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Drug delivery makes nano sense
18 October 2005
A major challenge in the area of biomaterials is to design functional materials that can recognise different environments and are responsive to biological molecules. With this in mind, Nicola Tirelli of the University of Manchester, UK, and colleagues at the Swiss Federal Institute of Technology and Eindhoven University of Technology in The Netherlands have designed a system of cross-linked nanoparticles based on poly(propylene sulfide).
These particles are made in the presence of glucose oxidase (GOx) or a glucose oxidase-Pluronic polymer mixture, which attaches itself to the nanostructure. This means that when the particles are exposed to glucose the GOx oxidizes the glucose, at the same time converting oxygen to hydrogen peroxide. In turn, the hydrogen peroxide oxidizes the polysulfide nanoparticles. This makes the nanoparticles more hydrophilic, causing them to swell.
The polysulfide nanoparticles can be loaded with hydrophobic drugs, such as doxorubicin, by relatively simple evaporation methods. The drug is then physically trapped within the polymer network, and can slowly diffuse out. However, when the nanoparticle is swollen - in the oxidizing conditions caused by the presence of glucose - the drug is released much more quickly. As a result the drug release is glucose-responsive.
It is hoped that this approach will prove to be effective for delivering drugs in cases where the presence of glucose is a marker, for example in treating diabetes.