In an Ask-the-Expert webinar on 4 December 2018, Jason Chiu (product marketing scientist at JSR Life Sciences) introduced the Chromassette chromatography cassette platform. This stackable, modular technology and resin-support device presents a productive and disposable process that can scale to any volume using any resin. An internal scaffold provides a uniquely supported resin bed, and the system is fully interchangeable with conventional column formats.
The Chromassette platform offers linear scalability, superior pressure-flow properties, high-productivity separations, and rapid and convenient turnover. The technology comes as self-contained individual cassettes with 4-mL volume and 6-cm bed height or 13 mL and 20-cm bed height. JSR Life Sciences is working on a 1-L cassette with a 20-cm bed height.
“Wall effect” is a well-known phenomenon in conventional chromatography columns. As column diameters widen, resin support weakens because the wall effect decreases. However, this is not an issue in the Chromassette system because its internal scaffold is filled with thousands of pockets that serve essentially as miniature columns. So the wall effect remains constant even as cassettes are stacked together. They can be scaled up linearly. Experiments have showed that as flow velocity increases, delta pressure increases linearly in cassettes but exponentially in columns.
Modern resins use large beads with small pore sizes that give a moderate dynamic binding capacity (DBC), slow binding, and moderate productivity. Without the pressure-flow limitations of columns, Chromassette cassettes allow for fast binding and high DBC (trademarked by SPF Technologies as Hyper-Productive Processing).
Questions and Answers
What resins have been packed in Chromassette cassettes? We have packed 15–20 size-exclusion, cation-exchange, anion-exchange, affinity, mixed-mode, and hydrophobic-interaction chromatography resins from different sources and manufacturers into 4-mL and 13-mL cassettes. We continue to explore new resins and are open to working with new companies.
Can you explain the scale-up strategy? How do you increase column diameter with constant bed length? At small scales, we have stacked four cassettes together such that their pressure-flow properties, elution volumes, asymmetry, HETP (height equivalent to a theoretic plate), and the DBC are comparable. We are testing 1-L prototypes and stacking four of them together for the same tests. So far, there are no issues.
How is the performance in terms of both HETP and real case studies purifying proteins from crude starting materials? HETP depends on the resin. In general, the reduced plate heights for almost all resins we have packed are >2,000 N/m. We’ve been working mainly with purified protein to run our DBC tests. In one case study, we packed Macro-Prep SP resin in both a column and a 6-cm bed-height cassette and compared breakthrough, elution, and salt-gradient profiles — all similar. The only difference was pressure flow, which was much higher for a column run at 200–2,000 cm/hour.
Does bead size affect cassette performance? Because of the wall support, a Chromassette resin bed is much more stable than that of a column, even with smaller resin beads. In studies with prototype 30-μm JSR A3 resin beads, we found that pressure-flow properties remain unchanged. It’s still a linear relationship. As you decrease resin bead size, DBC will go up. We obtained 200 g/L/hour productivity.
Do you plan to offer smaller scale cassettes that can stack like 1-L cassettes? We are launching 20-cm and 6-cm cassettes commercially for process development and scale-down work. These cassettes will be self-contained and won’t be stackable. Currently, we haven’t planned for development of other smaller scale cassettes that can stack like the 1-L cassettes.
We gauge market demand and needs before deciding on cassette sizes. After 1 L, we are most likely to go with a 5-L cassette, a handful of which could be large enough for a small to mid-scale clinical operation using resin volumes of 20–40 L. Larger cassettes (e.g., 10 L) could be useful, but that size brings ergonomic considerations for safe handling. Design would become the critical factor in scaling to that size.
The full presentation of this webcast can be found on the BioProcess International website at the link below.