Electronic nose and optoacoustics improve diagnosis of prostate cancer

Jun 2 2012

Chances of survival of prostate cancer depend strongly on the stage at which the disease is diagnosed. Now scientists have developed new methods relying on an electronic nose and optoacoustics to improve the diagnosis techniques and avoid fatal treatment delays

Prostate cancer is the most common malignant tumour and the second leading cause of cancer deaths in men. Men over 50 have a one in five chance of being diagnosed with prostate cancer. An EU research project, called the BOND project, for Bioelectronic Olfactory Neuron Device, is coming up with a new non-invasive method which could provide an early stage disease detection. In the same way that the eponymous British spy's role was to protect his country from enemy threat, this project stands to give an early warning before enemy cancer cells take over the control over patient body.

Scientists at the University in Barcelona have thus developed the main components of a bio-electronic nose, made of electrodes which act as a nerve cord, that already gave promising results. The artificial olfaction system relies on several hundred nanometric sized biosensors, which can detect even the tiniest amount of cancer cells. It is dipped into a patient's urine, in order to spy on and relay information concerning the substances contained in the liquid back to the computer.

But spying with a biosensor nose is not enough. Medical practitioners are faced with another issue, in the fight against prostate cancer: they lack detailed information about tumours. "Today's ultrasound examinations are not sufficient to clearly detect the dimensions of a tumour," explains urologist
Stephan Meesen at the hospital in Saarbrücken, Germany. "In practice we see that, unfortunately, we are often wrong or too cautious." Hence, the need for an integrated biosensor capable of delivering visual information on the progress of tumour cells is essential.

A step removed from the spy mythology associated with the BOND biosensors, scientists from the Fraunhofer Institute in St. Ingbert, Germany, have sought inspiration in Greek mythology when naming their imaging biosensor designed to assess tumour dimension. They called their project ADONIS. The name stands for Accurate Diagnosis of prostate cancer using Optoacoustic detection of biologically functionalized gold Nanoparticles - a new Integrated biosensor System.

This project consists in the development of a new sensing technique, relying on optoacoustics. It involves labelling some of the body's immune defence soldiers, known as antibodies, with gold. The gold-antibody nano-particles construct is put into solution and injected into patients. Thanks to the
ability of antigens to bind to specific receptors on the surface of cancer cells, this device delivers gold nano-particles into the tumour tissue.

A laser impulse heats the prostate cancer and induce a pressure wave, which can be detected with an ultra sound to assess the shape and size of the tumour. "The gold particles colour the tissue, so this area absorbs more light and sound is produced", explains physicist Robert Lemor from the Fraunhofer Institute. It is similar to the principle of the radar applied to the inner parts of our body. This method generates images based on sending a sound wave and recording the reflection signature after it bounced back from our inner cells. When the tumour is marked with the gold nano-particles, it looks different then the other cells and can be detected. In parallel, the infrared laser beam lights up the tissue and measures its reflection signature. Both together provide the scientists with high sensitive images which can be converted into three dimensional animations.

The basis of this method has already been tested with animals and first studies with humans are in the planning phase. In the future, scientists want to use a higher laser power as a means to heat the gold particles and subsequently destroy the cancer cells.