Application of Microfluidic Modulation Spectroscopy for Simultaneous Structural and Thermal Stability Analysis of Commercial Monoclonal Antibodies under Varying Formulation Conditions

Abstract

This study, by the National Institutes for Food and Drug Control of China, demonstrates the Microfluidic Modulation Spectroscopy (MMS) as a powerful tool for assessing simultaneous structural and thermal stability analysis of nine commercial monoclonal antibodies (mAbs) across various formulation conditions. The protein secondary structure is an important product quality attribute (PQA) that governs the structure–function relationship, safety, and efficacy in protein therapeutics.

These findings reveal that, comparing samples in original formulation buffers, diluted formulations, and phosphate-buffered saline (PBS), MMS is able to detect subtle but reproducible differences in secondary structure that were not easily observable using traditional techniques such as FTIR or circular dichroism. Thermal ramping MMS revealed distinct melting behaviors for different mAbs, confirming that even small structural changes can significantly impact thermal stability and unfolding pathways. Notably, diluting mAbs in their native formulation buffers did not alter structure, while reconstitution in PBS led to detectable shifts. These results underscore the high sensitivity, repeatability, and utility of MMS as a powerful biophysical tool for higher-order structural (HOS) characterization in mAb development and quality control.

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