Back in the bad old days, dealing with DNA and RNA in a lab setting was often fraught with peril. Detection technologies were limited to radioisotopes and hideous chemicals like ethidium bromide, a cherry-red solution that was a fast track to cancer if accidentally ingested. It took time, patience, and plenty of training to use them, and even then, mistakes were commonplace.
Luckily, things have progressed a lot since then, and fluorescence detection of nucleic acids has become much more common. The trouble is that the instruments needed to quantify these signals are priced out of the range of those who could benefit most from them. That’s why [Will Anderson] et al. came up with DIYNAFLUOR, an open-source nucleic acid fluorometer that can be built on a budget. The chemical principles behind fluorometry are simple — certain fluorescent dyes have the property of emitting much more light when they are bound to DNA or RNA than when they’re unbound, and that light can be measured easily. DIYNAFLUOR uses 3D-printed parts to hold a sample tube in an optical chamber that has a UV LED for excitation of the sample and a TLS2591 digital light sensor to read the emitted light. Optical bandpass filters clean up the excitation and emission spectra, and an Arduino runs the show.
The DIYNAFLUOR team put a lot of effort into making sure their instrument can get into as many hands as possible. First is the low BOM cost of around $40, which alone will open a lot of opportunities. They’ve also concentrated on making assembly as easy as possible, with a solder-optional design and printed parts that assemble with simple fasteners. The obvious target demographic for DIYNAFLUOR is STEM students, but the group also wants to see this used in austere settings such as field research and environmental monitoring. There’s a preprint available that shows results with commercial fluorescence nucleic acid detection kits, as well as detailing homebrew reagents that can be made in even modestly equipped labs.
Find me please one published evidence that ethydium bromide causes cancer in a complex organism. It us used in Africa by the g’s in cattles to fight parasites. This is all conspiracy theory to promote the abusely expensive fluo replacenent reagents.
So the ethidium bromide reference is a bit of a red herring. This device still operates using a fluorescent dye, but there also now available a “less hazardous” dye (“SYBR Safe”) to use instead of ethidium bromide.
The magic beans in here is not the light sensor, it’s the inexpensive bandpass filters the OP found from a seller on Ali Express. That’s the key to this nice, inexpensive build.
Back in the dawn of the Human Genome Project (1990s) it was still really hard (expensive, time consuming) to sequence DNA. But even then the choice technique was to tag each base (T, A, C, G) with a fluorophor of a different color, enabling the DNA base sequence to be read like reading the color bands on a resistor. The machines involved were big and complicated thermo-mechanical-fluid-chemical-optical mechanisms, and an attached printer would print out the (most probable) base as it passed through the analyzer column. A pretty neat trick. Pretty slow then. Newer, much faster and cheaper techniques exist now, but that was a pretty interesting epoch, because it was impossible to do shortly before.
This tool is much less specific, that’s used in support of modern sequencing methods: It just measures the quantity of DNA-like molecule present, irrespective of the base pair sequence.
It almost sounds like you forgot to attach your last paragraph:
“To enable this tool to sequence DNA, to enable it to be much more specific,would require….”
Nope. Beyond my ken.
Incredible project! Fluorometers have such an accuracy edge over spectrophotometry, and the price of a qubit is enough to stun.
Super cool to see this work!
OK, you stumped me. What does a qubit have to do with any of this?
Qubit is, among other things, a brand name for a DNA quantitation kit using a DNA intercalating dye and a dedicated spectroflourimeter.
I’m a molecular biologist and use ethidium bromide routinely. There is no evidence it causes or fast tracks cancer. To intercalate in your DNA it has to first have access to your DNA and it doesn’t as it’s incapable of traversing the cell membrane. It’s this property that makes it useful in live/dead cell detection assays. This is very irresponsible reporting. Please seek out a qualified person to review future articles you write on subjects with which you are not familiar.