Single-molecule Fluorescence Tracking

Description
Studying diffusion of molecules in sol-gel films and identify spatial heterogeneity in structure and molecular diffusivities for different regions of the film. Fluorescence intensity profiles from single-molecule spots in each frame are fit to a Gaussian function to determine the location of the molecules in the sol-gel film. The resolution for locating the centers of the molecular intensity distributions is below the optical-diffraction limit, typically ~100 nm. Scatter plots and histograms of molecular steps in the film are calculated from the trajectories of the fluorescence spots. Spatial variation in local diffusion rates shows the impact of structural heterogeneity on molecular transport in these films.

Implications
Sol-gels prepared from silicon alkoxides to produce porous silica are an important class of structures that are used in chromatographic separations, fuel cells, and as supports for optical sensors. Successful application of these sol-gel materials relies on efficient transport of molecules within the porous structure. For example, the response of a sensor depends on how quickly analyte molecules can diffuse to immobilized reagent molecules that produce the sensor response. Understanding molecular motions in sol-gel materials is challenging due to the structural inhomogeneity

Research Group Contacts
Joel M. Harris, Analytical Chemistry

NEXT nano research application: