cleaning / sterilising culture MEAs

Dear MCS / MEA users
We having started having problems culturing neurons (E17 hippocampal) on MEAs (standard 200/30ìm, internal ref), having previously been generally successful. I note the replies to the previous post (‘culturing on MEA chips’) and we will be trying some of the suggestions on coating. I would also be very grateful for users opinions on the best way to clean and sterilise MEAs used for repeated cultures, as I’m sure this impacts on the coating/adhesion issue. At the end of the culture, we clean arrays with a jet of distilled water, sterilise with 100% ethanol, air dry, and then either store in sterile distilled water, or start the coating process again. What are other users preferred methods? Enzyme treatment, if so which? (we have experimented with trypsin and proteinase K, but has not yet solved our problems) Does anyone use detergent (I’ve always been reluctant)? Ultrasonication? Autoclave / ethanol / UV to sterilise?
Also, has anyone found a limit to the number of times an MEA can be used for culture, however well they are treated?

Dear P Charlesworth

Firstly, you should make sure that the MEAs are still hidrophilic enough before coating. This can be tested with a drop of water. If the drop does not wet the surface, you likely need to make the surface more hydrophilic with a plasma-cleaning chamber.

Sterilization with 100 % ethanol is not very good, because contaminating microorganisms might get conserved in pure ethanol. 70 % is usually recommended. Silicon nitride MEAs can be sterilized with standard methods for cell culture materials using either 70 % ethanol, UV-light (about half an hour depending on the intensity), dry-heat sterilization, or vapor autoclavation. Maybe you should try one of the alternative methods instead of ethanol.

You can use any ph-neutral cleaning agent for cleaning standard MEAs. If more severe methods are needed, the MEA can also be cleaned in an ultrasonic bath for a short moment. But this method is a bit dangerous, because there are ultrasonic baths that are too
strong and will destroy the MEA. The behavior should be tested with an older MEA first.

I am sure you are careful not to touch the electrode field or to apply too much mechanical forces in any way during the coating or cleaning procedure, because the electrodes are easily damaged.

Long-time experiments with cell cultures and rigid cleaning methods shorten the MEA lifetime, but you can still reuse an MEA about 30 times, depending on the coating, cell culture, and cleaning procedure.

We would also like to encourage MEA users to contribute to this discussion, because a manufacturer can always learn a lot from users and use this information to improve the product documentation.

I am not sure whether you already have a revised version of the MEA User Manual, which provides some recommendations on storage, cleaning, coating and such stuff. Please contact me directly if you need one and I will be happy to send you a PDF.

leisgen@multichannelsystems.com

Please ask if you need more information.

Best regards, Christine (MCS)

we use a 3% Solution of "BM-flüssig" produced by biomed. it does the job and doesn´t harm the arrays.

hope that helps...

greetz

Could you tell me more about this "BM-flüssing" (composition or formula, color) ? I couln't find it among the Biomed products, and there are on the other side several "BM"compounds provided by Sigma Aldrich.
Thanks,
Catherine.

I also would appreciate more specific info on this. "Flüssig" meaning liquid I tried searching for "BM" only on the sigma site but that brings up things that are way too expensive to be used as detergents ... and "biomed" is a bit general

Thanks

Rudolf

Dear Rudolf

BM solution (BM – liquid, # 104 101) consists of CRHSO3 and hypochloride with a pH
value of > 7.
For further information on BM solution, please contact:
BIOMED Labordiagnostik
Bruckmannring 32
D-85764 Oberschleißheim, Germany

Please note:

We do not recommend to use the BM solution for MEA cleaning, as it will affect electrode lifetime due to its alkalic pH.

Please have a look at the MEA User Manual for recommended cleaning procedures. If you send an e-mail to support@multichannelsystems.com, I can also send you a cleaning protocol that I received from a customer and will be added to the MEA User Manual as soon as I have time.

Best regards, Christine

************************************************

Christine Leisgen
Multi Channel Systems MCS GmbH
Aspenhaustrasse 21
72770 Reutlingen
Germany
Tel: +49-7121-90925- 0
Fax: +49-7121-90925-11
www.mcs-download.com

Innovation in Electrophysiology

************************************************

Here is the link of the supplier. I just recommend to keep exposure to BM solution as short as possible and use it only if everythink else fails, as it is quite alkalic and might damage electrodes at longer exposure times.

http://www.biomed.de/html/produkte/produktlisten/laborhilfsmittel.php

Thomas

The best way is to sterilise it by whether
1 steam steriliser (autoclave) 134 C for 3 minutes
2 dry heat steriliser 121 C for 15 minutes
3 or you can disinfect it by exposing it to hot water 90 C for above (1) minute
if you have any query just email me at
mfoz@bigpond.net.au
My name is Mohamed Hussein and I am the manager of the Cental Sterilising Department in a hospital in Melbourne Australia
Cheers

Hi there Paul. Just thought I should add that we are currently recommending Terg-a-Zyme as a cleaning solution (many thanks to Cesare Terracciano at Harefield Hospital for the tip). It has been field tested very successfully and seems to be a very effective but gentle cleaner. In the UK you can get it from:-

http://www.coleparmer.com/catalog/product_view.asp?referred_id=168&sku=1777705

Just make up a low % solution (1-2% works but other percentages are avaialable!). A soak in this (again experiment with times) WITHOUT ultrasonic treatment does the job. We have just looked at a batch of MEAs that have come back from demo and they look great – in fact they went straight back out on another demo and worked very nicely.

Regards, Nick Best, Scientifica.

Hello everybody :-)

Our autoclav-program runs at 121°C for about 60 min or more, under dry conditions.
Is this too long?
At the moment we aren't observing any difficulties while coating and recording and also no visible damage is observable. The only thing is that MEAs, after the autovlav-program is done, often "stick togehter"; "back on back". When we try to seperate them to soon (if they are still warm), this sticking is rather strong (risk of fracture!). Therefore we have a 30min pause-step in our cleaning protocol, to let them cool out passivly, before further processing.
However, for long term usage: Would you recommend to change our autoclav-application?

Dear Richard,

usually 20min is sufficient for sterlizing. However 60min will not do any harm.

We usually avoid to have MEAs sticking together by placing them in a beaker in a way that they are not back-to-back.
Some of our customers use a teflon rack to store them in the autoclave avoiding any contact between MEAs

Greetings

Thomas