Probing the catalytic activity and heterogeneity of Au-nanoparticles at the single-molecule level.

Nanoparticles can catalyze many important chemical transformations in organic synthesis, pollutant removal, and energy production. Characterizing their catalytic properties is essential for understanding the fundamental principles governing their activities, but is challenging in ensemble measurements due to their intrinsic heterogeneity from their structural dispersions, heterogeneous surface sites, and surface restructuring dynamics. To remove ensemble averaging, we recently developed a single-particle approach to study the redox catalysis of individual Au-nanoparticles in solution.

Single-molecule nanocatalysis reveals heterogeneous reaction pathways and catalytic dynamics.

Nanoparticles are important catalysts for many chemical transformations. However, owing to their structural dispersions, heterogeneous distribution of surface sites and surface restructuring dynamics, nanoparticles are intrinsically heterogeneous and challenging to characterize in ensemble measurements. Using a single-nanoparticle single-turnover approach, we study the redox catalysis of individual colloidal Au nanoparticles in solution, using single-molecule detection of fluorogenic reactions.

Engineered holliday junctions as single-molecule reporters for protein-DNA interactions with application to a MerR-family regulator.

Protein-DNA interactions are essential for gene maintenance, replication, and expression. Characterizing how proteins interact with and change the structure of DNA is crucial in elucidating the mechanisms of protein function. Here, we present a novel and generalizable method of using engineered DNA Holliday junctions (HJs) that contain specific protein-recognition sequences to report protein-DNA interactions in single-molecule FRET measurements, utilizing the intrinsic structural dynamics of HJs.