A new strategy to integrate silver nanowires with waterborne coating to improve their antimicrobial and antiviral properties

PurposeThis study aims to focus on the preparation and characterization of the silver nanowire (AgNWs), as well as their application as antimicrobial and antivirus activities either with incorporation on the waterborne coating formulation or on their own.Design/methodology/approachPrepared AgNWs are characterized by different analytical instruments, such as ultraviolet-visible spectroscope, scanning electron microscope and X-ray diffraction spectrometer. All the paint formulation's physical and mechanical qualities were tested using American Society for Testing and Materials, a worldwide standard test procedure. The biological activities of the prepared AgNWs and the waterborne coating based on AgNWs were investigated. And, their effects on pathogenic bacteria, antioxidants, antiviral activity and cytotoxicity were also investigated.FindingsThe obtained results of the physical and mechanical characteristics of the paint formulation demonstrated the formulations' greatest performance, as well as giving good scrub resistance and film durability. In the antimicrobial activity, the paint did not have any activity against bacterial pathogen, whereas the AgNWs and AgNWs with paint have similar activity against bacterial pathogen with inhibition zone range from 10 to 14 mm. The development of antioxidant and cytotoxicity activity of the paint incorporated with AgNWs were also observed. The cytopathic effects of herpes simplex virus type 1 (HSV-1) were reduced in all three investigated modes of action when compared to the positive control group (HSV-1-infected cells), suggesting that these compounds have promising antiviral activity against a wide range of viruses, including DNA and RNA viruses.Originality/valueThe new waterborne coating based on nanoparticles has the potential to be promising in the manufacturing and development of paints, allowing them to function to prevent the spread of microbial infection, which is exactly what the world requires at this time.

Nanoparticles as an exotic antibacterial, antifungal, and antiviral agents

Globally, concerns regarding the COVID-19 pandemic its prevention have become important. Because of COVID-19 and other microbial diseases, enhance research work has emerged revealing new antimicrobial and antiviral materials and techniques. Tremendous growth in nanotechnology has opened up the door to fabricating numerous nanomaterials. These nanomaterials are employed as antimicrobial and antiviral agents for various applications with 99.99% effectiveness compared with conventional techniques. Nanoparticles possess unique physicochemical characteristics for multiple applications. This chapter details the use of nanoparticles for antifungal, antimicrobial, and antiviral applications. It describes various kinds of nanoparticles, such as nanometals, metal oxides, polymeric nanomaterials, and carbon-based nanomaterials. © 2023 Elsevier Inc. All rights reserved.

COVID-19 Vaccine and Booster Shots Compatibility Analyzer using CMOS-based Monochrome Encoding

The continuous increase in COVID-19 positive cases in the Philippines might further weaken the local healthcare system. As such, an efficient system must be implemented to further improve the immunization efforts of the country. In this paper, a contactless digital electronic device is proposed to assess the vaccine and booster brand compatibility. Using Logisim 2.7.1, the logic diagrams were designed and simulated with the help of truth tables and Boolean functions. Moreover, the finalized logic circuit design was converted into its equivalent complementary metal-oxide semiconductor (CMOS) and stick diagrams to help contextualize how the integrated circuits will be designed. Results have shown that the proposed device was able to accept three inputs of the top three COVID-19 vaccine brands (Sinovac, AstraZeneca, and Pfizer) and assess the compatibility of heterologous vaccinations. With the successful results of the circuit, it can be concluded that this low-power device can be used to manufacture a physical prototype for use in booster vaccination sites. © 2022 IEEE.

Impact of the COVID-19 Pandemic on theWorld Steel Market

The article analyzes the activities of steel companies during the COVID-19 pandemic in 2020. The COVID-19 pandemic and the subsequent economic crisis have become one of the most serious challenges for world steel companies. The consequences, which are expressed in a decrease in demand for steel products from the key consumer sectors—automotive industry and construction, and other consumers, have caused a high level of uncertainty in the international steel market, and have identified new development vectors that should help overcome the crisis in the steel industry. The article assesses the impact of the pandemic and current global economic crisis on the global steel industry, including Russia;identifies trends and prospects for the development of the global steel market;identifies key areas for the recovery of the steel industry after the COVID-19 pandemic. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

Zn2+ and Cu2+ Interaction with the Recognition Interface of ACE2 for SARS-CoV-2 Spike Protein.

