Characterization of lipid shelled microbubbles designed for targeting post-operative nascent abdominal adhesions

Peritoneal adhesions are bands of fibrous tissue that can bind adjacent tissue or organs together and have a high probability of occurrence after a patient undergoes deep abdominal surgery. These adhesions can cause complications, such as chronic pain, intestinal obstruction or constriction, organ displacement, and even death, yet there exists no common diagnostic for these adhesions prior to symptomatic appearance. Furthermore, the gold standard treatment is ironically surgical removal. Nascent adhesions formed in the first 48 hafter surgery are primarily composed of fibrin. In this study, lipid shelled microbubbles have been designed as a potential theranostic agent to detect and treat adhesions using a fibrin targeting peptide called CREKA (Cys-Arg-Glu-Lys-Ala). Low amplitude through-transmission experiments were conducted to characterize the mechanical properties of the microbubble lipid shell, such as the shear modulus of elasticity and shear viscosity. Passive cavitation detection (PCD) experiments were conducted to determine the inertial cavitation threshold by which the microbubbles may break up fibrin under ultrasound exposure. [Work supported by NIH SBIR and BU Mechanical Engineering Department.]