A team of engineers hopes a new device called the CRISPR-Chip could rapidly diagnose genetic mutations without needing to send data to a lab.
Genetics has entered unchartered territory at a blistering pace over the past few years, and now a team of researchers from UC Berkeley is hoping to take things a step further with a new device that could soon be in numerous doctors’ offices.
Dubbed the CRISPR-Chip, the device combines the pioneering gene-editing techniques of CRISPR with electronic transistors made from the ‘wonder material’ graphene. According to its designers, the handheld device could be used to diagnose genetic diseases or to evaluate the accuracy of gene-editing techniques in a matter of minutes.
“We have developed the first transistor that uses CRISPR to search your genome for potential mutations,” said Kiana Aran, who first came up with the idea for the device. “You just put your purified DNA sample on the chip, allow CRISPR to do the search and the graphene transistor reports the result of this search in minutes.”
Publishing its findings in Nature Biomedical Engineering, the team said that unlike most forms of genetic testing, the CRISPR-Chip uses nanoelectronics to detect any mutations in DNA samples without ‘amplifying’ or replicating the DNA segment millions of times over in a process known as polymerase chain reaction.
This means that the sample doesn’t need to be returned to a lab – which incurs great costs, both time and money – but can be analysed in a doctor’s office or even during fieldwork.
Explaining the science behind it further, the team said that typically the Cas9 protein that allows CRISPR to function requires a bulky snippet of ‘guide RNA’. The protein first unzips the double-stranded DNA and scans through until it finds the sequence that matches the guide RNA it wants to cut, and then latches on.
For its device, the UC Berkeley team took a deactivated Cas9 protein – a variant that can target locations in DNA but not cut it – and tethered it to transistors made of graphene. When the CRISPR complex finds the spot of DNA that it’s targeting, it binds to it and triggers a change in the electrical conductance of the graphene, notifying the CRISPR-Chip device when it detects a ‘hit’.
Achieving the ‘multiplex’
The eventual goal of the team is to ‘multiplex’ the device, allowing doctors to plug in multiple guide RNAs at once to simultaneously detect a number of genetic mutations in minutes.
“Imagine a page with a lot of search boxes – in our case, transistors – and you have your guide RNA information in these search boxes, and each of these transistors will do the search and report the result electronically,” Aran said.
For the study to prove its worthiness, the team used it to detect two common genetic mutations in blood samples from Duchenne muscular dystrophy (DMD) patients. If proven successful, the CRISPR-Chip would be especially useful for DMD screening as it is currently costly and time-consuming to test for the severe muscle-wasting disease.
Irina Conboy, a co-author of the study, explained: “With a digital device, you could design guide RNAs throughout the whole dystrophin gene, and then you could just screen the entire sequence of the gene in a matter of hours.
“You could screen parents, or even newborns, for the presence or absence of dystrophin mutations – and then, if the mutation is found, therapy could be started early, before the disease has actually developed.”