Untethering single molecule spectroscopy with 3D-SMART

Measuring the behavior of single molecules enables the discovery of states and dynamics obscured by bulk measurements. However, molecules in solution rapidly diffuse in three dimensions, precluding long-duration and high-temporal resolution measurement. In a new breakthrough, Shangguo (aka the TrackFather) has developed 3D single-molecule active real-time tracking (3D-SMART), which can “lock-on” to freely diffusing single molecules in solution for up to minutes at a time! This new single molecule tracking can be applied to continuously monitor single proteins and nucleic acids, including real-time measurement of transcription on a freely diffusing, single-dye labelled DNA strand. See the entire work in the recent paper in Nature Communications!

Not Your Typical Bulk Water – Probing Intracellular Solvation

The structure and dynamics of intracellular water constitute the cornerstone for understanding all aspects of cellular function. However, direct visualization of subcellular solvation heterogeneity has remained elusive. To explore this question, graduate student Xiaoqi Lang has demonstrated a vibrational-shift imaging approach to probe solvation at the microscopic level by combining spectral-focusing hyperspectral stimulated Raman scattering (hsSRS) with an environmentally-sensitive nitrile probe. When applied to quantitatively measure the spatial variation of solvation in live cells, this new method reveals significantly reduced solvation in the cytoplasm compared to the nuclear compartment and bulk water! This work sheds light on heterogenous solvation at the subcellular level and opens up new avenues to explore solvation variance in complex systems. For more, check out the recent publication in the Journal of Chemical Physics.

Cholesterol analogues increases delivery efficiency of lipid nanoparticles

Our collaborators in the Sahay lab (sahaylab.org) have recently reported that naturally occurring cholesterol analogues can increase the delivery efficiency of lipid nanoparticles (LNPs)! Way to go Gaurav and team! Josie and Shangguo applied 3D-DyPLoT to differentiate the intracellular trafficking behavior of different LNP constructs, showing that increased delivery efficiency correlated with increased linear directed motion of individual LNPs in live cells.

Link: www.nature.com/articles/s41467-020-14527-2

Optimized sparse sampling speeds up laser scanning microscopy!

Courtney has developed a new strategy for improving the speed of laser scanning microscopy. The technique, called 3D Fast Acquisition Scan by z-Translating Raster (3D-FASTR), uses an electrically tunable lens (ETL) to generate a reproducible 3D sparse sampling pattern which fully and efficiently scans a volume in the fastest possible time without repeating until the volume is complete. This method has shown a 4-fold improvement in the volumetric imaging rate of live cells. The theory underlying 3D-FASTR is completely general and can be applied to any scanning imaging method. Find details in the recent publication in Optics Express!

Link: doi.org/10.1364/OE.27.036241

Science Under the Stars!

Stacey spearheaded several outreach activities to introduce the concepts of light, fluorescence, and phosphorescence to the scientists of tomorrow!

Prisms and raytracing
Imaging with lenses – with an assist from Tom and Jerry!
Smartphone fluorescence viewer

ALIS Kickoff & Duke Chemistry Research Symposium

Busy week presenting for the group. Xiaoqi and Courtney presented posters at the Duke Chemistry Research Symposium (CRS). Courtney also presented her poster at the Advanced Light Imaging and Spectroscopy (ALIS) Kickoff meeting. Kevin even joined in on the fun and gave a talk at the ALIS Kickoff meeting. Learn more about the ALIS center here: https://alis.duke.edu

Xiaoqi gives a lightning talk at the CRS about her hsSRS scope – details coming soon to a journal near you!

Courtney presents her 3D-FASTR method. See the preprint here: https://arxiv.org/abs/1909.12893

Adaptive method for tracking viral first contacts

Shangguo has developed a 3D particle tracking method which adapts in real-time to changes in particle diffusion. This method is particularly well-suited for processes which exhibit highly heterogeneous dynamics, such as the binding of a single virion to a live cell from the extracellular space. See the full paper here:

Hou, S. & Welsher, K. An Adaptive Real-Time 3D Single Particle Tracking Method for Monitoring Viral First Contacts. Small (2019).