Search Results (20)

Infectious prion adsorption on metal, minerals, wood, and plastic is well documented, raising the specter of food safety hazards for meat packing workers, sport hunters, and consumers. We previously demonstrated that sodium hypochlorite, and to a lesser extent, potassium peroxymonosulfate, and hypochlorous acid can decontaminate prion-contaminated nonporous surfaces. However, the extent to which chemical aging of surfaces affects subsequent recoverable prion seeding activity is unknown. In this study, we investigated the potential for four chemical decontaminants known for their anti-prion activity (sodium hypochlorite [bleach], hypochlorous acid [Briotech], potassium peroxymonosulfate [Virkon-S], and Wex-Cide-128) to alter the surfaces of steel knives and the subsequent prion decontamination efficacy of each. We found that hypochlorous acid, sodium hypochlorite, and potassium peroxymonosulfate corrode the surfaces of steel knives, resulting in significant physical alterations. Knives exposed to hypochlorous acid exhibited the most substantial corrosion (rust), which is consistent with its oxidizing effects. Oxidation of the knife surface was corroborated by complementary energy-dispersive X-ray spectroscopy data trends. Scanning electron microscopy data indicate corrosion is apparent after minimal exposure to oxidizing agents. Finally, we used the real-time quaking-induced conversion assay on swabs collected from chemically aged knife surfaces to evaluate recoverable surface-associated CWD-prion seeding activity detected by RT-QuIC after prion exposure and decontamination. Our results indicate decreased recoverable prion seeding activity from knife surfaces aged with 40% bleach. We also observed some recoverable seeding activity post-decontamination on knives chemically aged with 10% bleach and Wex-Cide-128, but largely similar efficacy to prior studies. This implies that existing chemical prion decontaminants are likely effective after repeated use on steel surfaces. Full article

Microplastics (MPs) in wastewater treatment plants are exposed to oxidative conditions during disinfection and advanced oxidation processes (AOPs), which can alter morphology and surface chemistry and influence interactions with coexisting contaminants. Here, accelerated chemical oxidation was simulated using heat-activated potassium persulfate (K₂S₂O₈) and sodium hypochlorite (NaOCl) to examine the oxidative aging of MPs made from polyethylene (PE), polyethylene terephthalate (PET), and polypropylene (PP). Changes in particle morphology and surface chemistry before and after oxidant treatment were characterized using scanning electron microscopy (SEM) for morphological analysis and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy for chemical characterization. Carbonyl formation, an indicator of polymer oxidation, was evaluated using the carbonyl index (CI). Both oxidants induced surface morphological defects and carbonyl functional groups in the MPs, with CI increasing with degradation time. The CI trends suggest that MP oxidation varies with polymer type and oxidant. The effect of oxidative aging on MP sorption capacity was also investigated using copper ions as a model inorganic constituent. Although oxidative aging introduced oxygen-containing functional groups, no statistically significant differences in copper sorption were observed between pristine and oxidized MPs, indicating that MPs can act as vectors for copper regardless of their degree of surface oxidation. Full article

This study systematically compared the induction and resuscitation characteristics of the viable but non-culturable (VBNC) state in Klebsiella pneumoniae FY170-1 following sublethal exposure to sodium hypochlorite (NaClO) or glutaraldehyde (GA). Treatment with 30 mg/L NaClO or 60 mg/L GA for 60 min reduced culturability to below the detection limit (<1 CFU/mL). However, CTC staining showed that 50.80% and 63.44% of cells, respectively, retained respiratory activity, while SYTO 9/PI staining indicated that membrane integrity was largely preserved, consistent with induction of the VBNC state. Scanning electron microscopy revealed distinct morphological alterations in the two groups. NaClO-induced VBNC cells showed surface depressions and wrinkling, consistent with oxidative damage, whereas GA-induced cells exhibited filamentous and net-like surface structures, consistent with aldehyde-mediated cross-linking. Among the tested additives, sodium succinate showed the strongest resuscitation-promoting effect under the experimental conditions, with OD600 increasing after approximately 2 h of incubation. Post-resuscitation analysis further revealed marked differences between the two VBNC states. In resuscitated NaClO-induced VBNC cells, ATP partially recovered, but reactive oxygen species remained elevated and catalase activity showed little recovery. In contrast, resuscitated GA-induced VBNC cells exhibited lower ATP recovery but more rapid normalization of ROS and better recovery of oxidative stress-related parameters. Total protein analysis and SDS-PAGE further supported distinct patterns of protein-level alteration between the two treatments. Overall, these findings suggest that NaClO and GA induce phenotypically distinct VBNC states in K. pneumoniae, with different recovery behaviors and stress response profiles. Sodium succinate was identified as the most effective recovery-promoting additive under the tested conditions. These results highlight the risk of underestimating bacterial survival when culturability is used as the sole indicator of disinfection efficacy and support the need for more comprehensive viability assessment. Full article

