Synthesis, characterization, and evaluation of biodegradable polymers and biomimetic hydrogel scaffolds for biomedical applications

The biomaterials field has come a long way from its empirical beginnings, when researchers took whatever materials were available and attempted to integrate them into the human body, sometimes with disastrous results. Now the body's response to foreign materials is better understood than ever before. Furthermore, the past two decades have seen great strides in tissue engineering. Tissue engineering, especially of tissues derived from the patient's own cells, offers total acceptance by and integration with the patient's body, unlike nonliving materials or living tissues from other humans or species. The active ingredient in medicine is only part of the arsenal against disease. The drug must get to the right place at the right time. That's where drug delivery comes in. The main challenge is to create technologies for the easiest and most convenient systematic delivery systems.;From a practical perspective, medical applications of polymers fall into three broad categories: (1) extracorporeal uses (e.g. dialysis membranes/artifical kidneys, wound dressings, artifical skins), (2) permanently implanted devices (e.g. cardiovascular and dental devices), (3) temporary implants (e.g. degradable sutures, implantable drug delivery systems, polymeric scaffolds for cell or tissue implants). Today, biomaterials research has developed into a major interdisciplinary effort involving chemists, biologists, engineers, and physicians. As the biomaterials industry continues to grow, degradable polymers will increase at the expense of traditional biomaterials such as metals and conventional, biostable polymers. Biodegradation has become a very important technology, particularly for controlled release of excipients from degradable matrices, degradation of synthetic and more naturally derived polymeric materials, and time-related degradation of temporary support devices for a number of biomedical applications.;This thesis has an organizational format as follows. It consists of eight chapters. Chapter 1 is the introduction and comprises an overview of biodegradable polymers and hydrogels for biomedical applications reported in literature. Chapter 2 discusses in detail the synthesis, characterization, and evaluation of resorbable PEG-co-PGA block copolymers and their hydrogels using different photopolymerizable end-group chemistries. Chapter 3 describes the controlled release of plasmid DNA from hydrolysable PEG-co-PGA hydrogels. Chapter 4 focuses on the chemical modification of hyaluronic acid biopolymers and evaluation of the degree of functionalization of hydrogel properties to match a number of tissue regeneration processes. Chapter 5 is derived from the study conducted in Chapter 4, in which nanostructured hyaluronic acid hydrogels were designed by a combination of AGET ATRP and FRP for controlled delivery of multiple biomolecules from a scaffold. Chapter 6 reports on efforts toward the design of a minimally invasive in situ nanostructured hyaluronic acid hydrogel via Michael-type addition reaction under physiological conditions. Chapter 7 reports on the synthesis of cell-adhesive star polymers prepared by ATRP and their evaluation for drug delivery and tissue engineering applications. Finally, Chapter 8 briefly summarizes the different accomplishments achieved in my research and recommendations for future directions, which may inspire the reader to think further along the general theme of this thesis.