Published: December 13th, 2019 Last Modified: January 29th, 2020
Love that high transformation efficiency of electroporation, but hate throwing away cuvettes like they’re going out of style? No more! Wash those suckers out and save some serious money.
Electroporation is used for when high transformation efficiencies are needed, or you are transforming niche organisms that aren’t amenable to heat shock methods. The technique works great and it’s often much faster than the good ole’ heat shock.
Unfortunately, electroporation cuvettes aren’t the cheapest “disposables”, ranging anywhere from 5-10$ a piece, sometimes even more. There are days where I can easily smash through 20-30 of these transforming agrobacterium. Not that sustainable, and I’d rather spend the money on some Q5 polymerase any day.
So, what are our goals after using a cuvette?
1) Wash away and destroy left over cells
2) Destroy any leftover plasmid DNA
3) Leave a sterile, clean cuvette for re-use
What do we need?
1) Some decontamination mix
2) MilliQ water in a squirty bottle
3) 70% EtOH in a squirty bottle
4) 100% EtOH in a squirty bottle
5) A little brushy brush that can get up in there (Amazon Affiliate Link) (?)
Like those labels?
1) Brother PTD600 label maker (Amazon Affiliate Link) (?)
2) Off-brand labels (Amazon Affiliate Link) (?)
So, step one, decon those suckers. Take off the lids and throw the cuvettes in a container filled with decon mix, swirl them around so the decon gets down into the gap of the cuvettes. Let them sit for 5 minutes.
Take the cuvettes out and observe the hydrogen being evolved from the aluminum plates in the cuvette. This is the NaOH in the decon mix dissolving some of the aluminum. Don’t worry, it doesn’t harm the cuvettes, it’s just how you know it’s getting nice and clean. You are stripping off a few molecules of aluminum, after all.
Ooooo…pretty. Okay, don’t leave them soaking in decon for too long though (i.e. overnight). Don’t ask me how I know. Next, give em’ a little scrub with a wee brush, this is possibly optional though, I’m just paranoid.
Okay, goals #1 and #2 are done, there isn’t anything left of the cells or plasmids. Now we need to make sure all the decon mix is washed out of the cuvettes. This is absolutly critical and the most difficult part, squirt the best quality water you have into the gap of the cuvette, do this 5-10 times, shaking out the cuvette into the waste each time. It takes a bit of practice but you should be able to flick out all the liquid when you’re dumping it. Get the outside too while you’re at it.
Got all the decon out? You sure? Good! Now follow up with two rinses of 70% EtOH, then two of 100% EtOH. You’re not really using the ethanol for sterilizing here, more to displace and remove the leftover water. After you’re done place the cuvette upside down on a paper towel to soak up the excess ethanol.
Almost done! How about those lids? They’re easier. Pour away the decon, do it over a sink or use a funnel. Rinse with water and ethanol. Place on towel along with the cuvettes. After 10-15 minutes, turn the cuvettes over to let any left over ethanol evaporate. Let dry for another 30 minutes or so, just to be sure.
Put the caps back on and you’re done!!! They’re ready to be re-used without fear of plasmid carryover. Don’t believe me? Give it a try yourself, follow the procedure and put some competent cells into the cuvette (without plasmid), transform and plate. If you don’t see any colonies then you’re golden!
I have re-used cuvettes 5-10 times before retiring them, although if there aren’t cracks in the plastic you can use them as many times as you like. I have seen others autoclaving their cuvettes, but that process degrades the plastic, and you can’t autoclave the caps.
For the sake of speed, I do this process in the sink and do the drying in the flow hood. If you don’t have easy access to one then leaving them out in the air is not a big deal if your lab isn’t super dusty. I just didn’t want y’all to see the state of the sink, classic misdirection.
*** As always, use your good judgement when applying any method. This will probably get the cuvettes clean enough for mammalian cells HOWEVER good luck convincing someone who has had mycoplasma contamination in their cell lines. ***
*** A user reported that ethanol induced cracking of the plastic in their cuvettes, test a small batch first before committing your whole stock. Washing with just ddH2O will work, just will dry slower ***
How do you print on yellow tape. Do u have any hack for that also ?
It’s a Brother brand label maker, got it off Amazon with knockoff brand tape, works like a hot damn.
Can you use these labels for cryovials for saving glycerol stocks or as labels on DNA tubes for -20C?
I’d trust them down to -20C, haven’t tried them at -40, -80 or ln2. Will try and get back to you.
The major problem is always DNA stuck to the cuvette (in my case, Neon Tips). I will be trying this as an alternative to the 1M H3PO4 washes (it simply works with Neon tips as with silica columns), since even it you clean them nicely H3PO4 tends to stick somehow…
One question though – where I reside, it is really hard (and pricey) to get Alcanox and I don’t think the ones that you have wrote down are not regular dishwasher soap so what should we look for when we are searching for an alternative to Alcanox?
Take care,
ML
Hey man, hopefully this works well for you, you are stripping a small layer of aluminum off the inside so in theory it will clean it out good and proper. I frequently do a control with just cells in the cuvettes, and I get no colonies reproducibly. As long as your cuvettes don’t arc then it seems you can just keep reusing them.
Here’s the latest recipe:
Decontamination Solution (v1.4)
10% Store bought bleach (2L per 20L)
1% NaOH (200g per 20L)
1% Sparkleen (200g per 20L)
We use sparkleen because it’s easy to get and cheap as chips. Any sort of dishwashing powder will do, check the SDS, you’re looking for something with bicarbonate and a detergent. Don’t have to get to fancy, dish soap will work if you have nothing else.