Team:NEU CHINA/Implementation
In the course of human practices, it is easy to find places with heavy human traffic, such as markets, airports and hospitals. These places are easy for viruses spread and outbreaks, and there are often cases of virus infestation in such area. Therefore, it is useful and practical to apply our hardware to hospitals, shopping malls and other places for virus monitoring.
Fig. 1. Conception: researchers bring multivirus detector contained in the box to the crowded area.
The design of our hardware is initially based on an air sampler supplemented with a titration and detection system. The detail for our design is as the following.
Fig. 2. The flowchart for the design of multivirus detector.
Firstly, we use constant temperature constant current sampling to enrich and absorb the air samples into different absorption bulbs containing engineered bacterial solution that has been induced by IPTG to achieve detection of different viruses. Next, the solution to be tested in the absorption bulbs was titrated into 24-well culture plates. The fluorescence detection is then performed on the liquid in the 24-well culture plate, and a software that will analyze the fluorescence signal and finally output the results, and we also use a microscopic camera for timed filming to visualize the results. Therefore, when the air sample contains target viruses, the engineered bacteria are stimulated to express the reporter gene EGFP and emit green fluorescence. If the fluorescence signal reaches a threshold, an alarm will be activated. Finally, to ensure its safety and efficacy, the hardware is retrofitted with an inactivation system that can sterilize and replace the engineered bacterial solution at certain time intervals. Please see the hardware for the specific workflow.
Thus, our hardware is equipped with the ability to sample, detect, analyze and disinfect all in one, enabling safe multivirus detection.
Current virus detection methods mainly include nucleic acid detection, which is difficult to achieve real-time monitoring in the environment because of the high experimental equipment required. Our system enables simple multivirus detection by constructing spike protein for coronavirus detection by engineered bacteria, a method that requires low experimental conditions and allows real-time on-site monitoring of viruses in the environment. In future experiments, we will be able to modify more engineered bacteria to detect more types of coronaviruses.
In additions, our hardware facility has the function to kill viruses. We consider that the detector can be a source of contamination while detecting viruses. Therefore, we have adopted a method of sterilizing the bacterial solution in the hardware at regular intervals and replacing it with a new engineered bacterial solution to avoid contamination. This gives our hardware the ability to sample, detect and kill at the same time and has a wide range of applications.
Before our hardware is put into practical application, we have considered safety in many aspects.
1. The engineered bacteria using E. coli BL21 (DE3) are constructed as a chassis and placed in a fixed space in our hardware, which is not a threat to human health or the environment under the correct protective measures, and the self-inducing substances AHLs in the induction synthesized and secreted by the engineered bacteria are also non-toxic.
2. Our engineered bacteria are resistant to both ampicillin and chloramphenicol. Therefore, we added these two antibiotics to the liquid medium to ensure the survival of the engineered bacteria while avoiding contamination by other miscellaneous bacteria, and also to improve the accuracy of the assay.
3. The Spike protein used during our wet experiments is a segment of a peptide from the viral RBD, which is not infectious.
4. The engineered bacterial solution in the hardware is sterilized and replaced at fixed intervals and operated by professional staff to ensure the safety of personnel and the environment.
We have already constructed engineered bacteria to detect SARS-CoV-2, MERS-CoV and HCoV-229E, and we hope to construct engineered bacteria to detect more viruses in the future, and to further improve detection efficiency. We also hope that the hardware can be integrated with mobile to make the data publicly available.