An LED-Based structured illumination microscope using a digital micromirror device and GPU accelerated image reconstruction

LED-based multicolor extended resolution transmission fluorescence microscopy

Significance

The multiplexing capabilities of fluorescence imaging are enhanced by its exceptional molecular specificity with diverse fluorescent probes, making it a powerful tool for studying complex biological structures, organization, and functions. Recent advances in super-resolution fluorescence microscopy have further revolutionized our ability to explore biology and related fields. However, current multicolor super-resolution fluorescence imaging systems often come with high costs and bulky designs.

Aim

We present a multicolor extended resolution fluorescence imaging system that uses light-emitting diode to simplify the optical path, make the design more compact, and reduce system costs.

Approach

This multicolor extended resolution fluorescence imaging system is based on structured illumination, utilizing a simple diffraction unit positioned between the light source and the sample in a wide-field microscope. Notably, this design could be easily integrated into standard widefield microscopes as a convenient add-on unit, enabling extended resolution imaging.

Results

Our system demonstrates concurrent extended resolved imaging of three-color microsphere beads and successfully showcases multicolor extended resolution fluorescence imaging of biological tissue samples, revealing intricate structural details.

Conclusions

This system provides a structurally simple, cost-effective alternative to traditional microscopes, offering flexible multicolor extended resolution fluorescence imaging and potential applications in multimodal imaging.

Correlative single-molecule and structured illumination microscopy of fast dynamics at the plasma membrane

Total internal reflection fluorescence (TIRF) microscopy offers powerful means to uncover the functional organization of proteins in the plasma membrane with very high spatial and temporal resolution. Traditional TIRF illumination, however, shows a Gaussian intensity profile, which is typically deteriorated by overlaying interference fringes hampering precise quantification of intensities-an important requisite for quantitative analyses in single-molecule localization microscopy (SMLM). Here, we combine flat-field illumination by using a standard πShaper with multi-angular TIR illumination by incorporating a spatial light modulator compatible with fast super-resolution structured illumination microscopy (SIM). This distinct combination enables quantitative multi-color SMLM with a highly homogenous illumination. By using a dual camera setup with optimized image splitting optics, we achieve a versatile combination of SMLM and SIM with up to three channels. We deploy this setup for establishing robust detection of receptor stoichiometries based on single-molecule intensity analysis and single-molecule Förster resonance energy transfer (smFRET). Homogeneous illumination furthermore enables long-term tracking and localization microscopy (TALM) of cell surface receptors identifying spatial heterogeneity of mobility and accessibility in the plasma membrane. By combination of TALM and SIM, spatially and molecularly heterogenous diffusion properties can be correlated with nanoscale cytoskeletal organization and dynamics.

Open-source microscope add-on for structured illumination microscopy

Super-resolution techniques expand the abilities of researchers who have the knowledge and resources to either build or purchase a system. This excludes the part of the research community without these capabilities. Here we introduce the openSIM add-on to upgrade existing optical microscopes to Structured Illumination super-resolution Microscopes (SIM). The openSIM is an open-hardware system, designed and documented to be easily duplicated by other laboratories, making super-resolution modality accessible to facilitate innovative research. The add-on approach gives a performance improvement for pre-existing lab equipment without the need to build a completely new system.