A new compound based on iridium, a rare metal which landed in the Gulf of Mexico 66 million years ago, connected to albumin can attack the nucleus of cancerous cells when joined with albumin and activated by light, researchers have found. 

The treatment of cancer using light, called Photodynamic therapy, uses chemical compounds called photosensitisers, which can be switched on by light to produce oxidising species that are able to kill cancer cells.

The results of this study can be found in the international edition of Angewandte Chemie.

Clinicians can activate these compounds selectively at a precise location of the tumour (using optical fibres), thus killing cancerous cells while leaving healthy cells intact.

Thanks to the special chemical coating used, the group were able to combine iridium to the blood protein albumin, to enable fluorescence so their passage into cancer cells can be tracked.

Upon light activation, the cells' own oxygen is then converted to a lethal form which kills them.

Not only is the newly formed molecule an excellent photosensitiser, but albumin is able to deliver it to the nucleus within cancer cells.

The dormant compound can then be switched on by light irradiation and destroy the cancer cells from their very centre.

The bright luminescence of the iridium photosensitiser allows for the nuclear accumulation of tumour cells and its activation, which results in the death of the cancer cell.

These series of events can also be followed in real time using a microscope. 

Professor Peter Sadler, from the Department of Chemistry at the University of Warwick said, "It is amazing that this large protein can penetrate into cancer cells and deliver iridium which can kill them selectively on activation with visible light. If this technology can be translated into the clinic, it might be effective against resistant cancers and reduce the side effects of chemotherapy.

Dr Cinzia Imberti, from the University of Warwick also commented, "It is fascinating how albumin can deliver our photosensitiser so specifically to the nucleus. We are at a very early stage, but we are looking forward to see where the preclinical development of this new compound can lead. "Our team is not only extremely multidisciplinary, including biologists, chemists and pharmacists, but also highly international, including young researchers from China, India and Italy supported by Royal Society Newton and Sir Henry Wellcome Fellowships.

Source: University of Warwick