ABSTRACT

Localization-based fluorescence microscopy techniques (e.g., PALM and STORM) can circumvent the diffraction limit, providing greatly improved resolution (20-50 nm, typically). These techniques rely on attachment of antibody-linked dyes to specific molecules on the specimen and using a combination of laser pulses to switch individual dyes between an on state and an off state, recording their positions to build up a super-resolution image. Ultra-fluorescent photoswitching nanoparticles provide a localization resolution of better than 1 nm. However, at this resolution, the several nanometer long assembly, consisting of an antibody tethered to a nanoparticle, can introduce artifacts in the image. In order to develop methods to correct these artifacts, we need an improved understanding of the nanoscale motion of nanoparticles tethered to a surface in solution. We performed molecular dynamics simulations of two different oligopeptides (deca-alanine and deca-serine) held fixed at one end. Mean square displacement analysis was used and the results were compared to the predictions of various modified Brownian motion models. Preliminary results indicate that repeated measurements of tethered nanoparticles could be used to estimate the “true” position of the underlying target molecule, permitting partial correction of the tether artifact and improving the effective resolution of the technique.