AVS 56th International Symposium & Exhibition
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuP

Paper BI-TuP2
Formation of Stable Microbubbles by Encapsulation in Silica

Tuesday, November 10, 2009, 6:00 pm, Room Hall 3

Session: Biomaterial Interfaces Poster Session I
Presenter: K. Staggs, University of New Mexico
Authors: K. Staggs, University of New Mexico
G. Gupta, Los Alamos National Laboratory
M. Tartis, New Mexico Tech
G.P. Lopez, University of New Mexico
Correspondent: Click to Email
A new technique for stabilization of supramolecular assemblies (termed soft petrification) has been applied to the stabilization of microbubbles. Commonly used as ultrasound contrast agents, most types of microbubbles are inherently unstable. Current procedures require many types of microbubbles to be filled with hydrophobic, high molecular weight gases such as octafluoropropane and perfluorobutane. Special equipment including syringe pumps and sealing devices are required, because most microbubbles must be formed under these types of gases. This requirement limits the conditions under which microbubbles can be studied. They cannot be studied on a bench top open to atmosphere. Once microbubbles have undergone soft petrification, they can be studied in a wide range of environments. In soft petrification of air filled lipid coated microbubbles, a vapor deposition technique encapsulates the microbubbles in a thin silica shell. After undergoing soft petrification, it was observed that microbubble stability under adverse conditions is significantly improved. These adverse conditions include pressures up to 120 psig and temperatures up to 80°C. Those values are double the values found for microbubbles without the silica shell. Other unique characteristics of these microbubbles include the ability to withstand temperatures well below freezing, without loss of size. Air filled microbubbles have a bench top life span of approximately four hours before encapsulation. Following encapsulation, it is observed that the same microbubbles have a bench top lifespan of up to several months. Several formulations were characterized and unprecedented air filled microbubble studies are facilitated by this technique.