Failure of the endodontic treatment is often associated with persistent polymicrobial biofilms, particularly those involving Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans), which display synergistic pathogenicity and resistance to standard disinfection methods. This in vitro study compared the antimicrobial activity and oxidative damage induced by indocyanine green (ICG)–mediated laser ablation (LA) with that produced by antimicrobial photodynamic therapy (aPDT) using methylene blue (MB) or curcumin (CUR) in root canals infected with dual-species biofilms. The samples were divided into five experimental groups (n = 20): Group A—Methylene Blue + Red Laser (RL), Group B—Curcumin + Blue LED (BL), Group C—Indocyanine Green + Infrared Diode Laser (DL), Group D—saline solution (Negative Control—NC), Group E—2.5% sodium hypochlorite (Positive Control—PC). One hundred treated bovine incisors (20 per group) were analyzed for microbial viability (colony-forming unit (CFU/mL)), the metabolic functionality of biofilms was assessed through the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide (XTT) based reduction method, and oxidative stress markers, including Thiobarbituric Acid Reactive Substances (TBARS), protein carbonyl content, total oxidant capacity (TOC), and total protein levels. All experimental treatments significantly reduced microbial load compared to the negative control (p < 0.05), with ICG achieving the greatest reduction. ICG also induced the highest levels of oxidative stress across all parameters (p < 0.05). These findings suggest that LA with ICG is more effective than aPDT with MB or CUR, achieving disinfection outcomes comparable to those of 2.5% sodium hypochlorite, and warrant further investigation in complex clinical models. Full article

Cladophora-dominated filamentous algal blooms constitute a growing threat to aquatic ecosystem stability and aquaculture operations. This study systematically evaluated the algicidal efficacy of sodium hypochlorite (NaClO), both individually and in combination with an organosilicone adjuvant, against Cladophora sp., with particular focus on induced oxidative damage mechanisms. Results demonstrated that NaClO exhibited a dose- and time-dependent inhibitory effect, achieving ≥90% inhibition at 1.20 mmol L⁻¹ within 48 h and >99% by 120 h, significantly surpassing the efficacy of lower concentrations (0.40 mmol L⁻¹) (p < 0.05). Physiological assessment revealed that 1.20 mmol L⁻¹ NaClO significantly suppressed total antioxidant capacity (T-AOC) after 96 h (p < 0.05). Notably, synergistic enhancement was observed with adjuvant co-application: at 0.40 mmol L⁻¹ NaClO, superoxide dismutase (SOD) activity reached its minimum with 0.33 ppm organosilicone adjuvant, showing significant reduction compared to higher adjuvant concentrations (p < 0.05). Furthermore, combinations of 0.80 and 1.20 mmol L⁻¹ with organosilicone adjuvant consistently maintained inhibition rates ≥ 94% across all sampling intervals, achieving control efficacy equivalent to 2.00 and 2.40 mmol L⁻¹ NaClO alone within 48 h. These findings demonstrate that NaClO supplemented with low-dose organosilicone adjuvant constitutes a promising and efficient strategy for mitigating Cladophora blooms. Full article