The spike protein (S) of SARS-CoV-2 is able to bind to the human angiotensin-converting enzyme 2 (ACE2) receptor with a much higher affinity compared to other coronaviruses. The binding interface between the ACE2 receptor and the spike protein plays a critical role in the entry mechanism of the SARS-CoV-2 virus. There are specific amino acids involved in the interaction between the S protein and the ACE2 receptor. This specificity is critical for the virus to establish a systemic infection and cause COVID-19 disease. In the ACE2 receptor, the largest number of amino acids playing a crucial role in the mechanism of interaction and recognition with the S protein is located in the C-terminal part, which represents the main binding region between ACE2 and S. This fragment is abundant in coordination residues such as aspartates, glutamates, and histidine that could be targeted by metal ions. Zn2+ ions bind to the ACE2 receptor in its catalytic site and modulate its activity, but it could also contribute to the structural stability of the entire protein. The ability of the human ACE2 receptor to coordinate metal ions, such as Zn2+, in the same region where it binds to the S protein could have a crucial impact on the mechanism of recognition and interaction of ACE2-S, with consequences on their binding affinity that deserve to be investigated. To test this possibility, this study aims to characterize the coordination ability of Zn2+, and also Cu2+ for comparison, with selected peptide models of the ACE2 binding interface using spectroscopic and potentiometric techniques.

Novel oxazolidinone zinc(II) complexes as antibacterial and anti-SARS-CoV-2 agents: synthesis, characterization, DFT calculations, ADMET, in silico molecular docking and biological activities

A series of Zn(II) complexes with oxazolidinone derivatives has been synthesized and characterized using spectroscopic techniques: IR, H-1 NMR, UV-Vis spectroscopy, and TGA/DTG thermal investigation. Theoretical computations were carried out using B3LYP/6-31G(d) and B3LYP/LanL2DZ to analyze the vibrational properties, NBO charges, global chemical reactivity indices and to illustrate the FOMs. TD-DFT calculations using WB97XD functional were realized with 6-31 G(d) and LAN2DZ basis set on oxazolidinone ligands and their zinc complexes. The pharmacokinetic properties and toxicity of the investigated compounds were predicted using in silico ADMET studies. Moreover, the S. aureus, E. coli, S. pneumoniae, ribosome 50S subunit, SARS-Cov-2 spike protein and ACE2 human receptor were selected for molecular docking study. The docking study shows that HL4 and ZnL4 bind better to the spike protein and hACE2 receptor. The redox properties were also studied for ligands and their corresponding complexes using cyclic voltammetry. Finally, antioxidant activity studies using DPPH radical scavenging showed efficiency for HL2 and [Zn(L-2)(2)] with low values of IC50 compared to ascorbic acid. The antimicrobial activity against B. subtilis (ATCC 9372), E. faecalis (ATCC 29212), S. aureus (ATCC 6538), E. coli (ATCC 4157), bacteria strains, C. albicans (ATCC 24433) and A. niger fungi strains were evaluated.

Beyond silver sulfadiazine: A dive into more than 50 years of research and development on metal complexes of sulfonamides in medicinal inorganic chemistry

Sulfonamides revolutionized the treatment and management of bacterial infections. Prontosil was the very first synthetic antibacterial agent ever used in the clinics and its metabolite, sulfanilamide, led to the development of a diverse range of sulfonamides with a diverse spectrum of action. Although being developed as antibacterial agents, sulfonamides have also shown to present antitumor, antifungal, and antiviral activities. While for antibacterial applications the focus is on the dihydropteroate synthase enzyme, for antitumor compounds a lot of attention has been given to carbonic anhydrases. For antiviral applications some studies focus on inhibiting HIV replication, and with the COVID-19 pandemic in the last years, attention has been given to inhibit SARS-CoV-2 replication as well. For antifungal applications it seems there is a lack of target focus, but with some compounds presenting relevant activities. Silver sulfadiazine was the first metal complex of a sulfonamide to be used in the clinics as a topical agent for prevention and treatment of infections in burn patients and is vastly used to this day. Here, we covered the history of silver sulfadiazine development, its chemical properties, antibacterial activity and clinical data. Controversial results on the true efficacy of silver sulfadiazine as a topical treatment for burn wounds gave rise to ongoing debate on the advantages of using this compound when compared to other dressings loaded or not with silver-containing agents. Nonetheless, the 50-year history of silver sulfadiazine's successful use in the clinics has motivated the development of other metal complexes of sulfonamides, which are reviewed here. The biological endpoints for these novel metal complexes were not limited to antibacterial use, but expanded to antitumor, antifungal, and antiviral applications as well. Altogether, this review presents the developments in the applications of metal complexes of sulfonamides in medicinal inorganic chemistry in the past years.

