Design, Science and Technology

The device could be used to rapidly diagnose genetic diseases or to evaluate the accuracy of gene-editing techniques

 

Most methods for the detection of nucleic acids require many reagents and expensive and bulky instrumentation. Here, scientists now report the development and testing of a graphene-based field-effect transistor that uses clustered regularly interspaced short palindromic repeats (CRISPR) technology to enable the digital detection of a target sequence within intact genomic material. Termed CRISPR–Chip, the biosensor uses the gene-targeting capacity of catalytically deactivated CRISPR-associated protein 9 (Cas9) complexed with a specific single-guide RNA and immobilized on the transistor to yield a label-free nucleic-acid-testing device whose output signal can be measured with a simple handheld reader.

 

The team used the CRISPR–Chip to analyze DNA samples collected from HEK293T cell lines expressing blue fluorescent protein, and clinical samples of DNA with two distinct mutations at exons commonly deleted in individuals with Duchenne muscular dystrophy. In the presence of genomic DNA containing the target gene, CRISPR–Chip generates, within 15 min, with a sensitivity of 1.7 fM and without the need for amplification, a significant enhancement in output signal relative to samples lacking the target sequence. The CRISPR–Chip expands the applications of CRISPR–Cas9 technology to the on-chip electrical detection of nucleic acids.

Via Dr. Stefan Gruenwald

A virus that inserts itself into the genome of a type of banana plagues plantations in Africa, but CRISPR gene editing can be used to eliminate the viral DNA. Genome editing has been used to destroy a virus that lurks inside many of the bananas grown in Africa. Other teams are trying to use it to make the Cavendish bananas sold in supermarkets worldwide resistant to a disease that threatens to make it impossible to grow this variety commercially in future.

 

An Australian team has already genetically engineered the Cavendish to make it resistant by adding a gene from a wild banana. But because of the opposition to GM food worldwide, this variety may never be grown commercially. Using CRISPR is seen as preferable because some countries including the US do not regard genome edited plants as transgenic, depending on what has been done. Because the Cavendish is a sterile mutant that can only be propagated by cloning, there is no way to breed resistant varieties. Instead, several teams worldwide are trying to use CRISPR to make it resistant to Tropical Race 4.

 

Via Neelima Sinha, Dr. Stefan Gruenwald