Capture and Release Microfluidic Chip for Cancer Drug Screening

Microfluidic chip-based drug screening has attracted increasing attention owing to its miniaturization, automation, high throughput, simple operation, and excellent biocompatibility. Efficient release of target cells after co-culture with different drug concentrations is critical for investigating drug-induced alterations in cellular gene expression and enhancing microfluidic screening performance. In this study, a direction-sensitive microstructure with adaptive flow resistance regulation was constructed based on a fluidic-circuit-equivalent resistance model. This structure generated distinct distributions under forward and reverse flow directions, achieving efficient cell capture and release. Guided by theoretical analysis and simulation optimization, a microfluidic device integrating a concentration gradient generator, trap array, and flow resistance-regulating microchannels was fabricated. By simply switching the driving direction, the device can conveniently switch between forward capture and reverse release modes with high stability. In forward capture mode, the main channel exhibits the lowest flow resistance, and cells flow along the main channel and are captured in the traps. In reverse release mode, the main channel switches to the highest flow resistance, and cells in the traps are efficiently released backward along bypass channels to the collection outlet without recapture. Using K562 cells, the effects of channel width on cell capture and release efficiencies were investigated to determine the optimal design parameters. Finally, the device achieved a capture efficiency of 92.0 ± 4.4% and a release efficiency of 70.0 ± 8.6%, with maximum values of 97.2% and 87.8%, respectively. To further verify the device's applicability for drug screening, four concentrations of nilotinib were generated using the device. After K562 cells were cultured under the four concentrations for 48 h, the on-chip IC50 of nilotinib against K562 cells was determined to be approximately 10.79 μM, close to the result of 14.10 μM measured in the off-chip microplate. Subsequently, the treated cells were collected after reverse release and subjected to RNA-seq. The results showed that 20 μM nilotinib treatment significantly downregulated the expression of MYC, LYN, and BCL2L12, which are related to BCR-ABL signaling, by 18.3-fold, 3.6-fold, and 4.7-fold, respectively. Meanwhile, the treatment inhibited the viability of K562 cells to 23.9 ± 3.5%.