No abstract

High content screening (HCS) has quickly established itself as a core technique in the early stage of drug discovery for secondary compound screening. It allows several independent cellular parameters to be measured in a single cell or populations of cells in a single assay. In this work, we describe high content screening for the multiparametric measurement of cellular responses in human liver carcinoma (HepG2) cells using an integrated microfluidic device. This device consists of multiple drug gradient generators and parallel cell culture chambers, in which the processes of liquid dilution and diffusion, micro-scale cell culture, cell stimulation and cell labeling can be integrated into a single device. The simple assay provides multiparametric measurements of plasma membrane permeability, nuclear size, mitochondrial transmembrane potential and intracellular redox states in anti-cancer drug-induced apoptosis of HepG2 cells. The established platform is able to rapidly extract the maximum of information from tumor cells in response to several drugs varying in concentration, with minimal sample and less time, which is very useful for basic biomedical research and cancer treatment.

Microfluidic devices integrating membrane-based sample preparation with electrophoretic separation are demonstrated. These multilayer devices consist of 10 nm pore diameter membranes sandwiched between two layers of PDMS substrates with embedded microchannels. Because of the membrane isolation, material exchange between two fluidic layers can be precisely controlled by applied voltages. More importantly, since only small molecules can pass through the nanopores, the integrated membrane can serve as a filter or a concentrator prior to microchip electrophoresis under different design and operation modes. As a filter, they can be used for separation and selective injection of small analytes from sample matrix. This has been effectively applied in rapid determination of reduced glutathione in human plasma and red blood cells without any off-chip deproteinization procedure. Alternatively, in the concentrator mode, they can be used for online purification and preconcentration of macromolecules, which was illustrated by removing primers and preconcentrating the product DNA from a PCR product mixture.