CRISPR-Chip, the first transistor that uses CRISPR to search the genome for mutations, was developed by researchers at University of California, Berkeley and the Keck Graduate Institute (KGI) of The Claremont Colleges. Their invention was reported in Nature Biomedical Engineering in March, 2019 and assistant professor at KGI is Kiana Aran.
The device analyses purified DNA and gives a report in minutes. The speed comes from the fact that unlike most forms of genetic testing, CRISPR-Chip does not PCR amplify the DNA. The device uses a form of the CRISPR-Cas9 system with a deactivated Cas9 that does not cut. Guide RNA, complementary to the target DNA sequence guides Cas9 to the find exact location in the genome where it binds. In the device Cas9 is tethered to transistors made of graphene, which undergoes a change in electrical conductance when Cas9 binds to the target DNA. The resultant changes in the characteristics of the transistor are detectable in the hand-held device. Graphene is made of a single layer of carbon atoms and is electrically sensitive. In genomic DNA CRISPR-Chip detects a target in 15 minutes with 1.7fM sensitivity.
As of 2019, only one guide RNA is supplied, so only one mutation can be detected at a time, but Aran suggested that a multiplex device could be possible. The CRISPR-Chip device was tested on DNA from blood samples from Duchenne muscular dystrophy (DMD) patients an it was able to detect two of the common genetic mutations.
