Engineering soft matter for cell biology from a biophysical point of view

Cells– the key building blocks of life – are responsible for the majority of the processes behind biological function. Some of the greatest advances in cell biology have been under- pinned by technological innovations developed in soft matter physics. In this thesis, I have focused on applying biophysical views and tools to study bio-relevant soft matter systems, including the biomolecular condensates in cell nucleus and the bio-materials for cell culture applications. First, I describe a new role of a chromatin regulator protein, HMGA1a, that can undergo liquid-liquid phase separation in the nucleus. This has been achieved by brings together modeling and experiments to arrive at the essential role of intrinsically disordered sequence as well as the protein-DNA interactions. This sheds light on HMGAs phase separation as an emergent biophysical factor in regulating chromatin structure, and further highlight phase separation as a likely critical factor for nuclear chromatin organization. Second, I describe a microfluidic device, developed for simultaneous mechanical analysis of a large number of bio-relevant soft micron-scale objects. The applicability of this method is demonstrated by characterising the mechanical properties of gelatin composed protein mcirogels. Afterwards, I extend the microfluidic and bio-material expertise to a massive production of cell-laden microgels for cancer mciroenvironment research. This has been achieved by the development of a high-throughput micro-encapsulation platform and the 3D culture of cancer spheroid mcirogels. By applying the former mechanical testing method to the cultured spheroid-laden agarose mcirogels, I present the stiffness of the matrix affect the growth of cancer spheroids. Furthermore, I show that multiple cell lines (i.e. A549 cancer cells and IMR90 fibroblast cells) can be encapsulated and co-cultured in the agarose microgels as the in vitro models. Together with xenografting results, I hypothesise that proliferation of JAG1 expressing A549 cancer cells can be positively modulated through the NOTCH-mediated signalling of the stromal cells, such as IMR90. This thesis represents an interdisciplinary approach to address the challenges of biological fundamentals and applications. It is part of an ongoing exploration that synergistically com- bines physical tools with biological systems to generate innovative insights, comprehensions, methods and techniques.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2022

Author dc:creator

• Zhu, Hongjia

Advisor dc:contributor.advisor

• Knowles, Tuomas

• Bioengineering
• Biophysics
• HMGA
• Microgels

Licence

• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.92983

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/345563