Focusing of mammalian cells under an ultrahigh pH gradient created by unidirectional electropulsation in a confined microchamber

View/ Open
Downloads: 175
Downloads: 132
Downloads: 31
Downloads: 27
Date
2014-06-09Author
Loufakis, Despina N.
Cao, Zhenning
Ma, Sai
Mittelman, David
Lu, Chang
Metadata
Show full item recordAbstract
The transport and manipulation of cells in microfluidic structures are often critically required in cellular analysis. Cells typically make consistent movement in a dc electric field in a single direction, due to their electrophoretic mobility or electroosmotic flow or the combination of the two. Here we demonstrate that mammalian cells focus to the middle of a closed microfluidic chamber under the application of unidirectional direct current pulses. With experimental and computational data, we show that under the pulses electrochemical reactions take place in the confined microscale space and create an ultrahigh and nonlinear pH gradient (~2 orders of magnitude higher than the ones in protein isoelectric focusing) at the middle of the chamber. The varying local pH affects the cell surface charge and the electrophoretic mobility, leading to focusing in free solution. Our approach provides a new and simple method for focusing and concentrating mammalian cells at the microscale.