Guanidine Hydrochloride Research Articles

Non-sticky SiNx nanonets for single protein denaturation analysis.

Proteins play crucial roles in nearly all biological activities, with their functional structures deriving from stable folded conformations. Protein denaturation, induced by chemical and physical agents, is a complex process where proteins lose their stable structures, thereby impairing their biological functions. Characterizing protein denaturation at the single-molecule level remains a significant challenge. In this study, we developed non-adhesive silicon nitride nanonets coated with polyethylene glycol to capture individual proteins. We utilized these nanonets to investigate the denaturation of ovalbumin induced by guanidine hydrochloride (Gdn-HCl) and lead chloride. The entire denaturation and renaturation processes of a single ovalbumin molecule were monitored via ionic current measurements through the nanonets. These non-sticky nanonets offer a versatile tool for real-time studies of structural changes during protein denaturation.

Rapid microwave preparation of nitrogen doped carbon dots and their applications as highly sensitive nanoprobe for hematin

In this work, nitrogen-doped carbon dots (NCDs) were obtained by microwave rapid preparation method with lipase and guanidine hydrochloride as precursors in only 6 min. In order to achieve high sensitivity detection of hematin, based on obtained NCDs as a nanoprobe, a new detection method based on photoluminescence (PL) change was developed. Further studies have shown that the sensing strategy relied on the inner filter effect to selectively quench the PL emission of NCDs at 379 nm by hematin under 320 nm excitation. The nanoprobe had a wide linear range (0.2–13 μmol/L) and a detection limit of 0.07 μmol/L. The method was effectively applied to the identification of hematin in human blood samples. The proposed nanoprobe has the characteristics of simple and efficient design. It can achieve rapid and accurate detection, which is very suitable for real-time analysis of blood samples to facilitate diagnosis.

Evaluating the influence of the initial high molecular weight level on monoclonal antibody particle formation kinetics using a short-term chemical stress study

Protein formulations may form proteinaceous particles that vary in size from nanometers to millimeters. Monitoring the kinetics of protein particle formation, e.g., through accelerated degradation studies, is an attempt to understand and assess the rate and progression of particle populations. Little is known about whether the initial level of high molecular weight (HMW) species, or initial HMW level (IHL), of a protein solution influences the propagation of protein particle formation, and thus affects the storage stability of proteins.In this study, we have established a method to generate protein solutions of different IHLs by thermal stress. We have evaluated a 16-week thermal stability study at 40 °C of two monoclonal antibodies (mAb-A and mAb-B) at different IHLs using size exclusion chromatography (SEC) and sub-visible particle analysis. We have performed an isothermal stress study with guanidinium hydrochloride (GuaHCl) at room temperature for 300-min to evaluate the formation of HMWs analysed by SEC. The application of the Finke-Watzky (F-W) two-step nucleation model allowed us to mathematically describe the kinetics of HMW formation and to extract kinetic parameters of this process.For mAb-A, the IHLs had a marginal influence on the loss of monomer rate; instead, mAb-A exhibited fragmentation at 40 °C, which was independent of the IHL. Nevertheless, above a threshold of ≥ 7 % IHL, existing trimers/tetramers undergo conversion into higher-order oligomers at 40 °C, which is not observed at lower IHLs. In contrast, mAb-B exhibited an increased HMW formation rate above a threshold of ≥ 4 % IHL, which was reflected in the monomer decay rates at 40 °C and the F-W kinetic parameters of the chemical stress study.This case study shows that the initial level of HMWs exerts a differential influence on the progression of HMW formation. In one instance, there is a discernible acceleration in the formation of HMWs with rising IHLs. Conversely, in another example, the IHL exerts only a slight influence on HMW formation. Moreover, the results of our short-term chemical stress study are in accordance with those of a classical storage stability study conducted at 40 °C, which evaluated different IHLs. The analysis of HMW formation kinetics will enhance our understanding of the protein particle formation process and facilitate the formulation development of biotherapeutics.

