Minimal DNA Electron Transfer Catalysts Switched by a Chaotropic Ion

Abstract

† These authors contributed equally to this work. AbstractWe are nearing the end of a remarkable period that began in the 1960s in which semiconductor manufacturers succeeded in shrinking die and feature sizes logarithmically, thus growing transistor counts exponentially with time. As we reach the theoretical physical limits of classical MOSFET semiconductors, DNA is a highly attractive candidate for future miniaturization of microprocessors. Here we show a foundational electronic device -a transistor -can be constructed from DNA. The nanodevice is comprised of two strands, one of which can be selectively switched between a G-quadruplex and duplex or single-stranded conformations. This switching ability arises from our discovery that perchlorate, a chaotropic Hofmeister ion, selectively destabilizes duplex over G-quadruplex DNA. By varying perchlorate concentration, we show that the device can be operated as a switch or signal amplifier. State switching can be achieved in three ways: thermally, by dilution, or by concentration. In each case, when operated in the presence of the cofactor hemin, the device catalyzes electron transfer in only the Gquadruplex state.

Highly specific, multiplexed isothermal pathogen detection with fluorescent aptamer readout

“…A short Python script was written to control the image acquisition of fluorescent reactions and fluorescent intensity was determined based on pixel value. 25 The fluorescent curves obtained from Apta-NASBA on more expensive plate reader and qPCR-based fluorescent detection platforms are functionally identical to those observed on the Raspberry Pi-based detection platform (Figure 4A-4C). We show, with the addition of trehalose, Apta-NASBA reactions are viable post lyophilization, allowing for transportation to remote locations without a cold chain (Figure 4C and Supplementary Figure S19 and Supplementary Video S1).…”

Human Ribosomal G-Quadruplexes Regulate Heme Bioavailability

“…in that we too conclude that G4s bind hemin in vivo. Moreover, our observation of rRNA-heme interactions in vivo supports a physiological role of rRNA G4heme complexes in redox chemistry (37,38). Indeed, work by Sen concurrent with ours has established G4-heme interactions in vivo by exploiting the peroxidase activity of G4hemin complexes to self-biotinylate G4s in RNA and DNA using a phenolic-biotin derivative.…”