Micro-Flow Imaging™ (MFI) /
Flow imaging microscopy
Coriolis Pharma has been the first contract service provider worldwide to offer Micro-Flow Imaging™ (MFI) analysis to GMP level on a fully qualified instrument as an orthogonal technique to the compendial light obscuration method (USP <788>) for subvisible particle analysis.
Flow imaging microscopy (instruments are for example Micro-Flow Imaging™ or FlowCam™) is a method that quickly has found wide application in the biopharmaceutical industry over the last several years and - although still new today - it is relatively well established. In this technique bright-field images are captured in successive frames as a continuous sample stream passes through a flow cell positioned in the field of view of a microscopic system. The digital images of the particles present in the sample are processed by image morphology analysis software that allows their quantification in size and count.
Flow imaging microscopy allows not only enumerating the subvisible particles present in the sample, but also (visual) examination of the images of all captured particles. The latter capability gives an inherent advantage of this method over the traditionally used light obscuration, as it may allow identification of substances commonly present in biopharmaceuticals like silicone oil droplets, for example. A representative publication on differentiation of protein particles and silicone oil droplets has been published recently, using both MFI and Archimedes (RMM) in a comparative study.
One additional benefit that flow imaging microscopy provides over light obscuration is the fact it often provides a better capability to detect particles in protein formulations. The discrepancy in particle counts often found between the two techniques is largely dependent on shape, morphology and translucency differences of the proteinaceous particles and is particularly pronounced in the 1-10 μm size-range. More details can be found in one of our recent publications (How subvisible particles become invisible—relevance of the refractive index for protein particle analysis)
The two flow imaging microscopy systems (Protein Simple MFI-5200 (GMP compliant) and Brightwell DPA-4100) used at Coriolis Pharma are covering the size range of 1 to 200 µm. Although Micro-Flow Imaging is still used predominantly in R&D, it is a method which finds increasing use in the routine practice and in a confirmatory sense for regulatory submissions.
Four currently available Flow imaging microscopy systems MFI DPA-4100, MFI-5200, FlowCAM VS1 and FlowCAM PV have been evaluated at Coriolis for their suitability in protein particle analysis and our findings are summarized in a recent publication ("Flow imaging microscopy for protein particle analysis - a comparative evaluation of four different analytical instruments").
Need to know:
Required sample volume 0.5 - 1.0 ml per sample (single analysis)