Re-cycling Electroporation Cuvettes
If you have ever worked out the price of an electroporation cuvette you will realise that, at several dollars each, they are worth recycling.
Accounts on how amenable electroporation cuvettes are to recycling vary, but I find that as long as you treat them well it is possible to use single cuvette many times.
It’s the metal parts of the cuvette you need to worry about the most - you need to get them clean of DNA and cells and dry again quickly to prevent corrosion.
So the key is to wash and dry as soon as possible after transformation.
My protocol is to wash with water first to clear away most of the residual cells/DNA, then treat briefly with HCl to destroy any remaining DNA - which you obviously don’t want hanging around the next time you do a transformation - then wash with 70% ethanol. The ethanol rinses away the HCl and sterilises the cuvette but because it is volatile it makes it easy to dry the cuvette in air.
So the protocol in detail is:
1. Rinse the cuvette five times with purified water. Ensure, especially with 1-2mm gap cuvettes that the chamber is fully washed out in all washing steps.
2. Fill the cuvette with 0.2M HCl and allow to stand for 10 minutes (but no longer as this will promote corrosion).
3. Rinse the cuvette five times with 70% ethanol, again ensuring the chambers are fully washed.
4. Under a sterile hood if possible, decant the ethanol and use a pipette (or syringe and hypodermic needle for small gaps) to remove as much residual ethanol as possible.
5. Air dry for 60 minutes, then replace the cap.
…and now your cuvettes are ready to go again.
molecular biology
We also wrap them in foil (without the caps-which we wash and rinse and dry in hood as you describe)and autoclave.
We keep track of the number of times they are re-used (indelible marker) and we don’t usually exceed 4 repeats.
Thanks Wendy - I didn’t realise that cuvettes were autoclavable. That sounds like an interesting alternative
Drying upside down on UV table will help destroying any DNA or cells, could it hurt the cuvettes?
Hi Kurt. That’s a good idea.
UV can degrade some plastics, but I am not sure whether the plastic used in the cuvette would be affected.
Hi, Nick
Thanks a lot for the posting and it’s quite helpful!
I used to wash the used cuvettes briefly by Milli-Q water and absolute/70% ethanol, then soak them in 70% ethanol for several days, and then soak them in Milli-Q water for 2-3 days (changing the water daily), then dry them in air until all water drops are gone.
Those cuvettes cleaned in this way works OK, though the metal parts of some cuvettes turn black (probably because of the oxidation during the long time soaking) and their electroporation time constants are normally 0.2-0.3 millisecond higher than a new cuvette (under 1.8kV).
I will probably add the HCl treating step to my protocol and see how it goes.
A little correction to my last reply:
The electroporation time constant for the used cuvettes are normally 0.2-0.3 ms SHORTER than a new one.
Sorry for any inconvenience.
Our lab also re-uses cuvettes. Just rinse 3 times with DI water and 3 times with 70% EtOH. Set them upside down on a kimwipe to dry. It works great. No need for UV or autoclaving. Keep it simple!
Loralyn:
I would be a bit worried of DNA contamination!
I’ve never electroporated bacteria. Everyone in my lab is telling me that with these modern 10-9 bacteria there is no need to electroporate any more. I wonder if you agree with this?
Max - it depends on what you are trying to do. If you are doing routine cloning then chemically competent cells might be enough but if you want to build libraries then you want the maximum efficiency possible.
Also, electroporation is faster than chemical transformation (no need for the pre-incubation step), although the cuvettes and the electroporator itself are expensive.
Max:
There are other bacteria then E. coli!