Numerical Study of Titanium Dioxide and MXene Nanomaterial-Based Surface Plasmon Resonance Biosensor for Virus SARS-CoV-2 Detection.

A novel surface plasmon resonance-based biosensor for SARS-CoV-2 virus is proposed in this article. The biosensor is a Kretschmann configuration-based structure that consists of CaF2 prism as base, at which silver (Ag), TiO2, and MXene nanolayers are used to enhance the performance. Theoretically, the performance parameters have been investigated by means of Fresnel equations and transfer matrix method (TMM). The TiO2 nanolayer not only prevents oxidation of Ag layer but also enhances the evanescent field in its vicinity. The sensor provides an ultrahigh angular sensitivity of 346°/RIU for the detection of SARS-CoV-2 virus. Some other performance parameters, including FWHM (full width at half maxima), detection accuracy (DA), limit of detection (LOD), and quality factor (QF) have also been calculated for proposed SPR biosensor with their optimized values 2.907°, 0.3439 deg-1, 1.445 × 10-5, and 118.99 RIU-1, respectively. The obtained results designate that the proposed surface plasmon resonance (SPR) based biosensor has notably enhanced angular sensitivity as compared to previous results reported in the literatures till date. This work may facilitate a significant biological sample sensing device for fast and accurate diagnosis at early stage of SARS-CoV-2 virus.

Establishment of an in vitro assay to detect antibody-mediated procoagulant platelet formation on a single cell level in real time

Introduction Procoagulant platelets (PLTs), a subpopulation of PLTs that is characterized by increased externalization of phosphatidylserine (PS), are increasingly identified to promote a prothrombotic environment in different diseases. Recently we observed that procoagulant PLT formation can be induced via engagement of immune receptor Fc-gamma-RIIA by COVID-19, VITT and HIT patient immunoglobulin subclass G (IgG) antibodies (Abs). Here, Fc-gamma- RIIA engagement by patient Abs resulted in significant formation of procoagulant PLTs and loss of mitochondrial potential that was associated with high thrombin formation as well as increased thrombus formation. In the cur- rent study, we aim to establish a PLT adhesion assay that allows investigation of PLT mitochondria during procoagulant PLT formation. Method PLTs were spread on human serum albumin, fibrinogen or collagen precoated glass slides. Adhesion and subsequent shape change of PLTs as well as procoagulant PLT formation were investigated in real time using immune fluorescence microscopy. For the detection of PLT shape change, mitochondrial dynamics and PS externalization, PLTs were double stained with MitoTracker green, a mitochondrial dye that binds to free thiol groups of cysteine residues in the mitochondrial membrane, and Annexin-V, respectively. For the visualization of mitochondrial release from PLTs intracellular compartment, a monoclonal Ab that binds to a subunit of the translocase of the outer membrane (TOM) complex on the mitochondrial membrane, namely TOM22, was used. Results During the observation period, a subgroup of PLTs that was spread on collagen became procoagulant as determined by an increased binding of Annexin- V on the PLT surface. Contrary, these changes were nearly absent in PLTs that adhered to fibrinogen (percentage [ %] of Annexin-V positive cells: 19.80 +/- 3.42 % vs. 1.92 +/- 0.62 %, p value 0.0357). Interestingly, procoagulant PLT formation was associated with a significant loss of MitoTracker green signal in PLTs while it remained constant in non-procoagulant PLTs attached on both extracellular matrix coatings. Loss of MitoTracker green signal was associated with translocation of mitochondrial proteins from intracellular to extracellular, as a higher count of TOM22 Ab-positive labelled structures, most likely extracellular mitochondria were detected on collagen but not on fibrinogen coated glass slides. Conclusion Our findings indicate, that the formation of procoagulant PLTs is associated with dramatic changes of the mitochondrial integrity in PLTs. Further attempts, that investigate the potential pathophysiological role of PLT mitochondrial release in Ab-mediated prothrombotic disorders may contribute to a further understanding of the role of PLT mitochondria in these complex diseases.

