Microbicidal Effect Research Articles

Long-Term Storage Stability of Neutral Electrolyzed Water by Two-Stage Electrolysis: Optimal Storage Conditions for Intraoral Use

Electrolyzed water mainly containing hypochlorous acid is widely used because of its strong microbicidal effects, biosafety, and eco-friendliness. For frequent use in intraoral treatments, we focused on neutral electrolyzed water (NW) produced using two-stage electrolysis and investigated its storage stability. For standard-concentration NW preparations with a free available chlorine concentration (ACC) of 25, 35, and 50 mg/L and high-concentration NW preparations (100, 200, 300, 500, and 1000 mg/L), the changes in the pH, oxidation reduction potential, and ACC during a 126-day storage period and the bactericidal efficacies after storage were examined. Storage under non-shaded conditions at room temperature (LRT) and a higher ACC substantially altered the properties of the NW. NW (≤300 mg/L) had a pH of 5.9–7.3 even after storage under LRT; however, NW with a higher ACC (500 and 1000 mg/L) had a pH ˂ 5.5, critical for human enamel, even under shaded and refrigerated conditions (SLW). Only NW (25 mg/L) stored under LRT decreased the bactericidal effect (removal rate: 99.8%). When stored for use in intraoral treatments, NW should be prepared with an ACC of 25–300 mg/L and stored in SLW. It is suggested that stored NW, especially when diluting it, should be checked to ensure it maintains the properties appropriate for every intended purpose.

Polydopamine Nanoconjugate‐Coated Masks: An Efficient Barrier Against Airborne Pathogens

AbstractCurrent global burden of respiratory tract infections (RTIs) has thrown new challenges for researchers to design and develop efficient and multifaceted face masks. Airborne pathogens are highly transmissible through droplet nuclei/aerosol (<5 μm) which can be significantly reduced by wearing masks. Currently available disposable surgical masks have disparate limitations in terms of surface wettability, microbial penetration, dermal infections due to anaerobic reactions beneath the surface, discomfort, and eruption of chronic obstructive pulmonary diseases (COPD). These mask surfaces get contaminated with airborne pathogens along with commensal bacterial strains. Generation of high temperature and humidity during repetitive breathing allow bacteria to penetrate from the masks to respiratory tract causing serious complications. Till date, functionalized face masks with different microbicidal agents including nanomaterials experience restricted leaching of antimicrobial agents, cytotoxic effects, short‐lived microbicidal effects, inflammatory responses, negative impact on ecosystem, etc. To address these limitations, here, we have attempted fabrication of mussel mimetic biopolymer (PDA) and its aminoglycoside‐nanoconjugate‐coated face masks. Formation of a uniform layer on the surface not only acted as a potential barrier for infectious pathogens but also inhibited their entry, deactivated the adhered bacteria, imparted non‐immunogenic response with no harmful effects on the wearer's skin owing to the biocompatible nature and pH compatibility of PDA and their conjugates. Amongst all, PDA‐kanamycin (PDA−K)‐coated masks exhibited excellent microbicidal activity with the least bacterial infiltration efficiency.

Microbicidal Polymer Nanoparticles Containing Clotrimazole for Treatment of Vulvovaginal Candidiasis

Vulvovaginal candidiasis (VVC) alters the innate cervicovaginal immunity, which provides an important barrier against viruses and other infections. The incidence of this disease has not decreased in the last 30 years, so effective treatments are still needed. Nanoparticles (NPs) of cellulose acetate phthalate (CAP) and clotrimazole (CLZ) were prepared by the emulsification-diffusion method. NPs were characterized using dynamic light scattering, atomic force microscopy and differential scanning calorimetry; their release profile was determined by the dialysis bag technique and mucoadhesion was evaluated with the mucin-particle method. The growth inhibition study of Candida albicans was carried out using the plate counting technique. Finally, accelerated physical stability tests of NPs were carried out, both in water and in SVF. The CAP-CLZ NPs had an average diameter of 273.4 nm, a PDI of 0.284, smooth surfaces and spherical shapes. In vitro release of CLZ from the CAP NPs was categorized with the Weibull model as a matrix system in which initial release was rapid and subsequently sustained. The inhibition of C. albicans growth by the CAP-CLZ NPs was greater than that of free CLZ, and the CAP-only NPs had a microbicidal effect on C. albicans. The NPs showed poor mucoadhesiveness, which could lead to studies of their mucopenetration capacities. An accelerated physical stability test revealed the erosion of CAP in aqueous media. A nanoparticulate system was developed and provided sustained release of CLZ, and it combined an antifungal agent with a microbial polymer that exhibited antifungal activity against C. albicans.Graphical

Could light be a broad-spectrum antimicrobial?