Foodborne illness outbreaks from fresh produce underscore the urgent demand for sanitizing strategies that ensure safety while minimizing harmful by-products from high-dose chemical disinfectants such as sodium hypochlorite (NaOCl). Low-concentration combinations of organic acids and washing sanitizers were systematically evaluated to identify synergistic antibacterial effects, and citric acid (CA) was found to markedly potentiate the activity of NaOCl against Salmonella Typhimurium through a sequential assault on the cell envelope. A low-dose combination of sub-inhibitory concentrations (1/2 MIC of CA and 1/4 MIC of NaOCl) exhibited robust synergy, achieving a >6 log CFU/cm² reduction in the pathogen on a cherry tomato model within 3 min. Moreover, this synergistic entry leads to profound disruption of membrane integrity, resulting in leakage of nucleic acids and proteins, extensive oxidative damage, hyperpolarization, and cell lysis, as confirmed by electron and confocal microscopy together with physicochemical assays. Mechanistic investigation revealed that oxidative damage from NaOCl amplified CA-induced membrane acidification and permeability, facilitating deeper sanitizer penetration and accelerating envelope destruction. Collectively, these findings uncover a membrane-targeted synergistic mechanism, providing a solid scientific basis for the development of novel, low-residue, and high-efficacy food safety interventions. Full article

Salmonella is one of the main causes of food-borne illness worldwide. In most cases, Salmonella contamination can be traced back to food processing plants and/or to cross-contamination during food preparation. To avoid food-borne diseases, food processing plants use sanitizers and biocidal to reduce bacterial contaminants below acceptable levels. Despite these preventive actions, Salmonella can survive and consequently affect human health. This study investigates the adaptive capacity of the main Salmonella enterica serotypes isolated from the poultry production line, focusing on their replication, antimicrobial resistance, and biofilm formation under stressors such as acidic conditions, oxidative environment, and high osmolarity. Using growth curve analysis, crystal violet staining, and microscopy, we assessed replication, biofilm formation, and antimicrobial resistance under acidic, oxidative, and osmotic stress conditions. Disinfectant tolerance was evaluated by determining the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of sodium hypochlorite. The antibiotic resistance was assessed using the Kirby–Bauer method. The results indicate that, in general, acidic and osmotic stress reduce the growth of Salmonella. However, no significant differences were observed specifically for serotypes Infantis, Heidelberg, and Corvallis. The S. Infantis isolates were the strongest biofilm producers and showed the highest prevalence of multidrug resistance (71%). Interestingly, S. Infantis forming biofilms required up to 8-fold higher concentrations of sodium hypochlorite for eradication. Furthermore, osmotic and oxidative stress significantly induced biofilm production in industrial S. Infantis isolates compared to a reference strain. Understanding how Salmonella responds to industrial stressors is vital for designing strategies to control the proliferation of these highly adapted, multi-resistant pathogens. Full article

This paper presents a simple, post-synthesis treatment of carbon dots (C-dots) that relies on the oxidizing activity of sodium hypochlorite to induce surface oxidation, etching and pronounced structural rearrangements. The thus treated C-dots (ox-C-dots) exhibit up to six-fold enhancement in quantum yield compared to non-oxidised analogues, while maintaining low levels of cytotoxicity against HeLa and U87 cell lines. In addition, we demonstrate that a range of polymeric materials (polyurethane sponge, polyvinylidene fluoride membrane, polyester fabric) impregnated with ox-C-dots show advanced antifungal properties against Talaromyces pinophilus, while their untreated counterparts fail to do so. Full article

Water quality control employs techniques mostly targeting individual analytes; group detection is also practiced, but the choice of group methods is limited, which supports interest in developing such methods. We have examined the interaction of hypochlorite with a chlorine-containing heptamethine carbocyanine dye in the presence of 30 organic and inorganic model analytes that were found to induce diverse color changes in the system. The main supposed mechanisms are retardation of the dye oxidation with hypochlorite (presumably by scavenging chlorine radicals) and substitution of chlorine atom in the dye by the most nucleophilic analytes (amines, amino acids, proteins, DNA, phenol). The grass-green substitution product is more contrastingly visible against the dark-purple hypochlorite oxidation product of the dye than against the original emerald-green dye. The indicator reaction is monitored photographically for 10–40 min and the images are processed using principal component analysis (PCA) or linear discriminant analysis (LDA), allowing for data convolution for the complex color transitions. Nitrogen compounds are discriminated from the others, and more reactive analytes (tryptophan, cysteine, bovine serum albumin, and DNA) are detected in the presence of less reactive ones in natural water. The system is promising for the development of group assays for dissolved organic matter and the discrimination of water samples. Full article