Prognostic value of total thiol and D-dimer in patients hospitalized with COVID-19

The lack of specific treatment for COVID-19 and the fact that the clinical course differs between individuals makes it difficult to predict the prognosis. The aim was to investigate the prognostic value of total thiol, D-dimer, procalcitonin (PCT), ischemia-modified albumin (IMA), and complete blood count (CBC) in patients hospitalized with COVID-19.100 consecutive patients were hospitalized with COVID-19, confirmed by RT-PCR between December 2021-March 2022 and 30 healthy control participated in the study. According to the World Health Organization guideline, two groups were created as critical and non-critical. D-dimer, PCT, IMA, total thiol levels, and CBC were analyzed. Receiver-operating characteristic curves (ROC) were utilized to determine an optimum cut-off value for distinction.We defined a cut-off value of 1,030 μg/L for D-dimer (Area Under Curve, AUC): 0.691;p=0.001) and 148 μmol/L for total thiol (AUC: 0.749;p<0.001) via ROC analysis. The combination of D-dimer and total thiol reached 65% positive predictive value (PPV) and 80% negative predictive value (NPV).D-dimer and total thiol may help predict critical patients with COVID-19. [ FROM AUTHOR] Copyright of Turkish Journal of Biochemistry / Turk Biyokimya Dergisi is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

Exploring antiviral and anti-inflammatory effects of thiol drugs in COVID-19.

The redox status of the cysteine-rich SARS-CoV-2 spike glycoprotein (SARS-2-S) is important for the binding of SARS-2-S to angiotensin-converting enzyme 2 (ACE2), suggesting that drugs with a functional thiol group ("thiol drugs") may cleave cystines to disrupt SARS-CoV-2 cell entry. In addition, neutrophil-induced oxidative stress is a mechanism of COVID-19 lung injury, and the antioxidant and anti-inflammatory properties of thiol drugs, especially cysteamine, may limit this injury. To first explore the antiviral effects of thiol drugs in COVID-19, we used an ACE-2 binding assay and cell entry assays utilizing reporter pseudoviruses and authentic SARS-CoV-2 viruses. We found that multiple thiol drugs inhibit SARS-2-S binding to ACE2 and virus infection. The most potent drugs were effective in the low millimolar range, and IC50 values followed the order of their cystine cleavage rates and lower thiol pKa values. To determine if thiol drugs have antiviral effects in vivo and to explore any anti-inflammatory effects of thiol drugs in COVID-19, we tested the effects of cysteamine delivered intraperitoneally to hamsters infected with SARS-CoV-2. Cysteamine did not decrease lung viral infection, but it significantly decreased lung neutrophilic inflammation and alveolar hemorrhage. We speculate that the concentration of cysteamine achieved in the lungs with intraperitoneal delivery was insufficient for antiviral effects but sufficient for anti-inflammatory effects. We conclude that thiol drugs decrease SARS-CoV-2 lung inflammation and injury, and we provide rationale for future studies to test if direct (aerosol) delivery of thiol drugs to the airways might also result in antiviral effects.

Thiol level and total oxidant/antioxidant status in patients with COVID-19 infection.

BACKGROUND: Accumulating evidence suggests that oxidative stress is closely related to the pathogenesis and severity of COVID-19 infection. Here, we attempted to compare thiol, total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) levels between COVID-19 patients who need and do not need intensive care unit (ICU) support, and determine whether these markers could be used as predictors of ICU admission. METHODS: We recruited 86 patients with COVID-19 infection and classified them into two groups according to the level of care: ICU group (n = 40) and non-ICU group (n = 46). Thiol, TAS, TOS, and OSI levels were determined and compared between the two groups. RESULTS: The levels of thiol and TAS in serum were markedly lower in ICU patients than in the non-ICU patients. On the contrary, TOS and OSI levels were markedly higher. Inflammatory markers, including white blood cell, neutrophil, C-reactive protein, procalcitonin, and ferritin, were negatively correlated with the thiol and TAS, and positively correlated with the TOS and OSI. We determined that areas under the ROC curve for thiol, TAS, TOS, and OSI were 0.799, 0.778, 0.713, and 0.780, respectively. CONCLUSIONS: Our results revealed that the increase in oxidative stress and decrease in antioxidant levels in COVID-19-infected patients were associated with worsening of disease. Thiol, TAS, TOS, and OSI parameters can be used to distinguish between ICU patients and those who do not, among which thiol was the best predictor of ICU requirement.

