Colloidal microgels may be used for the absorption and controlled release of confirmationally sensitive molecules such
as proteins and peptides. These monodisperse microgels are easily prepared in a single pot reaction from e.g. Nisopropylacrylamide,
butyl acrylate and methacrylic acid in the presence of a cross-linking agent and a suitable free
radical initiator. The resultant materials display dramatic conformational changes in aqueous dispersion in response to
changes in e.g. environmental pH.
Colloidal microgels are capable of absorbing a range of different proteins and peptides at one pH, affording them
protection by changing the conformation of the microgel following a pH change. A further change in environmental pH
will allow the microgel to adopt a more extended confirmation and therefore allow the release of the encapsulated
material. In the case of e.g. insulin this would offer the possibility of an oral delivery route. At the pH of stomach the
microgel adopts a compact conformation, "protecting" the protein from denaturation. As the pH increases passing into
the GI tract, the microgel changes its conformation to a more expanded form and thereby allows the protein to be
released. Colloidal microgels offer an opportunity for the controlled release of conformationally sensitive protein and
peptide molecules via an oral route.
Wound dressings and other types of wound healing technologies are experiencing fast-paced development and rapid
growth. As the population ages, demand will continue to rise for advanced dressings used to treat chronic wounds, such
as pressure ulcers, venous stasis ulcers, and diabetic ulcers. Moist wound dressings, which facilitate natural wound
healing in a cost-effective manner, will be increasingly important.
In commercially available hydrogel / gauze wound dressings the gel swells to adsorb wound excreta and provide an
efficient non adhesive particle barrier. An alternative to hydrogels are microgels. Essentially discrete colloidal gel
particles, as a result of their very high surface area to volume ratio compared to bulk gels, they have a much faster
response to external stimuli such as temperature or pH. In response to either an increase or decrease in solvent quality
these porous networks shrink and swell reversibly. When swollen the interstitial regions within the polymer matrix are
available for further chemistry; such as the incorporation of small molecules. The reversible shrinking and swelling as a
function of external stimuli provides a novel drug release system. As the environmental conditions of a wound change
over its lifetime, tending to increase in pH if there is an infection combining these discrete polymeric particles with a
substrate such as cotton, results in a smart wound dressing.
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