CHEMICAL & BIOMEDICAL ENGINEERING GRAD STUDENT SEMINAR 

Adrianne Rosales, Ph.D.
ASSOCIATE PROFESSOR
Chemical Engineering, University of Texas at Austin

Transient polymer networks are found throughout biological systems, both intracellularly and extracellularly. Hydrogels with dynamic linkers have garnered intense interest as extracellular matrix (ECM) mimics and injectable delivery vehicles due to their tailorable viscoelasticity, stress relaxation, and self-healing behavior. However, to fully enable these applications, there remains a need to understand how linking chemistry affects gelation and nonlinear rheological properties. In this context, we have developed synthetic multi-arm poly(ethylene glycol) (PEG) hydrogels with either 1) dynamic covalent or 2) hierarchically structured crosslinkers. First, dynamic covalent linkages allow control over the bond exchange kinetics, which dictates hydrogel viscoelasticity under small amplitude oscillatory shear. At dilute concentrations, where the hydrogels are injectable, the networks exhibit shear thickening behavior that suggests chain stretching and a defect-rich network structure. Second, we designed hierarchically structured crosslinkers for hydrogels using peptoids, or N-substituted glycines. Helical peptoids increased the shear moduli of hydrogels due to increased chain stiffness as compared to non-helical peptoids, while keeping hydrogel network connectivity and swelling ratio fixed. We encapsulated human mesenchymal stromal cells (hMSCs) into the developed hydrogels and found that softer networks promoted hMSC secretory activity. Overall, this work suggests new strategies to control engineered ECM mechanics with constituent polymer structure.

Bio:

Adrianne Rosales is an Associate Professor of Chemical Engineering at the University of Texas at Austin. She received her B.S. in Chemical Engineering from UT Austin and obtained her Ph.D. in Chemical Engineering from UC-Berkeley. After completing her Ph.D. in 2013, she trained at the University of Colorado Boulder as an NIH NRSA post-doctoral fellow. Adrianne's group at UT Austin focuses on the development of bioinspired polymeric materials to model cellular microenvironments and engineer therapeutic technologies. She is also a co-lead of the Interdisciplinary Research Group “Fuel-Driven Pluripotent Materials” in UT Austin’s Materials Research Science and Engineering Center.