Since
its introduction to the world CRISPR technology has revolutionized every aspect
of life and is creating a huge impact in every man’s life. The tech enables the
editing of genes but with more focused research and technical advancements the
tech is being used for creation of more sophisticated devices, in a recent
efforts a team of researchers working at the UC Berkley, USA have recently developed a chip based device using CRISPR
molecules for the detection of mutations from unamplified DNA samples. The team
is headed by Dr. Kiana Aran who specialises
in bio-medical engineering.
Need for the technology:
Genome
sequencing and detection of anomalies inside the DNA are becoming prominent for
accurate diagnosis and treatment of the disease. This technique of presice
medicine has developed to a greater extent in past half century, but still
requires some expensive machines, reagents, and trained workforce for proper
functioning. Also it requires an additional imaging device for visualizing the
results. All this is a set-back and consumes both money and time. So, new techniques
regarding these kinds of diagnosis are required.
Development of Chip:
In
an effort to answer the problem Dr.
Kiana Aran and her team at UC Berkeley developed a chip based diagnostic device.
The device consists of two key components:
- The dRNP- CRISPR molecule
- Graphene based field effector transistor (gEFT)
The
chip is formed by combining the two components, the CRISPR-CAS is a DNA cutting
tool having the ability to detect specific DNA segment with extreme precision,
for the detection chip module a slightly modified module of CRISPR is being used
which is able to detect the specific DNA segment but its ability of cutting the
DNA has been deactivated. These modified CRISPR molecules are stacked on top of
the graphene transistor layer, the graphene layer was preferred over the
silicon based layer due to its higher electric sensitivity than the silicon.
What is graphene? See: https://crisprpedia.blogspot.com/2019/09/graphene-magic-material.html
What is graphene? See: https://crisprpedia.blogspot.com/2019/09/graphene-magic-material.html
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| CRISPR-gEFT Chip module |
Functioning of CRISPR-Chip:
The
raw DNA sample without subjecting to any amplification process is loaded on to
the chip set. The DNA is taken by the CRISPR molecules and unzipped, it analyzes
the whole segment of the DNA until it reaches hat part of the DNA where a
specific part of the DNA or gene is present that has complementary sequence to
the guide RNA present inside the CRISPR molecules. When the specific part is identified
it binds with it and this hybridization of target DNA with the CRISPR module
influence the electrical characteristics of graphene surface. This produces a
signal resulting detection of mutations and abnormalities in DNA in short
period of time.
Initial Trial:
For
initial validation of the device a trial was conducted to check the effectiveness
of the tech for this Duchenne muscular dystrophy (DMD) disease was selected. This
disease is caused by a exon deletion in the gene resulting in production of dysfunctional
dystrophin resulting in to malformation of muscle fibres. Two of these exons the
exon-3 and exon-51 are absent in all DMD patients. For the trial CRISPR chips
specific for exon 3 and 51 were designed and DNA samples from the DMD patients
and healthy donors were analysed using chip. Results exhibit that the healthy sample
with exon 3 and 51 produces a strong signal in comparison to the DMD patient DNA
sample.
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| Published Results-Courtesy Nature |
Conclusion:
The device is an effective way for detecting
certain mutation based disease on early stages, enabling on time detection and
better diagnosis and treatment of the disease. The tech is a promising and
effective one ensuring further enhancement in precision medicines.Courtesy: Nature, UC Berkeley, Aran Lab.
