Label-free imaging of DNA interactions with 2D materials

Abstract

Two-dimensional (2D) materials offer potential as substrates for biosensing devices, as their 15 properties can be engineered to tune interactions between the surface and biomolecules. Yet, not 16 many methods can measure these interactions in a liquid environment without introducing labeling 17 agents such as fluorophores. In this work, we harness interferometric scattering (iSCAT) microscopy, 18 a label-free imaging technique, to investigate the interactions of single molecules of long dsDNA with 19 2D materials. The millisecond temporal resolution of iSCAT allows us to capture the transient 20 interactions and to observe the dynamics of unlabeled DNA binding to a hexagonal boron nitride (hBN) 21 surface in solution for extended periods (including a fraction of 6%, of trajectories lasting longer than 22 100 ms). Using a Focused Ion Beam (FIB) technique to engineer defects, we find that DNA binding 23 affinity is enhanced at defects; when exposed to long lanes, DNA binds preferentially at lane edges. 24 Overall, we demonstrate that iSCAT imaging is a useful tool to study how biomolecules interact with 25 2D materials, a key component in engineering future biosensors.

Label-Free Techniques for Probing Biomolecular Condensates

“…The produced contrast value can be compared with a known protein mass standard to “weigh” the analyte, a technique known as mass photometry. This has been employed successfully for the detection of single proteins, nucleic acids, viruses, and other nanoscale objects. − Ray et al recently reported work that employed the same technique to study and quantify condensates formed by Alpha synuclein proteins during the nucleation and formation phase (Figure D,E) . They showed that even at dilute concentrations far from the concentrations needed for macroscopic assembly to be observed, these proteins nucleate and form nanoclusters that are kinetically trapped.…”

Diffusion of DNA on Atomically Flat 2D Material Surfaces

“…Despite these promising prospects, to date, only few experimental studies have addressed the binding and diffusion of biomolecules on vdWMs at single-molecule resolution 42 . This pursuit has been hindered by the stringent requirements of the surface, which must possess three key properties: (i) optimal binding energy allowing mobility of biomolecules while ensuring prolonged localization, (ii) chemical stability and high cleanliness in aqueous environments, and (iii) no attributes such as fluorescence quenching or autofluorescence that could compromise optical measurement techniques including single-molecule fluorescence.…”