Separation Techniques

Biography

Biography: Juan G. Santiago

Abstract

We use isotachophoresis (ITP) to achieve fast and specific analyses of molecular targets in complex mixtures. We use ITP to pre-concentrate and purify; molecular recognition for specificity; and ITP to control and increase the rate of chemical reactions between molecular probes and target macromolecules. ITP is an electrophoresis technique that uses two buffers which include a high mobility leading electrolyte (LE) and a low mobility trailing electrolyte (TE). Sample species with mobilities bracketed by those of the LE and TE focus into the TE-to-LE interface. For trace sample concentrations, multiple species focus in so-called peak mode wherein multiple analytes mix and strongly overlap within an order of 10 µm wide ionic concentration shock wave. This co-focusing mixes target species and pre-concentrates them to accelerate reactions. We have integrated DNA and RNA extraction with sequence-specific quantitation using a variety of mobile and immobile cDNA probes. We pre-concentrate target and probe molecules by >10,000x and achieve in 30 sec reactions which would normally take 4 days. We have shown specific and sensitive detection of target sequences in order 5 minutes with little or no off-chip sample preparation, and without target amplification.