RWTH research team creates the world’s first non-spherical microbubbles

Anisotropic microbubbles open up forward-looking possibilities for ultrasound imaging and drug delivery.

An international research team led by Anshuman Dasgupta and Twan Lammers from the Institute for Experimental Molecular Imaging at RWTH Aachen University has succeeded for the first time in generating stable non-spherical microbubbles. In collaboration with Samir Mitragotri from the Wyss Institutes at Harvard University and with colleagues from the Massachusetts General Hospital in Boston, the Italian Institute of Technology in Genoa and the DWI - Leibniz Institute for Interactive Materials in Aachen, materials and methods for one-dimensional mechanical microbubble strain were developed as part of the joint project.

Microbubbles are comparable to, for example, soap bubbles in the micrometer range. Soap bubbles normally always have a perfectly round shape. This results from a physical force known as surface tension. Scientifically, bubbles are therefore referred to as "minimal surface structures" that trap a maximum volume of air on the smallest possible surfactant surface. Microbubbles are used clinically as contrast agents for ultrasound imaging. In addition, they are increasingly being explored for drug delivery purposes, including opening the blood-brain barrier to facilitate drug accumulation into the central nervous system.

The international research team has now not only created disk-shaped microbubbles, but also gained insights that they outperform traditional spherical microbubbles in several ways. They move closer to blood vessel walls, show a longer circulation time in the blood after intravenous administration, and are more effective in opening the blood-brain barrier for local drug accumulation under focused ultrasound.

The work was published in the March issue of the journal PNAS and was funded by the European Commission (EuroNanoMed-III: NSC4DIPG), the European Research Council (CoG: Meta-Targeting) and the German Research Foundation (GRK2375: Tumor-targeted Drug Delivery).