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Brewing a drug delivery platform
26 June 2009
A pH responsive film that releases drugs to kill cancer cells could find applications from implant coatings to drug delivery systems, say scientists in the US and Korea.
- Frank Caruso
Usually it is difficult to incorporate hydrophobic species into layers under physiological conditions (pH 7.4) due to their limited functionality. Hammond overcame this problem by creating a hydrogen-bonded system, using tannic acid, a compound found in tea. The acid forms hydrogen bonds with the polymeric micelles ensuring that the multilayer remains stable and intact under biological conditions.
Drug-loaded micelles are trapped between layers of tannic acid to build the multilayer films
The pH-responsive linkers in the micelles can then be used to control doxorubicin's release from the film when it is required, by changing the pH conditions of the solution surrounding the film. Hammond's team was able to demonstrate this in tests with cancer cells and showed that the doxorubicin remained bioactive even after encapsulation in the film.
Frank Caruso, an expert in the field of LbL assembly for biomedical applications, based at the University of Melbourne, Australia, says that the strategy is an innovative approach to drug delivery. 'Such films are likely to serve as a platform technology to develop engineered thin films with potential in the delivery of therapeutics in biomedical applications,' he suggests.
Hammond says that future work could look at combining drug-loaded micelles that respond to different chemical or physical triggers, such as redox reactions or light. Hammond adds that their drug release system could be used as an ultrathin surface coating that she hopes 'will be of great interest for localised delivery of cancer therapeutics and vaccines.' To achieve this, she explains, a particular challenge will involve making all individual components of the LbL constructs fully biocompatible and non-toxic.
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Link to journal article
Hydrogen-bonded multilayer of pH-responsive polymeric micelles with tannic acid for surface drug delivery
Byeong-Su Kim, Hyung-il Lee, Yunhong Min, Zhiyong Poon and Paula T. Hammond, Chem. Commun., 2009, 4194
Also of interest
Frank Caruso and co-workers at the University of Melbourne, Australia, discuss how non-covalent interactions can be used for layer-by-layer surface modification
A peptide found in tumour cells can trigger the release of drugs from a novel nanocarrier, claim South Korean scientists