(387d) Stability of Mab-Surfactant at the Air-Water Interface Under Competitive Adsorption and Controlled Flow Deformations

While monoclonal antibodies (mAbs) have been used as biotherapeutics to treat numerous human ailments, the molecules are inherently unstable and have a natural tendency to aggregate in solution, impacting drug formulation stability. One source of instability for mAbs occurs at the air-water interface; their propensity to adsorb at this interface stems from their amphiphilic structure, including exposed hydrophobic domains. Thus, a robust understanding of mAb and surfactant behavior under competitive adsorption and both dilatational and shear strained-induced effects at air-water interfaces is necessary to evaluate overall interfacial stability and elucidate surface-mediated protein aggregation in solution. In this work we study a well-defined NIST reference mAb (RM #8671, pI = 9.3, an IgG1 protein) with and without surfactant poloxamer P188 (Kolliphor ®, Sigma-Aldrich) in buffered L-histidine/L-histidine HCl solution. Surface tension, neutron reflectometry, and interfacial shear rheology are used to characterize the adsorbed mAb interfacial layer with and without P188 along with the consideration of order of addition. Further, we study the effects of a controlled deformation history of the air-water interface using a novel interfacial rheometer (Quadrotrough (Rev. Sci. Inst. 2022, submitted) which enables both pure dilatation/compression and pure shear deformations at air-water interfaces. We observe that NISTmAb interface exhibits a strong gel-like network that adsorbs as aggregated antibodies on the air-water interface. P188 is often used to stabilize protein formulations and is capable of competitively adsorbing to the air-water interface to prevent NISTmAb adsorption but does not displace pre-adsorbed NISTmAb. Using the unique ability of the Quadrotrough in tandem with structural techniques, we can form robust structure-property relationships of protein-surfactant pairings to pinpoint the interfacial origins of formulation instability and provide guidance in designing stabilized formulations through excipient addition. New instrumentation combining advances in the Quadrotrough coupled with neutron reflectometry will be discussed.

This work was supported under NIST Cooperative Agreement #370NANB17H302. We acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the neutron research facilities used in this work. This work utilized facilities supported in part by the National Science Foundation under Agreement No. DMR-0944772. The statements, findings, conclusions and recommendations are those of the authors and do not necessarily reflect the view of NIST or the U.S. Department of Commerce.