Development of low-cost and simple paper-based capillary electrophoresis microdevice for foodborne pathogen detection

Abstract

In this thesis, the development of a novel paper-based capillary electrophoresis (pCE) microdevice using mineral paper is presented. The mineral paper is durable, oil and tear resistant, and waterproof. Thus, this material is better than quartz, glass or polymer in terms of facile chip fabrication, cost-effectiveness, and disposability. In this context, I presented the pCE microdevice without using an expensive and complicated conventional photolithography method. The pCE device consists of six layers: from top to bottom, PDMS reservoirs, an overhead projector (OHP) cover, a double-sided adhesive film layer, a micropatterned mineral paper layer, a double-sided adhesive film layer, and an OHP film. In the mineral paper, the typical cross-CE microchannel was patterned by using a cutting plotter, and the whole process for chip fabrication was completed in 1 hour. By conducting the applied voltages in the sample, waste, cathode, and anode reservoirs, the DNA could be injected, back-biased, and separated. In 2.9 cm separation channel, the DNA molecules with 4 bp difference in length were clearly separated. Moreover, two foodborne pathogen genes (rrsH of Escherichia coli O157:H7 and glnA of Staphylococcus aureus) were amplified, and the resultant amplicons (121 bp of rrsH and 225 bp of glnA) were distinguished on the pCE microdevice within 3 min. To assign the target peak in the electropherogram with high accuracy, two bracket ladders (80 bp and 326 bp) were used, so the target gene peaks could be exactly verified regardless of CE conditions. Such a pCE microdevice would be an ideal platform for DNA separation with high simplicity, speed, and accuracy in a resource-limited environments.