Mitigation of SARS-CoV-2 by Using Transition Metal Nanozeolites and Quaternary Ammonium Compounds as Antiviral Agents in Suspensions and Soft Fabric Materials.

Introduction: The coronavirus disease 2019 (COVID-19) pandemic has demonstrated the need for novel, affordable, and efficient reagents to help reduce viral transmission, especially in high-risk environments including medical treatment facilities, close quarters, and austere settings. We examined transition-metal nanozeolite suspensions and quaternary ammonium compounds as an antiviral surface coating for various textile materials. Methods: Zeolites are crystalline porous aluminosilicate materials, with the ability of ion-exchanging different cations. Nanozeolites (30 nm) were synthesized and then ion-exchanged with silver, zinc and copper ions. Benzalkonium nitrate (BZN) was examined as the quaternary ammonium ion (quat). Suspensions of these materials were tested for antiviral activity towards SARS-CoV-2 using plaque assay and immunostaining. Suspensions of the nanozeolite and quat were deposited on polyester and cotton fabrics and the ability of these textiles towards neutralizing SARS-CoV-2 was examined. Results: We hypothesized that transition metal ion containing zeolites, particularly silver and zinc (AM30) and silver and copper (AV30), would be effective in reducing the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Additionally, AM30 and AV30 antiviral potency was tested when combined with a quaternary ammonium carrier, BZN. Our results indicate that exposure of SARS-CoV-2 to AM30 and/or AV30 suspensions reduced viral loads with time and exhibited dose-dependence. Antiviral activities of the combination of zeolite and BZN compositions were significantly enhanced. When used in textiles, AM30 and AV30-coated cotton and polyester fabrics alone or in combination with BZN exhibited significant antiviral properties, which were maintained even after various stress tests, including washes, SARS-CoV-2-repeated exposures, or treatments with soil-like materials. Conclusion: This study shows the efficacy of transition metal nanozeolite formulations as novel antiviral agents and establishes that nanozeolite with silver and zinc ions (AM30) and nanozeolite with silver and copper ions (AV30) when combined with benzalkonium nitrate (BZN) quickly and continuously inactivate SARS-CoV-2 in suspension and on fabric materials.

Simultaneous removal of microplastics and benzalkonium chloride using electrocoagulation process: statistical modeling and techno-economic optimization.

Microplastics and benzyldimethyldodecylammonioum chloride (DDBAC) enter the environment more frequently during the COVID-19 pandemic and their co-occurrence will be a potential threat to the environment in the post-pandemic era. This study investigates the performance of an electrochemical system for the simultaneous removal of microplastics and DDBAC. During experimental studies, effects of applied voltage (3-15 V), pH (4-10), time (0-80 min), electrolyte concentration (0.01-0.0.09 M), electrode configuration, and perforated anode were investigated to identify their influence on DDBAC and microplastics removal efficiency. Eventually, the techno-economic optimization yielded to evaluate the commercial feasibility of this process. The central composite design (CCD) and analysis of variance (ANOVA) are employed for evaluation and optimization of the variables and response, DDBAC-microplastics removal, and for determining the adequacy and significance of mathematical models proposed by response surface methodology (RSM). Experimental results indicate that optimum conditions are pH = 7.4, time = 80 min, electrolyte concentration = 0.05 M, and applied voltage = 12.59, in which the removal of microplastics, DDBAC, and TOC reached the maximum level, which was 82.50%, 90.35%, and 83.60% respectively. The results confirm that the valid model is adequately significant for the target response. Overall, financial and energy consumption analyses confirmed that this process is a promising technology as a commercial method for the removal of DDBAC-microplastics complexes in water and wastewater treatment.

GS-2: A Novel Broad-Spectrum Agent for Environmental Microbial Control.

