In the second part of my series on Fluorescence microscopy (FM) I want to explain the principals behind the science involved. 
Finding an asbestos fibre in a bulk sample or even on a filter can often be like the proverbial needle in a haystack. But imagine if the needle was fluorescent, in simplified terms, all you would need to do is switch the lights off and the needle should glow in the dark, easy! And, in essence, that’s what FM is all about. 
But the challenge is how do you make a needle in a haystack fluorescent? Well let’s take this thought experiment a step further, let’s imagine someone develops a fluorescent dye that only stains needles and simply runs off hay. You just pour the dye over the haystack, let the residue run off, turn the lights out, and “hey presto” the needle glows in the dark. I’m sure you would agree, if you were in the business of finding needles in haystacks such a paint would be a “game changer”. 
Molecular Engineering 
The binding capabilities between proteins or peptides and inorganic materials is an emerging area of research in various fields of applied science these days. And of interest to asbestos analysts is the research taking place in engineering proteins and peptides that have an affinity to chrysotile and amphibole asbestos fibres, in effect binding themselves to the asbestos. Once you’ve found such a protein, again using molecular engineering, you can make it fluorescent, thereby staining the asbestos fibre and making the “needle” glow in the dark. 
But therein lies challenge. When you look through a Fluorescence Microscope what you are actually seeing is the fluorescent binding, therefore, if the fluorescent protein or peptide binds to something other than asbestos you’ll get false positives. However, even more worryingly, if it doesn’t always bind to asbestos fibres the result will be false negatives. 
Much work has gone into combining various molecular engineering techniques to produce peptides and proteins that not only strongly bind to, or stain, asbestos fibres but are highly specific in this regard, which basically means they don’t bind to other similar less dangerous fibres. A lot of this research has centred around E.coli proteins and recently there has been dramatic progress in this regard, in fact we’re now at a point where studies by the US National Institute of Health have shown that the FM analytical method was “approaching the sensitivity of Scanned Electron Microscopy (SEM)”. 
Is FM a game changer? 
So, is FM a “game changer”? Well potentially yes. It may be some years before it does “change the game”, and much work needs to be done by the regulatory bodies before that can happen, but in a field such as asbestos, where lives literally are at stake, we need the best tools science can offer and if the science continues to improve in the way it has progressed so far we are likely to see this method coming to the forefront. 
Brett Millward 
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