CRISPR-Chip Accurately Detecting Genetic Mutations in Minutes

Engineers from the UC Berkeley and the Keck Graduate Institute (KGI) of The Claremont Colleges have recently used CRISPR to create a sensor that detects specific genetic mutations in minutes. The researchers are calling the device CRISPR-Chip, and feel that it could potentially provide rapid diagnosis of genetic diseases, or evaluate accuracy of genetic editing efforts.

This handheld device combines CRISPR technology with electronic transistors made from graphene to provide genetic analyses. A study published in Nature Biomedical Engineering found that CRISPR-Chip was able to identify genetic mutations in sample from Duchenne muscular dystrophy patients.

The device, dubbed CRISPR-Chip, could be used to rapidly diagnose genetic diseases or to evaluate the accuracy of gene-editing techniques. The team used the device to identify genetic mutations in DNA samples from Duchenne muscular dystrophy patients.

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“We have developed the first transistor that uses CRISPR to search your genome for potential mutations,” claimed Kiana Aran, assistant professor at KGI who envisioned the device while in postdoctoral studies in UC Berkeley bioengineering professor Irina Conboy’s lab. “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.”

Unlike most available genetic testing methods, CRISPR-Chip uses nonoelectronics to find mutations in the DNA samples without needing to amplify the segment, or replicate it millions of times in polymerase chain reactions. This aspect of the CRISPR-Chip allows it to be used on the spot in a doctor’s office or in the field with no need for sending a sample elsewhere for amplification.

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“CRISPR-Chip has the benefit that it is really point of care, it is one of the few things where you could really do it at the bedside if you had a good DNA sample,” said Niren Murthy, a bioengineering professor at UC Berkeley and co-author of the paper. “Ultimately, you just need to take a person’s cells, extract the DNA and mix it with the CRISPR-Chip and you will be able to tell if a certain DNA sequence is there or not. That could potentially lead to a true bedside assay for DNA.”

Though use of CRISPR-Cas9 is typically intended for precisely snipping DNA samples to edit genes, the researchers utilized the complex for a different purpose in this study. The Cas9 protein usually binds a specific region of DNA and cuts it; however, the researchers in this study used a mutated Cas9 that properly bound DNA but was unable to cut it. The team also tethered this Cas9 variant to graphene transistors.

crisprWhen the CRISPR-Cas9 complex finds the specific region of DNA it is targeting, it binds the segment and triggers the graphene transistors to change electrical conductance, ultimately being detected in a hand-held device.

Graphene, a single atomic layer of carbon, has electrical sensitivity so acute that it can detect this DNA sequence match without polymerase chain reaction amplification performed prior.

“Graphene’s super-sensitivity enabled us to detect the DNA searching activities of CRISPR,” said Aran. “CRISPR brought the selectivity, graphene transistors brought the sensitivity and, together, we were able to do this PCR-free or amplification-free detection.”

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Sources: UC Berkeley