Multi-layered Microfluidic Drug Screening Platform Enabling Simultaneous Generation of Linear and Logarithmic Concentration Gradients

Abstract

AbstractSince many microfluidic devices have limited drug dose order of gradients and incorporate 2D cell culture, we here present a multi-layered platform with linear and logarithmic gradients with 3D-cell culturing chambers. By employing Hagen–Poiseuille flow resistance equation and the parallel electric schematics, we determined the appropriate channel dimensions to achieve the desired target concentrations (100%, 50%, 20%, 10%, 5%, 2%, 1%, 0%). To validate the gradient formation against theoretical values, we introduced a solution containing fluorescein into the microfluidic chip. Moreover, cell culturing chambers were spaced out laterally for every 9 mm, aligning with the dimensions with the standard plate reader, providing enhanced usability. Vertical layout of the chip minimized the lateral dimension required for housing various components while maintaining a favorable height for imaging. By preventing the need to use external tubing to connect concentration gradient generator and cell culturing chamber modules, our platform holds promise in facilitating the integration of microfluidics into drug evaluation processes. To demonstrate use of this flexible platform, we tested two chemotherapy drugs against human bladder cancer cells (T24) embedded in 3D fibrin gel and evaluated their cell viability and proliferation rate. IC50 values were extracted for cells exposed to varying doses of cisplatin, gemcitabine, and gemcitabine with a fixed cisplatin dose, confirming the enhanced apoptosis of the bladder cancer cells and the advantages of combination chemotherapy. This simple multi-layered device may accelerate screening of anti-cancer drugs for a specific cell type by extracting optimal dosage for two drugs.