The environmental control of microbial pathogens currently relies on compounds that do not exert long-lasting activity on surfaces, are impaired by soil, and contribute to the growing problem of antimicrobial resistance. This study presents the scientific development and characterization of GS-2, a novel, water-soluble ammonium carboxylate salt of capric acid and L-arginine that demonstrates activity against a range of bacteria (particularly Gram-negative bacteria), fungi, and viruses. In real-world surface testing, GS-2 was more effective than a benzalkonium chloride disinfectant at reducing the bacterial load on common touch-point surfaces in a high-traffic building (average 1.6 vs. 32.6 CFUs recovered from surfaces 90 min after application, respectively). Toxicology testing in rats confirmed GS-2 ingredients were rapidly cleared and posed no toxicities to humans or animals. To enhance the time-kill against Gram-positive bacteria, GS-2 was compounded at a specific ratio with a naturally occurring monoterpenoid, thymol, to produce a water-based antimicrobial solution. This GS-2 with thymol formulation could generate a bactericidal effect after five minutes of exposure and a viricidal effect after 10 min of exposure. Further testing of the GS-2 and thymol combination on glass slides demonstrated that the compound retained bactericidal activity for up to 60 days. Based on these results, GS-2 and GS-2 with thymol represent a novel antimicrobial solution that may have significant utility in the long-term reduction of environmental microbial pathogens in a variety of settings.

Disinfectants facilitate the transformation of exogenous antibiotic resistance genes via multiple pathways.

The prevalence and spread of multidrug-resistant (MDR) bacteria pose a global challenge to public health. Natural transformation is one of the essential ways for horizontal transfer of antibiotic resistance genes (ARGs). Although disinfectants are frequently used during COVID-19, little is known about whether these disinfectants are associated with the transformation of plasmid-borne ARGs. In our study, we assessed the effect of some disinfectants on bacterial transformation using resistance plasmids as extracellular DNA and E. coli DH5α as the recipient bacteria. The results showed that these disinfectants at environmentally relevant concentrations, including benzalkonium bromide (BB), benzalkonium chloride (BC) and polyhexamethylene guanidine hydrochloride (PHMG), significantly enhanced the transformation of plasmid-encoded ARGs. Furthermore, we investigated the mechanisms underlying the promotive effect of disinfectants on transformation. We revealed that the addition of disinfectants significantly increased the membrane permeability and promoted membrane-related genes expression. Moreover, disinfectants led to the boosted bacterial respiration, ATP production and flagellum motility, as well as increased expression of bacterial secretion system-related genes. Together, our findings shed insights into the spread of ARGs through bacterial transformation and indicate potential risks associated with the widespread use of disinfectants.

Study of Cationic Surfactants Raw Materials for COVID-19 Disinfecting Formulations by Potentiometric Surfactant Sensor.

The behavior of a new 1,3-dioctadecyl-1H-imidazol-3-ium tetraphenylborate (DODI-TPB) surfactant sensor was studied in single and complex mixtures of technical grade QACs-benzalkonium chloride (BAC), N,N-didecyl-N,N-dimethylammonium chloride (DDAC), and N,N-dioctyl-N,N-dimethylammonium chloride (DOAC) usually used in COVID-19 disinfecting agents formulations. The results obtained with the new DODI-TPB sensor were in good agreement with data measured by a 1,3-dihexadecyl-1H-benzo[d]imidazol-3-ium-tetraphenylborate (DMI-TPB) surfactant sensor, as well as two-phase titration used as a reference method. The quantitative titrations of a two-component mixture of the cationic homologs (a) DDAC and DOAC; and (b) BAC and DOAC showed that the new DODI-TPB surfactant sensor can clearly distinguish two separate mixture components in a single potentiometric titration curve with two characteristic inflexion points. The consumption of SDS (used as a titrant) in the end-point 1 (EP 1) corresponded to the content of DDAC (or BAC), whereas the consumption in the end-point 2 (EP 2) corresponded to the total content of both cationic surfactants in the mixture. DOAC content in both mixtures can be calculated from the difference of the titrant used to achieve EP1 and EP2. The addition of nonionic surfactants resulted in the signal change decrease from 333.2 mV (1:0; no nonionic surfactant added) to 243.0 mV (1:10, w/w). The sensor was successfully tested in ten two-component COVID-19 disinfecting formulations.

Exposure to benzalkonium chloride disinfectants promotes antibiotic resistance in sewage sludge microbiomes.