A review on antimicrobial resistance mechanisms discussing the main light-based antimicrobial approaches including ultraviolet light (UV), antimicrobial photodynamic therapy (aPDT), and antimicrobial blue light (aBL). To describe antimicrobial resistance mechanisms and to present potential light-based alternatives to conventional antimicrobials. The paper was divided into different topics, starting with an approach to antimicrobial resistance mechanisms. Subsequently, emphasis was placed on innovative light-based antimicrobials approaches, including aBL, UV, and aPDT. The review suggests that blue light (400-470 nm) acts on endogenous porphyrins with peak absorption at 405 nm, thus not requiring the administration of photosensitizers, to trigger antimicrobial effects. In this regarding, the direct effect of aBL could be attributed to both the generation of reactive oxygen species (ROS), which induces microbicidal effects, and the inactivation of bacterial defense mechanisms. In turn, blue light combined with curcumin has been used in the treatment of dental infections. Otherwise, green light (495-570 nm) associated with the photosensitizer Rose Bengal has shown promising results both in wound closure due to the induction of additional collagen cross-link formation and in reducing the viability of Pseudomonas aeruginosa. Red light (620-750 nm) is the wavelength most commonly used in aPDT, presenting superior tissue penetration capability compared to blue and green light. Both red and infrared light act directly as photobiomodulation agents, promoting tissue repair with greater penetration depth for the infrared spectrum. Conversely, red light combined with methylene blue is the most commonly used technique in the treatment of localized infections. Meanwhile, infrared light associated with indocyanine green acts as a photothermal and photosensitizing agent, promoting thermal damage and production of ROS. Ultraviolet lights UVA, UVB, and UVC (200-400 nm) have antimicrobial potential related to inducing changes in DNA and generating both ROS and singlet oxygen. Furthermore, light can enhance the efficacy of traditional antimicrobial agents by deactivating microbial resistance, both through increasing the permeability of the cell membrane and by inhibiting the efflux pump and β-lactamases of the bacteria. The antimicrobial potential of light is extensive; however, there is a limitation regarding the depth of penetration of certain wavelengths into infected areas. Furthermore, there is a need for additional studies to determine the safety and efficacy of various approaches using light at its different wavelengths.

Bio-inspired multifunctional and reusable LiP@MFO-GO and LiP@MFO-Chit hybrid enzyme complexes for efficient degradation of melanin

Melanin is a complex brown pigment, primarily responsible for the skin pigmentation. Therefore, cosmetic industries have always been in search of potent oxidative enzymes useful for melanin degradation, and to promise a fair complexion after using their products. In the present study, lignin peroxidase from Pseudomonas fluorescence LiP-RL5 isolate has been immobilized on super-paramagnetic nanoparticles to enhance its stability and reusability. The chitosan coated enzyme-nanomaterial complex (LiP@MFO-Chit) showed higher melanin decolorization (47.30 ± 2.3 %) compared to the graphene oxide coated nanoparticles (LiP@MFO-GO) (41.60 ± 1.6 %). Synthesized enzyme nanoparticle complexes showed microbicidal effect on skin infection causing pathogen, Pantoea agglomerans with an inhibitory zone of 6.0 ± 0.9 mm and 250 µg/100 µl minimum inhibitory concentration, and a 7.0 ± 1.5 mm zone and 170 µg/100 µl MIC for LiP@MFO-GO and LiP@MFO-Chit, respectively. Antioxidant potential of LiP@MFO-Chit and LiP@MFO-GO nano-conjugates showed a substantial DPPH scavenging activity of 75.7 % and 88.3 %, respectively. Therefore, LiP-nanoparticle hybrid complexes analyzed in this study are not only effective as skin whitening agents but they are potential molecules against various microbial skin infections as well as useful for different other biomedical applications like biorefinery, drug delivery, and dermatology, etc.

