Effective corona test in views?
In the Corona-crisis, we urgently need effective ways to protect us and a possible disease at an early stage to determine. Now, a new Sensor has been developed that allows for detection of corona viruses very quickly.
Through the cooperation between the Empa, the ETH Zurich and University hospital Zurich have developed a Sensor that can prove corona virus reliably. The results of the study were published in the English scientific journal “ACS Nano”.
Sensor for the detection of SARS-CoV-2?
The involved in the development researchers working on the measurement, analysis and reduction of air pollutants such as aerosols and artificially produced nano-particles. However, the current corona crisis led to the objectives of the research facility have changed. The Team tried to develop a Sensor that is able to demonstrate SARS-CoV-2 fast and reliable.
The existing Sensor has been further developed
Even before COVID-19 spread began the research staff of the investigation group of Sensors that are able to demonstrate bacteria and viruses in the air. In January, the research group came upon the idea of, on this basis, the Sensor is to the effect further develop that he can identify a particular Virus reliably.
Problems with existing test methods
Fast and reliable Tests in today’s time is urgently needed to bring the pandemic as quickly as possible under control. Most laboratories use a molecular method of virus detected in respiratory tract infections. This is able to demonstrate even the smallest amounts of virus. However, there is the Problem that the method can be time-consuming and error-prone.
Optical Biosensor as an Alternative?
In the current research work was developed an alternative test method in the Form of an optical biosensor. This Sensor combines two different effects, whereby he can prove the Virus is safer and more reliable. This is a optical and a thermal effect.
How is the Coronavirus?
The Test used nano-Islands of Gold, and artificially produced DNA receptors, which correspond with specific RNA-sequences of the SARS-CoV-2 Virus. In the case of the Coronavirus is a RNA Virus. This is characterized in that its genome is, as in the case of living organisms from a DNA double strand. It consists of a single strand of RNA. The artificial DNA receptors on the Sensor, then, are the complementary sequences to the unique RNA-genome sequences of the Virus, which can uniquely identify, report the researchers.
How does the Test work?
For the proof of the technology used, it is an optical phenomenon, which is common in metallic nano-structures occurs. These are stimulated, modulate the incident light in a specific wavelength range, and thus generate a so-called plasmonic near-field around the nano structure.
Optical Sensor to measure the occurring changes
When molecules bind to the surface changes the local refractive index within the near field. With an optical Sensor, can be measured, such a Change then and finally determine whether the sample contains the respective RNA strands.
What is the role played by heat in the Test?
In the process, it is very important that only those RNA strands are detected, the correspond exactly with the DNA Receptor on the Sensor. Here is a second effect, referred to as plasmonic photo-thermal (PPT) effect helps. The same nano is stimulated structure on the Sensor with a Laser in a specific wave length, it creates localized heat.
What is hybridization?
The genome of the Virus consists of a single strand of RNA. If this strand finds its complementary counterpart, connect both to a double strand. This process is known as hybridization.
Possibility for false test results?
When a double strand is split into single strands is called denaturation. This is done in the so-called melting temperature. If the ambient temperature is much lower than the melting temperature, can also be used to connect strands that are complementary to each other, which can lead to false test results, report the researchers.
Benefits PPT-effect caused by ambient temperature
The ambient temperature is only slightly below the melting temperature, can only connect complementary strands. This is exactly the result of the increased ambient temperature, which is caused by the PPT effect.
Sensor can clearly distinguish between RNA sequences
To find out how reliable the new Sensor provides the current SARS-CoV-2 Virus, was tested the device in a very closely related Virus. It was SARS-CoV (SARS-1), the Virus, which broke out in 2003, and at that time, the SARS-pandemic triggered. The two viruses differ only very slightly in their RNA. “Our Tests showed that the Sensor can clearly distinguish between the very similar RNA sequences of the two viruses,” says study author Jing Wang in a press release. In addition, the Test required is not long, in order to get results. (as)