Disinfectants are routinely used in human environments to control and prevent the transmission of microbial disease, and this is particularly true during the current COVID-19 crisis. However, it remains unclear whether the increased disinfectant loadings to wastewater treatment plants facilitate the dissemination of antibiotic resistance genes (ARGs) in sewage sludge microbiomes. Here, we investigated the impacts of benzalkonium chlorides (BACs), widely used disinfectants, on ARGs profiles and microbial community structures in sewage sludge by using high-throughput quantitative PCR and Illumina sequencing. A total of 147 unique ARGs and 39 mobile genetic elements (MGEs) were detected in all sewage sludge samples. Our results show that exposure to BACs disinfectants at environmentally relevant concentrations significantly promotes both the diversity and absolute abundance of ARGs in sludge microbiomes, indicating the co-selection of ARGs by BACs disinfectants. The enrichment of ARGs abundance varied from 2.15-fold to 3.63-fold compared to controls. In addition, BACs exposure significantly alters bacterial and protistan communities, resulting in dysbiosis of the sludge microbiota. The Mantel test and Procrustes analysis confirm that bacterial communities are significantly correlated with ARGs profiles under BACs treatments. The structural equation model explains 83.8 % of the total ARGs variation and further illustrates that the absolute abundance of MGEs exerts greater impacts on the variation of absolute abundance of ARGs than microbial communities under BACs exposure, suggesting BACs may promote antibiotic resistance by enhancing the horizontal gene transfer of ARGs across sludge microbiomes. Collectively, our results provide new insights into the proliferation of antibiotic resistance through disinfectant usage during the pandemic and highlight the necessity to minimize the environmental release of disinfectants into the non-target environment for combating antibiotic resistance.

LC-MS/MS methods for the determination of 30 quaternary ammonium compounds including benzalkonium and paraquat in human serum and urine.

Benzalkyldimethylammonium (or benzalkonium; BACs), alkyltrimethylammonium (ATMACs), and dialkyldimethylammonium compounds (DDACs) have been widely used for over six decades as disinfectants, especially during the COVID-19 pandemic. Here we describe methods for the determination of 7 BACs, 6 ATMACs, 6 DDACs, 8 BAC metabolites, and the structurally similar quaternary ammonium compound (QAC) herbicides diquat, paraquat, and difenzoquat in human serum and urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The methods were optimized using isotopically labelled internal standards and solid-phase extraction with weak cation-exchange cartridges. We separated diquat and paraquat chromatographically using a mixed-mode LC column, and BACs, ATMACs, DDACs, difenzoquat, and BAC metabolites using reversed-phase (C8 and C18) LC columns. Method limits of detection (MLODs) and quantification (MLOQs) were 0.002-0.42 and 0.006-1.40 ng/mL, respectively. Recoveries of all analytes fortified at 1, 5, and 20 ng/mL concentrations in serum and urine matrices were 61-129%, with standard deviations of 0-20%. Repeated analysis of similarly fortified serum and urine samples yielded intra-day and inter-day variations of 0.22-17.4% and 0.35-17.3%, respectively. Matrix effects for analytes spiked into serum and urine matrices ranged from -27% to 15.4%. Analysis of real urine and serum samples revealed the presence of several QACs in human serum. Although no parent BACs were found in urine, we detected, for the first time, several ω-hydroxy and ω-carboxylic acid metabolites of BACs at average concentrations in the range of 0.05-0.35 ng/mL. The developed method is suitable for application in large-scale biomonitoring of human exposure to QACs and their metabolites in human serum and urine.

Ecological Risk Analysis for Benzalkonium Chloride, Benzethonium Chloride, and Chloroxylenol in US Disinfecting and Sanitizing Products.

