By Douglas T Gjerde
PhyNexus is a life science company dedicated to producing tools which increase research and development productivity. Dual Flow Chromatography was developed by PhyNexus to purify proteins and plasmids that dramatically improve R&D productivity.
Chromatographic separations concepts and principles are used in dual flow chromatography, but in a novel manner using pipette tip columns. The chromatography functions with off-the-shelf liquid modified pipette tips in a 96-channel pipetting head. The pipette tip columns can be used on any of the leading robotic liquid handling instruments.
At the end of the pipette tip, there is a column bed. The bed is contained by a top and bottom screen of woven mesh. Each column is available in 200 µL and 1000 µL pipette tip sizes and 5 different column bed sizes ranging from 5 µL to 160 µL. Virtually any affinity resin type can be packed into the column format.
In Dual Flow Chromatography, the sample and mobile phase enter and exit the column tip. All flow is back and forth flow. This includes sample loading, column washing and elution, and recovery of the desired material. The columns are miniaturized and operate in parallel up to 96 at a time with automation.
Biomolecules interact slowly with these affinity columns – due to their slow kinetics of capture. Proteins purified from the columns are high purity and active and non-agglomerated products. This is very difficult to do because proteins denature or agglomerate very easily. Plasmids (transfection grade) are also purified by this technology.
The time of interaction of biomolecules with the column may be insufficient and difficult to control (the flow is not reproducible). The problem is exasperated with small columns. In dual flow chromatography, channeling does not matter, but the kinetics of interaction do. With back and forth flow, there are multiple chances of interaction and it becomes impossible for interaction not to be completed at the end of the process. Even separation beads along the walls of the column, where channeling can occur, capture sample.
With dual flow chromatography on a pipette tip column: time of interaction is easily controlled, complete interaction of the analyses with the column can be achieved, sample is brought to all of the resin functional groups, there are multiple chances of interaction of sample molecules to the resin functional groups, and interaction time is sufficient to drive the equilibrium of sample and column interaction to completion.
Due to back and forth flow, the column interaction is driven to completion or to equilibrium, and separations are: Independent of flow rate, Independent of column diameter, Independent of how well the column is packed, Independent of amount of resin in the column, and only dependent of column and mobile phase chemistry.
The chromatography is parallel, multivariable and scalable. In one set of experiments, 96 sets of separation conditions were studied. In the 8 conditions, each of capture, wash and elution, the conditions were varied with 4 different antibody proteins and captured on a Protein A affinity column. The yield and agglomeration were measured.
The results show the importance of doing these experiments. It proves that you can achieve high yield, but poor quality protein. You can get high quality protein, but poor yield. Only around 10 of the conditions studied gave both high yield and high protein quality. Frankly, not all researchers will perform this study on a new protein or resin because it is so difficult. With this technology, multi variant chromatography is very easy.
This technology has been adapted for all common robotic companies. Virtually any robotic liquid handler is easily turned into a high throughput, 96 in parallel liquid chromatograph.
Why is dual flow chromatography different?
Well for one thing, there is No effect of slow capture kinetics; it’s irrelevant
There is no effect of how well the column is packed; it’s irrelevant
What does it allow us to do?
Miniaturize culture and sample (plate format used)
We can automate.
We can process samples in parallel.
Purifications conditions can scaled. Scaling is important because conditions developed for a process are always scaled.