Date of Award

Spring 1-1-2017

Document Type


Degree Name

Master of Science (MS)


Chemical & Biochemical Engineering

First Advisor

Stephanie J. Bryant

Second Advisor

Joel Kaar

Third Advisor

Jennifer Cha


This thesis investigates the incorporation of hydroxyapatite (HA)

nanoparticles into poly(ethylene glycol) (PEG) hydrogels as a scaffold to enhance

osteogenic differentiation of the encapsulated murine pre-osteoblast MC3T3-E1

cells for applications in tissue engineering.

Specifically, poly(ethylene-glycol) (PEG) hydrogels have been chosen because

they offer several advantages that make them promising scaffolds to investigate.

They provide an adequate 3D matrix that mimics the ECM and helps cell growth

and proliferation maintaining an elevated cell viability and improve the formation

of new bone. They are also highly tunable for a number cell types easing the

incorporation of biological moieties which make possible to regulate the degradation

rate in order to match the rate of tissue formation. Hydroxyapatite, which is a

bioactive mineral, was incorporated into the synthetic PEG hydrogels because it is

known that it helps providing a biomimetic environment for the hydrogels which

enhance their osteoconductive and osteoinductive capabilities.

However, it is known that, in vivo, synthetic materials elicit a foreign body

reaction (FBR) when they are implanted. The FBR, which is an immune reponse

that is regulated by activated macrophages, is characterized by the formation of a

fibrous capsule around the hydrogels that limits their performance.

Therefore, the purpose of this thesis is first, to characterize an 8-arm thiolnorbornene

PEG hydrogel with added HA nanoparticles to elucidate how they affect

the differentiation into osteoblasts of the encapsulated MC3T3-E1 cells. After

understanding the effects of adding HA nanoparticles to the synthetic scaffolds, and

showing that they enhanced bone tissue depositon, the hydrogels containing 1%

(w/w) of hydroxyapatite were used to study how the foreign body response impacts

the performance of this MMP-sensitive PEG hydrogels. This was done by characterizing the influence that the macrophages have over encapsulated preosteoblast MC3T3-E1 cells in vitro when they are activated in a co-culture system.