Abstract

Electrokinetic Size Mobility Trap for Point of Care Analysis

Rosanne Guijt, Senior Lecturer, University of Tasmania

The extraction of target analytes from biological samples is a bottleneck in clinical analysis. Electrokinetic size and mobility traps (SMT) consist two nanojunctions connecting microfluidic sample and waste chambers with an adjacent microchannel. Both junctions have different pore size, allowing target analytes to cross the fist, large pore size junction but not the second, small pore size junction. Upon application of an electric field, analytical targets can be selectively extracted and concentrated from complex samples. Subsequent switching of the electric fields allows for electrophoretic separation for quantitative analysis. In this presentation, two embodiments of a SMT will be discussed. In the first, an SMT was created through controlling the dielectric breakdown of the wall separating adjacent microchannels, with an increased breakthrough current correlated to larger pores. This device was applied to the analysis of ampicillin levels in blood within 5 min and a linear response over the range of 2.5–20 mg mL-1. This covers the recommended levels for treating sepsis. In the second embodiment, the SMT was improved for enhanced salt tolerance by the integration of track etched membranes. This device was used for the analysis of human serum albumin from urine. With a LOD of 1.5 µg mL-1 and linear range up to 100 µg mL-1this membrane chip would be suitable for the detection microalbuminuria (30 µg mL-1). These two clinically relevant applications demonstrate that the SMT provides new opportunities for integrated sample treatment in point of care analysis.