Thursday, November 8, 2007 - 9:54 AM

Microfluidic Gdna Quantification by Flow Rate Analysis

Rajesh Surapaneni1, Jungkyu Kim2, and Bruce Gale1. (1) Mechanical Engineering, University of Utah, 50 S Central Campus Dr Rm 2110, Salt Lake City, UT 84112, (2) Bioengineering, University of Utah, 50 S Central Campus Dr, Salt Lake City, UT 84112

A system for DNA extraction and quantification was designed and fabricated using a nanoporous aluminum oxide membrane. In this system, as DNA was collected on the membrane, the flow resistance through the membrane increased, which was measured using a flow rate sensor. Based on this concept, an existing DNA extraction system was modified to quantify gDNA (genomic DNA) collected. The DNA extraction system was fabricated with PDMS micro-channels, double-sided tape and aluminum oxide membrane. The nanoporous membrane was embedded in a microfluidic system and DNA was collected over the membrane. To demonstrate the system, nanoparticles (370nm diameter) were used and extracted over the membrane of pore size 200nm. Over a period of time, particles were collected over the membrane with flow rates falling exponentially. After the proof of concept was tested, gDNA of 25ng/Ál and 10ng/Ál concentrations were extracted over 20nm pore sized membranes and similar results were obtained. The flow rate dropped drastically after 461.01▒40.73 seconds of flow over the membrane for 25ng/Ál and 1181.57▒84.5 seconds for a 10ng/Ál concentration using a flow rate sensor. For 10ng/ul and 25ng/Ál DNA samples, the amount of DNA collected over the membrane for 461.01seconds and 1881.57seconds were 1312.857▒93.99ng and 1280.6▒113.13ng respectively. From this data it was evident that approximately 1300ng of DNA was required to make monolayer of DNA on nanoporous membrane. This experiment was repeated for various known concentrations of gDNA. An empirical graph was constructed with time on the x-axis and known concentrations on y-axis. With the empirical graph, gDNA sample concentration was possible to estimate from the time (value of first time derivative was maximum). By integrating with a microfluidic DNA sample preparation system, we can extract and quantify the DNA sample simultaneously.