Events

Seminar of the Division of Biomedical Physicochemistry

Engineering Photostable Probes for Ultralong-term, Single-Molecule Imaging in Live Cells

Prof. Sam Peng

Pfizer Gerald D. Laubach Assistant Professor, Department of Chemistry, MIT Core Institute Member, The Broad Institute of MIT and Harvard

Seminarium odbędzie się w trybie zdalnym przy użyciu programu Microsoft Teams. Osoby w domenie intibs.pl mogą dołączyć do zespołu Seminarium OFB przy użyciu kodu: 7aoxdkd. Pozostałe osoby proszone są o kontakt pod adresem  

The seminar will be held remotely using Microsoft Teams. People in the intibs.pl domain can join the Seminarium OFB team using the code: 7aoxdkd. Other persons are asked to contact us at 

Engineering Photostable Probes for Ultralong-term, Single-Molecule Imaging in Live Cells 

Sam Peng

Pfizer Gerald D. Laubach Assistant Professor,
Department of Chemistry, MIT
Core Institute Member, 
The Broad Institute of MIT and Harvard

Sam Peng – MIT Department of Chemistry

Single-particle tracking (SPT) is a powerful technique to unveil molecular behaviors crucial to the understanding of many biological processes, but it is limited by factors such as probe photostability and spectral orthogonality. To overcome these limitations, we develop upconverting nanoparticles (UCNPs), which are photostable over several hours at the single-particle level, enabling long-term multicolor SPT. I will present one biological application where we investigate the dynamics of cytoplasmic dynein that is essential for intracellular transport. Despite extensive in vitro characterizations, how the dynein motors work collectively to transport vesicles and how they step in live cells remains elusive because of the much faster speed of dynein under physiological conditions. Using long-term SPT with high spatiotemporal resolutions, we found that the number of active dynein motors transporting the cargo switched stochastically from one to five pairs during the long-range transport. Moreover, our results from temperature-dependent dwell time measurements suggested that two ATP molecules were hydrolyzed sequentially during each dynein step. Our observations shed new light on the chemomechanical cycle of dynein in living cells. Finally, to enable more biological applications, we engineered 10 nm UCNPs with different colors. We found that UCNPs doped with 2% Tm³⁺/30% Yb³⁺, 10% Er³⁺/90% Yb³⁺, and 15% Tm³⁺/85% Yb³⁺ represent the optimal probes for blue, green, and near-infrared emission, respectively. The multiplexed 10 nm probes enable three-color single-particle tracking on live HeLa cells for tens of minutes. These photostable and multiplexed probes open new avenues for numerous biological applications.

1. C. S. Peng, Y Zhang, Q. Liu, G.E. Marti, Y-W. A. Huang, T.C. Südhof, B. Cui, S. Chu. Nanometer-Resolution Real-Time Tracking of Single Cargos During Axonal Transport by Dynein. Nature Chemical Biology (2024).
2. J. F. Shida*, K. Ma*, H. W. Toll*, O. Salinas*, X. Ma, C. S. Peng. Multicolor ultralong-term single-particle tracking using 10 nm upconverting nanoparticles. Nano Letters 24, 14, 4194-4201 (2024).
3. Q. Liu*, Y Zhang*, C. S. Peng*, T. Yang, L-M. Joubert, and S. Chu. Single upconversion nanoparticle imaging at sub-10 W/cm² irradiance. Nature Photonics 12, 548-553 (2018).