Virtual screening of sulfur compounds of Allium against coronavirus proteases: E-Ajoene is a potential dual protease targeting covalent inhibitor

Mitigation of the activity of the main protease (Mpro) and papain-like protease (PLpro) of SARS CoV-2 has direct implications in combating the ongoing deadly COVID-19 pandemic. The active site of these proteases contains cysteine thiols which are covalently modified by the sulfur drugs such as ebselen and disulfiram. The natural product of Allium contains several reactive sulfur compounds that may covalently modify the active site cysteine thiols of coronavirus proteases. The report has assessed the binding affinity of the 52 different sulfur compounds of Allium against both Mpro and PLpro of coronavirus by conventional docking methods. Three of the top six compounds have demonstrated high affinity for both the proteases, namely, E-ajoene (S3), S-(3-pentanyl)-L-cysteine-sulfoxide (S49), and 1-propenyl allyl thiosulfinate (S14). The reactive sulfur compounds E-ajoene and 1-propenyl allyl thiosulfinate were subjected to the calculation of energetics of the putative reactions and covalent docking studies. The results indicate they covalently modify the active site cysteine thiols of the proteases through S-thioallylation, S-thioallyl sulfinyl propenylation, and S-thiopropenylation. The diversity of covalent modifications, high affinity for both the proteases and sulfur-mediated hydrogen bonds at the active site indicate that E-ajoene is a potential dual protease targeting covalent inhibitor of SARS CoV-2.

Aminothiols exchange in coronavirus disease 2019

Clinical manifestation of the inflammatory process in its relation to biochemical markers (total cysteine [Cys], cysteine-glycine [CysGly], glutathione [GSH], glutamate-cysteine [Glu-Cys], homocysteine [Hcy], the ratio of reduced to oxidized glutathione [GSH/GSSG], the ratio of reduced to oxidized cysteine [CySH/CySS], malondialdehyde-oxidized low-density lipoproteins [MDA-oxLDL]) has been studied in patients with coronavirus disease 2019 (COVID-19). 48 patients with mild to severe COVID-19 and 20 healthy volunteers were included in our research. The participants were divided into 4 experimental groups according to inflammation intensity estimated based on the serum levels of interleukin 6 (IL-6). All 4 groups showed the prevalence of male patients and elevated serum levels of IL-6 (by 54.6%). There was no comorbidity in patients with mild COVID-19 (nasopharyngitis symptoms) and in healthy control subjects. 50% of patients with lung damage had accompanying diseases. Alterations of aminoethyl metabolism were detected in COVID-19 patients: as reflected by the decreased levels of Cys, CysGly, and Glu-Cys and the increased levels of GSH as compared to the control group. Elevation of IL-6 over 7.5 pg/mL was associated with decreased GSH/GSSG and CySH/CySS ratios indicating enhanced oxidative stress and was followed by protein oxidation, specifically MDA-oxLDL. [ FROM AUTHOR]

Value of thiol and ischemia modified albumin (IMA) in predicting mortality in serious COVID-19 pneumonia.

Background/aim: Viral infections of the respiratory tract are generally related to many factors such as excessive production of cytokines, inflammation, cellular death, redox imbalance or oxidative stress. The aim of this study was to determine the serum levels of thiol and IMA in patients with severe COVID-19 pneumonia to evaluate oxidative stress. Study design: This was a prospective, sectional cohort study conducted at a pandemics hospital between 01.01.2022 and 01.02.2022. Methods: A total of 153 patients who had been confirmed with severe COVID-19 pneumonia in the emergency unit were prospectively analyzed. The control group was formed by 50 healthy volunteers with similar age and no chronic disease history. Thiol and IMA levels were statistically compared both in the patient and the control groups, and within the patient groups (survived and non-survival). Results: While 96 out of 153 patients had survived, 57 patients had non-survival. There was a statistically significant distinction between the survived and non-survival patients with regard to Thiol and IMA levels (p < 0.001). The thiol levels in the patient group were significantly lower compared to the control group, and the IMA levels were significantly higher (p < 0.001). The sensitivity, specificity and NPV were 70.2%, 86.5% and 83% when thiol cut-off value was ≤345.2 µmol/L (AUC: 0.886, p < 0.001). The sensitivity, specificity and NPV were 70.2%, 85.4% and 82.8% when the IMA cut-off was >302.9 ABSU (AUC: 0.875, p < 0.001). Conclusions: Our results demonstrate that thiol and IMA levels may be used as bioindicators for risk classification and mortality in patients with serious COVID-19 pneumonia.

