Protein Aggregation Size and Concentration Analyzer
The new PSS AccuSizer FX Nano system is a single particle optical sizing system (SPOS) designed to work at the smaller particle sizes and at higher concentrations required to quantify protein aggregation. This is accomplished by using two sensors; the FX Nano sensor to measure from 0.15-0.6 µm and the LE400 sensor to measure from 0.5-20 µm. The new FX Nano sensor uses a focused beam to reduce the total volume inspected, thus increasing the concentration limit of the sensor. This sensor is coupled with the SIS sampler, modified to allow for sample volume as low as 250 µL. Aggregated proteins are sized and counted one at a time using the two sensors to cover the entire dynamic range. This is an ideal system to measure subvisble particles for therapeutic injections following the USP <787> test protocol.
Example 1: IgG protein (1%) was prepared and then allowed to aggregate. The sample was measured before (blue) and after (red) filtration (0.2 µm filter). The concentration reduced from 9.7 to 3.1 x 108particles/mL after the filtration step. The decrease in the tail of aggregated proteins is clearly visible and easily identified by the AccuSizer FX Nano system.
Example 2: IgG protein was measured before and after incubation. The results show how the tail of aggregated protein changed with time.