Physical, Chemical and Biological Properties of Injectable Smart Hydrogels

Abstract

The human body tissue hosts a diverse array of biomaterials, ranging from the polysaccharide hyaluronic acid to the protein collagen. The physico-chemical properties of biomaterials and those of the resulting structures that they form are tailored to interact with the biological living components of the body. Normally, after a wound, the human body deploys a complex machinery for repair. Usually chronic, deep, and infected wounds overwhelm this machinery, and this challenge is often overcome with the use of tissue engineering scaffolds. Hydrogels form part of scaffolds, which are used for deep, non-uniform, exuding or infected wounds. These tissue engineering hydrogel scaffolds need to have physico-chemical properties that can match those of the damaged tissue for adequate and necessary cell–material interactions. To improve the versatility of hydrogels, injectability and the capability to accommodate small bioactive molecules have given rise to smart injectable hydrogels. This advanced family of hydrogels have been used for the delivery of cells and therapeutic molecules and for tissue repair, in the treatment of challenging diseases, such as myocardial infarction, osteoarthritis, spinal cord injury and neurological disorders. A wide range of injectable hydrogel systems have thus been synthesized for bone, cartilage, cardiac and nerve tissues. This chapter gives an overview of the design, physico-chemical properties, and bioactivity of smart injectable hydrogels as scaffolds.