Electron-transfer kinetics through nucleic acids untangled by single-molecular fluorescence blinking

Abstract

•Kinetics of distance-dependent electron transfer (ET) in single molecules •ET rate shows large heterogeneity •Blinking allows site-specific single-molecule measurement on cell blocks •Measurement of single mRNAs can identify point mutations on cell blocks Ensemble-averaged measurements have revealed the physicochemical basis of electron transfer (ET) through biomolecules, which is foundational to the development of bioelectronic devices for analysis and diagnosis. However, such measurements can obscure single-molecule kinetics that are pertinent to the underlying science and practical applications. We used DNA to study the distance dependence of the intramolecular ET kinetics by measuring fluorescence blinking. The systematic measurement of the distance dependence of the ET rate up to ∼27 Å clearly demonstrated the single-molecule measurement of ET kinetics and highlighted the large heterogeneity in the ET rate. Each nucleic acid has a specific ET rate, and thus one can obtain sequence information by measuring the ET rate through nucleic acids. We applied single-molecule ET measurement to detect isocitrate dehydrogenase (IDH) mRNA point mutations, which are correlated with treatment efficacy in adult gliomas. We identified the mRNA point mutation in pathological specimens prepared from human glioma model cultured cells. Ensemble-averaged measurements have revealed the physicochemical basis of electron transfer (ET) through biomolecules, which is foundational to the development of bioelectronic devices for analysis and diagnosis. However, such measurements can obscure single-molecule kinetics that are pertinent to the underlying science and practical applications. We used DNA to study the distance dependence of the intramolecular ET kinetics by measuring fluorescence blinking. The systematic measurement of the distance dependence of the ET rate up to ∼27 Å clearly demonstrated the single-molecule measurement of ET kinetics and highlighted the large heterogeneity in the ET rate. Each nucleic acid has a specific ET rate, and thus one can obtain sequence information by measuring the ET rate through nucleic acids. We applied single-molecule ET measurement to detect isocitrate dehydrogenase (IDH) mRNA point mutations, which are correlated with treatment efficacy in adult gliomas. We identified the mRNA point mutation in pathological specimens prepared from human glioma model cultured cells.