Covid19 Impact OnTwelve Sectors Of The Indian Economy

This study aims to investigate the reaction of COVID-19 cases (confirmed, deaths, recovered, & active) on twelve sectors of Indian economy by using sectoral indices of national stock exchange. Daily frequency of COVID-19 case categories was obtained from Worldometer from January 30, 2020 to June 30, 2020 and dataset of daily closing prices of twelve sectoral indices (auto, banks, financial services, fast moving consumer goods, information technology, media, metal, oil & gas, pharmaceutical, public sector banks, private banks, realty sector) was obtained from national stock exchange web portal for the same period as of COVID-19. In this study, the ordinary least square regression was used to study the significance of COVID-19 cases (confirmed, deaths, recovered, & active) on twelve sectoral indices. Empirical evidence suggested no significant impact of COVID-19 cases on daily returns of twelve major sectors represented by sectoral indices except in the case of pharmaceutical sector, where daily growth in number of deaths is impacting daily returns on pharmaceutical sectoral index in a positive way. The twelve sectoral indices went into a downward spiral at the beginning of COVID-19 pandemic, but as government and central bank introduced various policy measures, the impact of COVID-19 pandemic on sectoral indices faded away.Copyright © 2020 Ubiquity Press. All rights reserved.

Inadvertent Treatment of a Vertical Banded Gastroplasty Stricture With a LAMS for Two Years

Introduction: Lumen-apposing metal stents (LAMS) are innovative endoscopic devices representing the next significant advancement in stent technology. LAMS have demonstrated success, most notably with improving drainage of pancreatic fluid collections. Other clinical indications for using LAMS include biliary drainage, gastroenterostomy, or the managment of luminal tract strictures. The stent has a larger lumen diameter than previously created stents as well as a unique "dumbbell" shape to limit migration. Studies have demonstrated advantages such as shorter procedure times and overall reduced repeat endoscopic procedures. As LAMS has gained notoriety, there have been increasing studies demonstrating potential complications of the device. Most common consequences of LAMS include bleeding, biliary stricture, and buried LAMS syndrome. As the anatomical design has decreased migration risk, prompt removal is recommended to prevent buried LAMS syndrome, where the stent is embedded in the wall of the gastric mucosa and can eventually not be visualized endoscopically. In this case, we will present a patient with an endoscopically placed LAMS, which was successfully removed with minimal complications after two years in place. Case Description/Methods: Our patient is a 68 year old female with a Vertical Banded Gastroplasty Stricture. She had required multiple repeat endoscopies for dilation therapy but the stricture was refractory to dilation, as a result, she underwent LAMS placement Due to the onset of the COVID pandemic, patient was lost to follow up. On a repeat EGD two years after placement, the stent remained in its original location. There were signs of mild gastric tissue overgrowth at the right lateral side of the LAMS. The stent was then removed easily with no signs of bleeding. After removal, the stricture remained dilated as the scope could be passed without difficulty. Over course of COVID she ate better than she had in years. (Figure) Discussion: LAMS have demonstrated significant success in a variety of endoscopic interventions. Their potential complications are well documented in various studies. This case is unique in regards to the length of time in which the LAMS remained in position. From a literature review, no study has demonstrated a LAMS in place as long as two years for stricture management. More remarkable is the lack of complications from the stent such as no bleeding with removal and no true buried LAMS syndrome as there was minimal tissue overgrowth. (Figure Presented).

A Review on Antiviral Plants Effective against Different Virus Types

The treatment of microbial infections has proven challenging for humans in recent years. Synthetic medications, such as antimicrobial agents, are used for treating these infections. Antimicrobials derived from natural sources have gained popularity as an alternative to manufactured medications due to their lack of adverse effects. Plants, which play a significant role in this setting, have historically served as a reliable natural defence against several pathogens. In this study, studies on plants used against viral diseases are mentioned. Studies on viruses that cause disease have been compiled in the literature. According to the findings, it has been reported in the literature that many different plant species are effective against herpes simplex virus (HSV-1, HSV-2), human immunodeficiency virus (HIV), influenza virus (A, B) and parainfluenza, Poliovirus, Astrovirus, Parvovirus, Sindbis virus (SINV), Feline calicivirus (FCV), Rhinovirus, Echovirus, Rotavirus, Bovine alphaherpesvirus 1 (BoHV-1), Reovirus, Vaccinia virus (VACV), Cardiovirus A (Encephalomyocarditis virus;EMCV), Coxsackie virus, Semliki forest, Measles virus, Newcastle disease virus (NDV), Coronavirus, Adenovirus (ADV-3, ADV-5, ADV-8, ADV-11), Canine distemper virus (CDV), Lumpy skin disease virus (LSDV), Hepatitis A, B, C virus and Enterovirus. To combat viruses, plants can be considered a potentially invaluable natural resource.

