Bubbles for ultrasound treatment

Ultrasound is the most widely used imaging technique in the world. It is a versatile, non-invasive, low risk, low cost, and portable real-time imaging technique. Ultrasound contrast agents (UCA) are micro bubbles composed of a thin polymer or protein shell filled with air or a high-molecular weight gas. On the shell of the bubble, target molecules are present (see Figure 1). These micro bubbles are efficient ultrasound reflectors when subjected to an acoustic field. Therewith, the contrast agent allows the examination and visualization of the organs, structure and borders of the tissues such as cardiac chamber, blood, and blood flow in the narrow capillary veins; which gives diagnostic and therapeutic benefits.


The aim of this project is to design, prepare, and test designated ultrasound contrast agents for molecular imaging and therapy. To achieve such a goal, well-defined physico-chemical properties of UCA particles are required and these include: small particles, high particle shell elasticity, long in vivo persistence, colloidal stability, high sensitivity (good resonance in the acoustic field), and reproducibility.  


The mentioned application depends strongly on the physical and chemical properties of the UCA, which, amongst others depends on the method of preparation. With the traditional UCA production methods like sonication, it is difficult to have such particle properties. In this project, UCA will be prepared by emulsification. Different techniques such as membrane-, micro channel- and micro sieve emulsification will be examined and compared for dedicated UCA production. Figure 2 shows a schematic diagram of a cross flow membrane emulsification process. 


The project is part of the IS initiative of Senter/Novem. Participants within this project are: Philips Research Eindhoven, Materials, Devices, and Microsystems group, Erasmus MC Rotterdam, Thorax Centre, Experimental Echocardiography group, and University of Twente, Physics of Fluids group.