Aptamers

About

Background  The polymerase chain reaction (PCR) has been the gold standard for the detection and identification of nucleic acids. Specifically, PCR’s sensitivity makes it easy to detect trace amounts of the target molecule. However, within the larger field of molecular detection and diagnostics, PCR is fundamentally limited because it is designed for the detection of nucleic acids, and does not have the capability to identify other analytes. Sensitive and high throughput platforms are needed that detect not only nucleic acids, but other analytes as well. Research suggests that the global market for diagnostic biomarkers may exceed $30 billion by 2020. Aptamers are short nucleic acid molecules capable of binding species such as small organic molecules, nucleic acids, proteins, antibodies and even cells. The advantageous properties of aptamers as a molecular recognition element make them excellent candidates for biosensors if aptamer-ligand binding can be suitably detected and quantified. Technology Robust Analyte Detection P/f A University of Colorado research group led by Daniel Schwartz has designed a system for monitoring both aptamer-ligand binding and nucleic acid hybridization that employs a liquid crystal (LC) reporting signal. In Dr. Schwartz’s research, oligonucleotides were anchored within a bilayer of dispersed liposomes and at a PEG-lipid laden LC interface. If the oligonucleotides are not complementary, no hybridization occurs, preventing liposome fusion. But, when the oligonucleotides in the liposomes and lipid bilayer are complementary, DNA hybridization occurs, resulting in lipid mixing at the LC interface, initiating a re-orientation of the LC surface that is visible to the naked eye.