Hydrogels in Biomedicine

Dear Colleagues,

Hydrogels are three-dimensional networks of hydrophilic natural, synthetic, or semi-synthetic polymers that can absorb and retain large water amounts. Naturally derived hydrogels (natural hydrogels) include cellulose, chitosan, collagen, alginate, agarose, hyaluronic acid, gelatine, and fibrin, etc. Semi-synthetic polymers are chemically modified natural polymers or a combination of natural and synthetic polymers. Synthetic hydrogels are prepared through the polymerization of a synthetic monomer, such as polyvinyl alcohol, polyethylene glycol, poly-2-hydroxyethyl methacrylate, poly-N-isopropyl acrylamide, polyacrylic acid, polyacrylamide, etc. The classification depends on their source, composition, environmental stimuli, crosslinking, property, configuration, and ionic charge. Their frequent biocompatibility, bioactivity, and nontoxicity, together with their creative adjustability for the different uses, make them very attractive and excellent candidates for a wide variety of medical applications such as 3D cell cultures, drug delivery, wound dressings, and tissue engineering. One expanding area is the use of gels as surgical aides to prevent bleeding, infection, and post-operative complications.

There are some criteria to follow for their successful in vivo application in the field of biomedicine. For a biomedical response, hydrogels must exhibit biocompatibility, i.e., a high tissue compatibility, biodegradability and bioremovability, and suitable mechanical strength; they should provide cues for cells, i.e., as a scaffold to support cell signalling and to allow for cell growth and migration, immune system modulation, storage, and release of therapeutics.

Despite the well-established role in many fields, the potential of hydrogels in many areas of science is yet to be explored. Over the past decades, important evolution has been achieved in the field of hydrogels as useful biomaterials. Several hydrogel-based drug delivery devices and scaffolds have been designed and studied, but many of them have not yet reached the market, sometimes hindered by the toxicity of crosslinking agents and limitations of gel formation under physiological conditions.

The large variety of natural and synthetic polymers, the wide range of physical or chemical crosslinks to be explored, and the increased understanding of biological processes ensure the possibility of obtaining new promising versatile materials, especially for controlled drug release and tissue engineering, even if several challenges remain to be overcome for biomedical applications.

Prof. Dr. Eleonora Russo
Prof. Dr. Carla Villa
Guest Editors

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• hydrogels
• drug delivery
• rheology
• characterization
• biomedical application
• wound healing
• nanotechnology
• tissue engineering