This paper reports on development of an optical biosensor for the detection of antibodies against SARS-CoV-2 virus proteins in blood serum. ZnO nanotetrapods with high surface area and stable room ...temperature photoluminescence (PL) were selected as transducers. Structure and optical properties of the ZnO tetrapods have been studied by XRD, SEM and Raman spectroscopy. Crystallinity, dimensions and emission peaks of the ZnO tetrapods were determined. The ZnO tetrapods were fixed on glass chip. Silanization of ZnO tetrapods surface resulted in forming of functional surface groups suitable for the immobilization of bioselective layer. Two types of recombinant proteins (rS and rN) have been used to form bioselective layer on the surface of the ZnO tetrapods. Flow through microfluidic system, integrated with optical system, has been used for the determination of antibodies against SARS-CoV-2 virus proteins present in blood samples. The SARS-CoV-2 probes, prepared in PBS solution, have been injected into the measurement chamber with a constant pumping speed. Steady-state photoluminescence spectra and photoluminescence kinetics have been studied before and after injection of the probes. The biosensor signal has been tested to anti-SARS-CoV-2 antibodies in the range of 0.001 nM–1 nM. Control measurements have been performed with blood serum of healthy person. ZnO-SARS-CoV-2-rS and ZnO-SARS-CoV-2-rN biosensors showed high stability and sensitivity to anti-SARS-CoV-2 antibodies in the range of 0.025–0.5 nM (LOD 0.01 nM) and 0.3–1 nM (LOD 0.3 nM), respectively. Gibbs free energy of interaction between ZnO/SARS-CoV-2-rS and ZnO/SARS-CoV-2-rN bioselective layers with anti-SARS-CoV-2 antibodies showed −35.5 and −21.4 kJ/mol, respectively. Average detection time of biosensor integrated within microfluidic system was 15–20 min. The detection time and pumping speed (50 μL/min) were optimized to make detection faster. The developed system and ZnO-SARS-CoV-2-rS nanostructures have good potential for detection of anti-SARS-CoV-2 antibodies from patient's probes.
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•Glass-chip was modified by ZnO tetrapods as photoluminescence (PL) transducers.•PL-based system for detection of antibodies against SARS-CoV-2 virus was designed.•Two types of recombinant proteins (rS and rN) were immobilized on the ZnO tetrapods.•Sensor was integrated within flow through microfluidic system.•Sensitivity towards antibodies against SARS-CoV-2 virus proteins was determined.
COVID-19 is a severe acute respiratory syndrome caused by the Coronavirus-2 virus (SARS-CoV-2). The virus spreads from one to another through droplets from an infected person, and sometimes these ...droplets can contaminate surfaces that may be another infection pathway. In this study, we developed a COVID-19 model based on data and observations in Thailand. The country has strictly distributed masks, vaccination, and social distancing measures to control the disease. Hence, we have classified the susceptible individuals into two classes: one who follows the measures and another who does not take the control guidelines seriously. We conduct epidemic and endemic analyses and represent the threshold dynamics characterized by the basic reproduction number. We have examined the parameter values used in our model using the mean general interval (GI). From the calculation, the value is 5.5 days which is the optimal value of the COVID-19 model. Besides, we have formulated an optimal control problem to seek guidelines maintaining the spread of COVID-19. Our simulations suggest that high-risk groups with no precaution to prevent the disease (maybe due to lack of budgets or equipment) are crucial to getting vaccinated to reduce the number of infections. The results also indicate that preventive measures are the keys to controlling the disease.
In order to determine the effectiveness of non-pharmaceutical interventions on an epidemic, we develop an agent-based model that simulates the spread of an infectious disease in a small community and ...its emerging phenomena. We vary parameters such as initial population, initial infected, infection rate, recovery rate, death rate, and asymptomatic rates, as inputs. Our simulations show that (i) random mass testing decreases the number of deaths, infections and time duration; (ii) as well as quarantines; (iii) social distancing lengthen outbreak period to an extent and helps flatten the epidemic curve; and (iv) the most effective combination of NPIs to minimize death, infection and duration is no mass testing, no social distancing and a total lockdown. Results of this study can aid decision makers in their policies to be implemented to have an optimal output.
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