Luminescent Ag nanoclusters (Ag NCs) are a promising probe material for sensing and bioimaging applications. However, the intrinsic obstacle of poor water stability and photostability greatly restrict their practical application in biological systems. Herein, we report the intracellular hypochlorite (ClO⁻) detection with amphiphilic copolymer-modified luminescent Ag NCs with good biocompatibility and photostability. The Ag NCs were synthesized by using chemically inert hydrophobic ligands and then modified with an amphiphilic (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(poly(ethylene glycol))-2000]) (DSPE-PEG-2000) and sodium dodecyl sulfonate (SDS) for phase transfer. It was found that the approach of the removal of organic solvents during the phase transfer has remarkable influences on the properties of the Ag NCs, including their size, luminescence property, and aqueous stability. Furthermore, the silver core of Ag NCs could be oxidatively damaged by ClO⁻, thereby causing photoluminescence (PL) quenching. The ClO⁻-induced PL quenching was specific over the other common reactive oxygen species (ROS) as well as some common interferences. Finally, they have been successfully applied as a fluorescent nanoprobe for detecting exogenous and endogenous ClO⁻ in living cells. Full article

Given the importance of molecular structure in pharmacological activity and interaction with biological receptors, we conducted a study on the 3,4-dihydroxybenzaldehyde hydrazone derivative of 5-methoxy-indole carboxylic acid (5MICA) and a newly synthesised analogue bearing a 2-methoxy-4-hydroxyphenyl ring using single-crystal X-ray diffraction. We studied the ability of the two compounds to scavenge hypochlorite ions using luminol-enhanced chemiluminescence and their potential to modulate oxidative damage induced by iron on the biologically significant molecules lecithin and deoxyribose in order to evaluate possible antioxidant and prooxidant effects. The X-ray study revealed highly conserved geometry and limited rotation and deformation freedom of the respective indole and phenyl fragments. Interestingly, a conformational difference between the two independent molecules in the asymmetric unit of 3b was found. The X-ray study revealed a combination of hydrogen bonding interactions, short contacts, and π–π stacking stabilizing the specific three-dimensional packing of the molecules of 3a and 3b in the crystal structures. The three-dimensional packing of the molecules of 3b produced a zigzag layering projected along the c-axis. Both compounds effectively decreased luminol-dependent chemiluminescence in model systems with KO₂-produced superoxide. They displayed opposite effects when applied in a xanthine/xanthine oxidase system. The hydrazones of 5MICA do not trigger a prooxidant effect or subsequent toxicity under conditions of iron-induced oxidative stress. The 3,4-dihydroxy-substituted derivative demonstrated excellent radical scavenging properties in all model systems, making it the lead compound for the development of compounds with combined neuroprotective and antioxidant properties. Full article

Sodium hypochlorite was widely used as a supplementary disinfectant in reclaimed water (RW) production during the COVID-19 epidemic. It is well known that the chlorination of RW results in a relatively high bacterial regrowth potential in pipeline systems. However, the algal growth and algal–bacterial interactions would be another concern in RW-replenished surface water with light irradiation. In this study, microcosmic experiments were used to explore the impact of hypochlorite on the algae–bacteria community, including the influence of hypochlorite on algal–bacterial regrowth, microbial community structure, and the specific bacteria that can survive chlorination. Results demonstrated that algal growth potential could be promoted after chlorination of the RW, and bacteria abundance increased along with an increase in algal density, which is probably related to DOM decomposition by chlorine oxidation. Additionally, the characteristics of the bacterial community were altered. It is more likely that phytospheric bacteria will survive chlorination. It was discovered that the secondary risks of chlorine disinfection include the growth of algae in addition to bacterial regeneration, which is an extension of the common perception. As a consequence, when chlorinated reclaimed water is used as a supplement for urban landscape ponds, particular attention should be paid to controlling bio-available organic matter induced by reactive chlorine, as well as the algal bloom, to decrease the risk of pathogen transmission. Full article