Targeting SARS-CoV-2 by synthetic dual-acting thiol compounds that inhibit Spike/ACE2 interaction and viral protein production.

The SARS-CoV-2 life cycle is strictly dependent on the environmental redox state that influences both virus entry and replication. A reducing environment impairs the binding of the spike protein (S) to the angiotensin-converting enzyme 2 receptor (ACE2), while a highly oxidizing environment is thought to favor S interaction with ACE2. Moreover, SARS-CoV-2 interferes with redox homeostasis in infected cells to promote the oxidative folding of its own proteins. Here we demonstrate that synthetic low molecular weight (LMW) monothiol and dithiol compounds induce a redox switch in the S protein receptor binding domain (RBD) toward a more reduced state. Reactive cysteine residue profiling revealed that all the disulfides present in RBD are targets of the thiol compounds. The reduction of disulfides in RBD decreases the binding to ACE2 in a cell-free system as demonstrated by enzyme-linked immunosorbent and surface plasmon resonance (SPR) assays. Moreover, LMW thiols interfere with protein oxidative folding and the production of newly synthesized polypeptides in HEK293 cells expressing the S1 and RBD domain, respectively. Based on these results, we hypothesize that these thiol compounds impair both the binding of S protein to its cellular receptor during the early stage of viral infection, as well as viral protein folding/maturation and thus the formation of new viral mature particles. Indeed, all the tested molecules, although at different concentrations, efficiently inhibit both SARS-CoV-2 entry and replication in Vero E6 cells. LMW thiols may represent innovative anti-SARS-CoV-2 therapeutics acting directly on viral targets and indirectly by inhibiting cellular functions mandatory for viral replication.

Thiol-ene-based microfluidic chips for glycopeptide enrichment and online digestion of inflammation-related proteins osteopontin and immunoglobulin G.

Proteins, and more specifically glycoproteins, have been widely used as biomarkers, e.g., to monitor disease states. Bottom-up approaches based on mass spectrometry (MS) are techniques commonly utilized in glycoproteomics, involving protein digestion and glycopeptide enrichment. Here, a dual function polymeric thiol-ene-based microfluidic chip (TE microchip) was applied for the analysis of the proteins osteopontin (OPN) and immunoglobulin G (IgG), which have important roles in autoimmune diseases, in inflammatory diseases, and in coronavirus disease 2019 (COVID-19). TE microchips with larger internal surface features immobilized with trypsin were successfully utilized for OPN digestion, providing rapid and efficient digestion with a residence time of a few seconds. Furthermore, TE microchips surface-modified with ascorbic acid linker (TEA microchip) have been successfully utilized for IgG glycopeptide enrichment. To illustrate the use of the chips for more complex samples, they were applied to enrich IgG glycopeptides from human serum samples with antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The dual functional TE microchips could provide high throughput for online protein digestion and glycopeptide enrichment, showing great promise for future extended applications in proteomics and the study of related diseases.

Synthesis and Anticancer and Antiviral Activities of C-2'-Branched Arabinonucleosides.

