They said the cheap centrifuge can be assembled for less than $ 5 per unit.
New York:
The researchers, led by an Indian scientist, have developed a cheap, powerless centrifuge to separate the components of the patient’s saliva samples for detection of the new coronavirus, an advance that may increase the accessibility of COVID-19 diagnostics in the poor regions of the world.
According to scientists, including Manu Prakash of Stanford University in the USA, the “Handyfuge” device spins tubes containing samples at very high speeds, enough to separate the virus genome from the samples of patient’s saliva, without electricity.
They said that the cheap centrifuge, described in a peer-reviewed study published on the medRxiv platform, can be assembled using readily available components for less than $ 5 per unit.
The scientists noted that it can allow doctors and scientists to perform a cheap and quick diagnostic technique called the LAMP assay to detect the presence of the new coronavirus genome in patients’ saliva samples.
The LAMP protocol, according to the researchers, “has the benefits of being simple, does not require specialized equipment, is fast, takes less than an hour from sample collection to reading, and is inexpensive, costs around a dollar per reaction using commercial reagents “
While the trial has these benefits, the scientists said there could be variability in the production of diagnostic methods based on detection of the viral genome in saliva samples.
They explained that this is due to saliva-containing substances that can inhibit diagnostic reagents.
“Centrifugation to separate inhibitors from the inactivated sample reaction was shown to be an effective way to ensure reliable LAMP amplification,” the scientists wrote in the study.
However, they said that a centrifuge capable of safely reaching the required speeds of 2000 rotations per minute (RPM), for several minutes, costs hundreds of dollars, and also requires a power source.
With Handyfuge, this limitation can be overcome, said Prakash, a bioengineering professor at Stanford University, whose lab had previously developed a cheap “origami microscope” called the “Foldscope.”
Scientists explained that the new device uses a mechanical strategy similar to “Dyno-torch” flashlights to generate centrifugal force using the user’s kinetic input.
“The user repeatedly squeezes the handle to rotate a small freewheel connected to a centrifuge shaft,” they wrote in the study.
After a designated period of time, enough centrifugal force is applied to the tubes containing samples, the scientists said, producing a separate liquid layer that is free of chemicals that can inhibit the coronavirus’ genetic material, its RNA.
“This supernatant can be reliably used for LAMP detection of SARS-CoV-2 or other viruses using the Rabe and Cepko assay,” the researchers wrote.
According to the study, the Handyfuge-LAMP trial works based on the protocol for the diagnostic method developed by scientists, Brian Rabe and Constance Cepko, from Harvard University in the United States.
“This simple LAMP protocol without electricity builds on the fantastic work of the Cepko laboratory at Harvard, but with a manual centrifuge to make this assay completely electricity-free for resource-limited settings,” said Mr. Prakash’s laboratory in a tweet.
“The advantage of handyfuge is the increased stability and limited fluctuations in RPM and it fits in with the need for greedy testing,” the scientists noted on Twitter.
According to scientists, the idea started from a flash light collected from a toy store, which they hacked to build Handyfuge.
They then validated the performance of the device using the LAMP protocol from Rabe and Cepko.
They said that Handyfuge, combined with the Cepko and Rabe analysis, works reliably in detecting synthetic COVID-19 RNA “up to 10-100 copies per microliter in saliva.”
“With the use of insulated coolers for the reagent supply chain and delivery, the presented assay can be completed without the need for electricity or laboratory infrastructure,” the study noted.
However, to determine the effectiveness of the device as a point-of-care tool, the researchers said it should be validated with samples from real patients.
“We are currently preparing to test this protocol and Handyfuge in field settings,” they wrote in the study.
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