Enhancement of loop-mediated isothermal amplification (LAMP) with guanidine hydrochloride for the detection of Streptococcus equi subspecies equi (Strangles).

Streptococcus equi subspecies equi, commonly referred to as "strangles", poses a significant biosecurity challenge across equine farms worldwide. The continuous prevalence and highly transmissibility of strangles necessitates a rapid and accurate diagnostic procedure. However, current "gold-standard" techniques, such as cultures and quantitative polymerase chain reaction (qPCR), are unreliable or inaccessible, and require lengthy periods between sample collection and results. Moreover, the lack of a standardized detection protocol can lead to variations in results. This study aimed to develop a reproducible and field-deployable diagnostic assay to detect strangles in real-time. Utilising the rapid technique loop-mediated isothermal amplification (LAMP), we developed an assay targeting a conserved region of the S. equi-specific M gene (SeM). Additionally, we optimised our assay with guanidine hydrochloride (GuHCl) to enhance the assay's performance and detection capabilities. The Str-LAMP was able to detect S. equi within 13 minutes and 20 seconds for both synthetic DNA and clinical isolates, with a limit of detection (LOD) of 53 copies/µl. Our assay demonstrated high repeatability with the inter-coefficient of variation ranging from 0.17% to 3.93%. Furthermore, the clinical sensitivity and specificity was calculated at 91.3% and 93.3%, respectively, with a correct classification rate of 91.8%. The implementation of this newly developed strangles assay can be employed as an efficient aid for in-field surveillance programs. The assay's reproducibility can allow for equine managers to undertake routine self-surveillance on their properties, without the requirement of specialised training. The Str-LAMP assay has the potential to be a valuable tool to help mitigate potential strangles outbreaks.

In Situ Driven Formation of Anatase/Brookite/Rutile Heterojunction N/TiO2 Nanocrystals as Sustainable Visible-Light Catalysts.

Visible-light active anatase/brookite/rutile (A/B/R) ternary N-doped titania (N/TiO2) crystals are successfully prepared by a facile sol-gel method using titanium butoxide and benign N-dopant source, guanidinium chloride. Systematically varying the aging time (1, 4, 8, and 12 d), its influence on physicochemical properties of as-obtained spherical heterojunction nanomaterials is studied. Detailed characterizations confirm that a substantial amount of anatase (88% to 50%) is transformed to rutile (2% to 38%) via intermediate brookite phase (9% to 25%) as the function of aging time; not only the A/B/R phase content of the samples is tuned by sol-gel aging time of the precursors solution but also their optical-response and methylene blue photocatalytic properties are profoundly dictated. Notably under visible-light irradiation, the photostable rutile rich mesoporous A/B/R triphasic N/TiO2 (50% A, 12% B, 38% R) aged for 12 d demonstrates higher degradation activity (97%) with a faster degradation rate (0.033 min-1) than both lesser aged N/TiO2 and undoped titania. This enhancement is attributed to the synergistic effect of interstitial-N-doping and optimal A/B/R interfacial charge transfer that leads to higher light absorption, lower bandgap energy and well-separated charge carriers. The current work provides a new perspective for designing highly active visible-light heterostructure nanomaterials with controllable phase composition.

“Guanidine hydrochloride assisted one-pot synthesis of 2-amino-4,6-disubstituted-3-cyanopyridine derivatives: a sustainable and greener strategy with catalyst recyclability”

“Guanidine hydrochloride assisted one-pot synthesis of 2-amino-4,6-disubstituted-3-cyanopyridine derivatives: a sustainable and greener strategy with catalyst recyclability”

