Nuclear Magnetic Resonance Study of Monoclonal Antibodies Near an Oil-Water Interface

TL;DR

This study uses localized NMR spectroscopy to investigate how monoclonal antibodies interact with oil-water interfaces, revealing structural and dynamic changes that could impact their stability in therapeutic formulations.

Contribution

It introduces a novel application of spatially resolved NMR to analyze monoclonal antibody behavior at interfaces, providing insights into their structural and dynamic alterations near oil-water boundaries.

Findings

Adsorption of mAb to oil-water interface confirmed by surface tension measurements.

Spectral line broadening indicates restricted molecular motion near the interface.

Reduced diffusion coefficient suggests interaction and exchange between bulk and interfacial mAb.

Abstract

Monoclonal antibodies (mAb) represent an important class of biologic therapeutics that can treat a variety of diseases including cancer, autoimmune disorders or respiratory conditions (e.g. COVID-19). However, throughout their development, mAb are exposed to air-water or oil-water interfaces that may trigger mAb partial unfolding that can lead to the formation of proteinaceous aggregates. Using a combination of dynamic surface tensiometry and spatially resolved 1D 1H NMR spectroscopy, this study investigates if adsorption of a model IgG2a-\k{appa} mAb to the oil-water interface affects its structure. Localized NMR spectroscopy was performed using voxels of 375 um, incrementally approaching the oil-water interface. Dynamic interfacial tension progressively decreases at the oil-water interface over time, confirming mAb adsorption to the interface. Localized NMR spectroscopy results indicate that, while the number of mAb-related chemical resonances and chemical shift frequencies remain unaffected, spectral line broadening is observed as voxels incrementally approach the oil-water interface. Moreover, the spin-spin (T2) relaxation of the mAb molecule was measured for a voxel centered at the interface and shown to be affected differentially across the mAb resonances, indicating a rotational restriction for mAb molecules due to presence of the interface. Finally, the apparent diffusion coefficient of the mAb for the voxel centered at the interface is lower than the bulk mAb. These results suggest that this specific mAb interacts with and may be in exchange with bulk mAb phase in the vicinity of the interface. As such, these localized NMR techniques offer the potential to probe and quantify alterations of mAb properties near interfacial layers.