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 Sigma Aldrich, EX-CELL® Antifoam, p/n 59920C

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.

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

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.

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 and 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.

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.

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% Sigma Aldrich, EX-CELL® Antifoam, p/n 59920C can also be used. Either of these methods usually will work to reduce foaming and restore high culture viability.

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.

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.

We see that there are three classes of transfection reagents that have varying efficiencies:

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.