Antibacterial and mothproofing wool fabrics modified by M-Arg/PHMG and ZnO

The increasing focus on sustainable and eco-friendly materials has sparked a growing interest in wool as a natural fiber for sustainable fashion, thanks to its skin-friendly properties, warmth, breathability, renewability and biodegradability. The advancement of wool fabrics with durable antimicrobial and moth-resistant qualities could significantly enhance the utilization of wool in the production of high-quality textiles. This study investigates the synthesis of M−Arg and polyhexamethylene guanidine hydrochloride (PHMG) and their application in the surface modification of wool fibers, with an evaluation of the antimicrobial properties of the treated fabrics. Initially, plasma was used to pre-treat the wool fibers, followed by the adsorption of M−Arg and PHMG and ZnO in situ on the fiber’s surface. The antibacterial effectiveness against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) microorganisms was assessed through antibacterial testing of the M−Arg/PHMG/ZnO-Fiber (MPN-Fiber). Results showed that the MPN-Fiber exhibited a significantly higher antimicrobial rate compared to untreated wool fiber. The prepared MPN-Fiber inhibited E. coli and S. aureus by 99.64 ± 1.04 % and 96.47 ± 2.14 %, respectively. Additionally, the MPN-fiber has good washing resistance (20 times, lose only 10 %). The experimental results clearly demonstrated that the MPN-Fiber exhibited exemplary antibacterial and moth-proof properties, confirming the success of the innovative surface modification approach.

Effect of γ-irradiation and antimicrobial agent on properties of poly(L-lactide) active films

Data on irradiation of poly(L-lactide) (PLLA) based active packaging is still limited. Therefore, effect of γ-irradiation on neat PLLA and active packaging with oligohexamethylene guanidine hydrochloride (OHMG·HCl) has been studied. Combined use of irradiation and active packaging technology is promising approach to maintain food safety and prolong shelf life. It has been found that regardless of the OHMG·HCl content PLLA undergoes chain scission during irradiation and this process becomes less pronounced at doses higher than 50 kGy. Slight racemization of PLLA during exposure has been observed using polarimetry and 13C NMR spectroscopy. Mechanical properties of films have been examined. Biocide addition led to a 30% decrease in films elongation at break. Irradiation either caused elongation decrease. Dose of 50 kGy and higher made PLLA active films brittle. Multiple melting behavior of irradiated PLLA has been analyzed by differential scanning calorimetry. Fraction of crystals with higher melting temperature rose with dose. Possible reason for this phenomenon is formation of α′ form with less ordered chain packaging that recrystallizes during heating. The biocide addition has not affected this process. Furthermore, in vitro antimicrobial test has shown efficacy of films with 2 wt.% of OHMG·HCl against gram-negative, gram-positive bacteria and fungi.

Wearable Device with High Thermoelectric Performance and Long-Lasting Usability Based on Gel-Thermocells for Body Heat Harvesting.

Utilizing the thermogalvanic effect, flexible thermoelectric materials present a compelling avenue for converting heat into electricity, especially in the context of wearable electronics. However, prolonged usage is hampered by the limitation imposed on the thermoelectric device's operational time due to the evaporation of moisture. Deep eutectic solvents (DESs) offer a promising solution for low-moisture gel fabrication. In this study, a bacterial cellulose (BC)/polyacrylic acid (PAA)/guanidinium chloride (GdmCl) gel is synthesized by incorporating BC into the DES. High-performance n-type and p-type thermocells (TECs) are developed by introducing Fe(ClO4)2/3 and K3/4Fe(CN)6, respectively. BC enhances the mechanical properties through the construction of an interpenetrating network structure. The coordination of carboxyl groups on PAA with Fe3+ and the crystallization induced by Gdm+ with [Fe(CN)6]4- remarkably improve the thermoelectric performance, achieving a Seebeck coefficient (S) of 2.4mVK-1 and ion conductivity (σ) of 1.4 Sm-1 for the n-type TEC, and ‒2.8mVK-1 and 1.9 Sm-1 for the p-type TEC. A flexible wearable thermoelectric device is fabricated with a S of 82mVK-1 and it maintains a stable output over one month. This research broadens the application scope of DESs in the thermoelectric field and offers promising strategies for long-lasting wearable energy solutions.

Solvation free energy in governing equations for DNA hybridization, protein-ligand binding, and protein folding.

