Development of Aptasensor for the Diagnosis of Covid-19

Objectives: The objective is to develop a low-cost, practical, portable aptasensor platform for the diagnosis of COVID-19. Materials -Methods: Amino-terminated aptamers to be used for the design of an aptasensor were synthesized by SELEX method, and interaction of aptamers with SARS-CoV-2 S1 protein was investigated by isothermal titration calorimetry (ITC). Gold electrodes were used to design the biosensor platform. After the electrode surface was functionalized with cysteamine, the amino-terminated aptamer was conjugated to the surface via glutaraldehyde crosslinker. Then, the surface characterization and analytical parameters of the designed sensing platform were determined by adding commercial S1 proteins on the surface using differential pulse voltammetry (DPV), cyclic voltammetry (CV) and impedance spectroscopy (EIS). To evaluate the working performance of the system, S1 proteins were added to the synthetic serum samples using the standard addition method and the measurements were repeated. Result(s): Surface characterization of the platform designed with EIS and CV measurements was performed and it was found that the modification was successfully performed. In addition, DPV results and analytical parameters of the platform (calibration plot, limit of detection(LOD) , repeatability, coefficient of variation) were determined and the working performance of system was evaluated. Moreover, working performance of the biosensor in real samples and its specificity for COVID -19 were determined by experiments with synthetic serum and influenza A and B proteins. Conclusion(s): According the results, the system has potential to be used for the detection of COVID -19, and also it can be rapidly adapted in different pandemic situations that may occur in the future.

An Examination of the Characteristics of Cellulosic Handsheets Treated with Glutaraldehyde

The COVID-19 pandemic has influenced the demand for products that are considered hygienic, thereby increasing the production rate and variety of hygienic products. Researching new antimicrobial materials is gaining importance with increasing awareness of the topic of infectious diseases caused by various microorganisms. In the present work, cellulosic handsheets were produced and then coated with coatings having different glutaraldehyde concentrations by a roller bar technique. The surface water absorption capacity of the sample groups and their structural and strength characteristics were analyzed. Also, the cross-linking effect of glutaraldehyde was determined by FTIR analysis. The results not only showed that, after being exposed to glutaraldehyde on their surface, the handsheets presented a higher hydrophilic structure and higher tensile strength properties, but also confirmed that coatings containing 1-5% glutaraldehyde lessened fungal activity on their surfaces.

Acute stress of the typical disinfectant glutaraldehyde-didecyldimethylammonium bromide (GD) on sludge microecology in livestock wastewater treatment plants: Effect and its mechanisms.

Glutaraldehyde and didecyldimethylammonium bromide (GD) is a disinfectant widely used to prevent African swine fever (ASF) in livestock farms. However, the effect of residual GD on the activated sludge microbial ecology of receiving wastewater treatment plants (WWTPs) remains largely unknown. In this study, seven simulated systems were established to research the effects of GD on WWTPs and reveal the underlying mechanisms of microecological responses to GD at different concentrations. Both the nitrogen and carbon removal rates decreased with increasing GD concentrations, and nitrogen metabolism was inhibited more obviously, but the inhibition weakened with increasing stress duration. Microorganisms activated their SoxRS systems to promote ATP synthesis and electron transfer to support the hydrolysis and efflux of GD by producing a small number of ROS when exposed to GD at less than 1 mg/L. The overproduction of ROS led to a decrease of antioxidant and nitrogen removal enzyme activities, and upregulation of the porin gene increased the risk of GD entering the intracellular space upon exposure to GD at concentrations higher than 1 mg/L. Some denitrifiers survived via resistance and their basic capabilities of sugar metabolism and nitrogen assimilation. Notably, low concentrations of disinfectants could promote vertical and horizontal transfer of multiple resistance genes, especially aminoglycosides, among microorganisms, which might increase not only the adaptation capability of denitrifiers but also the risk to ecological systems. Therefore, the risks of disinfectants targeting ASF on ecology and health as well as the effects of disinfectant residuals from the COVID-19 epidemic should receive more attention.

Development of amperometric enzyme-based biosensor to evaluate the adulteration in virgin coconut oil. (Special Issue: Innovative methods in food process engineering.)