Dry-spun carbon nanotube ultrafiltration membranes tailored by anti-viral metal oxide coatings for human coronavirus 229E capture in water.

Although waterborne virus removal may be achieved using separation membrane technologies, such technologies remain largely inefficient at generating virus-free effluents due to the lack of anti-viral reactivity of conventional membrane materials required to deactivating viruses. Here, a stepwise approach towards simultaneous filtration and disinfection of Human Coronavirus 229E (HCoV-229E) in water effluents, is proposed by engineering dry-spun ultrafiltration carbon nanotube (CNT) membranes, coated with anti-viral SnO2 thin films via atomic layer deposition. The thickness and pore size of the engineered CNT membranes were fine-tuned by varying spinnable CNT sheets and their relative orientations on carbon nanofibre (CNF) porous supports to reach thicknesses less than 1 µm and pore size around 28 nm. The nanoscale SnO2 coatings were found to further reduce the pore size down to ∼21 nm and provide more functional groups on the membrane surface to capture the viruses via size exclusion and electrostatic attractions. The synthesized CNT and SnO2 coated CNT membranes were shown to attain a viral removal efficiency above 6.7 log10 against HCoV-229E virus with fast water permeance up to ∼4 × 103 and 3.5 × 103 L.m-2.h-1.bar-1, respectively. Such high performance was achieved by increasing the dry-spun CNT sheets up to 60 layers, orienting successive 30 CNT layers at 45°, and coating 40 nm SnO2 on the synthesized membranes. The current study provides an efficient scalable fabrication scheme to engineer flexible ultrafiltration CNT-based membranes for cost-effective filtration and inactivation of waterborne viruses to outperform the state-of-the-art ultrafiltration membranes.

The reaction of the metal and gold resource planning in the post-COVID-19 era and Russia-Ukrainian conflict: Role of fossil fuel markets for portfolio hedging strategies

The prime objective of this article is to examine the policy-making role of metal markets, gold resources, and clean energy markets in the post-COVID-19 era and the Russia-Ukrainian military conflict. In doing so, we analyze the role of fossil fuels, clean energy, and metals markets, considering the military conflict in Ukraine in 2022. The study employs event study methodology (ESM), Total connectedness index (TCI), and network analyses. The results indicate that natural gas and clean energy prices are less affected by conflict in the aftermath of an invasion than traditional energy and metals markets. In addition, we observe an increase in the TCI in the energy markets during announcement days. The TCI of the metals market is greater than that of the energy market. According to network connectivity, the key asset class transmitters of the shock in Europe are the Geopolitical index (GPR), gold, and the clean energy stock index (ERIX). The U.S. markets are less affected by the situation in Ukraine. The average hedge suggests that the optimal hedge differs from one market to the next, with fossil fuels and renewable energy, respectively, being more hedge effective and reducing risk by an average of around 0.80 and 0.59, given their ability to function as a hedging instrument.

Characterization and Source Apportionment of PM in Handan—A Case Study during the COVID-19

Handan is a typical city affected by regional particulate pollution. In order to investigate particulate matter (PM) characterization, source contributions and health risks for the general populations, we collected PM samples at two sites affected by a pollution event (12–18 May 2020) during the COVID-19 pandemic and analyzed the major components (SNA, OCEC, WSIIs, and metal elements). A PCA-MLR model was used for source apportionment. The carcinogenic and non-carcinogenic risks caused by metal elements in the PM were assessed. The results show that the renewal of old neighborhoods significantly influences local PM, and primarily the PM10;the average contribution to PM10 was 27 μg/m3. The source apportionment has indicated that all other elements came from dust, except Cd, Pb and Zn, and the contribution of the dust source to PM was 60.4%. As PM2.5 grew to PM10, the PM changed from basic to acidic, resulting in a lower NH4+ concentration in PM10 than PM2.5. The carcinogenic risk of PM10 was more than 1 × 10−6 for both children and adults, and the excess mortality caused by the renewal of the community increased by 23%. Authorities should pay more attention to the impact of renewal on air quality. The backward trajectory and PSCF calculations show that both local sources and short-distance transport contribute to PM—local sources for PM10, and short-distance transport in southern Hebei, northern Henan and northern Anhui for PM2.5, SO2 and NO2. © 2023 by the authors.

