Multifunctional Contrast Agents for Ultrasound

Wynter Duncanson
Harvard University
Monday, February 27, 2012
Duke University, Schiciano A | 4:25pm

Ultrasound is an important and widely used because it is non-invasive, cost effective, and inexpensive to maintain; however, its use is limited because it lacks the sufficient contrast to distinguish between two similar materials.  To overcome this constraint, gas-filled microparticles have been used to selectively enhance contrast; these can be gas-filled microparticles with either high porosityor core-shell structures. Interestingly, similar structures are also used in drug delivery to control drug release rates.  Thus, this suggests combining the functionality of contrast agents and drug delivery microparticles; this would enable image-guided drug delivery.  However, the lack of control of size, shape and composition of microparticles formed by conventional fabrication techniques precludes fabrication of highly-controlled, multifunctional microparticles with the specified properties required.  One potentially promising approach to overcome these limitations is through use of droplet microfluidics to produce highly controlled and uniform emulsion-based templates.  In addition, the flexibility of the choice of fluids that is possible with microfluidics enables the use of a variety of materials, including self-assembling materials, and unique surfactants to make smarter materials for contrast enhancement as well as payload delivery. I describe the use of sophisticated microfluidic technologies to fabricate porous and core-shell microspheres using self-assembling, and stimulus-responsive materials.  These advanced techniques coupled with the benefits of the smart materials create new opportunities to not only produce simple microspheres, but also highly complex functional microspheres; these multifunctional contrast agents can contribute to realizing image-guided delivery to improve detection and treatment of disease.