Build and operation of a custom 3D, multicolor, single-molecule localization microscope.

Single-molecule localization microscopy (SMLM) enables imaging scientists to visualize biological structures with unprecedented resolution. Particularly powerful implementations of SMLM are capable of three-dimensional, multicolor and high-throughput imaging and can yield key biological insights. However, widespread access to these technologies is limited, primarily by the cost of commercial options and complexity of de novo development of custom systems.

Image restoration of degraded time-lapse microscopy data mediated by near-infrared imaging.

Time-lapse fluorescence microscopy is key to unraveling biological development and function; however, living systems, by their nature, permit only limited interrogation and contain untapped information that can only be captured by more invasive methods. Deep-tissue live imaging presents a particular challenge owing to the spectral range of live-cell imaging probes/fluorescent proteins, which offer only modest optical penetration into scattering tissues. Herein, we employ convolutional neural networks to augment live-imaging data with deep-tissue images taken on fixed samples.

Compact, high-speed multi-directional selective plane illumination microscopy.

We present an elegant scheme for providing multi-directional illumination in selective plane illumination microscopy (SPIM). Light sheets can be delivered from one of two opposed directions at a time and pivoted about their center for efficient stripe artifact suppression using only a single galvanometric scanning mirror to perform both functions. The scheme results in a much smaller instrument footprint and allows multi-directional illumination with reduced expense compared with comparable schemes.

Oblique plane microscope for mesoscopic imaging of freely moving organisms with cellular resolution.

Several important questions in biology require non-invasive and three-dimensional imaging techniques with an appropriate spatiotemporal resolution that permits live organisms to move in an unconstrained fashion over an extended field-of-view. While selective-plane illumination microscopy (SPIM) has emerged as a powerful method to observe live biological specimens at high spatio-temporal resolution, typical implementations often necessitate constraining sample mounting or lack the required volumetric speed. Here, we report on an open-top, dual-objective oblique plane microscope (OPM) capable of observing millimeter-sized, freely moving animals at cellular resolution.

Super-Resolution Microscopy of the Synaptonemal Complex within the Caenorhabditis elegans Germline.

During meiosis, homologous chromosomes must recognize and adhere to one another to allow for their correct segregation. One of the key events that secures the interaction of homologous chromosomes is the assembly of the synaptonemal complex (SC) in meiotic prophase I. Even though there is little sequence homology between protein components within the SC among different species, the general structure of the SC has been highly conserved during evolution.

Dynamic and non-contact 3D sample rotation for microscopy.

Precise sample orientation is crucial for microscopy but is often performed with macroscopic tools and low accuracy. In vivo imaging of growing and developing samples even requires dynamic adaptation of the sample orientation to continuously achieve optimal imaging. Here, we present a method for freely positioning a sample in 3D by introducing magnetic beads and applying a magnetic field.

Adaptable, illumination patterning light sheet microscopy.

Minimally-invasive optical imaging requires that light is delivered efficiently to limit the detrimental impact of photodamage on delicate biological systems. Light sheet microscopy represents the exemplar in tissue specific optical imaging of small and mesoscopic samples alike. However, further gains towards gentler imaging require a more selective imaging strategy to limit exposure to multiple yet discrete tissues without overexposing the sample, particularly where the information content is sparse or particularly optically sensitive tissues are present.

A guide to light-sheet fluorescence microscopy for multiscale imaging.

The impact of light-sheet fluorescence microscopy (LSFM) is visible in fields as diverse as developmental and cell biology, anatomical science, biophysics and neuroscience. Although adoption among biologists has been steady, LSFM has not displaced more traditional imaging methods despite its often-superior performance. One reason for this is that the field has largely conformed to a do-it-yourself ethic, although the challenges of big image data cannot be overstated.

Diffusion and reactivity in ultraviscous aerosol and the correlation with particle viscosity.

The slow transport of water, organic species and oxidants in viscous aerosol can lead to aerosol existing in transient states that are not solely governed by thermodynamic principles but by the kinetics of gas-particle partitioning. The relationship between molecular diffusion constants and particle viscosity (for example, as reflected in the Stokes-Einstein equation) is frequently considered to provide an approximate guide to relate the kinetics of aerosol transformation with a material property of the aerosol. We report direct studies of both molecular diffusion and viscosity in the aerosol phase for the ternary system water/maleic acid/sucrose, considering the relationship between the hygroscopic response associated with the change in water partitioning, the volatilisation of maleic acid, the ozonolysis kinetics of maleic acid and the particle viscosity.

Precise, contactless measurements of the surface tension of picolitre aerosol droplets.

The surface composition and surface tension of aqueous droplets can influence key aerosol characteristics and processes including the critical supersaturation required for activation to form cloud droplets in the atmosphere. Despite its fundamental importance, surface tension measurements on droplets represent a considerable challenge owing to their small volumes. In this work, we utilize holographic optical tweezers to study the damped surface oscillations of a suspended droplet (<10 μm radius) following the controlled coalescence of a pair of droplets and report the first contactless measurements of the surface tension and viscosity of droplets containing only 1-4 pL of material.

Toward optical-tweezers-based force microscopy for airborne microparticles.

Optical tweezers have found widespread application in biological and colloidal physics for the measurement of pN forces over nanometer to micrometer length scales. Similar aerosol-phase measurements of interparticle force have not been reported in spite of the potential to better resolve particle coagulation kinetics. Various refractive index mismatches in the beam path as well as the need to explicitly account for gravity and inertial particle motion provide a number of challenges that must be overcome to make such measurements tractable.

Probing the micro-rheological properties of aerosol particles using optical tweezers.

The use of optical trapping techniques to manipulate probe particles for performing micro-rheological measurements on a surrounding fluid is well-established. Here, we review recent advances made in the use of optical trapping to probe the rheological properties of trapped particles themselves. In particular, we review observations of the continuous transition from liquid to solid-like viscosity of sub-picolitre supersaturated solution aerosol droplets using optical trapping techniques.