Biomaterials Tutorial

Hydrogels

Maxi Boeckl
University of Washington Engineered Biomaterials

Hydrogels are crosslinked polymer networks that are insoluble in aqueous solutions, but are able to swell, and often have a water content of up to 90%.  These can be formed by crosslinking one or several types of monomer units into a network, forming a homopolymer, copolymer or multipolymer.  With the incorporation of different monomers, gels with wide-ranging chemical and physical properties can be formed.  The gels can be neutral or charged, soft or stiff, strong or brittle.  Hydrogels are routinely used for biomedical and pharmaceutical applications, such as drug release, artificial tendons, wound-healing bioadhesives, artificial kidney membranes, artificial skin and contact lenses.

Poly(HEMA)

Poly(hydroxyethyl methacrylic) acid, or poly(HEMA), is one of the most important hydrogels in the biomaterials world since it has many advantages over other hydrogels.  These include a water-content similar to living tissue, inertness to biological processes, resistance to degradation, permeability to metabolites, resistance to absorbtion by the body.   It can be easily manufactured into many shapes and forms, and be easily sterilized.  The most common example of poly(HEMA) is its use as contact lenses.

References: 

1.  Peppas NA. Hydrogels in medicine and pharmacy.  Boca Raton, FL: CRC Press, 1987. 

2.  Andrade JD. Hydrogels for medical and related applications. ACS Symposium Series, vol. 31.  Washington, DC: American Chemical Society, 1976.