Plasminogen activator inhibitor type-2 (PAI-2), a member of the serpin family, is dramatically upregulated during pregnancy and in response to inflammation. Although PAI-2 exists in glycosylated and non-glycosylated forms in vivo, the majority of in vitro studies of PAI-2 have exclusively involved the intracellular non-glycosylated form. This study shows that exposure to inflammation-associated hypochlorite induces the oligomerisation of PAI-2 via a mechanism involving dityrosine formation. Compared to plasminogen activator inhibitor type-1 (PAI-1), both forms of PAI-2 are more resistant to hypochlorite-induced inactivation of its protease inhibitory activity. Holdase-type extracellular chaperone activity plays a putative non-canonical role for PAI-2. Our data demonstrate that glycosylated PAI-2 more efficiently inhibits the aggregation of Alzheimer’s disease and preeclampsia-associated amyloid beta peptide (Aβ), compared to non-glycosylated PAI-2 in vitro. However, hypochlorite-induced modification of non-glycosylated PAI-2 dramatically enhances its holdase activity by promoting the formation of very high-molecular-mass chaperone-active PAI-2 oligomers. Both PAI-2 forms protect against Aβ-induced cytotoxicity in the SH-SY5Y neuroblastoma cell line in vitro. In the villous placenta, PAI-2 is localised primarily to syncytiotrophoblast with wide interpersonal variation in women with preeclampsia and in gestational-age-matched controls. Although intracellular PAI-2 and Aβ staining localised to different placental cell types, some PAI-2 co-localised with Aβ in the extracellular plaque-like aggregated deposits abundant in preeclamptic placenta. Thus, PAI-2 potentially contributes to controlling aberrant fibrinolysis and the accumulation of misfolded proteins in states characterised by oxidative and proteostasis stress, such as in Alzheimer’s disease and preeclampsia. Full article

High homocysteine (Hcy) levels, mainly caused by vitamin B₁₂ deficiency, have been reported to induce amyloid-β (Aβ) formation and tau hyperphosphorylation in mouse models of Alzheimer’s disease. However, the relationship between B₁₂ deficiency and Aβ aggregation is poorly understood, as is the associated mechanism. In the current study, we used the transgenic C. elegans strain GMC101, which expresses human Aβ_1–42 peptides in muscle cells, to investigate the effects of B₁₂ deficiency on Aβ aggregation–associated paralysis. C. elegans GMC101 was grown on nematode growth medium with or without B₁₂ supplementation or with 2-O-α-D-glucopyranosyl-L-ascorbic acid (AsA-2G) supplementation. The worms were age-synchronized by hypochlorite bleaching and incubated at 20 °C. After the worms reached the young adult stage, the temperature was increased to 25 °C to induce Aβ production. Worms lacking B₁₂ supplementation exhibited paralysis faster and more severely than those that received it. Furthermore, supplementing B₁₂-deficient growth medium with AsA-2G rescued the paralysis phenotype. However, AsA-2G had no effect on the aggregation of Aβ peptides. Our results indicated that B₁₂ supplementation lowered Hcy levels and alleviated Aβ toxicity, suggesting that oxidative stress caused by elevated Hcy levels is an important factor in Aβ toxicity. Full article

Via inhalation we are continuously exposed to environmental and occupational irritants which can induce adverse health effects, such as irritant-induced asthma (IIA). The airway epithelium forms the first barrier encountered by these agents. We investigated the effect of environmental and occupational irritants on the airway epithelial barrier in vitro. The airway epithelial barrier was mimicked using a coculture model, consisting of bronchial epithelial cells (16HBE) and monocytes (THP-1) seeded on the apical side of a permeable support, and human lung microvascular endothelial cells (HLMVEC) grown on the basal side. Upon exposure to graphene (G) and graphene oxide (GO) in a suspension with fetal calf serum (FCS), ammonium persulfate (AP), sodium persulfate (SP) and hypochlorite (ClO⁻), the transepithelial electrical resistance (TEER) and flux of fluorescent labelled dextran (FD4-flux), was determined. Exposure to graphene nanoparticles (GNPs) induced an immediate negative effect on the epithelial barrier, whereas ClO⁻ only had a negative impact after 24 h of exposure. AP and SP did not affect the barrier properties. The tight junctions (TJ) network showed less connected zonula occludens 1 (ZO-1) and occludin staining in GNP-exposed cocultures. Functional analysis of the phosphoproteomic data indicated that proteins in the adherens junction (AJ) and TJ pathways showed an altered phosphorylation due to GNP exposure. To conclude, the negative effect of GNPs on the epithelial barrier can be explained by the slightly altered the TJ organization which could be caused by alterations in the phosphorylation level of proteins in the AJ and TJ pathway. Full article