Your tissue culture hood, cell culture hood, biosafety cabinet (or BSC), the hood-y thing in your tissue culture room or whatever you like to call it, is a precious tool that requires occasional love. Here we’ll teach you how to correctly clean your hood and reduce your lab’s risk of getting a “CONTAMINATED” sign stuck to your tissue culture room’s door.
As a child, I remember learning how to properly mop the kitchen floor. I don’t know who said it to me, but the advice I was given was:
“The floor should be so clean you can eat off it!”
This is great advice that makes you more of a perfectionist when it comes to cleanliness so I propose that the same be true for your tissue culture hood.
Now no one is suggesting you should enjoy your next quesadilla while splitting cells but innumerable researchers have lost months or even years of work because of contamination so keeping this idiom in mind could very well save you big-time down the road. Good aseptic technique is key to minimizing contamination but this can only go as far as everyone is the lab is thorough. You need a backup to further reduce risks: regularly deep cleaning your hood. Here we’re going to teach you how to do it.
This level of deep cleaning is best done every 6 months so keep a rotating scheduling and have people sign off when they did it. Pin these steps up in your tissue culture room. Before you start, make sure you know what type of hood you’re working with. These steps cover class II biological safety cabinets as they’re the most common type of hoods for tissue culture rooms but they can be applied to class I cabinets and fume hoods too (although you don’t need to be as meticulous). Lastly, any apparatus you’ll need for this job is highlighted in red so have these ready.
GIVE FOLKS A HEADS UP THAT CLEANING DAY IS COMING UP.
Let your labmates know the time and date of cleaning the tissue culture hood so folks can plan accordingly. Put up a sign on the door and if needed locate alternative hoods for use in the meantime.
MAKE SURE NO DOORS OR WINDOWS ARE OPEN IN THE ROOM.
Windows should never ever be opened in a tissue culture room and doors should be kept closed at all times. This is always the case but is especially necessary during a cleaning.
SET UP YOUR SPACE.
Set up a large sink or basin as well as an area to let things dry, such as a drying rack. You’ll also need cleaning detergents. I recommend using whatever your lab’s prefered detergent is but be aware that 10% bleach is corrosive on metal so it isn’t recommended. Dishwashing detergent or lab grade chemicals like Alconox are both great as they don’t leave residues or damage metal or glassware. Remember that the solution doesn’t need to sterilize completely as sterilization will come in step 8. I like to leave the sink set up with very hot water and the detergent already in the water while I go on to step 4 and 5.
TAKE ANY EQUIPMENT PERMANENTLY STORED IN THE HOOD OUT.
This includes pipettes, tip boxes, racks, pipette trees and any other apparatus that lives there. Leave them in the room out of the way, like on a disposable mat or paper towels. We’ll get to them in step 10.
DISMANTLE THE HOOD.
Use your hood’s manual for this one. The rule of thumb here is if you can remove it, then it needs to be taken out. Don’t be afraid to introduce a screwdriver where needed. Make sure to note how you took the hood apart so you don’t end up in an IKEA furniture situation (sitting on the floor surrounded by parts, weeping, “there is no way these parts fit together! Who designed this STUPID manual!!!“)
Add the parts of the hood you removed to the sink of soapy water and let it sit while you go on to step 7. BEWARE! Leaving metal in water overnight may cause it to go rusty!
GO LOOKING FOR TREASURE.
You’ll be amazed what you’ll find after taking out the removable parts. It will also give you an idea of how careful people really are when using the hood! Remove any stray lids, tips and the like. Wipe down all surfaces in the hood with soapy water and then 70% ethanol starting from the back and working your way forwards. Again, products that contain bleach are not ideal here as you do not want to damage the hood. Don’t forget the sash and the outside of the hood. Once this step is finished, close the sash and turn on the UV light for 15-20 minutes.
Wash everything you put in the sink using a sponge or similar. This is to dislodge any gross* contamination. Rinse and leave to air dry on a rack or proceed directly to step 8.
*Gross here meaning large rather than icky. All contamination is icky!
HEAT WAVE IN THE AUTOCLAVE.
Add all your glass and metalware to an autoclave to get a nice tan be fully sterilized. The temperature and pressure should be sufficient to kill whatever bug may be present.
BACK TOGETHER AGAIN.
Put your hood back together again. Make sure that you remove the parts from the autoclave using gloves that have been cleaned with 70% ethanol. Once out of the autoclave, all parts should be handled with gloves only.
ASEPTICIZING YOUR APPARATUS.
Take apart any pipettes and other apparatus that lives in the hood and thoroughly clean and sterilize them. I like to do this part last as otherwise you’ve thoroughly clean everything but can’t put them immediately back into the hood. Before putting anything in your now gloriously clean hood, spray with it with 70% ethanol without wiping.
Congratulations! Your hood is now contamination-free!