Aptamer-based microfluidic biosensors

Micro- and nanofabrication has allowed the creation of ultra-sensitive, miniaturized, and inexpensive biosensors. These devices generally utilize chemical or biological receptors which recognize a particular compound of interest and transduce this recognition event into a measurable signal. Recent advances in RNA and DNA synthesis have enabled the use of aptamers, which are in-vitro generated oligonucleotides offering high affinity biomolecular recognition to a theoretically limitless variety of analytes. DNA and RNA aptamers have become increasingly popular in the biosensor community, to the extent that they have begun competing with more established affinity ligands including enzymes, lectins, and most immunoreceptors such as antibodies. We present an overview of our recent research effort in developing an aptamer-functionalized microfluidic platform that by design exploits the specificity and temperature-dependent reversibility of aptamers to enable enhanced biosensing. Using the specificity of aptamers, we demonstrate highly selective capture and enrichment of biomolecules. Employing thermally induced, reversible disruption of aptamer-target binding, we accomplish isocratic elution of the captured analytes and regeneration of the aptamer aptamer-functionalized surfaces, thereby eliminating the use of potentially harsh reagents. Using integrated microfluidic control, the eluted analytes are detected in a label-free fashion by mass spectrometric methods.