Maybe you’re a teacher hoping to do something different, maybe you’re a student trying to drag out their funding, or maybe you just want to build something really cool.
Did you know that PCR used to be done by hand? Imagine three water baths with thermometers, a timer going off every few minutes, and a PhD student, who feels the glamour of being a scientist wearing off, moving tubes from bath to bath. Eek! But the lesson to learn here is that PCR doesn’t need to cost the price of a holiday.
We’ve already seen how you can reduce the price of your PCR by making your own Taq polymerase. Now, let’s talk about how to knock off some zeros from the cost of buying and running a PCR machine, that is, let’s talk about how to build your own.
Build Your Own PCR Machine
That’s right folks, despite how intimidating it may sound, you can build your own machine using tools and equipment you can get easily and without breaking the bank.
A few awesome folks have come up with ways of making a PCR machine from scratch and made the information open-source, including OpenPCR ($649), the Coffee Cup PCR ($350), Arduino PCR ($85), and even the Lab World Group ($50). I’ve even seen some Kickstarter Projects hoping to create models you wouldn’t be ashamed to have in your lab.
I’m not sure you’ll want to submit a paper on the results you get, but for menial applications, this could be just the ticket. Some DIY machines call for some shopping around for parts and are pretty reasonable to make. Alternatively, you could be looking at building every last component from scratch yourself. This latter option is going to require some more savvy skills, time, and troubleshooting as well as more specialized equipment.
What You Need for a DIY PCR Machine
So, what do you need to build your machine? We’ll look over the broader concepts here.
PCR works by looping through cycles of temperatures. This allows you to denature the strands of nucleic acids (by heating the reaction to around 95°C) to separate the two strands, annealing of the primers (by cooling it to somewhere between 55-65°C—give or take some degrees) that will act as sites for replication initiation, and then extension (by raising the temperature to around 72°C—plus or minus a few degrees—for a minute or so) to allow the DNA polymerase to get to work synthesizing your DNA. This repeats for 20-40 cycles. Click here for more info on these stages of PCR. But what controls these temperature oscillations? It’s called a thermocycler, which is a fancy way of saying a temperature controller. You can buy temperature controllers online on sites like Amazon or at your local hardware store. Fancier models are more expensive, but you can get some good deals. So, shop around and read reviews before buying.
A Heat Source
This is essential: you can’t cook without a stove. Now, depending on whose PCR machine you’re gonna make, you could be looking at something as simple as a 150-watt lightbulb to a heating block or you could be looking at building a heating source completely from scratch. What you do depends on how big of a project you’d like this to be and your own skill level or, more importantly, your level of patience.
Making heat is all very well and good, but you’ve got to have a reasonable way of cooling your reaction down. This is where some sort of fan will usually be called for.
Some wires and wire cutters are also needed, so all these parts can communicate.
You’ll need a platform to add your tubes and also a support structure that contains all your other parts.
Everybody needs fuel, and your machine is going to need a power source, which brings us on to the next point.
Everybody needs a brain, a central chip like an Arduino that acts as the nucleus and tells everything what it needs to do. This is how you program your cycles into your machine, what you connect to in order to monitor the reaction; essentially it’s the component that lets you harness the fuel and send it to where it needs to go, when it needs to be there. You’re also going to need some relay, to control the flow of the fuel.
A Red Button
Not necessarily literally but some way of turning this contraption on and off.
A faceplate or computer connected to the machine via a serial cable to act as an interface display (or it’d be like you’re using a computer with the screen off, so you’ve not a clue what’s going on!). The software you’ll need is available for free download from whatever protocol you’re following (see links above).
Some Basic Tools
What you need specifically depends on which model you’re trying but these include: electric tape, a soldering iron, screwdrivers, screws, a bandsaw, and a drill press or at least a hand drill.
Well, what are you waiting for? Go test your food to see if it’s really GMO-free, take a swab and see what you find, test yourself for MRSA, Staph, or Strep! The world is your oyster!
For more tips, tricks, and hacks for getting your experiments done, check out the Bitesize Bio DIY in the Lab Hub.