BME PhD Preliminary Exam Announcement for Han Dang Nhat Nguyen (C. Lin and J. Liu, co-advisors) Everyone is invited to attend the public presentation beginning at 3:00 PM EST. Title: Dynamic Tuning of Hydrogel Stiffness and Viscoelasticity to Probe Cell Behaviors Date: August 1st, 2022 Time: 3:00 PM EST Location: IUPUI SL 220 A and Zoom Zoom Link*: https://purdue-edu.zoom.us/j/7085972423 Committee: Chien-Chi Lin, Major Professor; Julie C. Liu, Co-Chair; Hiroki Yokota; Sungsoo Na Abstract: Hydrogels have proven to be highly useful for 3D cell culture applications as their chemical and mechanical properties can be easily tuned to mimic the dynamic nature of the extracellular matrix within the native tissues. However, most current biomimetic hydrogel models are elastic and lack tissue-relevant viscoelastic properties such as hysteresis and stress-relaxation. Stress-relaxation refers to a material's ability to reduce the stress response over time under a constant force and has been reported to affect many cellular processes including differentiation, proliferation, and cancer progression. In this regard, we have developed viscoelastic hydrogels with tunable stiffness and stress-relaxation rate to investigate how different cell types respond to changes in matrix physical properties. Specifically, two chemistries, thiol-norbornene photopolymerization and boronic ester dynamic bond were employed to fabricate gelatin-based hydrogels. Gels formed solely via irreversible thiol-norbornene chemistry are elastic (EL) and non-stress-relaxing while gels formed with both thiol-norbornene and the reversible boronic ester bonds are viscoelastic (VE) and stress-relaxing. We found that osteocytes encapsulated within EL gels and VE gels displayed significant differences in cell morphology as well as cytokine secretion. Next, we demonstrated that our hydrogels can be dynamically stiffened via an enzymatic reaction to match the mechanics (e.g stiffness and stress relaxation rate) of pancreatic cancer progression and explored the cells' transcriptional changes associated with sensing stiffness and viscoelasticity. Finally, future work will be focused on the differentiation of induced pluripotent stem cells (iPSCs) into pancreatic progenitor cells in EL and VE gels. We anticipate that our versatile hydrogel systems will provide promising means to explore cellular mechanoresponsive mechanisms and pathways. *Han Dang Nhat Nguyen is inviting you to a scheduled Zoom meeting. Topic: Han Nguyen Prelim Exam Time: Aug 1, 2022 03:00 PM Eastern Time (US and Canada) Join Zoom Meeting https://purdue-edu.zoom.us/j/7085972423 Meeting ID: 708 597 2423 One tap mobile +13126266799,,7085972423# US (Chicago) +16465588656,,7085972423# US (New York) Dial by your location +1 312 626 6799 US (Chicago) +1 646 558 8656 US (New York) +1 646 931 3860 US +1 301 715 8592 US (Washington DC) +1 346 248 7799 US (Houston) +1 669 444 9171 US +1 669 900 6833 US (San Jose) +1 253 215 8782 US (Tacoma) Meeting ID: 708 597 2423 Find your local number: https://purdue-edu.zoom.us/u/aJfUKCJg8