ASTID

Chiral Temperature Gradient Focusing for Ultra-Sensitive In Situ Analysis of Biomarkers (2)

PI: David Ross

This proposal is for a proof-of-concept study to develop a new technique for ultra-sensitive in situ biomarker analysis that can be easily integrated into a microfluidics-based platform such as the Mars Organic Analyzer (MOA). The goal is to provide new capabilities for biomarker detection with 1) detection limits orders of magnitude lower than that provided by other techniques, and 2) the ability to conduct both achiral and chiral analyses with the same injected sample and with the same ultra-low detection limits. These performance gains will be achieved by using a new technique for the
concentration and separation of analytical samples – Temperature Gradient Focusing (TGF) – that has been recently developed at NIST. With TGF, the combination of a temperature gradient and an applied electric field is used to concentrate and separate molecules in a microfluidic channel. As with Capillary Electrophoresis (CE), different molecules are separated in TGF by differences in their electrophoretic mobility. However, in contrast to CE in which different molecules are separated as they migrate with different velocities, in TGF, different molecules are separated as they are focused, or localized at different positions. In a TGF separation, analyte peaks get narrower and more concentrated as the separation proceeds rather than wider and more diffuse as with CE. Consequently, TGF can provide a unique combination of high resolution and low detection limits. The TGF technique will be examined as both a stand-alone technique and as a pre-fractionation and pre-concentration step before CE for a 2-D separation technique that combines the strengths of TGF with those of CE. The capabilities of the TGF technique will be optimized and demonstrated for the chiral analysis of extremely dilute amino acid samples. Successful completion of this project will result in a technique with which future microfluidic platforms such as the MOA will be able to determine amino acid enantiomeric ratios at concentrations where state-of-the-art instrumentation would fail to detect even the presence of amino acids; thus enabling a greater chance for the successful detection of signs of past or present life on Mars, Europa, and other future mission targets.