What if cancer, HIV could be diagnosed at home and that too for less than the cost of a bus ticket?
MIT researchers have developed a disposable DNA-based sensor that not only detects disease with precision, but can also survive weeks without refrigeration, making it ideal for use far beyond traditional labs.
These electrochemical sensors harness a DNA-chopping enzyme from the CRISPR gene-editing system.
Lawnmower logic meets CRISPR
When the enzyme encounters a target, such as a cancer-linked gene, it activates and begins shredding nearby DNA on the sensor’s electrode, like a lawnmower cutting grass. This disruption changes the electrical signal, revealing the presence of disease.
Until now, the DNA coating degraded quickly, forcing sensors to be freshly made and refrigerated, limiting its real-world use.
MIT researchers have solved this with a simple polymer coating that keeps the DNA stable for up to two months, even in high heat.
After storage, the sensor successfully detected PCA3, a prostate cancer biomarker found in urine, without performance loss.
Costing just 50 cents to produce, these disposable sensors could offer an accessible, low-resource alternative for diagnosing a wide range of diseases.
“Our focus is on diagnostics that many people have limited access to, and our goal is to create a point-of-use sensor. People wouldn’t even need to be in a clinic to use it. You could do it at home,” said senior author Ariel Furst, a chemical engineering professor at MIT.
From lab to living room
Electrochemical sensors detect disease by tracking changes in electric current when a target molecule interacts with an enzyme, much like glucose meters.
MIT’s version uses a strip of gold leaf coated with DNA and laminated onto plastic, with the DNA anchored by a sulfur-based molecule called a thiol.
First demonstrated in 2021, the sensor detects genetic material from viruses like HIV and HPV using a programmable guide RNA linked to Cas12, an enzyme related to CRISPR’s Cas9.
When the target is present, Cas12 activates and cleaves surrounding DNA, including the strands on the sensor.
This DNA “chopping” alters the electrical signal, which is read by a handheld device called a potentiostat to confirm the presence of the target gene.
“If Cas12 is on, it’s like a lawnmower that cuts off all the DNA on your electrode, and that turns off your signal,” Furst says.
Earlier versions also required the DNA coating to be applied just before use. To fix this, researchers used polyvinyl alcohol (PVA), a low-cost polymer that forms a thin, protective film over the DNA. Once dried, it shields the sensor from environmental damage, significantly extending its shelf life.
“Once it’s dried, it seems to make a very strong barrier against the main things that can harm DNA, such as reactive oxygen species that can either damage the DNA itself or break the thiol bond with the gold and strip your DNA off the electrode,” Furst says.
The polymer coating kept the DNA stable for at least two months, even at 150°F. After storage, the film was rinsed off, and the sensor successfully detected PCA3, a prostate cancer gene found in urine.
The test works with various sample types, including saliva and nasal swabs, and could be adapted for low-cost detection of infectious diseases like HPV and HIV.
The platform is also flexible enough to target emerging pathogens.
To move toward real-world deployment, members of Furst’s lab have joined MIT’s delta v startup accelerator. With shelf-stable sensors now viable, the team plans to begin shipping them for field testing.
“Our goal is to continue to test with patient samples against different diseases in real world environments,” Furst said.
“Our limitation before was that we had to make the sensors on site, but now that we can protect them, we can ship them. We don’t have to use refrigeration. That allows us to access a lot more rugged or non-ideal environments for testing.”
The study was published on June 30 in the journal ACS Sensors.