Use of three topical antiseptic compounds-benzalkonium chloride (BAC), benzethonium chloride (BZT), and chloroxylenol (PCMX)-has recently increased because of the phaseout of other antimicrobial ingredients (such as triclosan) in soaps and other disinfecting and sanitizing products. Further, use of sanitizing products in general increased during the coronavirus (COVID-19) pandemic. We assessed the environmental safety of BAC, BZT, and PCMX based on best available environmental fate and effects data from the scientific literature and privately held sources. The ecological exposure assessment focused on aquatic systems receiving effluent from wastewater-treatment plants (WWTPs) and terrestrial systems receiving land-applied WWTP biosolids. Recent exposure levels were characterized based on environmental monitoring data supplemented by modeling, while future exposures were modeled based on a hypothetical triclosan replacement scenario. Hazard profiles were developed based on acute and chronic studies examining toxicity to aquatic life (fish, invertebrates, algae, vascular plants) and terrestrial endpoints (plants, soil invertebrates, and microbial functions related to soil fertility). Risks to higher trophic levels were not assessed because these compounds are not appreciably bioaccumulative. The risk analysis indicated that neither BZT nor PCMX in any exposure media is likely to cause adverse ecological effects under the exposure scenarios assessed in the present study. Under these scenarios, total BAC exposures are at least three times less than estimated effect thresholds, while margins of safety for freely dissolved BAC are estimated to be greater than an order of magnitude. Because the modeling did not specifically account for COVID-19 pandemic-related usage, further environmental monitoring is anticipated to understand potential changes in environmental exposures as a result of increased antiseptic use. The analysis presented provides a framework to interpret future antiseptic monitoring results, including monitoring parameters and modeling approaches to address bioavailability of the chemicals of interest. Environ Toxicol Chem 2022;41:3095-3115. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Capsanthin from Capsicum annum fruits exerts anti-glaucoma, antioxidant, anti-inflammatory activity, and corneal pro-inflammatory cytokine gene expression in a benzalkonium chloride-induced rat dry eye model.

Dry eye disease (DED) is a complex ocular surface inflammatory disease. Its occurrence varies widely over the world, ranging from 5% to 34%. The use of preservatives, specifically benzalkonium chloride, in the ocular drops worsens the DED conditions. Furthermore, the Covid-19 pandemic increased screen time and the use of face masks and shields. As a result, the number of people suffering from dry eye disease (DED) has increased significantly in recent years. The main objective of our study is to find a solution to manage the dry eye disease (DED) preferably from natural source without any adverse events. In this study, the beneficial effects of capsanthin from Capsicum annum (CCA) were evaluated on benzalkonium chloride (BAC)-induced dry eye disease (DED) in Albino Wistar rats. Oral supplementation of CCA resulted in a statistically significant decrease in intraocular pressure (IOP) (p < .0001), increase in tear break-up time (TBUT) (p < .01), decline in Schirmer test results (p < .01), and decrease in corneal surface inflammation (p < .01). Capsanthin ameliorated in reducing oxidative stress by increasing serum antioxidant levels such as glutathione peroxidase (GPX), nitric oxide (NO), and lactoferrin (LTF) and inhibiting matrix metalloproteinases 2 and 9 (MMP2 and MMP9) (p < .0001). Capsanthin treatment significantly inhibited the expression of inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), interleukins (IL-2, IL-4, IL-6), and pro-inflammatory mediator, matrix metalloproteinase-9 (MMP9). Furthermore, the lacrimal gland expressed vascular cell adhesion molecule (VCAM-1), and prostaglandin-endoperoxide synthase 2 (PTGS2) was suppressed by CCA treatment. PRACTICAL APPLICATIONS: Benzalkonium chloride (BAC), a preservative widely used in the topical ocular drug delivery system (ODDS), causes undesirable effects such as dry eye disease as well as ameliorating intraocular pressure leading to optical nerve damage and irreversible vision loss. Capsanthin from Capsicum annum (CCA) can be used to treat symptoms related to dry eye disease such as inflammation, eye irritation, visual disturbance, ocular discomfort with potential damage to the ocular surface. The CCA may be beneficial in the treatment of glaucoma, an elevated intraocular pressure. Capsanthin from C. annum can be useful in managing DED by increasing tear break-up time (TBUT), declining in Schirmer test results and decreasing in corneal surface inflammation.

