Upgrade of a Scanning Confocal Microscope to a Single-Beam Path STED Microscope

PLoS One. 2015 Jun 19;10(6):e0130717. doi: 10.1371/journal.pone.0130717. eCollection 2015.

Abstract

By overcoming the diffraction limit in light microscopy, super-resolution techniques, such as stimulated emission depletion (STED) microscopy, are experiencing an increasing impact on life sciences. High costs and technically demanding setups, however, may still hinder a wider distribution of this innovation in biomedical research laboratories. As far-field microscopy is the most widely employed microscopy modality in the life sciences, upgrading already existing systems seems to be an attractive option for achieving diffraction-unlimited fluorescence microscopy in a cost-effective manner. Here, we demonstrate the successful upgrade of a commercial time-resolved confocal fluorescence microscope to an easy-to-align STED microscope in the single-beam path layout, previously proposed as "easy-STED", achieving lateral resolution < λ/10 corresponding to a five-fold improvement over a confocal modality. For this purpose, both the excitation and depletion laser beams pass through a commercially available segmented phase plate that creates the STED-doughnut light distribution in the focal plane, while leaving the excitation beam unaltered when implemented into the joint beam path. Diffraction-unlimited imaging of 20 nm-sized fluorescent beads as reference were achieved with the wavelength combination of 635 nm excitation and 766 nm depletion. To evaluate the STED performance in biological systems, we compared the popular phalloidin-coupled fluorescent dyes Atto647N and Abberior STAR635 by labeling F-actin filaments in vitro as well as through immunofluorescence recordings of microtubules in a complex epithelial tissue. Here, we applied a recently proposed deconvolution approach and showed that images obtained from time-gated pulsed STED microscopy may benefit concerning the signal-to-background ratio, from the joint deconvolution of sub-images with different spatial information which were extracted from offline time gating.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / chemistry
  • Actin Cytoskeleton / pathology
  • Algorithms
  • Animals
  • Diptera / metabolism
  • Equipment Design
  • Microscopy, Confocal / instrumentation*
  • Microtubules / chemistry
  • Microtubules / pathology
  • Muscle, Skeletal / metabolism
  • Rabbits
  • Salivary Glands / metabolism

Grants and funding

This work was funded by the German Research Foundation (grant number 1850/30001355,www.dfg.de), the Federal Ministry of Education and Research ("ALSComBi", grant number 03IPT517Y, www.bmbf.de), and the European Commission ("CHARMING", call FP7-ICT-2011-7, grant number 288786, ec.europa.eu). The funders had no role in design, data collection and analysis, decision to publish, or preparation of the manuscript. PicoQuant GmbH provided support in the form of salaries for authors MK, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.