Ring-Sheared Drop - Interfacial Bioprocessing of Pharmaceuticals

The Ring-Sheared Drop (RSD) is a Microgravity Science Glovebox experiment that launched in July 2019 to the ISS to study shearing flow in the absence of solid walls. The major goals of this project were to adapt and use the RSD module to develop and test predictive models of non-Newtonian flow of high-concentration proteins at the interface. Incorporating non-Newtonian constitutive equations for both interfacial and bulk flows and coupling the interfacial and bulk stresses is essential for mechanistic models that would be capable of predicting behavior under flow conditions of practical interest. The coupled problem is intrinsically nonlinear and there is a need to develop robust and accurate numerical techniques to interrogate flow dynamics and experimentally validate and verify results. The ring-sheared drop interfacial bioprocessing of pharmaceuticals-I (RSD-IBP-I) campaign aimed to study non-Newtonian interfacial hydrodynamics of the blood transport proteins bovine serum albumin (BSA) and human serum albumin (HSA) in microgravity. Specifically, scientific aims focus on the effects of protein primary structure (BSA or HSA), protein concentration (4, 40, or 400 mg/mL), and interfacial shear rate (3, 10, or 30 rpm) on microgravity fluid flow, measured using velocimetry of hollow glass microsphere tracer particles within protein samples. This campaign intended to confer improved understanding of interfacial protein flows in relation to physiology, the environment, and industry relevant to both spaceflight and Earth.