Expert Insight: Is protein sample preparation taking too much time in your lab?

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Donna Chen, Unchained Labs

Conventional buffer exchange methods can take a long time to complete, be labor-intensive and difficult to manage in large numbers. In this on-demand SelectScience^® webinar, Donna Chen, from Unchained Labs, discusses how Big Tuna, a fully automated buffer exchange platform, is designed to address these challenges.

Catch up on this webinar to learn how Big Tuna can benefit multiple applications including concentrating dilute proteins after purification, biologics formulation development and protein cleanup after labeling. 

Think you could benefit from this webinar, but missed it? You can now watch it on demand at a time that suits you and find highlights from the live Q&A session below>> 

Q: Can I use parts of a plate in a single run, or do I have to use the whole thing?

DC: Yes, you can use partial plates when you're running the Big Tuna. All you need to do is set up the run on the part of the plate you want to use, the unused wells you can save for the next run – no problem.

Q: Can you run samples at different viscosities or concentrations at the same time? 

DC: Batching similar viscosity and concentration samples together in the same plate will always run the most efficiently. Since this is not predictable or always known a priori, Big Tuna can handle samples with different viscosities and concentration in the same run with its smart algorithm that automatically adjusts pressure duration and cycle numbers to compensate for variations.

Q: When the plates are pressurized, does it always use the same pressure, or can you tune the applied pressure? 

DC: Big Tuna always pressurizes at 60 psi, for the entire plate and applies this uniformly across every well. However, it does adjust the amount of time it pressurizes based on the measured flow rate.

Q: How can it handle samples with volumes over the maximum volume, for example, 25 mL?

DC: The Unfilter 24 has a maximum capacity of 8 mL. In this case, the best recommendation would be to split the volumes into four different wells at 6.2 mL each. Then go ahead with the buffer exchange and concentration and pool the sample back together at the end of the process. 

Q: Is the protein concentration monitored by UV in Big Tuna?

DC: Big Tuna does not monitor the concentration of protein but instead calculates the concentration based on the initial protein concentration the user input and the final volume measured by Big Tuna.

Q: How long does it take for Big Tuna to finish buffer exchange for one plate?

DC: Buffer exchange completion time is dependent on the protein concentration, buffer components, sample volume, and user-defined parameters, and these four things impact the total run time. As a rule of thumb, the less concentrated the protein is, the faster the buffer exchange. Our data show that, for example, if you have 1 mg/mL IgG exchanged at a volume of 450 µL, it can take as little as one hour, but the same experiment with 1 mg/mL IgG at a volume of 4 mL per well may take about four hours to run — it is concentration, volume, parameter setting, and buffer-component dependent.

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