d-Arabinofuranosyl-pyrimidine and -purine nucleoside analogues containing alkylthio-, acetylthio- or 1-thiosugar substituents at the C2' position were prepared from the corresponding 3',5'-O-silylene acetal-protected nucleoside 2'-exomethylenes by photoinitiated, radical-mediated hydrothiolation reactions. Although the stereochemical outcome of the hydrothiolation depended on the structure of both the thiol and the furanoside aglycone, in general, high d-arabino selectivity was obtained. The cytotoxic effect of the arabinonucleosides was studied on tumorous SCC (mouse squamous cell) and immortalized control HaCaT (human keratinocyte) cell lines by MTT assay. Three pyrimidine nucleosides containing C2'-butylsulfanylmethyl or -acetylthiomethyl groups showed promising cytotoxicity at low micromolar concentrations with good selectivity towards tumor cells. SAR analysis using a methyl ß-d-arabinofuranoside reference compound showed that the silyl-protecting group, the nucleobase and the corresponding C2' substituent are crucial for the cell growth inhibitory activity. The effects of the three most active nucleoside analogues on parameters indicative of cytotoxicity, such as cell size, division time and cell generation time, were investigated by near-infrared live cell imaging, which showed that the 2'-acetylthiomethyluridine derivative induced the most significant functional and morphological changes. Some nucleoside analogues also exerted anti-SARS-CoV-2 and/or anti-HCoV-229E activity with low micromolar EC50 values; however, the antiviral activity was always accompanied by significant cytotoxicity.

CEFAZOLIN-INDUCED COAGULOPATHY

SESSION TITLE: Critical Thinking SESSION TYPE: Case Reports PRESENTED ON: 10/19/2022 09:15 am - 10:15 am INTRODUCTION: Cephalosporins have been known to cause hypo-prothrombinemia and prothrombin prolongation (1). The proposed mechanism of this coagulopathy is secondary to a N-methylthiotetrazole side chain interfering with vitamin-k metabolism (1). Current literature supporting the association between cefazolin and hypo-prothombinemia have only been reported through case reports. As cefazolin is a commonly used antibiotic, it is important that healthcare professionals are aware of its potential bleeding risk. We present a case of a 72 year old female with cefazolin-induced hypo-prothrombinemia. CASE PRESENTATION: A malnourished 72-year old female with a past medical history of recent methicillin-susceptible Staphyloccocus aureus (MSSA) bacteremia and COVID-19 pneumonia presented to the emergency department from a skilled nursing facility (SNF) due to shortness of breath. The patient was previously discharged to SNF to complete a 14 day course of IV cefazolin due to her MSSA bacteremia. On admission, vital signs were significant for a respiratory rate of 22 and a pulse oximetry reading of 78% on room air. Laboratory findings were significant for an elevated prothrombin time of >100 seconds, an INR >15, and a D-dimer of 42,344 ng/mlL. A computed tomography angiography (CTA) of the chest revealed a small segmental pulmonary embolus in the right lower lobe of the lung. The patient was started on a heparin drip, placed on a non-rebreather mask, and admitted to the ICU for closer monitoring. Infectious disease was consulted and cefazolin was discontinued. Due to the patient's risk of bleeding her heparin drip was stopped. It was decided not to reverse the patient's coagulopathy with vitamin K as there were no signs of an acute bleed in the setting of an acute pulmonary embolus. The patient was started on nafcillin in place of cefazolin. Four days after discontinuation of cefazolin, the patient's INR had trended down from >15 to 1.6 and she was started on Lovenox 1mg/kg for the treatment of her acute PE. DISCUSSION: Due to the timing of the discontinuation of cefazolin and the correction of the hypo-prothrombinemia, a clear association between the two can be made. It has been proposed that cefazolin's side chain, heterocyclic thiol, 2-methyl-1,3,4-thiadiazole-5-thiol (MTD), causes a similar reaction that other cephalosporins have on the metabolism of Vitamin K (2). This altered Vitamin K metabolism was also likely exacerbated due to the patient's malnourishment and likely depleted vitamin k reserves (2). CONCLUSIONS: Although rare, this case demonstrates the need for clinicians to be aware of the potential bleeding risk associated with cephalosporins and cefazolin in particular. In the future, routine monitoring of PT/INR levels may be recommended when initiating cephalosporins. Reference #1: Park GH, Kim S, Kim MS, Yu YM, Kim GH, Lee JS, Lee E. The Association Between Cephalosporin and Hypoprothrombinemia: A Systematic Review and Meta-Analysis. Int J Environ Res Public Health. 2019 Oct 16;16(20):3937 Reference #2: Shearer, M. J., Bechtold, H., Andrassy, K., Koderisch, J., McCarthy, P. T., Trenk, D., Jähnchen, E., & Ritz, E. (1988). Mechanism of cephalosporin-induced hypoprothrombinemia: relation to cephalosporin side chain, vitamin K metabolism, and vitamin K status. Journal of clinical pharmacology, 28(1), 88–95 DISCLOSURES: no disclosure on file for John Abernathy;No relevant relationships by Ethan Goldberg No relevant relationships by Renee Miu No relevant relationships by Luis Osorio no disclosure on file for Satesh Saroop;no disclosure on file for Oliver Sevilla;no disclosure on file for Kristen Zubel;

