MembersJason Casar

My goal is to develop in vivo stress sensors that enable researchers to interpret the mechanical “conversations” that cells use to communicate with each other, and which ultimately have massive implications for organism health. This platform relies on the colorimetric sensitivity of lanthanide doped upconverting nanoparticles embedded in a biocompatible polymer matrix. Combining atomic force and confocal microscopies, I calibrate the optical response of these micron sized gauges against biologically relevant isotropic compressive forces (on the order of 10 uN), and use this information to inform synthetic strategies to optimize brightness and sensitivity. Working closely with Professor Miriam Goodman, the Chair of the Molecular and Cellular Physiology Department at Stanford, I also deploy these sensors to image feeding mechanics within the model organism C. elegans and demonstrate how they are affected by chemical and genetic intervention. Ultimately, assays like these could reveal novel biomarkers of disease, or pinpoint the chemical therapeutics to treat them.

Casar, J. R., McLellan, C. A., Shi, C., Stiber, A., Lay, A., Siefe, C., Parakh, A., Gaerlan, M., Gu, X. W., Goodman, M. B., Dionne, J. A. (2025). Upconverting microgauges reveal intraluminal force dynamics in vivo. Nature, 637 (8044), 76-83.

Casar, J. R., McLellan, C. A., Siefe, C., & Dionne, J. A. (2020). Lanthanide-based nanosensors: refining nanoparticle responsiveness for single particle imaging of stimuli. ACS photonics, 8(1), 3-17.

McLellan, C. A., Siefe, C., Casar, J. R., Peng, C. S., Fischer, S., Lay, A., … & Dionne, J. A. (2022). Engineering Bright and Mechanosensitive Alkaline-Earth Rare-Earth Upconverting Nanoparticles. The Journal of Physical Chemistry Letters, 13(6), 1547-1553.