Paper/polymer composited microfluidic platform for screening cell viability and protein expression under a chemical gradient environment.

Culturing cells in three-dimensional (3D) environment can obtain a better clinical prediction for evaluating chemotherapy protocols and become a standard culture practice in cancer research. However, it involves tedious and time consuming operation. In the current work, a paper/polymer composited microfluidic platform was developed for screening cell viability and protein expression under chemical gradient environment. Cells were cultured in a paper sheet and expressed cell properties in 3D environment. The paper sheet was encapsulated in the microfluidic platform generating chemical gradient. After the culture course, investigations of cell viability and protein expression were respectively achieved by directly adding reagent and conducting on-paper immunoassay. Activation of respective signaling pathway could be identified and responded to different stimulations including nutrient gradient, IL-6 cytokine gradient, and anti-cancer drug gradient. On-paper analysis of protein expression could be completed within 1.5 h. The present technique integrates tedious operations on a single paper substrate. It provides a first-tier screening tool for cellular response under chemical gradient.