Shear flow during reciprocal shaking does not disrupt protein films at the solid-liquid interface.

Area of Science:

• Biopharmaceutical development
• Protein science
• Chemical engineering

Background:

• Protein aggregation is a significant hurdle in biopharmaceutical manufacturing.
• Mechanical stresses like shaking induce aggregation via interfaces.
• The specific roles of air-liquid, solid-liquid, and air-liquid-solid interfaces in shake-induced aggregation are not fully understood.

Purpose of the Study:

• To systematically investigate the contribution of individual interfaces to protein aggregation during shaking.
• To differentiate the impact of solid-liquid interface shear flow versus other interfaces.

Main Methods:

• Computational fluid dynamics (CFD) modeled shear rates at the vial surface during shaking.
• Controlled experiments applied shear flow to protein-coated glass vials in buffer (eliminating air-liquid interfaces).
• Shaking experiments with headspace assessed air-liquid-solid interface contributions.

Main Results:

• No significant protein aggregation increase was observed at the solid-liquid interface under shear flow conditions.
• The air-liquid-solid interface did not contribute measurably to protein aggregation.
• The air-liquid interface was identified as the primary driver of protein aggregation during shaking.

Conclusions:

• The air-liquid interface is the dominant factor in shake-induced protein aggregation.
• Solid-liquid shear flow has a minimal role in disrupting protein films and causing aggregation.
• Findings provide crucial insights for optimizing biopharmaceutical formulation and handling to minimize aggregation.