In vitro neurotoxicity evaluation of biocidal disinfectants in a human neuron-astrocyte co-culture model.

Biocidal disinfectants (BDs) that kill microorganisms or pathogens are widely used in hospitals and other healthcare fields. Recently, the use of BDs has rapidly increased as personal hygiene has become more apparent owing to the pandemic, namely the coronavirus outbreak. Despite frequent exposure to BDs, toxicity data of their potential neurotoxicity (NT) are lacking. In this study, a human-derived SH-SY5Y/astrocyte was used as a co-culture model to evaluate the chemical effects of BDs. Automated high-content screening was used to evaluate the potential NT of BDs through neurite growth analysis. A set of 12 BD substances classified from previous reports were tested. Our study confirms the potential NT of benzalkonium chloride (BKC) and provides the first evidence of the potential NT of poly(hexamethylenebicyanoguanide-hexamethylenediamine) hydrochloride (PHMB). BKC and PHMB showed significant NT at concentrations without cytotoxicity. This test system for analyzing the potential NT of BDs may be useful in early screening studies for NT prior to starting in vivo studies.

Antiseptic Materials on the Base of Polymer Interpenetrating Networks Microgels and Benzalkonium Chloride.

Polymer microgels, including those based on interpenetrating networks (IPNs), are currently vastly studied, and their practical applications are a matter of thriving research. In this work, we show the perspective for the use of polyelectrolyte IPN microgels either as scavengers or carriers of antiseptic substances. Here, we report that poly-N-isopropylacrylamide/polyacrylic acid IPN microgels can efficiently absorb the common bactericidal and virucidal compound benzalkonium chloride. The particles can form a stable aqueous colloidal suspension or be used as building blocks for soft free-standing films. Both materials showed antiseptic efficacy on the examples of Bacillus subtilis and S. aureus, which was approximately equal to the commercial antibiotic. Such polymer biocides can be used as liquid disinfectants, stable surface coatings, or parts of biomedical devices and can enhance the versatility of the possible practical applications of polymer microgels.

Pronounced temporal changes in soil microbial community and nitrogen transformation caused by benzalkonium chloride.

As one typical cationic disinfectant, quaternary ammonium compounds (QACs) were approved for surface disinfection in the coronavirus disease 2019 pandemic and then unintentionally or intentionally released into the surrounding environment. Concerningly, it is still unclear how the soil microbial community succession happens and the nitrogen (N) cycling processes alter when exposed to QACs. In this study, one common QAC (benzalkonium chloride (BAC) was selected as the target contaminant, and its effects on the temporal changes in soil microbial community structure and nitrogen transformation processes were determined by qPCR and 16S rRNA sequencing-based methods. The results showed that the aerobic microbial degradation of BAC in the two different soils followed first-order kinetics with a half-life (4.92 vs. 17.33 days) highly dependent on the properties of the soil. BAC activated the abundance of N fixation gene (nifH) and nitrification genes (AOA and AOB) in the soil and inhibited that of denitrification gene (narG). BAC exposure resulted in the decrease of the alpha diversity of soil microbial community and the enrichment of Crenarchaeota and Proteobacteria. This study demonstrates that BAC degradation is accompanied by changes in soil microbial community structure and N transformation capacity.

Short-term exposure to benzalkonium chloride in bacteria from activated sludge alters the community diversity and the antibiotic resistance profile.

The continuous introduction of cleaning products containing benzalkonium chloride (BAC) from household discharges can mold the microbial communities in wastewater treatment plants (WWTPs) in a way still poorly understood. In this study, we performed an in vitro exposure of activated sludge from a WWTP in Costa Rica to BAC, quantified the changes in intI1, sul2, and qacE/qacEΔ1 gene profiles, and determined alterations in the bacterial community composition. The analysis of the qPCR data revealed elevated charges of antibiotic resistance genes in the microbial community; after BAC's exposure, a significant increase in the qacE/qacEΔ1 gene, which is related to ammonium quaternary resistance, was observed. The 16S rRNA gene sequences' analysis showed pronounced variations in the structure of the bacterial communities, including reduction of the alpha diversity values and an increase of the relative abundance of Alphaproteobacteria, particularly of Rhodospseudomonas and Rhodobacter. We confirmed that the microbial communities presented high resilience to BAC at the mg/mL concentration, probably due to constant exposure to this pollutant. They also presented antibiotic resistance-related genes with similar mechanisms to tolerate this substance. These mechanisms should be explored more thoroughly, especially in the context of high use of disinfectant.

