MICROBUBBLE : AS A THERAPUTIC AND DIGNOSTIC TOOL

Gas filled microbubbles are well known as ultrasound contrast agents for medical ultrasound imagingand for non-invasive delivery of drugs and genes to different tissues. Microbubbles designate air or gasfilled microspheres suspended in a liquid carrier phase which generally results from the introduction ofair or gas. The liquid phase contains surfactants to control the surface properties as well as stability ofthe bubble. Microbubbles are manufactured from biocompatible materials, so they can be injectedintravenously. Microbubbles have an average size (1-8 μm) less than that of RBC’s i.e. they are capableof penetrating even into the smallest blood capillaries & releasing drugs or genes, incorporated on theirsurface, under the action of ultrasound. Ultrasound radiation are used which are non hazardous. Most ofthe physicians today prefer imaging with ultrasound in combination with microbubbles compared toother diagnostic techniques for low cost and rapidity. The ultrasonic field can be focused at the targettissues and organs; thus, selectivity of the treatment can be improved, reducing undesirable side effects.Recently, targeting ligands are attached to the surface of the microbubbles, which have been widely usedin cardiovascular system, tumour diagnosis and therapy. This review focuses on the characteristics ofmicrobubbles that give them therapeutic properties and some important aspects of ultrasound parametersthat are known to influence microbubble-mediated drug delivery. In addition, current studies involvediscussion of novel therapeutical application of microbubbles.