NU 2019-117B
INVENTORS Chad Mirkin* Sasha Ebrahimi Devleena Samanta Ho Fung Cheng
SHORT DESCRIPTION A new class of signaling aptamers which contain a single modification, yet can be used to detect a broad range of targets
ABSTRACT Aptamers are oligonucleotide sequences that can be evolved to bind to various analytes of interest. Northwestern researchers have developed a general design strategy that transduces an aptamer-target binding event into a fluorescence readout via the use of a viscosity-sensitive dye. Target binding to the aptamer leads to forced intercalation (FIT) of the dye between oligonucleotide base pairs, increasing its fluorescence by up to 20-fold. The application of this technology is particularly useful in challenging scenarios where studying analytes in living cells and complex media with high sensitivity and specificity remains difficult. Fluorescence-based methods offer advantages like simplicity, low-cost, high-throughput, and ability to multiplex. They demonstrate that FIT-aptamers can report target presence through intramolecular conformational changes, sandwich assays, as well as target-templated reassociation of split-aptamers, showing that the most common aptamer-target binding modes can be coupled to a FIT-based readout. Further, this strategy also can be used to detect the formation of a metallo-base pair within a duplexed strand and is therefore attractive for screening for metal-mediated base pairing events. The strategy can also be used to deliver different molecules, via functionalization of nanoparticles, for diagnostic and theranostic purposes in vitro. Taken together, FIT-aptamers are a new class of signaling aptamers which contain a single modification, yet detect a broad range of targets.
APPLICATIONS Report target presence through intramolecular conformational changes, sandwich assays, and target-templated reassociation of split-aptamers in cells and complex media Detects and images analytes Quantifies analyte levels Regulates and detects analytes for thernostic purposes Screening for metal-mediated base pairing events by detection of the formation of a metallo-base pair within a duplexed strand
ADVANTAGES Reduces false-positive signals typically associated with fluorophore-quencher based systems (No requirement of quencher) Quantitatively outperforms FRET-based probes by providing up to 15-fold higher signal to background ratios and superior readout kinetics Allows rapid and highly sensitive target detection (nanomolar range) in complex media such as human serum with low signal to noise ratios Enables delivery of detection elements in live cells without transfection agents Requires only a single modification in its target of interest to fluoresce
PUBLICATIONS Ebrahimi S. B., Smanta D, Cheng H. F., Nathan L, and Mirkin C. A. (2019) Forced Intercalation (FIT) Aptamers. Journal of American Chemical Society. 141: 13744-48.
Smanta D, Ebrahimi S. B., Kusmierz C. D., Cheng H. F., and Mirkin C. A. (2020) Protein Spherical Nucleic Acids. Journal of American Chemical Society. 142, 31,: 13350-13355
IP STATUS U.S. and Europe nationalization has been filed.