What have people done successfully to change vessels from Spinner flasks & Roller bottles to Optimum Growth™ Flasks (patented)?
Cells adapted to Spinner Flasks and Roller Bottles can be easily transitioned to Optimum Growth™ Flasks. Adjusting existing cultures from different formats to Optimum Growth™ Flasks requires reducing the volume and shake speeds of the first 1-2 passages*. The addition of up to 1% of surfactant** to the media may be needed due to spinner flasks and roller bottles having lower shear than shake flasks. Once the cells have adjusted to the shake flasks, recommended speeds will work well.
* See chart with fill volumes and shake speeds.
** ThermoFisher Pluronic, p/n 24040032 or MilliporeSigma Simethicone, p/n 59920C
Why do Optimum Growth™ Flasks work better than other disposable flasks (non-baffled or baffled) for mammalian cell lines (CHO, HEK293, etc.) & insect cell lines (SF-9, SF-21, High Fives, Trichoplusia ni)?
Optimum Growth™ Flasks are patented shake flasks designed for high aeration and low shear. Optimum Growth™ Flasks achieve high aeration due to a unique baffle design that has been optimized for mammalian and insect cell lines. They provide enhanced gas exchange with low shear mixing, which can increase yields significantly when combined with both nutrient enriched media and proper pH balance.
What clamps and shakers work best with the Optimum Growth™ Flasks?
Optimum Growth™ Flasks are designed to shake in 1″ or 2″ orbit shakers. Sticky tape or rug gripper pad is recommended for under 170rpm. Our 125mL, 250mL and 500mL flasks will work with standard shake flask clamps. See our clamp cart for specific clamps
Are the Optimum Growth™ Flasks single use?
Yes, the Optimum Growth™ Flasks are designed for single use and are not autoclavable. They are competitively priced compared to disposable bioreactors or shake flasks from other manufacturers.
What are the Transfer Caps that go along with the Optimum Growth™ Flasks?
Inversion & Bidirectional Optimum Growth™ Transfer Caps (patented) allow for a quick stress free cell transfer between flask and downstream vessel (Optimum Growth™ Flasks, cell culture bags, bioreactors, etc.). Inversion Transfer Caps use the power of gravity to facilitate transfer, thus maintaining higher culture viability than pumping methods. Bidirectional Transfer Caps use a standard pump to transfer culture and/or media; come in a wide variety of tubing sizes. Transfer Caps come with multiple types of end fittings; quick connect, luer lock, and tube fusing. See our transfer caps page For more details
High cell death and a large amount of foam and/or cell clumping issues?
Cell death and foaming in the Optimum Growth™ Flasks is usually due to cell shearing. Adding up to 1% surfactant will reduce foaming and increase cell viability without stressing the cells.
How can you best use media from ThermoFisher such as F17 and its derivatives?
FreeStyle™ F17 Expression Medium contains lower amounts of pluronic than other comparable medium. Cells grown in this media may experience more shear stress due to the lower amount of surfactant. To avoid this, add in additional pluronic (ThermoFisher p/n 24040032). The recommended range of pluronic is 0.05 gm/L to 0.2 gm/L. Up to 1% simethicone from MilliporeSigma (p/n 59920C) can also be used. Either of these methods usually will work to reduce foaming and restore high culture viability.
What can I do if the doubling time for my cell culture is longer than expected when using the Optimum Growth™ Flasks?
This varies between cell types and strains, as well as with environmental conditions. If the doubling time for your culture is taking longer than expected or desired in the Thomson Optimum Growth™ Flasks, we recommend increasing the shake speed beyond our recommended speeds by 10 to 20 rpm. The reason for the increased doubling time is that the oxygen transfer rate maybe lower with higher fill volumes, and the increase in speed will compensate for this.
Disposable shake flasks are hard to remove from the sticky pad. What do we do?
  1. Some suggestions from people who find it too sticky:
  2. Spray ethanol on the sticky pad until you reach the desired stickiness. Ethanol will lower the bonding strength, as will any alcohol.
  3. Some people use rug gripper pads on top of the sticky tape.
Which transfection reagent works best with CHO & HEK293 cells?
We see that there are three classes of transfection reagents that have varying efficiencies:
Class Example Efficiency of Transfection
Polymers PEI <65%
Cationic Liposomes Lipofectamine™ 70-95%
Electroporation Maxcyte® >96%
Polymers/PEI: The most common transfection reagent used in the market. It is inexpensive, but may not lead to as high of a transfection rate, and requires higher DNA quantities. Commonly used for all small and large scale transfections.
Cationic Liposomes/Lipofectamine™: This class of transfection reagents is highly efficient and is commonly used in CHO-S, 293F and other high titer systems. Cationic Liposomes work well with our flasks. We have seen consistent transfection with great viability from TransIT-Pro®. This used with CHOgro® from Mirus in 24 well plates (2.5mL), small scale flasks, and production in Optimum Growth Flasks (50mL-2.5L) have given scalable usable results.
Electroporation: Most often used method for large scale, >1L transfection. Unfortunately, electroporation is not as useful for multiple transfections at one time. Customer feedback shows that stabilizing the cells with a 1%-1.2% addition of surfactant (pluronic/PF68) 30 minutes after transfection leads to higher titers and viability.

Thomson Instrument Company is not affiliated with Corning Life Sciences®, ThermoFisher Pluronic, MilliporeSigma, Eppendorf®, INFORS HT®, Kuhner®, Fisher, Scientific®, VWR®, Mirus or their products