Using ncarbon anotubes specialized engineers Massachusetts Institute of Technology (MIT) have developed a new sensor that can detect SARS-CoV-2 without the need for antibodies and in a matter of minutes.
According to the researchers, their sensor is based on technology that could also be used to generate quick and effective diagnoses not just for covid-19, but also for other epidemic diseases. The results are published in Analytical chemistry.
“A quick test means that trips can be opened much sooner in a future pandemic. You can test travelers as they exit the plane and determine whether or not they should be quarantined. It could also be done in other places, such as the workplace”, explains the co-author. Michael Strano, professor of chemical engineering at MIT, who recognizes: “We still don’t have the technology that will allow us to develop and use these sensors quickly, in a way to avoid economic losses”.
The technique is based on carbon nanotubes, nanometer-thick hollow cylinders that fluoresce when exposed to laser light. By wrapping them with different polymers, they detect specific molecules.
The diagnostic device is based on a technology that uses carbon nanotubes created in Professor Strano’s lab, so when researchers began designing a sensor to detect the covid-19 virus, it took them just ten days to find and test a modified carbon molecule that was capable of detecting and selecting proteins. the viruses they were looking for, and later incorporate it into a working prototype.
This new approach eliminates the need for time-consuming antibodies or other chemical agents to generate and purify.
Take advantage of the material’s fluorescence
Strano’s team technique is based on carbon nanotubes, nanometer-thick hollow cylinders made of carbon, which become fluorescent naturally when exposed to laser light.
Their research found that by wrapping these tubes in different polymers, can create sensors that respond to specific molecules recognizing them chemically.
The method, known as Molecular Recognition of Corona in Phase (CoPhMoRe), takes advantage of a phenomenon that occurs when certain types of polymers are attached to a nanoparticle.
The binding of the molecule changes the intensity or wavelength of the fluorescence peak produced by the carbon nanotube, which can be used to make the diagnosis
the calls amphiphilic polymers are molecules that have regions hydrophobic, that adhere to tubes as anchors and regions hydrophilic, which form a series of loops on the outside, forming the crown that surrounds the nanotube.
Depending on the arrangement of the loops, different types of target molecules can fit into the spaces between them.
Binding the molecule changes the intensity or wavelength of the fluorescence peak produced by the carbon nanotube, which can be used to make the diagnosis.
Detection using polymers
In early 2021, the Strano team, together with the company InnoTech Precision Medicine, based in Boston, received an agency grant National Institute of Health (NIH) from the United States to create a CoPhMoRe sensor that would detect the SARS-CoV-2 proteins.
Strano’s laboratory researchers have already developed the technique that allows them to predict what amphiphilic polymers They will interact better with a specific molecule, so they were able to quickly generate a set of 11 coronavirus candidates.
This device produces a result in about five minutes and can detect concentrations as low as 2.4 picograms of viral protein per milliliter of sample.
Ten days after the start of the project, the researchers identified accurate sensors for both nucleocapsid about the protein peak SARS-CoV-2 virus.
During that time, they were also able to incorporate the sensors into a prototype with a optical fiber, which can detect fluorescence changes of the biofluid sample in real time, which eliminates the need to send the sample to the laboratory, a requirement to perform the PCR that detects Covid-19.
Strano’s team’s device produces a result in about five minutes and can detect concentrations as low as 2.4 picograms of viral protein per milliliter of sample.
quick detection test
In more recent experiments conducted after this article was submitted, the researchers achieved a lower limit of detection than the rapid tests currently on the market.
The researchers also showed that the device can detect the nucleocapsid protein of SARS-CoV-2 (but not peak protein) when dissolved in saliva.
The detection of viral proteins in saliva is often difficult because saliva contains sticky molecules of carbohydrates and digestive enzymes that interfere with protein detection, which is why most diagnoses to detect Covid-19 require nasal swabs.
The device produces a result in about five minutes and can detect concentrations as low as 2.4 picograms of viral protein per milliliter of sample. / MIT
“This sensor has a wider range of detection limit, response time and saliva compatibility, even without a design based on antibodies and enzyme receptors”, says another of the authors, Sooyeon Cho.
“A unique feature of this type of molecular recognition device is that it can be designed and tested much faster than conventional devices, based on antibodies or enzyme receptors”, highlights the researcher.
Shorter development time
Antibody-based sensors to detect viral proteins, which form the basis of many of the rapid COVID-19 tests available today, take much longer to develop because the process of creating the right protein antibody is time-consuming.
For Michael Strano, the speed with which researchers were able to develop a working prototype suggests that this approach can be useful when it comes to develop quickly diagnostic devices in the event of another global pandemic.
According to the researcher, his team is able to design “a fiber optic sensor that works from viral markers in a very short period of time”.
While continuing to refine it, the MIT team has already applied for a patent on this technology to begin marketing it as a diagnostic device for covid-19.
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