Virgin Coconut oil (VCO), owing to its functional properties (important in COVID-19), is costly and, therefore, susceptible to adulteration with other cheaper oils like coconut oil. An enzyme-based biosensor confirmative test of VCO was constructed by co-immobilizing enzymes onto a glassy carbon electrode. The performance of the biosensor was optimized at a potential of +0.5 V with 45 mg gelatin, 30 mg BSA coupled with 2.5% glutaraldehyde at pH 7.0 with an incubation time of 1 hr. Adulterated samples of VCO with coconut oil (CO) were analyzed. The concentration of diglyceride (DG) was estimated from the empirical relation, which showed a linear increase with the increase in adulteration. The developed biosensor was validated using high-performance liquid chromatography (HPLC) methods using a paired sample t test at a 5% significance level. The biosensor could detect adulteration in VCO with CO above 20% within 3-5 s and can be reused for 25 days.

Use of Cysteamine and Glutaraldehyde Chemicals for Robust Functionalization of Substrates with Protein Biomarkers-An Overview on the Construction of Biosensors with Different Transductions.

Currently, several biosensors are reported to confirm the absence/presence of an abnormal level of specific human biomarkers in research laboratories. Unfortunately, public marketing and/or pharmacy accessibility are not yet possible for many bodily fluid biomarkers. The questions are numerous, starting from the preparation of the substrates, the wet/dry form of recognizing the (bio)ligands, the exposure time, and the choice of the running buffers. In this context, for the first time, the present overview summarizes the pre-functionalization of standard and nanostructured solid/flexible supports with cysteamine (Cys) and glutaraldehyde (GA) chemicals for robust protein immobilization and detection of biomarkers in body fluids (serum, saliva, and urine) using three transductions: piezoelectrical, electrochemical, and optical, respectively. Thus, the reader can easily access and compare step-by-step conjugate protocols published over the past 10 years. In conclusion, Cys/GA chemistry seems widely used for electrochemical sensing applications with different types of recorded signals, either current, potential, or impedance. On the other hand, piezoelectric detection via quartz crystal microbalance (QCM) and optical detection by surface plasmon resonance (LSPR)/surface-enhanced Raman spectroscopy (SERS) are ultrasensitive platforms and very good candidates for the miniaturization of medical devices in the near future.

Can ketone bodies inactivate coronavirus spike protein? The potential of biocidal agents against SARS-CoV-2.

Biocidal agents such as formaldehyde and glutaraldehyde are able to inactivate several coronaviruses including SARS-CoV-2. In this article, an insight into one mechanism for the inactivation of these viruses by those two agents is presented, based on analysis of previous observations during electron microscopic examination of several members of the orthocoronavirinae subfamily, including the new virus SARS-CoV-2. This inactivation is proposed to occur through Schiff base reaction-induced conformational changes in the spike glycoprotein leading to its disruption or breakage, which can prevent binding of the virus to cellular receptors. Also, a new prophylactic and therapeutic measure against SARS-CoV-2 using acetoacetate is proposed, suggesting that it could similarly break the viral spike through Schiff base reaction with lysines of the spike protein. This measure needs to be confirmed experimentally before consideration. In addition, a new line of research is proposed to help find a broad-spectrum antivirus against several members of this subfamily.

Chemical disinfectants in ophthalmic practice.

The instrumentation used in ophthalmic clinics can be a source of epidemics in health care set up. Contact tonometry with Schiotz or Applanation tonometer is associated with nosocomial epidemic keratoconjunctivitis outbreaks. Recently identified SARS-CoV-2 (COVID -19) spreads mainly via the respiratory route and fomites and can transmit through other body fluids, including tear film. Various ophthalmic instruments can become a common source of spreading cross infections. Chemical disinfection is one of the most common methods employed to decontaminate instruments and environmental surfaces and prevent transmission of infectious pathogens to patients through medical and surgical instruments. Various chemical disinfectants are available with a varied spectrum to work on a different group of organisms. In this article, we briefly cover commonly used chemical disinfectants in ophthalmic practice like Alcohol (Ethyl Alcohol, Isopropyl Alcohol), Chlorine-based solution (mainly Sodium Hypochlorite), Glutaraldehyde, Hydrogen Peroxide, Formaldehyde, Iodophors, and Quaternary Ammonium Compounds.