This work examines the thermodynamics of model biomolecular interactions using a governing equation that accounts for the participation of bulk water in the equilibria. In the first example, the binding affinities of two DNA duplexes, one of nine and one of 10 base pairs in length, are measured and characterized by isothermal titration calorimetry (ITC) as a function of concentration. The results indicate that the change in solvation free energy that accompanies duplex formation (ΔGS) is large and unfavorable. The duplex with the larger number of G:C pairings yields the largest change in solvation free energy, ΔGS = +460 kcal·mol-1per base pair at 25 °C. A van't Hoff analysis of the data is complicated by the varying degree of intramolecular base stacking within each DNA strand as a function of temperature. A modeling study reveals how the solvation free energy alters the output of a typical ITC experiment and leads to a good, though misleading, fit to the classical equilibrium equation. The same thermodynamic framework is applied to a model protein-ligand interaction, the binding of ribonuclease A with the nucleotide inhibitor 3'-UMP, and to a conformational equilibrium, the change in tertiary structure of α-lactalbumin in molar guanidinium chloride solutions. The ribonuclease study yields a value of ΔGS = +160 kcal·mol-1, whereas the folding equilibrium yields ΔGS ≈ 0, an apparent characteristic of hydrophobic interactions. These examples provide insight on the role of solvation energy in binding equilibria and suggest a pivot in the fundamental application of thermodynamics to solution chemistry.

Solid-liquid phase behaviour of novel kosmotrope/chaotrope binary mixtures involving sarcosine

The concept of deep eutectic solvents (DESs) has been recently applied to osmolytes (kosmotropes or chaotropes), small organic molecules responsible for stabilization of proteins and other biomolecules in various biological systems. In this study the combinations of the kosmotrope sarcosine (Sar) with chaotrope urea (U) or guanidine hydrochloride (G) across various molar ratios was studied experimentally by the differential scanning calorimetry and infrared spectroscopy. Theoretical prediction of thermodynamic interaction terms based on screening of the charge density was used to support interpretation of experimental findings. Phase diagrams were constructed for both Sar-U and Sar-G systems and eutectic behaviour was identified. Neither of the two systems showed depression of the eutectic temperature compared to its ideal solution values, and therefore neither of the systems could be classified as a deep eutectic solvent in the classical sense. The Sar-G system did show at least partial crystallization of its eutectic solution upon cooling. However, the eutectic solution of the Sar-U system remained amorphous at decreased temperatures, and the phenomenon was attributed to be kinetic in nature and originating from strong intermolecular hydrogen bonding interactions of the components. Thus, it was speculated that the role of osmolytes in stabilizing cellular biomolecules might not come from the thermodynamics only.

Molecular Aggregation to and from Disaggregation of an Organic Emitter for Strategic Emission Modulation

“Aggregation‐caused fluorescence quenching” is a well‐established phenomenon by now. The procedure from aggregation to disaggregation usually causes a revival of emission signals, and thus affords an interesting new path to design “turn‐on” optical probes. For this purpose, the photophysics, energetics and dynamics of supra‐molecular encapsulation induced disaggregation of a self‐assembled bis‐indole derivative, 3,3’‐bisindolyl(phenyl)methane (BIPM), and its further reaggregation are reported herein. Compared to disaggregation strategies, its reverse process, reaggregation, has received much less attention so far. The gamma‐cyclodextrin (γ‐CD) molecules were found to be effective in disaggregating the BIPM associations and emission enhancement, whereas, the incorporation of guanidine hydrochloride (Gnd‐HCl) into the aqueous solution of disaggregated BIPM monomers in γ‐CD environment resulted in probe reaggregation leading to quenching of the restored emission. Here, γ‐CD and Gnd‐HCl can be considered as the molecular modulators of BIPM fluorescence based on the disaggregation–reaggregation mechanisms. The spectroscopic and thermodynamic findings associated with the disaggregation‐reaggregation processes might be insightful in reversible controlling of molecular aggregation and the associated optical properties for diverse applications.