Adsorption of benzalkonium chlorides onto polyethylene microplastics: Mechanism and toxicity evaluation.

Usage of disposable plastic products and disinfectants has been skyrocketing due to the COVID-19 pandemic. The random disposal of plastic products may result in greater microplastic pollution. Benzalkonium chloride is known as one of the most common ingredients of disinfectants. In this study, the adsorption behavior of benzalkonium chlorides (BAC12, BAC14, BAC16) on polyethylene microplastics (PE-MPs) and the combined toxic effects were investigated using batch adsorption experiment and Daphnia magna. The results showed that PE-MPs had strong adsorption capacity for BACs and the adsorption capacity increased (11.03-22.77 mg g-1) with their octanol-water distribution coefficients. The effect of pH was negligible while dissolved organic matter inhibited the adsorption. A slightly inverse relationship between particle size of PE-MPs and adsorption was observed. Additionally, the MP aging with UV/H2O2 increased the adsorption of BAC12 but decreased that of relatively hydrophobic BAC14 and BAC16. The survival rate of Daphnia magna increased up to 100% in the presence of PE-MPs depending upon their adsorption capacities, suggesting that PE-MPs do not act as a carrier but rather as a scavenger for BACs. This study provides important information necessary for environmental risk assessment with regard to the combined pollution of MPs and toxic chemicals.

Cationic Compounds with SARS-CoV-2 Antiviral Activity and Their Interaction with Organic Cation Transporter/Multidrug and Toxin Extruder Secretory Transporters.

In the wake of the COVID-19 pandemic, drug repurposing has been highlighted for rapid introduction of therapeutics. Proposed drugs with activity against SARS-CoV-2 include compounds with positive charges at physiologic pH, making them potential targets for the organic cation secretory transporters of kidney and liver, i.e., the basolateral organic cation transporters, OCT1 and OCT2; and the apical multidrug and toxin extruders, MATE1 and MATE2-K. We selected several compounds proposed to have in vitro activity against SARS-CoV-2 (chloroquine, hydroxychloroquine, quinacrine, tilorone, pyronaridine, cetylpyridinium, and miramistin) to test their interaction with OCT and MATE transporters. We used Bayesian machine learning models to generate predictions for each molecule with each transporter and also experimentally determined IC50 values for each compound against labeled substrate transport into CHO cells that stably expressed OCT2, MATE1, or MATE2-K using three structurally distinct substrates (atenolol, metformin and 1-methyl-4-phenylpyridinium) to assess the impact of substrate structure on inhibitory efficacy. For the OCTs substrate identity influenced IC50 values, although the effect was larger and more systematic for OCT2. In contrast, inhibition of MATE1-mediated transport was largely insensitive to substrate identity. Unlike MATE1, inhibition of MATE2-K was influenced, albeit modestly, by substrate identity. Maximum unbound plasma concentration/IC50 ratios were used to identify potential clinical DDI recommendations; all the compounds interacted with the OCT/MATE secretory pathway, most with sufficient avidity to represent potential DDI issues for secretion of cationic drugs. This should be considered when proposing cationic agents as repurposed antivirals. SIGNIFICANCE STATEMENT: Drugs proposed as potential COVID-19 therapeutics based on in vitro activity data against SARS-CoV-2 include compounds with positive charges at physiological pH, making them potential interactors with the OCT/MATE renal secretory pathway. We tested seven such molecules as inhibitors of OCT1/2 and MATE1/2-K. All the compounds blocked transport activity regardless of substrate used to monitor activity. Suggesting that plasma concentrations achieved by normal clinical application of the test agents could be expected to influence the pharmacokinetics of selected cationic drugs.

