Title: Chemical Systems at the Limits of Biological Complexity
Abstract: Chemical systems encode biological information at the level of individual molecules, whether organized into minimal assemblies that define the threshold for replication and function, or dispersed as rare molecular signals within complex physiological environments. My work examines how chemical design and quantitative measurement can be used to identify and interpret minimal information-bearing units across distinct biological contexts.
I will first describe bottom-up studies of minimal artificial systems that investigate how nonenzymatic RNA replication and RNA-catalyzed assembly can be supported in protocell-like compartments under prebiotically plausible conditions, providing insight into the chemical requirements for the emergence of biological function. I will then turn to single-molecule detection strategies that recover biologically meaningful information from highly diluted and heterogeneous molecular populations in biofluids, enabling sensitive reconstruction of disease-relevant states from liquid biopsies.
Together, these approaches highlight how chemistry defines the minimal informational units underlying both the early biological systems and the molecular signatures of disease, and how accessing these limits enables new strategies for biological discovery and advancing precision diagnostics.
Bio: Stephanie Zhang is a postdoctoral research fellow in Dr. David Walt’s laboratory at Brigham and Women’s Hospital and the Wyss Institute for Biologically Inspired Engineering at Harvard University, where she develops ultrasensitive single-molecule detection platforms with applications in early disease diagnostics. She received her Ph.D. in Chemistry from Harvard University under the mentorship of Dr. Jack W. Szostak, during which she built minimal artificial systems to explore how RNA replication, catalysis, and membrane dynamics could be coupled within protocell models. She obtained her B.S. in Chemical Biology from the University of California, Berkeley, where she worked with Dr. Peidong Yang on inorganic-biological hybrid photocatalytic systems for solar energy conversion. During her training, Stephanie received multiple honors, including the Regents’ and Chancellor’s Scholarship, an NSF award, and an NIH Ruth L. Kirschstein F32 Postdoctoral Fellowship.
Hosts: Jeff Martell & Helen Blackwell