Nicole Voce: Bridging length scales in biophysics: from molecular ensembles to few-spin systems

Abstract:
Biomolecular functions, such as ion transport and redox reactions, emerge from dynamics spanning orders of magnitude in length. Constructing a bottom-up picture of how single- molecule dynamics govern collective behaviors remains challenging; dynamics at the few-nanometer scale are difficult to measure, thus motivating the development of new experimental techniques. To sense molecular dynamics at the nanoscale, spin-based measurement methods have emerged as an attractive complement to conventional optical, mechanical, and electrochemical techniques due to the diverse spin sources native to biological systems. Quantum sensors offer a  route towards these measurements, providing access to molecular dynamics and intrinsic magnetic signatures of biomolecules. However, there remain many challenges to overcome before the potential of quantum sensing in biophysics can be fully realized, ranging from redesigning sensing approaches to target stochastic, non-sinusoidal signals in biology to developing new strategies to integrate sensing targets with sensing platforms. Here, I will discuss how quantum sensing techniques—using platforms like the nitrogen-vacancy center in diamond—enable us to probe hidden dynamics and intrinsic magnetic signatures in biophysical systems. First, I will demonstrate that what we detect depends on the length scale we probe; in a model biomembrane system, we observe that apparent diffusive behavior above the diffraction limit differs from that at the limit itself. Whether this difference persists down to the few-nanometer scale is unknown, leaving the bottom-up picture incomplete. This gap motivates the development of quantum sensing techniques suited to biological signals. Next, I will describe a new experimental method we have developed that enables quantum sensors to access the spectral characteristics of stochastic signals, such as those ubiquitous in membrane channel gating and electron transfer. Finally, I will discuss our progress developing a diamond-based platform to probe chirality-dependent spin effects in biological systems. Together, these results underscore the role of quantum sensors in detecting previously inaccessible biomolecular dynamics and magnetic signatures.

Biography:

Nicole Voce is a Ph.D. candidate in physics at Northeastern University, where she works with Prof. Paul Stevenson on quantum sensing and fluorescence microscopy techniques for probing biomolecular dynamics and magnetic signatures across length scales. Her work has been featured on the cover of the Journal of Physical Chemistry B and recognized with student awards from the Biophysical Society and Northeastern University. She received a dual B.S. in physics and mathematics from James Madison University in 2020, where she studied the mechanics of thin elastic shells with Profs. Marcelo Dias and Klebert Feitosa.