Researchers from Korea have developed a drug delivery system that uses pH changes to simultaneously diagnose and treat tumours in the body.

Photodynamic therapy (PDT) is an effective and non-invasive method used to treat prostate, skin and lung cancers. It works by injecting a photosensitiser into the body and then irradiating it at an appropriate wavelength. The photosensitiser produces singlet oxygen that damages the tissue around it. Encasing the photosensitiser in a nanosphere or polymer micelle makes delivery more successful and protects the photosensitiser from being removed from the body through the renal system.

Heebeom Koo at the Korea Institute of Science and Technology in Seoul and colleagues have developed a pH responsive polymeric micelle that releases its contents at the acidic extracellular pH of tumour tissue. When used in PDT, the photosensitiser is released producing fluorescence and singlet oxygen, simultaneously diagnosing and treating the tumour. When used in mice with tumours, the micelles showed clear fluorescent imaging of tumours and complete removal of them using PDT.

This research was undertaken to provide 'solutions to overcome the urgent limitations in photosensitiser delivery and it will contribute to the clinical utility of PDT in cancer therapy,' says Koo, and they hope their research 'can assist development of personalised medicine in the future.'

Shawn Chen, from the National Institute of Biomedical Imaging and Bioengineering, USA, was impressed with the research saying, 'it is highly significant that the combination of pH-responsive micelle and photosensitiser showed synergetic effects for both cancer imaging and therapy.'

Rebecca Brodie 

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