Tunable Dual-Effector Allostery System for Nucleic Acid Analysis with Enhanced Sensitivity and an Extended Dynamic Range.

In the last few years, studies have demonstrated the existence of dual-effector allosteric cooperativity in nature and the mechanism underlying enhanced activation/inhibition performance. In this work, we design an artificial dual-effector allostery system for the construction of a dynamic biosensor that can achieve nucleic acid detection with superior sensitivity and across an extraordinary broad detection range. Our dual-effector allostery-regulated biosensor is based on the multibranched hybridization chain reaction (mHCR) involving three hairpins (H1, H2, and H3). In the presence of the target nucleic acid, the mHCR is initiated via cascading strand displacement events. The products of mHCR are then captured on the electrode surface based on the mechanism of the multivalent proximity ligation assay (mPLA) and the multivalent binding assay (mBA). The subsequent conjugation of streptavidin-modified horseradish peroxidase (SA-HRP) can lead to an increase in the electrochemical signal. Importantly, two distinct allosteric activation sites and two distinct allosteric inhibition sites in H1 are designed to fine-tune the nucleic acid detection sensitivity and the dynamic range. Using this new dual-effector allostery tool, we report the detection of nucleic acid at a dynamic range spanning 10-10 aM, 11 orders of magnitude showing the broadest dynamic range reported to date with an allosteric regulation biosensor construct.