Pocket-sized DNA reader that can detect signs of disease in blood or urine samples could diagnose coronavirus in less than TWO HOURS, scientist claims
- Cheap and versatile testing kit could rapidly detect and track infectious diseases
- ‘POCKET’ consists of a 3D-printed chip for a blood sample and a foldable box
- The device uses heat from a smartphone to read samples and display the results
- Here’s how to help people impacted by Covid-19
A new DNA-testing kit that pairs up with a smartphone could be used to diagnose COVID-19 in less than two hours, scientists say.
‘POCKET’ (point of care kit for the entire test) identifies changes in DNA that signal disease in real time from samples of blood, urine or saliva.
It contains two components – a 3D-printed integrated chip, or i-chip, and a box that holds a smartphone, which is used as a heater, signal detector and result readout.
The ultra-portable POCKET kit, which costs less than $10 to make, fits into a small plastic bag or a regular-sized envelope.
Weighing about 3 ounces and measuring less than 10 inches long, the tool could be vital in the war against future pandemics, the Chinese researchers claim.
POCKET can also be used to perform point-of-care (POC) DNA tests for agriculture, environmental protection and food safety.
The 3D-printed integrated chip, or i-chip, which makes up one component of the POCKET device. The i-chip was designed to be smaller than one fingertip. i-chip, which is only 4g in weight, integrates two units: a 3D-printed sample preparation unit and a microfluidic signal amplification unit
‘This inexpensive, ultra-portable POCKET platform may become a versatile sample-to-answer platform for clinical diagnostics, food safety, agricultural protection and environmental monitoring,’ said corresponding author Dr Ming Chen, of the Army Medical University in Chongqing, China.
‘We detected different types of DNA from clinics to environment to food to agriculture.
‘The system could potentially be employed for the rapid detection and tracking of infectious diseases like COVID-19.
‘The detection is sensitive, specific and speedy – less than two hours. It’s also stable, with a shelf-life of more than 10 weeks.’
Previous attempts to create similar POC systems have been hampered by the need to use large equipment such as centrifuges.
The ‘ultraportable and versatile’ system consists of an i-chip and f-box, which is stored in a B5-sized plastic pocket – slightly smaller than A4
POCKET, meanwhile, is cheap and mobile, dispensing with the bulky laboratory equipment usually required for POC tests.
Viral or bacterial DNA is often only found in small amounts so it has to be purified and replicated many times in a process called amplification.
This requires heating the sample to precise temperatures alongside specific chemicals.
It’s also been difficult to detect DNA in a variety of types of samples such as blood, urine, plant matter, river water or food.
POCKET gets round these obstacles using small, lightweight, easily fabricated parts and special reagents with help from a smartphone.
The i-chip uses the heat that is generated by the smartphone’s processor. Because viral or bacterial DNA is often only found in small amounts, scientists must purify and replicate the DNA many times in a process called amplification, which requires heating the sample to precise temperatures alongside specific reagents
The kit uses the heat of a phone’s processor to warm a sample to a target temperature as reagents, or chemicals, trigger reactions.
If DNA of interest is present these will create visual signals such as light or colour that can be seen using the smartphone’s camera.
POCKET detects different types of DNA from blood, mucous and urine to food such as milk, river water and plant leaves.
Smartphones are among the most convenient, user-friendly and powerful interfaces for point-of-care detection in resource-limited settings.
This means the ultra-portable POCKET kit, which fits into a plastic bag smaller than a sheet of A4 paper, could greatly benefit developing countries.
Thanks to a smartphone’s internet connectivity, POCKET can also locate and track the distribution of illness in real time.
The smartphone in the foldable f-box. If DNA of interest is present in the i-chip visual signals – such as light or colour – are captured by the smartphone’s camera lens and displayed on the screen
‘On the basis of smartphones’ built-in wireless communication and geolocation capabilities, our POCKET platform makes it possible to real-time locate the distribution of the disease,’ said Dr Chen.
‘Furthermore, the POCKET platform can serve as the Internet of Medical Things (IoMT) in DNA analysis to transmit on-site testing results to the centralised hospital or public health officials.
‘This would provide spatio-temporal disease mapping for further investigation – in addition, end users including patients can receive fast feedbacks on disease control and prevention.’
POCKET, which also has the potential to detect other nucleic acids such as RNA, has been described further in Science Advances.
WHAT IS THE DIFFERENCE BETWEEN DNA AND RNA?
DNA – deoxyribonucleic acid – is widely known as the molecule found in the nucleus of all our cells that contains genetic information.
It is shaped like a double-helix and made of small sections called nucleotides.
Each nucleotide contains a nucleobase, a sugar, and a phosphate group.
The sugar component in this particular molecule is called deoxyribose and makes up the D in DNA.
This is a cyclic carbon-based chemical with five carbon atoms arranged as a pentagon.
At the second carbon atom there is an attached singular hydrogen atom in deoxyribose.
This can also have an additional oxygen attached as well.
In this case, the oxygenated chemical then forms what is simply known as ribose – the R in RNA.
The deoxy prefix literally means without oxygen.
Shape of RNA and DNA
RIbose can do almost everything deoxyribose can and also codes for genetic information in some cells and organisms.
When the oxygen is present it drastically alters how the chemicals bonds and sits alongside other molecules.
When oxygen is present – in RNA – it can take a variety of shapes.
When oxygen is not present in this specific location – in DNA – the molecule forms as the iconic double helix.
Uses of RNA
DNA is often broken down into RNA and read by the cells in order to translate and transcribe the genetic code in order to make proteins and other molecules essential for life.
RNA uses three of the same base pairs as DNA: Cytosine, Guanine, Adenine.
The othe base pair, Thymine, is swapped out in RNA for Uracil.
RNA is also often found in simpler organisms, such as bacteria.
It is often also a virus, with Hepatitis, flu and HIV all forms of RNA.
All animal cells use DNA, with one notable exception: the mitochondria.
Mitochondrian are the powerhouses of the cell and turn glucose into pyruvate and then into Adenosine triphosphate (ATP) via the Krebs cycle.
This process is all done in this one organelle in the cells and ATP is the universal form of energy and used throughout every aerobic organism.
In the mitochondria there is a small strand of RNA which is unique in the animal kingdom.
It is passed down from the mother exclusively (the father’s lives in the sperm but is dissolved during fertilisation) and allows humans to trace their maternal lineage back throughout time.
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