Effect of ozone on the inactivation of indoor airborne viruses with the COVID-19 virus approach: a systematic review

Background: Nowadays, the COVID-19 pandemic has become a global problem that new methods must be used to prevent it. The virus is highly contagious and is mainly transmitted through the air. Ozone is a powerful oxidant that can be used to inactivate a wide range of viruses that may be resistant to other disinfectants. The purpose of this study was to review the use and effect of ozone in inactivating indoor viruses. Methods: To conduct this review study, the keywords such as ozone, virus and air were used to search the PubMed and Scopus databases. Articles were searched from 2010 to 2020. As a result of the search, 57 articles in this field were selected and their content and results were used in this review study. Results: This review study showed that ozone has been successfully used to prevent several viral diseases such as COVED-19. In addition, some viruses, such as coronaviruses, contain sulfhydryl functional groups containing cysteine and tryptophan that react better with ozone gas. The infected person's sneezing may result in the formation of 40,000 droplets in the air. The droplets can be transferred to the nearest surface up to approximately 2 meters before falling and also may remain in the air for 30 hours. Conclusion: The use of ozone gas has many potential applications in inactivating viruses in enclosed spaces. Given the importance of virus-containing aerosols in the transmission of COVED-19, ozone can be a promising way to prevent the disease. The degree of inactivation of viruses by ozone gas depends on the gas concentration, contact time, temperature, humidity and type of virus. In general, studies in this field have shown the use of ozone gas in preventing the spread of viral diseases such as COVED-19. Necessary safety measures and precautions are also recommended in using this gas.

Thiol Modifications in the Extracellular Space-Key Proteins in Inflammation and Viral Infection.

Posttranslational modifications (PTMs) allow to control molecular and cellular functions in response to specific signals and changes in the microenvironment of cells. They regulate structure, localization, stability, and function of proteins in a spatial and temporal manner. Among them, specific thiol modifications of cysteine (Cys) residues facilitate rapid signal transduction. In fact, Cys is unique because it contains the highly reactive thiol group that can undergo different reversible and irreversible modifications. Upon inflammation and changes in the cellular microenvironment, many extracellular soluble and membrane proteins undergo thiol modifications, particularly dithiol-disulfide exchange, S-glutathionylation, and S-nitrosylation. Among others, these thiol switches are essential for inflammatory signaling, regulation of gene expression, cytokine release, immunoglobulin function and isoform variation, and antigen presentation. Interestingly, also the redox state of bacterial and viral proteins depends on host cell-mediated redox reactions that are critical for invasion and infection. Here, we highlight mechanistic thiol switches in inflammatory pathways and infections including cholera, diphtheria, hepatitis, human immunodeficiency virus (HIV), influenza, and coronavirus disease 2019 (COVID-19).

Sensitivity enhancement of microelectromechanical sensors using femtosecond laser for biological and chemical applications