Analytical and biomedical applications of microfluidics in traditional Chinese medicine research

Traditional Chinese medicine (TCM) has significant benefits in the prevention and treatment of diseases due to its unique theoretical system and research techniques. However, there are still key issues to be resolved in the full interpretation and use of TCM, such as vague active compounds and mechanism of action. Therefore, it is promising to promote the research on TCM through innovative strategies and advanced cutting-edge technologies. Microfluidic chips have provided controllable unique platforms for biomedical applications in TCM research with flexible composition and large-scale integration. In this review, the analysis and biomedical applications of microfluidics in the field of TCM are highlighted, including quality control of Chinese herbal medicines (CHMs), delivery of CHMs, evaluation of pharmacological activity as well as disease diagnosis. Finally, potential challenges and prospects of existing microfluidic technologies in the inheritance and innovation of TCM are discussed.Copyright © 2022 Elsevier B.V.

Determining the Effect of KmtR Mutants, E101Q, H102Q, and H111Q on the Metal Binding Affinities

Mycobacterium tuberculosis is the second leading infectious killer after COVID-19. The bacteria utilizes several metal transport systems to help it survive in the host.With an increase in the number of multiresistant, extensively resistant and totally drug-resistant strains, the development of new therapeutic strategies that target other essential pathways in the bacteria is critical. The bacteria contain several metal transport systems which are necessary for its survival. Additionally, the bacteria has two metalloregulators that are associated with nickel and cobalt export, NmtR and KmtR. The focus of this research is on KmtR, which represses the expression of the genes, cdf (which encodes the export protein) and kmtR. The goal of our research is to identify the residues that are responsible for binding the cognate metals, nickel and cobalt, as well as the noncognate metal, zinc, to KmtR. Mutagenesis studies coupled with metal binding experiments will be used to determine how KmtR binds these metals. The E101Q, H102Q, and H111Q mutants, among others, have been made, expressed, and purified in our lab. Data obtained from Isothermal Titration Calorimetry determined that all three mutant proteins bind cobalt with nanomolar affinities and the H111Q mutant KmtR proteins binds cobalt an order of magnitude weaker than the other two mutant proteins. Research reported as supported fully by the RI Institutional Development Award (IDeA) Network for Biomedical Research Excellence (RI-INBRE) from the National Institute of General Medical Sciences of the National Institutes of Health under grant #P20GM103430.Copyright © 2023 The American Society for Biochemistry and Molecular Biology, Inc.

Emerging membrane technologies and disinfection methods for efficient removal of waterborne pathogens during the COVID-19 pandemic and post-pandemic

Viruses and other microorganisms can enter water sources from different routes and cause pollution and irreparable damage. So, cost-effective and efficient systems for providing safe water are necessary. Efficient filtration systems based on antimicrobial materials have received a lot of attention in this regard. A wide range of materials play an important role in the production of efficient water filtration systems. Metal and metal oxide particles with anti-viral and antimicrobial properties comprising Cu, Cu2O, Ag, TiO2, and ZnO play a valuable role in the preparation of water filtration systems. Biopolymers such as cellulose or carbon nanomaterials like graphene or its derivatives have been reported to provide safe water. In this review, we summarize the use of diverse materials in the preparation of efficient filtration-based systems like membranes and paper filters for water treatment. Pathogen-containing water samples were effectively disinfected using the prepared water disinfection systems.Copyright © 2023 The Royal Society of Chemistry.

Comparison of the Effect of Cetylpyridinium Chloride 0.05% and Povidone-Iodine 1%, Two Types of Mouthwash Effective Against COVID-19, on the Shear Bond Strength of Metal Orthodontic Brackets: a Laboratory Study

