TORONTO – Two-Photon Research Inc. (TPR) has launched a diagnostics platform it said improves coronavirus detection via aptamers, small molecules that change shape when binding to a protein at the surface of the SARS-CoV-2 molecule that causes COVID-19. Light shone onto a vial containing a patient’s saliva and the Aptamer Molecular Photonic Beacon (AMPB) generates negative or positive results that are instantly displayed on a smartphone and stored for planning purposes by public health officials.
“This is a great benefit that no other test yet has, automatically communicating COVID-19 test results to a central health authority,” TPR CEO Najeeb Khalid told BioWorld. “This can be used for tracking purposes, for example, but by far the biggest thing will be to meet government requirements for building a national database of COVID-19 testing results.”
Like a key in a lock
Montreal-based TPR explores photons, those bundles of electromagnetic energy that make up light, to create innovative applications in optics, micro packaging, and more recently COVID-19 diagnostics. Its CAST platform works by binding DNA aptamers to the S1 protein in the spikes dotting the surface of the SARS-CoV-2 molecule.
The first task is to change the aptamer’s shape so that it complements a chain of atoms in the S1 protein, very much in the way a key matches a lock. Khalid surmised that by changing the aptamer and finding the right shape, multiple viruses or virus mutations could be detected with a single test.
The result is a new aptamer, the AMPB, placed in a 4 mL vial where it will bind with the virus’s S1 protein, if present in the patient’s saliva sample. Light emitted by the AMPB is detected by CMOS sensors contained in a smartphone camera and activated via an app.
“The wavelength of that light I chose to be at peak sensitivity so that the camera achieves the highest quantities of photon capture,” said Khalid. “The app does the image processing and calculations and gives you the results.”
See a green icon pop up on your smartphone screen and you’re free of the disease, said Khalid. A red icon sends you to the doctor for COVID-19 treatment. “No photons,” Khalid added, “no virus.”
How does the APTM measure up against RT-PCR testing, widely used to diagnose COVID-19? Both tests use the same method of light excitation, emission and fluorescence to detect the virus. However, the PCR test is elaborate and expensive, requiring transportation of samples to a lab, reagents for the RNA extraction, reverse transcription and amplification reagents and probes.
“One must also account for the personnel required to collect the samples and specialized laboratory staff to perform complex RT-PCR procedures,” a report published by TPR noted. By contrast the CAST test-kit contains single-use vials that are scaleable and can be mass-produced at a very low cost. Khalid estimated a test kit with a batch of five vials could cost up to CA$40 (US$31).
“If you’re going into a restaurant to spend $150 on a meal each test performed there will cost about five dollars, which the restaurant can easily absorb or pass on to the customer in the price of the meal,” said Khalid. A small price to pay compared to COVID-19’s potential negative impacts on human health, he added.
Entirely self-financed, TPR “is quite independent and makes decisions quickly,” said Khalid. That includes getting an instant, accurate and low-cost test kit for COVID-19 out the door as quickly as possible. TPR has just completed in vitro testing of its technology, where it has shown itself to be at least as accurate as PCR. In vivo testing is expected to begin in January.
“This is essential in containing the pandemic,” Khalid said. “Together with vaccines we can control the COVID-19 outbreak and return our lives and world economies to normal.”