Another DNA damage experiment that I’ve been trying to get working in our lab is called the gamma-H2AX assay. And if you’ve been following my blog for a while, then you’ll know that back in late February I travelled to Oxford to learn the technique at one of the Public Health England labs.
This assay has its advantages over the Comet assay that I’ve been using as it can provide a measure of the number of double-stranded breaks in DNA, rather than an indication of the total damage within a cell. The basis of the gamma-H2AX experiment is to detect a protein (called gamma-H2AX – no surprises there!) that forms at the site of broken DNA. You can read a little bit more about how the experiment works in one of my previous posts here.
Anyway, as I’ve mentioned, I’ve been trying to get the experiment to work with our cell samples and I think one of the coolest things about this experiment is working with the microscope slides that we order from an American company. There are so many companies out there that design microscope slides of all shapes and sizes depending on what you want to do in your experiment, and these ones we have are designed to accommodate 14 different samples on just a single slide using designated ‘wells’.
But why go to the trouble of ordering these special slides when normal microscope slides would be much cheaper? Well first, let’s consider we want to look at just one sample on a microscope slide… it would be quite simple – you would attach your cells onto the slide and carry on with the experiment from there. But what if you wanted to analyse 100 samples..? You would need 100 microscope slides, each with your individual sample on… It would take days to prepare all of those slides, let alone the amount of time it would take collecting all of your data using the microscope! And so this is why these special slides are super useful.
The black coating on the slides that separates the 14 wells is not only there to visually separate the different wells, it also acts as a physical barrier because it has hydrophobic properties. Hydrophobic literally translates to ‘water-fearing’ and it means that the water molecules in your sample are repelled by the coating between the wells on the slide. It’s super useful for making sure that your different samples are kept separate whilst trying to get as many samples on a single slide and I wanted to show you the cool spheres that form in the wells whilst the water is trying to avoid contact with the coating.
Materials with hydrophobic properties are also used outside of the lab too. Many good raincoats are coated with a water-repellent finish to help keep you dry, and you can even buy shoe protection sprays that are hydrophobic to protect your shoes from the wet. Where else you have found materials in the real-world that use hydrophobic properties to do their job?