Development of antifouling antibacterial polylactic acid (PLA) -based packaging and application for chicken meat preservation

Microbial contamination is the leading cause of food spoilage and food-borne disease. Here, we developed a multifunctional surface based on polylactic acid (PLA) bioplastic with antifouling and antibacterial properties via a facile dual-coating approach. The surface was designed with hierarchical micro/nano-scale roughness and low surface energy. Bactericidal agent polyhexamethylene guanidine hydrochloride (PHMG) was incorporated to endow the film with bactericidal activity. The film had good superhydrophobic, antifouling and antibacterial performance, with a water contact angle of 154.3°, antibacterial efficiency against E. coli and S. aureus of 99.9 % and 99.6 %, respectively, and biofilm inhibition against E. coli and S. aureus of 63.5 % and 68.9 %, respectively. Synergistic effects of antibacterial adhesion and contact killing of bacteria contributed to the significant antibacterial performance of the film. The biobased biodegradable film was highly effective in preventing microbial growth when applied as antibacterial food packaging for poultry product, extending the shelf life of fresh chicken breast up to eight days.

Synthesis, Characterization, Band gap calculation, DFT study and Biological implication of Two Nitrogen-rich Proligands: Polymorphic Crystal Structures and Hirshfeld surface analyses of a Thiocarbohydrazone

A novel dihydrazone proligand 1,3-bis(pyridin-4-ylmethylideneamino)guanidine hydrochloride (H3L1) is reported along with polymorphic crystal structures of an analogous proligand 1,5-bis(4-pyridinecarboxaldehyde) thiocarbohydrazone (H2L2. H2O & H2L2. 2H2O). The crystal systems of H2L2. H2O and H2L2. 2H2O are monoclinic with P21/c and C2/c space groups. Strong hydrogen bonding interactions are found to be predominate in the H2L2. 2H2O crystal lattice. Hirshfeld surface analysis reveals that, after isotropic H···H interactions, N···H and C···H interactions are found to have the highest contribution to the overall Hirshfeld surface areas of H2L2. H2O and H2L2. 2H2O respectively. The pore volume and surface area of the thiocarbohydrazone polymorphs are also calculated. Direct band gap energies for H3L1 and H2L2 in their solid-states were estimated as 2.33 and 2.58 eV respectively using the Kubelka-Munk model. Molecular geometry of both the compounds are optimised using density functional theory and quantum chemical parameters are calculated. Frontier molecular orbital energy gaps in the gas phase for H3L1 and H2L2 are found to be 4.49 and 3.55 eV respectively, which indicates strong intermolecular interaction in the solid lattice of H3L1. Absorption, distribution, metabolism and excretion (ADME) attributes indicate both compound's potential as drug candidates. In vitro antibacterial study reveals that the thiocarbohydrazone based proligand is a more efficient inhibitor against gram-positive Staphylococcus aureus bacterial species. The anticancer activities of the compounds against MCF-7 human breast cancer cells suggested that H3L1 with an IC50 value of 172.6798 µg/mL has more potent than H2L2 (IC50 value of 279.1881 µg/mL).

On the Stabilizing Effect of Aspartate and Glutamate and Its Counteraction by Common Denaturants.

By performing differential scanning calorimetry(DSC) measurements on RNase A, we studied the stabilization provided by the addition of potassium aspartate(KAsp) or potassium glutamate (KGlu) and found that it leads to a significant increase in the denaturation temperature of the protein. The stabilization proves to be mainly entropic in origin. A counteraction of the stabilization provided by KAsp or KGlu is obtained by adding common denaturants such as urea, guanidinium chloride, or guanidinium thiocyanate. A rationalization of the experimental data is devised on the basis of a theoretical approach developed by one of the authors. The main contribution to the conformational stability of globular proteins comes from the gain in translational entropy of water and co-solute ions and/or molecules for the decrease in solvent-excluded volume associated with polypeptide folding (i.e., there is a large decrease in solvent-accessible surface area). The magnitude of this entropic contribution increases with the number density and volume packing density of the solution. The two destabilizing contributions come from the conformational entropy of the chain, which should not depend significantly on the presence of co-solutes, and from the direct energetic interactions between co-solutes and the protein surface in both the native and denatured states. It is the magnitude of the latter that discriminates between stabilizing and destabilizing agents.

