Why Morphology Matters in Biologics
In biologic drug development, particle analysis isn't just about counting—it's about understanding type and source. This distinction impacts patient safety, regulatory compliance, and process optimization. Traditional methods, such as light obscuration (LO) and membrane microscopy (MM), fall short in particle identification. Flow Imaging Microscopy (FIM), as implemented in FlowCam, bridges this gap with morphology-based detection and high-throughput imaging - distinguishing silicone oil droplets from protein aggregates in a single run.
Why Particle Classification Matters
Subvisible particles can originate from multiple sources:
- Inherent particles: particles derived from the drug substance, such as protein aggregates
- Intrinsic particles: particles derived from formulation components (e.g., fatty acid particles), container-closure (e.g., silicone oil droplets), or the manufacturing process (e.g., stainless steel particles)
- Extrinsic particles: contaminant particles such as fibers and bacterial contamination
Accurate classification is essential for risk assessment and regulatory compliance. As Austin Daniels, PhD, explains:
"Knowing whether a particle is a protein aggregate or silicone oil droplet changes how you respond. One may indicate a formulation issue; the other might point to packaging".
Check out the full interview on Spectroscopy with Dr. Austin Daniels, PhD.
Regulatory Context: USP <1787> and USP <1788>
To ensure consistent evaluation of subvisible particles, regulatory standards from the United States Pharmacopeia (USP) outline expectations for distinguishing and characterizing subvisible particles in biologic particles.
USP <1787>: emphasizes distinguishing extrinsic and intrinsic particles from inherent protein aggregates
USP <1788>: recognizes FIM as a complementary technique to LO and MM for particle source identification
Unlike MM, which requires buffer removal and can distort results, FlowCam analyzes samples directly in their native buffer, preserving integrity and avoiding measurement bias.
For more information about USP standards, please refer to our white paper.
USP Reference Standards for Subvisible Particulate Matter
Silicone Oil vs Protein Aggregates: Why it Matters
For injectable biologics, differentiating these particle types is especially critical for patient safety, and FlowCam's morphology data makes this distinction clear:
| Particle Type | Safety Concern | Morphology |
| Protein Aggregates | Linked to immunogenic responses | Irregular, amorphous, and textured |
| Silicone Oil Droplets | Likely less harmful, but still a product quality concern | Round and circular |
These differences can be identified visually or through the use of automated classification tools, including AI software.
Additional advantages of Flow Imaging Microscopy include:
- Low sample volume: requires as little as 100 μL, ideal for scarce biologic formulations
- Viscosity robustness: obtain accurate particle concentration and composition measurement, even in viscous samples
- Scalability: supports both early development and commercial QC workflows
Compliance, Safety, and Process Optimization
Integrating morphology-based particle analysis into biologics workflows provides multiple benefits:
- Compliance: meets USP <1787> and <1788> expectations for particle source classification
- Improved patient safety: accurate identification of protein aggregates and other potentially harmful particle types
- Process optimization: reveals dominant particle types, guiding targeted mitigation strategies
Why FlowCam Stands Out
FlowCam delivers a single, efficient solution for particle size, concentration, and morphology—preserving particles in their native state and avoiding artifacts introduced by traditional methods such as MM. For biologics developers, morphology-based particle analysis with FlowCam isn’t just a differentiator—it’s an essential tool for ensuring safety, compliance, and efficiency.
Curious to learn more about subvisible particle analysis? Download our eBook offering insights into the latest flow imaging microscopy applications for identifying subvisible particles, including relevant USP chapters.
Advancing Subvisible Particle Analysis: Flow Imaging Microscopy
