Microscale Purification Systems for Biological Sample Preparation

Abstract

This work is focused on the development of miniaturized instrumentation formats for integrated biochemical and biological sample preparation. In particular, the paper is focused on microfluidic systems for the purification of cells, uncoated nano particles, and surface coated nano particles. Microfluidic systems will be described for purifying cells from whole blood, sorting of blood cells based on their electrophysiological characteristics, and separating and purifying the components of a blood cell homogenate. Additionally, the microscale sample preparation systems will be shown to be effective in purifying complex samples of nano particles based on the particles physical size and effective electrical charge. The microsystems will be demonstrated for the purification of samples containing polystyrene nano particles with multiple diameters as well as for samples containing a mixture of uncoated and surface coated nano particles. The formats discussed in this work include the micro-electrophysiological characterization (μ-EPC) system; the micro-thermal field flow fractionation (μ-TFFF) system; and the micro-electrical field flow fractionation (μ-EFFF) system. The microscale cellular electrophysiological characterization system is used for cell sorting and selection. The cell sorting and selection is accomplished using impedance spectroscopy on single cells. The system has been shown to be effective in sorting blood cells by cell type (i.e., red, white) and by sub populations (e.g., viable leukocytes, non viable leukocytes). The μ-TFFF system is a chromatographic separation technique for fractionating particle samples based on the heat capacity, thermal conductivity and physical size of the particles. The μ-EFFF system fractionates particle samples based on the physical size and zeta potential (effective electrical charge) of the particles within the sample. The electrical and thermal FFF systems are capable of separating particle samples with constituents in the diameter range from approximately 1 nm to 1 μm. The separation and purification of a variety of nano particles will be demonstrated in the field flow fractionation systems including cells, cellular sub-components, uncoated polystyrene nano particles, and protein coated (Protein A) polystyrene nano particles.