Novel method for finishing nonwoven fabrics from domestic raw materials with flame retardant and antimicrobial properties

This study aims to obtain a non-woven material with flame retardant and biocidal properties, considering the use of salicylic acid, copper sulfate, and guanidine hydrochloride in a finishing composition, based on preliminary studies. The concentrations of copper sulfate, guanidine hydrochloride, and salicylic acid were varied, respectively, within 1–5 g/L, 5–15 g/L, and 3–7 g/L. The conditions of the finishing process involved the application of the aqueous solutions, by spraying on the surface of the material, followed by drying at 120 °C for 5 min and heat treatment at 180 °C on a thermal press. In the production of nonwovens, treatment with a flame retardant and biocidal composition can be combined with emulsification of a mixture of fibers, or carried out after the formation of the canvas with subsequent heat treatment and calendering. The untreated sample of non-woven material, when tested for flammability with an ignition time of 15 s, burns completely in 40 s. For the sample treated by the proposed method, the self-burning is reduced to zero (DIN 53906). To study the biocidal activity, a microbiological essay was conducted according to ASTM E2149. It was found that the tested sample exhibits fungicidal activity against the tested strains. In addition, tests conducted on the skin-irritating effects of nonwovens treated with the proposed method have shown its safety for human health.

High power density charging-free thermally regenerative electrochemical flow cycle for low-temperature thermoelectric conversion

Low-temperature thermal energy widely exists in nature and is sustainable. The thermally regenerative electrochemical cycle (TREC) based on the Seebeck effect has attracted widespread attention due to its high thermoelectric efficiency and good cycle stability. However, it has a low power density and cannot sustain continuous operation for extended periods. This work proposes a continuous charging-free thermally regenerative electrochemically cycled flow battery (TREC-FB) system, which can discharge continuously at both high and low temperatures without the assistance of external power source. By adding guanidine hydrochloride (GdmCl) and inorganic salt ions (Cs+, Ca2+, Mg2+, etc.) to the K3Fe(CN)6/K4Fe(CN)6 and I2/KI electrolytes respectively, precipitates are formed in the electrolytes at low temperature and dissolve at high temperature, which creates the concentration gradient of ions. As a result, the temperature coefficient of the full cell increases from −2.24 mV/K to −3.6 mV/K, and both voltage and power density are doubled. Theoretical analysis of the temperature coefficient enhancement is conducted based on the Nernst equation, and the mechanism of the temperature coefficient enhancement is verified using UV–vis spectra. The discharging capacity and energy of the charging-free TREC-FB with high temperature coefficient reach 5 Ah/L and 1.9 kJ/L, respectively, and the thermoelectric efficiency reaches 8.9 % under sufficient heat recuperation. Two TREC-FBs at high and low temperatures are connected to carry out continuous operation experiments of the charging-free TREC-FB system. The use of charge-reinforced ion-selective membrane can effectively inhibit the migration of I− and I3− ions, achieving about 36 h of continuous operation, and the average power density achieves 0.6 W/m2.

