Hydrogels and Tissue Engineering

Abstract

Hydrogels are water-swollen polymeric materials that maintain a distinct three-dimensional structure. They were the first biomaterials designed for use in the human body. Traditional methods of biomaterial synthesis include crosslinking copolymerization, crosslinking of reactive polymer precursors, and crosslinking via polymer-polymer reaction. These methods of hydrogel synthesis were limited in the control of their detailed structure. Other inadequacies of traditional hydrogels have been poor mechanical properties and slow or delayed response times to external stimuli. The huge field of biomaterials research has received a strong revitalization by several novel approaches in hydrogel design. Enhanced biomechanical properties of hydrogel preparation, superporous and comb-type grafted hydrogels with fast response times, and self-assembly are just a few examples of hydrogel biomaterials with a smart future. Potential applications of all the types of hydrogels include: tissue engineering, synthetic extracellular matrix, implantable devices, biosensors, separation systems (valves to control permeability across porous membranes, or materials for affinity separation based on the specific recognition of monomelic strands), materials controlling the activity of enzymes, phospholipid bilayer destabilizing agents, materials controlling reversible cell attachment, nanoreactors with precisely placed reactive groups in three-dimensional space and smart microfluidics. With regard to the applications of hydrogels in recent years, particular attention has been devoted to drug delivery, clinical application as well as to the use of hydrogels as scaffolds for tissue engineering and regenerative medicine. Among the materials used for regenerative applications, hydrogels seem very promising and are receiving increasing attention due to their ability to entrap large amount of water, good biocompatibility and the ability to mimic tissue environment.