The sizing and counting of subvisible particles in the size range 2 μm to 100 μm is an essential component of product quality assurance in therapeutic protein formulations. Particles may originate from aggregation of the protein, or from non-proteinaceous sources such as the packaging, silicone oil, and other contaminants. Of particular concern are particles from protein aggregates as their presence can contribute to an immunogenic response as well as affect the potency of a drug. Characterization tools for particles in this size range include light obscuration (LO), flow microscopy (FM), and electrical sensing zone (ESZ). While generally these methods agree with one another when measuring standard reference spherical beads, reports on measurements of particles in protein formulations often provide significantly different results. To resolve these discrepancies, this project uses a microfluidic approach to characterize particles simultaneously using two or more techniques, for example FM and ESZ. Lithographically designed particles will be used as models to clarify particular aspects of the measurements.
The results of this work should provide instrument manufacturers with data, methods, and algorithms for enhancing the clarity and accuracy of information their instruments provide to their customers. Users of these instruments (pharma companies) and regulators, will have better understanding of the factors to consider when comparing results on different types of instruments. In addition, the research may lead to new microfluidic instruments that provide more comprehensive data using smaller sample sizes.
The primary objective is to identify the factors that influence the parameters reported by different measurement techniques. Simultaneous measurement of particle morphology, electrical signal, fluorescence, etc. on each particle produces a data set that will facilitate comparison of results using these techniques separately. In addition, the research will test the capabilities for microfluidics to perform comprehensive subvisible particle analysis on small samples.
A microfluidic device consisting of a microchannel with four electrodes is mounted in a fluorescence/optical microscope. The microscope is outfitted with fast, computer-controlled cameras (both optical and fluorescence) and with a bright 480 nm light emitting diode(LED). The microchannel features an electrical sensing zone, between two electrodes, where the channel width is reduced.
Michael Carrier -IFPAC 2013 Session on Particle Characterization Engineered Particles for the Characterization of the Performance of Protein Particle Analysis Instruments, Jan. 25.
WCBP: 17th Symposium on the Interface of Regulatory and Analytical Sciences for Biotechnology Health Products, Jan. 29-31. "Comparison of particle analysis tools using engineered particles as simulants for protein aggregates"
Invited talk at 5th Annual The Bioprocessing Summit "Comparison of Methods for Characterizing Subvisible Particles Using Manufactured Particles and Microfluidics" Boston, MA, Aug. 21.
Michael Carrier-Invited IBC's 17th Annual Well Characterized Biologicals, October 21-22, "Understanding the response of particle detection instruments to non-spherical particles" 2013