Know4Nano

A wide range of nanomaterials are used in fluorescence sensing due to their ability to quench fluorescence in a distance-dependent manner via nonradiative energy transfer. Most, including graphene and its derivatives, are typically applied in ensemble off/on assays for DNA hybridization or aptasensing, where target molecule recognition (a complementary DNA sequence or protein) results in an averaged, concentration-dependent fluorescence increase. Recently, distance-dependent energy transfer has shown promise for more quantitative applications in single-molecule biosensing, allowing nanoscale localization of single fluorescent molecules, with important implications in biophysics and structural biology. In this talk, I present our work in exploring these properties with 2D titanium carbide MXene. We used single-molecule fluorescence microscopy and DNA origami nanopositioners to investigate the distance-dependent quenching of a dye (ATTO 542) on spin-coated Ti3C2Tx MXene films. DNA origami structures precisely positioned dye molecules at specific heights, facilitated by a glycine-based immobilization chemistry. Our findings reveal a cubic distance dependence in fluorescence quenching within 1-10 nm, consistent with Förster near-field energy transfer. MXenes, therefore, present unique potential as short-distance spectroscopic nanorulers, enabling precise biomolecular measurements beyond the reach of conventional tools. Here, we demonstrate MXenes’ application in single-molecule biosensing, with a particular focus on examining nanoscale dynamics in model cell membranes.