Antimicrobial Face Shield: Next Generation of Facial Protective Equipment against SARS-CoV-2 and Multidrug-Resistant Bacteria.

Transparent materials used for facial protection equipment provide protection against microbial infections caused by viruses and bacteria, including multidrug-resistant strains. However, transparent materials used for this type of application are made of materials that do not possess antimicrobial activity. They just avoid direct contact between the person and the biological agent. Therefore, healthy people can become infected through contact of the contaminated material surfaces and this equipment constitute an increasing source of infectious biological waste. Furthermore, infected people can transmit microbial infections easily because the protective equipment do not inactivate the microbial load generated while breathing, sneezing or coughing. In this regard, the goal of this work consisted of fabricating a transparent face shield with intrinsic antimicrobial activity that could provide extra-protection against infectious agents and reduce the generation of infectious waste. Thus, a single-use transparent antimicrobial face shield composed of polyethylene terephthalate and an antimicrobial coating of benzalkonium chloride has been developed for the next generation of facial protective equipment. The antimicrobial coating was analyzed by atomic force microscopy and field emission scanning electron microscopy with elemental analysis. This is the first facial transparent protective material capable of inactivating enveloped viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in less than one minute of contact, and the methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. Bacterial infections contribute to severe pneumonia associated with the SARS-CoV-2 infection, and their resistance to antibiotics is increasing. Our extra protective broad-spectrum antimicrobial composite material could also be applied for the fabrication of other facial protective tools such as such as goggles, helmets, plastic masks and space separation screens used for counters or vehicles. This low-cost technology would be very useful to combat the current pandemic and protect health care workers from multidrug-resistant infections in developed and underdeveloped countries.

Systemic absorption of benzalkonium chloride after maximal use of a consumer antiseptic wash product.

An in vivo pharmacokinetic study was conducted using consumer antiseptic wash containing 0.13% benzalkonium chloride (BAC) to assess the effect of dermal absorption on long-term systemic exposure to BAC. The objective of the study was to determine blood levels of BAC under maximal use conditions. Subjects were enlisted to wash their hands 60 s with soap containing 0.13% BAC 30 times per day over an 8-9 h time period for 5 consecutive days. The test product with the highest absorption potential was selected based on market share and results from in vitro permeation testing. Blood plasma was collected from subjects on 32 occasions over the 6-day study period. Plasma samples were analyzed for the C12 and C14 homologs of BAC using LC-MS/MS with a lower limit of quantitation (LLOQ) of 106.9 and 32.6 ng/L, respectively. For the 32 subjects, C12 homolog was detected above the LLOQ in only four of 1,024 plasma samples at 117.8-191.7 ng/L, and C14 homolog was detected in only one sample at 59.5 ng/L. Consequently, systemic exposure to BAC in antimicrobial soap is very low and below the level of concern identified by the U.S. Food and Drug Administration (500 ng/L) even under maximal use conditions.

Biological removal of benzalkonium chlorides from wastewater by immobilized cells of Pseudomonas sp. BIOMIG1 in an up-flow packed bed reactor.

Quaternary ammonium compounds (QACs) are active ingredients of many disinfectants used against SARS-CoV-2 to control the transmission of the virus through human-contact surfaces. As a result, QAC consumption has increased more than twice during the pandemic. Consequently, the concentration of QACs in wastewater and receiving environments may increase. Due to their antimicrobial activity, high levels of QACs in wastewater may cause malfunctioning of biological treatment systems resulting in inadequate treatment of wastewater. In this study, a biocatalyst was produced by entrapping Pseudomonas sp. BIOMIG1 capable of degrading QACs in calcium alginate. Bioactive 3-mm alginate beads degraded benzalkonium chlorides (BACs), a group of QACs, with a rate of 0.47 µM-BACs/h in shake flasks. A bench-scale continuous up-flow reactor packed with BIOMIG1-beads was operated over one and a half months with either synthetic wastewater or secondary effluent containing 2-20 µM BACs at an empty bed contact time (EBCT) ranging between 0.6 and 4.7 h. Almost complete BAC removal was achieved from synthetic and real wastewater at and above 1.2 h EBCT without aeration and effluent recirculation. The microbial community in beads dominantly composed of BIOMIG1 with trace number of Achromobacter spp. after the operation of the reactor with the real wastewater, suggesting that BIOMIG1 over-competed native wastewater bacteria during the operation. This reactor system offers a low cost and robust treatment of QACs in wastewater. It can be integrated to conventional treatment systems for efficient removal of QACs from the wastewater, especially during the pandemic period.

