Proteins are perhaps the most important yet frustratingly complicated and difficult class of compounds to analyze, manipulate, and use. One very attractive option to characterize and differentially concentrate proteins is dielectrophoresis, but according to accepted theory, the force on smaller particles the size of proteins is too low to overcome diffusive action. Here, three model proteins, immunoglobulin G, α-chymotrypsinogen A, and lysozyme, are shown to generate forces much larger than predicted by established theory are more consistent with new theoretical constructs, which include the dipole moment and interfacial polarizability. The forces exerted on the proteins are quantitatively measured against well-established electrophoretic and diffusive processes and differ for each. These forces are orders of magnitude larger than previously predicted and enable the selective isolation and concentration of proteins consistent with an extremely high-resolution separation and concentration system based on the higher-order electric properties. The separations occur over a small footprint, happen quickly, and can be made in series or parallel (and in any order) on simple devices.

This study presents an unbiased high-resolution separation and characterization of NSPC subpopulations using direct current insulator-based dielectrophoresis.

Acute leukemia is the most common form of leukemia in adults. Drug differentiation control is critical for the treatment of acute leukemia. Unfortunately, current techniques detecting differentiation control experience long time and complex steps of verification hindering the steps of medicine discovery: flow cytometry and RT-PCR are highly accurate and efficient at a cost of inconvenient fluorescent labeling or a high risk of contamination; conventional staining leads to cell death unavailable for further pharmacological tests. Simple, fast and non-invasive techniques for medicine screening are in demand. DC-iDEP is an emerging label-free identification technique sorting cell populations taking advantage of the whole cell native biophysical property. Here, HL-60 cell line has been used as a model to study the differentiation process towards granulocytes and medicine efficacy. The results showed that DEP could detect the DMSO promoted differentiation degree by the weighted average characterization factor. This factor is related to the single cell biophysical property, which accumulate to generate differences in each population with distinct constitutions. Furthermore, chichoric acid was first found to promote DMSO-induced differentiation efficiently. The change induced by chichoric acid has been detected by DEP for primary medicine screening application. A rapid, label-free medicine screening method has been established monitoring HL-60 differentiation towards granulocyte for control and has great potential for medicine screening.