Microbubbles are miniature gas bubbles, mostly containing oxygen or air, which can be uniformly suspended in a liquid such as blood. Due to their size, they can pass through even the smallest of blood vessels, and therefore are commonly used together with medical ultrasound imaging. Microbubbles reflect ultrasound better than blood or soft tissues, thus allowing them to be used for highlighting blood in ultrasound images. Until now, their common use was only as contrast agents. However, scientists at Philips Research are now developing a new drug delivery technology that relies on the contrast-enhancing quality of microbubbles. The system is designed to help ultrasound operators locate tumours based on their density and the tumour-specific network of small blood vessels. When the tumour is located, the system shatters the shells of the microbubbles by means of a focused, high-energy ultrasound pulse. Once the shells are destroyed, the contents of the microbubbles spill into the surrounding area and the drugs reach the tumour directly instead of going through the whole bloodstream. This localized release technique prevents the drugs from influencing other systems in the body, thus preventing gruelling side-effects and improving the quality of life of the patient undergoing chemotherapy. http://thefutureofthings.com/news/5879/ultrasound-activated-microbubbles-fight-cancer.html
