Enzyme-Mediated Smart Materials for Tissue Engineering
Biological evolution is a process through which living organisms respond and adjust to changes in the external environment for survival. Similarly, smart materials are characterized by their unique ability to respond to external stimuli. Stimuli-responsive materials undergo changes in their chemical structures and/or physical properties in response to physical cues such as pH, temperature, light, mechanical property, and magnetic field, and/or chemical cues such as ions and small molecules. Particularly, smart materials have recently been found to possess potential application in the biomedical field including imaging, diagnosis, drug and/or gene delivery, and tissue engineering. Although various types of stimuli-responsive hydrogels have been designed for these applications, enzymes have recently been receiving much attention as stimuli agents. Most of the essential activities in the body tissues or organs proceed systematically under the action of various enzymes, thus indicating that enzyme-catalyzed reactions proceed under sufficiently mild conditions for biological entities such as cells and proteins. Therefore, enzyme-catalyzed reactions offer a chemical pathway to activate smart materials for biomedical applications. In this chapter we introduce various types of enzyme-responsive materials as well as their associated design strategies for tissue engineering applications.