Self-contained and modular structured illumination microscope

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

When combined with computational approaches, fluorescence imaging becomes one of the most powerful tools in biomedical research. It is possible to achieve resolution figures beyond the diffraction limit, and improve the performance and flexibility of high-resolution imaging systems with techniques such as structured illumination microscopy (SIM) reconstruction. In this study, the hardware and software implementation of an LED-based super-resolution imaging system using SIM employing GPU accelerated parallel image reconstruction is presented. The sample is illuminated with two-dimensional sinusoidal patterns with various orientations and lateral phase shifts generated using a digital micromirror device (DMD). SIM reconstruction is carried out in frequency space using parallel CUDA kernel functions. Furthermore, a general purpose toolbox for the parallel image reconstruction algorithm and an infrastructure that allows all users to perform parallel operations on images without developing any CUDA kernel code is presented. The developed image reconstruction algorithm was run separately on a CPU and a GPU. Two different SIM reconstruction algorithms have been developed for the CPU as mono-thread CPU algorithm and multi-thread OpenMP CPU algorithm. SIM reconstruction of 1024 × 1024 px images was achieved in 1.49 s using GPU computation, indicating an enhancement by ∼28 and ∼20 in computation time when compared with mono-thread CPU computation and multi-thread OpenMP CPU computation, respectively.

Integrated optical device for Structured Illumination Microscopy

Structured Illumination Microscopy (SIM) is a key technology for high resolution and super-resolution imaging of biological cells and molecules. The spread of portable and easy-to-align SIM systems requires the development of novel methods to generate a light pattern and to shift it across the field of view of the microscope. Here we show a miniaturized chip that incorporates optical waveguides, splitters, and phase shifters, to generate a 2D structured illumination pattern suitable for SIM microscopy. The chip creates three point-sources, coherent and controlled in phase, without the need for further alignment. Placed in the pupil of a microscope's objective, the three sources generate a hexagonal illumination pattern on the sample, which is spatially translated thanks to thermal phase shifters. We validate and use the chip, upgrading a commercial inverted fluorescence microscope to a SIM setup and we image biological sample slides, extending the resolution of the microscope.

Technological advances in super-resolution microscopy to study cellular processes

Since its initial demonstration in 2000, far-field super-resolution light microscopy has undergone tremendous technological developments. In parallel, these developments have opened a new window into visualizing the inner life of cells at unprecedented levels of detail. Here, we review the technical details behind the most common implementations of super-resolution microscopy and highlight some of the recent, promising advances in this field.

Assessing the Resolution of Methyltransferase-Mediated DNA Optical Mapping

Interest in the human microbiome is growing and has been, for the past decade, leading to new insights into disease etiology and general human biology. Stimulated by these advances and in a parallel trend, new DNA sequencing platforms have been developed, radically expanding the possibilities in microbiome research. While DNA sequencing plays a pivotal role in this field, there are some technological hurdles that are yet to be overcome. Targeting of the 16S rRNA gene with amplicon sequencing, for instance, is frequently used for sample composition profiling due to its short sample-to-result time and low cost, which counterbalance its low resolution (genus to species level). On the other hand, more comprehensive methods, namely, whole-genome sequencing (WGS) and shallow shotgun sequencing, are capable of yielding single-gene- and functional-level resolution at a higher cost and much higher sample processing time. It goes without saying that the existing gap between these two types of approaches still calls for the development of a fast, robust, and low-cost analytical platform. In search of the latter, we investigated the taxonomic resolution of methyltransferase-mediated DNA optical mapping and found that strain-level identification can be achieved with both global and whole-genome analyses as well as using a unique identifier (UI) database. In addition, we demonstrated that UI selection in DNA optical mapping, unlike variable region selection in 16S amplicon sequencing, is not limited to any genomic location, explaining the increase in resolution. This latter aspect was highlighted by SCCmec typing in methicillin-resistant Staphylococcus aureus (MRSA) using a simulated data set. In conclusion, we propose DNA optical mapping as a method that has the potential to be highly complementary to current sequencing platforms.