Rapid, selective, and highly sensitive microelectromechanical sensors are a promising technology for biosensing, medical recognition, and the detection of chemical hazards. At the same time, the surfaces of silicon microcantilevers cannot bond with thiols and cannot be functionalized without a bonding layer, such as gold. Therefore, in past literature, the surfaces of silicon microcantilevers have been coated with gold to facilitate their bonding with the thiol functional groups on the probe layers. However, gold coating produces thermal noise in the results owing to the metallic effect. Accordingly, this study aimed to modify the surface of silicon microcantilevers by patterning it using femtosecond laser (FSL) micromachining so that it could bond with the thiol functional groups with high sensitivity. The surface patterning of silicon microcantilevers enhances their physical, micromechanical, and chemical properties, increasing sensitivity by increasing the quality factor, specific surface area, and creating trapping areas on the microcantilever surfaces. The surfaces of the silicon microcantilever were patterned by microgrooves aligned from the free end to the bounded end, with each microgroove comprising submicrogrooves. To demonstrate their use in a biosensing applications, the modified microcantilevers were functionalized to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2;COVID-19) by immobilizing thiolated oligonucleotides on the surfaces, which worked as the probe layer. The modified biosensor was used to detect low concentrations of SSDNA sequence targets ranging from 300 nM down to 100 pM. The modified silicon-microcantilever sensors were directly functionalized without a joining layer, such as a gold layer. The results revealed a selective response to SARS-CoV-2 SSDNA down to a 9-nM concentration. To detect hazardous chemicals, the modified microcantilever was functionalized using reduced L-cysteine to detect Pb2+ at low concentrations down to 100 pM. The results revealed enhanced sensitivity and selectivity and demonstrated that the FSL patterning activated the microcantilevers to bond with probe layers through the interaction of the silanol created on the surface with the functional groups, such as the thiols, on the probe layers. The microcantilevers patterned with 10 microgrooves exhibited higher responses than those patterned with seven microgrooves. © 2022 John Wiley & Sons Ltd.

Towards Label-free detection of viral disease agents through their cell surface proteins: Rapid screening SARS-CoV-2 in biological specimens.

Current methods for the screening of viral infections in clinical settings, such as reverse transcription polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA), are expensive, time-consuming, require trained personnel and sophisticated instruments. Therefore, novel sensors that can save time and cost are required specially in remote areas and developing countries that may lack the advanced scientific infrastructure for this task. In this work, we present a sensitive, and highly specific biosensing approach for the detection of harmful viruses that have cysteine residues within the structure of their cell surface proteins. We utilized new method for the rapid screening of SARS-CoV-2 virus in biological fluids through its S1 protein by surface enhanced Raman spectroscopy (SERS). The protein is captured from aqueous solutions and biological specimens using a target-specific extractor substrate. The structure of the purified protein is then modified to convert it into a bio-thiol by breaking the disulfide bonds and freeing up the sulfhydryl (SH) groups of the cysteine residues. The formed biothiol chemisorbs favourably onto a highly sensitive plasmonic sensor and probed by a handheld Raman device in few seconds. The new method was used to screen the S1 protein in aqueous medium, spiked human blood plasma, mucus, and saliva samples down to 150 fg/L. The label-free SERS biosensing method has strong potential for the fingerprint identification many viruses (e.g. the human immunodeficiency virus, the human polyomavirus, the human papilloma virus, the adeno associated viruses, the enteroviruses) through the cysteine residues of their capsid proteins. The new method can be applied at points of care (POC) in remote areas and developing countries lacking sophisticated scientific infrastructure.

Investigation of prognostic indicators in patients with covid 19

OBJECTIVES: The aim was to evaluate the prognostic role of D-dimer, procalcitonin (PCT), ischemia modified albumin (IMA) total thiol and lymphocyte% in patients with COVID-19. MATERIALS-METHODS: Total of 80 patients with COVID-19, confirmed with reverse transcriptase polymerase chain reaction between September and October 2020 were included in the study. The patients with COVID-19 hospitalized in the service or intensive care unit were devided into critical and non-critical according to the criteria found in the World Health Organization interim guidelines. D-dimer, PCT, IMA, total thiol levels and lymphocyte% were determined and compared groups. Receiver-operating characteristic curves (ROC) were used to detect an optimal cut-off value for discrimination. RESULTS: D-dimer and PCT levels were found to be significantly higher (p<0.001 and p=0.032, respectively);total thiol levels and lymphocyte% were significantly lower (p=0.026 and p<0.001, respectively) in critical patients with COVID-19 than those non-critical. We determined a cut-off value of 790 μg/L for D-dimer (82.6% sensitivity;70% specificity;Area Under Curve (AUC): 0.827;p<0.001), 8.9 for lymphocyte% (74% sensitivity;79% specificity;AUC: 0.839;p<0.001) and 211 μmol/L for total thiol (91.3% sensitivity;47.4% specificity;AUC: 0.699;p=0.003) via ROC analysis. CONCLUSION: We can say that the performance of D-dimer and lymphocyte% as prognostic factors is good and total thiol levels have limited discriminating power for COVID-19 disease.

