(698e) Switch-like DNA Amplification for Biomarker Detection

Detection of low concentration biomolecules is time and labor intensive, particularly when found in complex matrices such as bodily fluids. A switch-like chemistry for signal amplification is advantageous for simple, robust biomolecule detection. An “ON” or “OFF” signal is not affected by drifting signal or changes in reaction kinetics. We have developed a switch-like DNA amplification system that responds to short DNA oligonucleotide reporter molecules. It is well known in literature that small DNA oligonucleotide “reporters” can be transduced from proteins, miRNA, and genomic DNA. Our switch-based chemistry can amplify the oligonucleotide reporter in a biphasic fashion; during the initial phase the reporter molecule is produced at a low rate, and eventually the production of the reporter significantly slows. When the reporter molecule reaches a threshold concentration, the chemistry produces a high-gain burst of reporter DNA molecules. If the initial reaction rate or reporter concentration is high enough, the amplification moves directly into the high-gain phase. The DNA amplification chemistry thus provides a built-in switch function, with low-output DNA amplification serving as an “OFF” phase, and high-output DNA amplification serving as an “ON” phase. The high-gain amplification phase shows ultrasensitive, Hill-type kinetics; researchers have noted the utility of Hill-type amplification kinetics in biosensors, genetic logic gates, and other materials that are required to be highly responsive. The kinetics of each phase and the reporter DNA threshold concentration can be controlled by thermodynamics of DNA complexes or the reaction solution conditions. Ultimately, we will use this chemistry for simple, robust detection of biologically relevant molecules.