Hydrogels: Biological Properties and Applications

Book Preface

Hydrogels are a particular class of compounds of which the major constituent is water. In fact, water is present in the hydrogel up to 90% and is contained in a scaffold which is generally polymeric and obviously hydrophilic. As a result, hydrogels resemble each other even though obtained from different polymers. Nevertheless, the polymeric matrix gives particular characteristics to the hydrogel leading to applications in different fields.

Water is the main element of the human body, thus hydrogels are excellent structures to favourably shelter proteins, cells etc., without altering their characteristics and properties. This is why hydrogels are mainly designed and synthesized for their use in the biological field; hence the name biohydrogels. Their properties point to their use as scaffolds for stem cells which has turned out to be a very promising technique for tissue and organ regeneration. For this reason their investigation falls within the Biomaterials Science. Paradoxically, the conceptual simplicity of hydro gels up to now has led to a superficial study of their chemistry, chemical physics and mechanics preventing their wider application in the human body due to a lack of knowledge of biological component interactions. For example, it is not clear, yet, how to store hydrogels without altering their characteristics. In fact, hydrogels re-hydrated after lyophylization or oven drying, generally show corrupted properties once swollen in water, in comparison with their native counterparts. This is why the properties of water and its capacity to bind to hydrophilic chemical groups must be taken into account, as well as how the water is organized around hydrophobic groups and also the organization of the layers of water molecules surrounding a polymer. Obviously, all of this determines the hydrogel swelling degree in water and consequently its biological response.’

This book aims to give a contribution to hydrogel knowledge from the chemical, physico-chemical, mechanical, biological and biomedical point of view.