In many applications the use of a single material does not meet the desired properties and can result in material failure. This is often addressed by composite or hybrid materials, i.e. a material made from two or more different materials that, when combined, are higher performing than those individual materials by themselves.
Hydrogels are materials able to retain a large amount of water while keeping shape integrity. The high water content makes them highly suitable for medical applications of which contact lenses is a prominent example. Moreover, the ability to match hydrogel properties to those of the extracellular matrix and biological tissue has also triggered an enormous interest in hydrogels in drug delivery, tissue engineering and wound healing. Polymer hydrogels, either derived from natural or synthetic polymers, are three-dimensional networks which can be covalently cross-linked, physically cross-linked (e.g. by hydrogen bonds or ionic interactions), or both. The type and extent of crosslinking affects the mechanical properties of hydrogels. While physical hydrogels are typically mechanically weak, i.e. they cannot bear any load, chemical hydrogels are stronger but often lack elasticity, i.e. they are brittle and break when stretched. In many applications, the use of hydrogels is severely limited by their mechanical properties. The way to design hydrogels with improved mechanical properties is by the formation of hydrogel hybrids or double networks (DN). DN comprise of an interpenetrating network (IPN) of two chemically different individual networks, and exhibit high toughness and strength compared to a conventional single network (SN) hydrogel. The first network usually consists of a rigid physically or lightly covalently cross-linked network. This network is load bearing and provides stability. A second network is then formed within the first network, which is soft and highly flexible and provides the overall mechanical toughness and elasticity to the material. The resulting hybrid material usually possess a remarkable stretchability and toughness significantly outperforming the properties of the individual networks. By the addition of an adhesive layer, a highly flexible and stretchable wet adhesive tape might be created for wound dressing and tissue repair.
The problem of designing new hydrogel materials is extremely important today, especially for the dressing materials industry. According to a market report, the global transdermal drug delivery systems market is expected to reach 7.1 billion USD by 2023 at a Compound Annual Growth Rate of 4.5%.
The overall research aim of this project is to develop a new biodegradable and bioabsorbable class of double network hydrogels with mechanical properties suitable for the design of drug delivery patches. Specifically:
• To develop and optimize the chemistry and formation of microscopic and macroscopic poly(peptide-acrylate) hydrogel DN and evaluate their physico-chemical properties
• Investigate the biocompatibility as a function of the DN composition.
• Demonstrate applicability of DN hydrogel materials in the transdermal delivery of drugs.
• Develop a DN school experiment for secondary school pupils.