GUANIDINE-CONTAINING ALIPHATIC OLIGOMERS WITH BACTERICIDAL ACTIVITY

A method for the synthesis of reactive aliphatic guanidine oligomers (GO) of different MM by the reaction of oligomeric oxyalkylaliphatic diepoxide with guanidine by varying the ratio of the starting components with subsequent neutralization of the obtained product with hydrochloric acid was developed. A characteristic feature of the structure of the obtained GO oligomers is their amphiphilicity, with the presence of hydroxy-containing guanidine fragments both at the ends and inside the chain. The obtained oligomers are reactive to further chemical transformations. The chemical structure of GO was characterized by FTIR and 1H-NMR spectroscopy, molecular weight was determined by liquid chromatography and titration data. The bactericidal properties of aliphatic guanidine oligomers against a number of gram-positive (Micrococcus luteus, Rhodococcus erythropolis, Rhodococcus rubber, Bacillus megaterium, Bacillus subtilis, Bacillus cereus) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Serratia marcescen), depending on the MW of GO were investigated. The minimum inhibitory concentration of aliphatic guanidine oligomers against the studied bacterial strains was determined. It has been shown that the oligomer with the highest content of guanidine fragments has the greatest bactericidal activity and, accordingly, the lowest minimum inhibitory concentration against gram-positive and gram-negative bacteria. The reactive guanidine oligomers obtained by analogy with polyhexamethylene guanidine chloride can be recommended as substances with biocidal and fungicidal properties. In addition, the inherent reactivity of the synthesized GO makes them promising for obtaining various new types of polymers and composites based on them.

A systematic review and BMD modeling approach to develop an AOP for humidifier disinfectant-induced pulmonary fibrosis and cell death

Dosimetry modeling and point of departure (POD) estimation using in vitro data are essential for mechanism-based hazard identification and risk assessment. This study aimed to develop a putative adverse outcome pathway (AOP) for humidifier disinfectant (HD) substances used in South Korea through a systematic review and benchmark dose (BMD) modeling. We collected in vitro toxicological studies on HD substances, including polyhexamethylene guanidine hydrochloride (PHMG-HCl), PHMG phosphate (PHMG-p), a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (CMIT/MIT), CMIT, and MIT from scientific databases. A total of 193 sets of dose-response data were extracted from 34 articles reporting in vitro experimental results of HD toxicity. The risk of bias (RoB) in each study was assessed following the office of health assessment and translation (OHAT) guideline. The BMD of each HD substance at different toxicity endpoints was estimated using the US Environmental Protection Agency (EPA) BMD software (BMDS). Interspecies- or interorgan differences or most critical effects in the toxicity of the HD substances were analyzed using a 95% lower confidence limit of the BMD (BMDL). We found a critical molecular event and cells susceptible to each HD substance and constructed an AOP of PHMG-p- or CMIT/MIT-induced damage. Notably, PHMG-p induced ATP depletion at the lowest in vitro concentration, endoplasmic reticulum (ER) stress, epithelial-to-mesenchymal transition (EMT), inflammation, leading to fibrosis. CMIT/MIT enhanced mitochondrial reactive oxygen species (ROS) production, oxidative stress, mitochondrial dysfunction, resulting in cell death. Our approach will increase the current understanding of the effects of HD substances on human health and contribute to evidence-based risk assessment of these compounds.

EVALUATION OF THE EFFICACY OF CHLORINE-CONTAINING COMMERCIAL PRODUCTS FOR WATER DECONTAMINATION AGAINST COLIFORM BACTERIA

Problem. Water is a key factor in the transmission of intestinal infections. During war conflicts, the risk of outbreaks of such infections increases due to infrastructure damage, the inaccessibility of central water supplies, and the impossibility of governmental institutions to control drinking water quality. In such situations, the need arises for household water treatment methods. Aim. To evaluate the efficacy of seven commercial water treatment products available in the Ukrainian market against enteric bacteria and to compare their efficacy. Methods. The activity of water purification products against the model microorganism Escherichia coli ATCC25922 was evaluated using serial dilution methods followed by viable count assessment. The main results: High efficacy of the studied preparations against enteric bacteria was detected. In each test, a significant decrease in the initial titer of Escherichia coli from 1,2·10 6 CFU/cm 3 to ˂ 10 CFU/cm 3 was observed after the exposure time declared by the manufacturer. Conclusions: The studied water treatment products from Ukrainian and foreign manufacturers were effective against enteric bacteria and met the WHO criteria for efficiency, regardless of the nature of the active compound (chlorine dioxide, sodium dichloroisocyanurate, or polyhexamethylene guanidine hydrochloride).