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.