Kausik Sarkar's Talk

Jul 18, 2013 - 17:00

Jul 18, 2013 - 17:00

Creativity Hall (Room 118) Chemical Engineering

Seminars

Kausik Sarkar Department of Mechanical and Aerospace Engineering George Washington University

Abstract : Micron-size gas bubbles encapsulated by a nanometer layer of proteins lipids and other surfactants are injected into a patient’s body to improve ultrasound imaging. Currently two such contrast agentsOptison (GE Health Care) and Definity (Lantheus Medical Imaging)are approved by the Food and Drug Administration for echocardiography. They can also be functionalized for molecular imaging and conjugated with drugs for targeted delivery. For the past decade we have been performing experimental and analytical research on contrast microbubbles. We are the first to propose and subsequently develop an interface model of the encapsulationhas an intrinsic surface rheology with surface viscosities and elasticitiesthat addresses the wide disparity of scales between the overall bubble size and that of the encapsulation. In this talk I will discuss material characterization of these contrast agents that includes determination of rheological properties of a contrast microbubble’s encapsulation using one set of in vitro experiments followed by model validation using another set. I will offer a hierarchical approach with increasing sophistication in constitutive modeling of the encapsulation as warranted by the determining experiments and underlying physics. A new model for the dissolution of microbubbles will be presented. I will discuss subharmonic signals used for noninvasive monitoring of organ-level blood pressure and explain their unusual behaviors in sharp contrast to “plausible expectations” and classical bubble dynamics results. I will also briefly discuss specifically targeted and cytosolic delivery of cancer drugs from “echogenic liposomes”. Time permitting I will provide an overview of other research efforts at our lab. It includes direct numerical simulation of multiphase flowsemulsions of deformable viscous and viscoelastic drops capsules (encapsulated by a hyperelastic membrane) their rheology adhesion and migration of leukocytes on active substrates in presence of receptor-ligand bindingas well as ultrasound mediated bone fracture healing and cancer therapy.