Integrated Method Advances Biotherapeutic Characterization

Bio‑Techne Corporation announced a first‑of‑its‑kind integrated workflow for the characterization of charge and size variants in bispecific antibodies and biosimilars. 

By combining R&D Systems MauriceFlex™ imaged capillary isoelectric focusing (icIEF) fractionation system with Refeyn’s TwoMP mass photometry platform, researchers can directly correlate charge heterogeneity with molecular weight and aggregation at single‑molecule resolution in a streamlined four‑hour workflow. 

Bispecific antibodies are among the fastest-growing classes of biotherapeutics, but their structural complexity makes thorough characterization challenging. Incomplete characterization can delay development, increase manufacturing risk, and lead to costly late‑stage failures. 

The MauriceFlex™ system delivers high-resolution separation and fractionation of charge variants, a capability increasingly expected in regulatory submissions. However, analyzing the size and aggregation of individual charge fractions has historically been difficult due to the large sample requirements of traditional methods. 

The integrated workflow addresses this challenge directly by pairing icIEF fractionation with mass photometry. Charge variants are first separated using MauriceFlex™, then analyzed on Refeyn’s TwoMP platform, which requires only nanogram‑level sample and reveals size distribution and aggregation at single‑molecule resolution. 

Together, the technologies enable direct characterization of aggregation and size within icIEF-resolved charge variants-an insight not accessible with standalone methods-reducing reliance on multiple tests and enabling faster, more efficient process development. 

“Bispecifics are the fastest growing segment within next‑generation antibodies, but they are very difficult to characterize. This approach directly addresses one of the biggest challenges by combining icIEF fractionation with mass photometry. Researchers can now interrogate charge and size variants together in a single workflow,” said Gerry Mackay, CEO of Refeyn.

“Our customers are under intense pressure to develop and manufacture increasingly complex biologics faster and more efficiently. Enabling deeper characterization with less sample helps them reduce risk, control costs, and make better decisions earlier in development,” said Will Geist, President Bio‑Techne  Protein Sciences Segment. 

In a joint webinar, scientists demonstrated the workflow using Mosunetuzumab‑axgb and a biosimilar, tracking size-related changes in the molecule across charge variant fractions under multiple conditions. An application note “Characterizing charge and size variants of bispecific antibodies by icIEF fractionation and mass photometry,” with full findings is also available.

The workflow will also be presented at the American Society for Mass Spectrometry (ASMS) conference, taking place May 31 – June 4, 2026, in San Diego. 

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