Disinfectant effectiveness against SARS-CoV-2 and influenza viruses present on human skin: model-based evaluation.

OBJECTIVES: Disinfection effectiveness against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on human skin remains unclear because of the hazards of viral exposure. An evaluation model, which has been previously generated using human skin obtained from forensic autopsy samples, accurately mimics in vivo skin conditions for evaluating the effectiveness of disinfection against the virus. Using this model, we evaluated disinfection effectiveness against viruses on human skin. METHODS: Ethanol (EA), isopropanol (IPA), chlorhexidine gluconate (CHG) and benzalkonium chloride (BAC) were used as target disinfectants. First, disinfectant effectiveness against SARS-CoV-2 and influenza A virus (IAV) was evaluated in vitro. Disinfectant effectiveness against SARS-CoV-2 and IAV on human skin was then evaluated by titrating viruses present on the skin after applying each disinfectant on the skin for 5-60 seconds. RESULTS: Both, SARS-CoV-2 and IAV on human skin were completely inactivated within 5 seconds by 40%-80% EA and 70% IPA (log reduction values (LRVs) were >4). However, SARS-CoV-2 and IAV were barely inactivated by 20% EA (LRVs were <1). In vitro evaluation showed that, compared with EA and IPA, CHG and BAC were significantly inferior in terms of disinfection effectiveness. Conversely, the disinfection effectiveness of CHG and BAC against SARS-CoV-2 was higher on human skin than in vitro, and increased with increases in their concentration and reaction time (LRVs of 0.2% CHG/0.05% BAC were >2, and LRVs of 1.0% CHG/0.2% BAC were >2.5). CONCLUSIONS: Proper hand hygiene practices using alcohol-based disinfectants such as EA/IPA effectively inactivate SARS-CoV-2 and IAV on human skin.

Neutralization of the eye and skin irritant benzalkonium chloride using UVC radiation.

PURPOSE: Benzalkonium chloride (BAK) is a widely used disinfectant and preservative which is effective against a wide range of viruses (e.g. SARS-CoV and SARS-CoV-2), bacteria and fungi. However, it is toxic to the eye and skin. This study investigated the neutralization of BAK using ultraviolet C (UVC) radiation as an effort to reduce BAK toxicity potential. METHODS: BAK solutions were irradiated with a germicidal UVC lamp at various doses. Human corneal epithelial cells (HCEC) were then exposed to the UVC-irradiated BAK solutions for 5 minutes. After exposure, the cultures were assessed for metabolic activity using PrestoBlue; for cell viability using confocal microscopy with viability dyes; and for tight junction proteins using immunofluorescence staining for zonula occludens (ZO)-1. RESULTS: UVC radiation reduced BAK toxicity on cell metabolic activity in a dose-dependent manner. When the solution depth of BAK was 1.7 mm, the UVC doses needed to completely neutralize the toxicity of BAK 0.005% and 0.01% were 2.093 J/cm2 and 8.374 J/cm2, respectively. The cultures treated with UVC-neutralized BAK showed similar cell metabolic activity and cell viability to those treated with phosphate buffered saline (PBS) (p = 0.806 ∼ 1.000). The expression of ZO-1 was greatly disturbed by untreated BAK; in contrast, ZO-1 proteins were well maintained after exposure to UVC-neutralized BAK. CONCLUSIONS: Our study demonstrates that the cell toxicity of BAK can be neutralized by UVC radiation, which provides a unique way of detoxifying BAK residues. This finding may be of great value in utilizing the antimicrobial efficacy of BAK (e.g. fighting against SARS-CoV-2) while minimizing its potential hazards to human health and the environment.