Control of Triplet Blinking Using Cyclooctatetraene to Access the Dynamics of Biomolecules at the Single‐Molecule Level
Jie Xu, Shuya Fan, Lei Xu, Atsushi Maruyama, Mamoru Fujitsuka, Kiyohiko Kawai
Abstract
Abstract To explore the dynamics of biomolecules, tracing the kinetics of photo‐induced chemical reactions via the triplet excited state (T 1 ) of probe molecules offers a timescale that is about 10 6 times wider than via the singlet excited state (S 1 ). Using cyclooctatetraene (COT) as a triplet energy acceptor and at the same time as a photostabilizer, the triplet–triplet energy transfer (TTET) kinetics governed by oligonucleotide (oligo) dynamics were studied at the single‐molecule level by measuring fluorescence blinking. TTET kinetics measurement allowed us to access the length‐ and sequence‐dependent dynamics of oligos and realize the single‐molecule detection of a model microRNA biomarker. In sharp contrast to the singlet–singlet Förster resonance energy transfer (FRET) that occurs in the 1–10 nm range, TTET requires a Van der Waals contact. The present method is thus a complementary method to FRET and provides direct information on biomolecular dynamics on the μs to ms timescale.