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Date of Award

2017

Document Type

Campus Access Master's Report

Degree Name

Master of Science in Biomedical Engineering (MS)

Administrative Home Department

Department of Biomedical Engineering

Advisor 1

Rupak M. Rajachar

Advisor 2

Bruce P. Lee

Committee Member 1

Megan C. Frost

Committee Member 2

Lanrong Bi

Committee Member 3

Feng Zhao

Abstract

Cell infiltration is one of the most important characteristics of a degradable and bioactive biomaterial. Poly (ethylene glycol) (PEG), as one of the most commonly used polymer in medicine, also faces such problems. This issue also prevalence in PEG derivatives such as poly (ethylene glycol)-glutaric acid-dopamine (PEG-GA-DM) which is a versatile bioadhesive. As a promising bioadhesive system that can be used and modified to suit various type of applications, modification to overcome cellular infiltration and degradation issues will help further expand the usefulness of the material in tissue repair application. The degradation issue is already preliminary solved by introducing ester linkage through carboxylic acid functionalization via glutaric acid incorporation. However, the resulting degradation rate is still not ideal. To further modify the porosity, pore structure, and degradation rate of the polymer, various types of non-crystalline silica particles were introduced into the polymer network. The benefit of including silica particles into the gel system may not limited only to the degradation and pore structure. One of the most interesting effects that this ceramic material may contain is its ability to release silica byproduct, specifically hydrolyzed silica or orthosilicic acid. Orthosilicic acid was proved to positively affect collagenous extracellular matrix formation as well as improves keratin and collagen based organ’s health. Using various formulations, a number of PEG-GA-DA and silica composite improvements were investigated. The silica’s contributions to a number of changes include shortened gelation time, increased mechanical strength, faster initial degradation, higher structural stability after degradation, and, ultimately, change in porous structure. It is interesting that PEG-GA-DA silica composite not only provided improvement for the PEG network but also provide benefit for innate property of silica particle. With silicic acid as degraded product, the composite also facilitates extracellular matrix formation as well as therapeutic macrophages recruitment.

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