An evaluation of maternal serum dynamic thiol-disulfide homeostasis and ischemia modified albumin changes in pregnant women with COVID-19.

Objective: It is thought that oxidative stress, free radicals, reactive oxygen species and reactive nitrogen species affect the pathophysiology of coronavirus disease-2019 (COVID-19). This study aimed to evaluate the oxidative status in pregnant patients with COVID-19 infection according to the changes seen in the levels of maternal serum thiol-disulfide and ischemia-modified albumin (IMA). Materials and Methods: A study group was formed of 40 pregnant women with confirmed COVID-19 infection (study group) and a control group of 40 healthy pregnant women with no risk factors determined. In this prospective, case-controlled study, analyses were made of the maternal serum native thiol, total thiol, disulfide, IMA, and disulfide/native thiol concentrations. Results: The maternal serum native thiol and total thiol concentrations in the study group were determined to be statistically significantly lower (p=0.007 and p=0.006, respectively), and the disulfide/native thiol ratio was higher but not to a level of statistical significance (p=0.473). There was no difference between the two groups regarding IMA levels (p=0.731). Conclusion: The thiol-disulfide balance was seen to shift in the oxidant direction in pregnancies with COVID-19, which might support the view that ischemic processes play a role in the etiopathogenesis of this novel disease.

Thiol-based chemical probes exhibit antiviral activity against SARS-CoV-2 via allosteric disulfide disruption in the spike glycoprotein.

The development of small-molecules targeting different components of SARS-CoV-2 is a key strategy to complement antibody-based treatments and vaccination campaigns in managing the COVID-19 pandemic. Here, we show that two thiol-based chemical probes that act as reducing agents, P2119 and P2165, inhibit infection by human coronaviruses, including SARS-CoV-2, and decrease the binding of spike glycoprotein to its receptor, the angiotensin-converting enzyme 2 (ACE2). Proteomics and reactive cysteine profiling link the antiviral activity to the reduction of key disulfides, specifically by disruption of the Cys379-Cys432 and Cys391-Cys525 pairs distal to the receptor binding motif in the receptor binding domain (RBD) of the spike glycoprotein. Computational analyses provide insight into conformation changes that occur when these disulfides break or form, consistent with an allosteric role, and indicate that P2119/P2165 target a conserved hydrophobic binding pocket in the RBD with the benzyl thiol-reducing moiety pointed directly toward Cys432. These collective findings establish the vulnerability of human coronaviruses to thiol-based chemical probes and lay the groundwork for developing compounds of this class, as a strategy to inhibit the SARS-CoV-2 infection by shifting the spike glycoprotein redox scaffold.

Oxidative Stress Status and its correlation with Redox Status as Measured By An Electrochemical (PAOT®) Methodology: A Pilot Study in Critical COVID-19 Pneumonia Survivors

Background: In most serious COVID-19 forms which required prolonged stay in intensive care unit, pulmonary, cardiovascular, renal, neurological and psychological sequelae have been reported after the infection. All these complications can be sustained by chronic inflammatory problems and/ or increased oxidative stress. Material and Methods: Biomarkers of the systemic oxidative stress status (OSS) including enzymatic and non-enzymatic antioxidants, total antioxidant capacity of plasma (PAOT®-Sore), trace elements, oxidative damage to lipids and inflammation markers, were investigated in 12 patients admitted to a revalidation center for post-19 COVID pneumonia. Results: From blood samples collected two months after hospital discharge and one month after admission to the revalidation center, vitamin C, thiol proteins, reduced glutathione, gamma-tocopherol and beta carotene were significantly decreased compared to reference values. By contrast, lipid peroxides and markers of inflammation (neutrophils, myeloperoxidase) were significantly higher than the norms. Lipid peroxides was strongly correlated with Cu (r = 0.95, P < 0.005) and Cu/Zn ratio (0.66, P = 0.020). Using an electrochemical method (PAOT®), total antioxidant capacity (TAC) evaluated in saliva and urine negatively correlated with copper and lipid peroxides. Similar findings were obtained for PAOT®-skin score. Conclusions: Systemic OSS was strongly altered in patients admitted in revalidation after C0VID-19 infection. This suggests the need for supplementing these patients with antioxidants.