Aggregation in protein solution based therapeutics can have deleterious effects such as inducing a response from the immune system.  Measurement of these aggregates has been possible for larger aggregates, but smaller aggregates in the range of 0.150 nm to 2 microns have been difficult to quantify.  Dynamic Light Scattering (DLS) techniques can demonstrate the existence of aggregation, but does not provide and information on the absolute concentration of the aggregates. Single optical particle sizing (SOPS) can measure both the size and concentration of aggregated proteins and is becoming a preferred technique for this application.

The FX Nano SIS system is specifically designed to measure protein aggregation. The two sensor approach covers the widest dynamic range available - from 0.15 - 150 µm. Sample volumes are as small as 150 µL and the sample is recovered after the measurement. This system meets all requirements of USP<787> and can also measure submicron particles down to 150 nm.  The particle size and count results are displayed in up to 64 size channels.

The results shown below show how the size and concentration of aggregated protein greatly reduced after filtration and increased after incubation.

Aggregated protein before and after filtration









Incubation time in hours: 0 blue, 1 red, 6 black 









Visit the Document Download Center to download Application Note 708 on Protein Aggregation