Functional proteins synthesis, refolding and surface active palladium nano-thin-film sensors development for virus sensing and anti-infectious drugs screening*

In COVID-19 pandemics era, a rapid, specific and sensitive sensing platform is highly desired. By combining molecular biology, thermodynamics nanotechnology processes, both virus spike proteins and human ACE2 receptors have been recombinant synthesized and refolded into functional state via over-critical refolding process. Furthermore,  a 20 nm in thickness, a surface-active Pd nano-thin-film (NTF) on PET substrate has been developed by pulse DC sputtering process. This Pd nano-thin film contained unique nano-islands and nano-edges. These nanostructures made bio-molecules which bound to the working electrodes directly within 20 mins. Due to the unique Pd nano-thin film structure the Raman signal of protein sample with 0.8 μg can be detected. This ultrasensitive detection of Raman spectroscopy signals at low sample amounts in the current analysis may be attributed to the induction of a local surface plasmon resonance (LSPR) and an enhanced surface electric field phenomena. Furthermore,this unique Pd-NTF could be used as electrochemical spectroscopy probe. By using this sensing system both wild type and mutant SARS CoV-2 virus can be detected within 21 min. Furthermore, the drugs which can block the virus infections can be screened too. The limit of detection (LOD) of these biosensors were as low as 1 ~4 μg per-test in 1 microliter. At the same time, these sensors can also be used to screen other infectious disease and drugs.