Introduction: Povidone-iodine 1% and cetylpyridinium chloride 0.05% mouthwashes have been used to remove microbial plaque and reduce gingivitis and the dysfunction of COVID-19. The present research was conducted to determine these two types of mouthwash effects on the shear bond strength of orthodontic brackets in laboratory conditions. Method: In this experimental-laboratory research, healthy human premolar teeth were selected and preserved in 1% thymol. The samples were divided into three groups, including control and 0.05% cetylpyridinium chloride and 1% povidone-iodine mouthwashes. The shear bond strength values of the brackets were measured with a UTM device and with a blade speed of 1 mm/min After keeping each group in mouthwash and applying thermal cycles. The Adhesive Remnant Index (ARI) observed the amount of residual adhesive using a stereomicroscope at ten magnifications. The bond strength of brackets was investigated by one-way Analysis of Variance (ANOVA) in three groups, and pairwise comparisons were performed with Tukey's test. The chi-square test also analyzed the remaining adhesive degrees in the groups. Results: Significant differences were observed in the shear bond strength of brackets in three groups (p=0.02). The bond strength of the brackets in the povidone-iodine mouthwash group was significantly higher than the control group (p=0.01). However, in other pairwise comparisons, no significant differences were observed between the groups. There were no significant differences in the amount of residual adhesive in the different groups. Conclusion: Immersion in mouthwashes, effective against COVID-19, had no adverse effects on metal orthodontic brackets' shear bond strength values. Therefore, these mouthwashes can establish oral and dental hygiene and destroy COVID-19's function in orthodontic patients. [ FROM AUTHOR] Copyright of Journal of Pharmaceutical Negative Results is the property of ResearchTrentz 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.)

SARS-CoV-2 Nsp13 Catalytic Efficiency is Regulated by ATP: Mg2+ Stoichiometry and Functional Cooperativity Among Nsp13 Molecules

Coronavirus disease 19 (COVID-19) is a highly contagious and lethal disease caused by the SARS-CoV-2 positive-strand RNA virus. Nonstructural protein 13 (Nsp13) is the highly conserved ATPase/helicase required for replication of the SARS-CoV-2 genome which allows for the infection and transmission of COVID-19. We biochemically characterized the purified recombinant SARS-CoV-2 Nsp13 helicase protein expressed using a eukaryotic cell-based system and characterized its catalytic functions, focusing on optimization of its reaction conditions and assessment of functional cooperativity among Nsp13 molecules during unwinding of duplex RNA substrates. These studies allowed us to carefully determine the optimal reaction conditions for binding and unwinding various nucleic acid substrates. Previously, ATP concentration was suggested to be an important factor for optimal helicase activity by recombinant SARS-CoV-1 Nsp13. Apart from a single study conducted using fixed concentrations of ATP, the importance of the essential divalent cation for Nsp13 helicase activity had not been examined. Given the importance of the divalent metal ion cofactor for ATP hydrolysis and helicase activity, we assessed if the molar ratio of ATP to Mg2+ was important for optimal SARS-CoV-2 Nsp13 RNA helicase activity. We determined that Nsp13 RNA helicase activity was dependent on ATP and Mg2+ concentrations with an optimum of 1 mM Mg2+ and 2 mM ATP. Next, we examined Nsp13 helicase activity as a function of equimolar ATP:Mg2+ ratio and determined that helicase activity decreased as the equimolar concentration increased, especially above 5 mM. We determined that Nsp13 catalytic functions are sensitive to Mg2+ concentration suggesting a regulatory mechanism for ATP hydrolysis, duplex unwinding, and protein remodeling, processes that are implicated in SARS-CoV-2 replication and proofreading to ensure RNA synthesis fidelity. Evidence is presented that excess Mg2+ impairs Nsp13 helicase activity by dual mechanisms involving both allostery and ionic strength. In addition, using single-turnover reaction conditions, Nsp13 unwound partial duplex RNA substrates of increasing doublestranded regions (16-30 base pairs) with similar kinetic efficiency, suggesting the enzyme unwinds processively in this range under optimal reaction conditions. Furthermore, we determined that Nsp13 displayed sigmoidal behavior for helicase activity as a function of enzyme concentration, suggesting that functional cooperativity and oligomerization are important for optimal activity. The observed functional cooperativity of Nsp13 protomers suggests the essential coronavirus RNA helicase has roles in RNA processing events beyond its currently understood involvement in the SARS-CoV-2 replication-transcription complex (RTC), in which it was suggested that only one of the two Nsp13 subunits has a catalytic function, whereas the other has only a structural role in complex stability. Altogether, the intimate regulation of Nsp13 RNA helicase by divalent cation and protein oligomerization suggests drug targets for modulation of enzymatic activity that may prove useful for the development of novel anti-coronavirus therapeutic strategies. This work was supported by the Intramural Training Program, National Institute on Aging (NIA), NIH, and a Special COVID-19 Grant from the Office of the Scientific Director, NIA, NIH.Copyright © 2023 The American Society for Biochemistry and Molecular Biology, Inc.