Sub-Diffraction Limited Imaging of Sliding Microtubules Based on Nanoscale Localization Sampling using Nanoantenna Arrays

Abstract

We investigate sub-diffraction limited imaging of fluorescent subunits on sliding microtubules by nanoscale localization sampling (NLS). NLS is based on periodic circular nanoantenna arrays with diameter=300nm and period=1um that create locally amplified electromagnetic hot-spots through localization of surface plasmon. The localized near-field hot-spot samples microtubular movement in the time domain for improved spatial resolution. We have demonstrated enhancement of spatial resolution by four-times compared to conventional wide-field microscopy (figure below). The resolution enhancement was analyzed by imaging rhodamine-labeled microtubules that were sampled by hot-spots to provide sub-diffraction limited images at 76nm resolution in the direction of movement and 135nm orthogonally. Degradation of signal-to-noise ratio due to side lobe modes was measured to be 6-dB. Intensity distribution generated by the NLS was measured to be broader than that of conventional imaging, which is consistent with the enhancement of imaging resolution. We have also studied correlation analysis between neighboring nanoantennas. This proves the possibility of measuring microtubular transport dynamics. NLS can be useful for moving objects that have a high labeling density or for performing fluctuation spectroscopy in small volumes and may allow ‘super-resolution on demand’ by customizing nanostructures.View Large Image | View Hi-Res Image | Download PowerPoint Slide