Quantitative laser diffraction method for the assessment of protein subvisible particles.

Area of Science:

• Biopharmaceutical analysis
• Particle characterization
• Analytical chemistry

Background:

• Laser diffraction (LD) is a common technique for particle size distribution analysis.
• Accurate quantification of subvisible particles (SVPs) is crucial for biopharmaceutical quality control.
• Existing methods may face challenges in precisely quantifying protein particles within the 0.2-10 μm range.

Purpose of the Study:

• To evaluate a quantitative laser diffraction (qLD) system for the precise measurement of protein particle sizes.
• To determine the capability of qLD in quantifying subvisible particles (SVPs) in the 0.2-10 μm diameter range.
• To assess the impact of different stress conditions on protein particle formation and quantify them using qLD.

Main Methods:

• Utilized a quantitative laser diffraction (qLD) system incorporating deconvolution analysis.
• Validated qLD performance using silica beads with known sizes and refractive indices similar to proteins.
• Applied qLD to analyze protein particles in stressed intravenous immunoglobulin samples, using experimentally determined refractive indices.

Main Results:

• qLD accurately estimated concentration distributions for silica beads (0.2-10 μm), demonstrating linearity and quantification in mixed-size populations.
• The system successfully quantified protein particles in stressed intravenous immunoglobulin samples.
• Protein particle concentration distributions varied between stir- and heat-stressed samples.
• qLD-derived number concentrations correlated well with results from flow microscopy.

Conclusions:

• Quantitative laser diffraction (qLD) is a reliable method for the quantitative assessment of protein particle sizes, particularly for subvisible particles (SVPs) from 0.2-10 μm.
• qLD provides accurate and comparable results to established methods like flow microscopy for protein aggregate quantification.
• This technique offers a valuable tool for monitoring protein aggregation and ensuring the quality of biopharmaceutical products.