Kavli Affiliate: Paul W. K. Rothemund
| First 5 Authors: Byoung-jin Jeon, Matteo M. Guareschi, Jaimie M. Stewart, Emily Wu, Ashwin Gopinath
| Summary:
The diversity and heterogeneity of biomarkers has made the development of
general methods for single-step quantification of analytes difficult. For
individual biomarkers, electrochemical methods that detect a conformational
change in an affinity binder upon analyte binding have shown promise. However,
because the conformational change must operate within a nanometer-scale working
distance, an entirely new sensor, with a unique conformational change, must be
developed for each analyte. Here, we demonstrate a modular electrochemical
biosensor, built from DNA origami, which is easily adapted to diverse molecules
by merely replacing its analyte binding domains. Instead of relying on a unique
nanometer-scale movement of a single redox reporter, all sensor variants rely
on the same 100-nanometer scale conformational change, which brings dozens of
reporters close enough to a gold electrode surface that a signal can be
measured via square wave voltammetry, a standard electrochemical technique. To
validate our sensor’s mechanism, we used single-stranded DNA as an analyte, and
optimized the number of redox reporters and various linker lengths. Adaptation
of the sensor to streptavidin and PDGF-BB analytes was achieved by simply
adding biotin or anti-PDGF aptamers to appropriate DNA linkers.
Geometrically-optimized streptavidin sensors exhibited signal gain and limit of
detection markedly better than comparable reagentless electrochemical sensors.
After use, the same sensors could be regenerated under mild conditions:
performance was largely maintained over four cycles of DNA strand displacement
and rehybridization. By leveraging the modularity of DNA nanostructures, our
work provides a straightforward route to the single-step quantification of
arbitrary nucleic acids and proteins.
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