Surface properties and antibacterial characteristics of polyurethane modified by corona discharge for food processing industry

Thermal properties and durability make polyurethane (PU) ideal for conveyor belts in food processing industry. On the other hand, its susceptibility to adhesion of pathogens subjects him to surface treatment techniques. In this study, substrates of PU were exposed to corona discharge using air as treatment gas. The process parameters, such as treatment time and nozzle-substrate distance, and the microbicidal effects of the polymer surfaces against Staphylococcus aureus and Escherichia coli were examined. Changes in surface hydrophobicity occurred at short treatment times due to the introduction of polar groups, as proofed by X-ray Photoelectron Spectroscopy (XPS), while the surface morphology suffered minor changes as revealed by Scanning Electron Microscopy (SEM) imaging. Moreover, the hydrophilicity of plasma treated PU was minimal affected by the variation of nozzle-substrate distance, as long as the discharge was in contact with the polymer surface. The hydrophilic surfaces developed a very good resistance to bacteria adherence in few hours after incubation.

Synergistic anti-virulence efficacy of citral and carvacrol against mixed vaginitis causing Candida albicans and Gardnerella vaginalis: An in vitro and in vivo study.

Mixed vaginitis due to bacterial vaginosis (BV) and vulvovaginal candidiasis (VVC) is the most prevalent form and presents a significant therapeutic challenge globally. Since, the administration of monotherapy leads to subsequent recurrent infections, synergistic therapy that completely eradicates both pathogens is of dire need to manage mixed vaginities scenario and to prevent its recurrence. The current investigation was focused on exploring the synergistic inhibitory efficacy of phytochemicals against the virulence traits of individual and mixed species of C. albicans and G. vaginalis in vitro and in vivo (Galleria mellonella). Out of five phytochemicals (carvacrol, thymol, cinnamaldehyde, eugenol, and borneol) screened for synergism with citral [(Ct) as the prime molecule owing to its myriad therapeutic potential], carvacrol (Ca) in combination with citral exhibited promising synergistic effect. Time-kill kinetics and one-minute contact-killing assays demonstrated the phenomenal microbicidal effect of Ct-Ca combination against both mono and dual-species within 30 min and one-minute time intervals, respectively. Furthermore, the sub-CMICs (synergistic combinatorial MIC) of Ct-Ca have significantly eradicated the mature biofilms and remarkably reduced the virulence attributes of both C. albicans and G. vaginalis (viz., yeast to hyphae transition, filamentation, protease production, and hydrophobicity index), in single and dual species states. The non-toxic nature of Ct-Ca combination was authenticated using in vitro (human erythrocyte cells) and in vivo (Galleria mellonella) models. In addition, the in vivo efficacy evaluation and subsequent histopathological investigation was done using the invertebrate model system G. mellonella, which further ascertained the effectiveness of Ct-Ca combination in fighting off the infection caused by individual and mixed species of C. albicans and G. vaginalis. Concomitantly, the current work is the first of its kind to delineate the in vitro interaction of C. albicans and G. vaginalis mixed species at their growth and biofilm states, together emphasizes the promising therapeutic potential of acclaimed phytochemicals as combinatorial synergistic therapy against mixed vaginitis.

The effect of octenidine dihydrochloride on the antibacterial activity of a formulated resin composite: an in vitro study

BackgroundIt has been noticed that failure of composite resin restorations can be attributed to either of the two following causes: fracture or secondary caries. For that reason, it is mandatory to formulate a restorative material with antibacterial effect. An octenidine dihydrochloride (OCT) has been assessed as an alternative to antimicrobial material, such as chlorhexidine due to their higher microbicidal effect and less cytotoxicity.ObjectiveCurrent study aimed to add different concentrations of octenidine dihydrochloride into experimental flowable resin composite and evaluate its antibacterial activity over different periods of time to provide the manufacturers with more precise information.MethodsA flowable resin composite material mix was formulated. Octenidine dihydrochloride antibacterial material was then added separately to the formulated mix at 1% wt. and 1.5% wt. concentration, respectively. Antibacterial activity was assessed against Streptococcus mutans using agar diffusion test and compared to a commercial resin composite.ResultsIt showed that by increasing the percentage of incorporated octenidine dihydrochloride (1% and 1.5%), respectively, the antibacterial efficacy against the Streptococcus mutans increased. Results of this study also showed the time had a significant decrease in the antibacterial effect.ConclusionsIt can be concluded that by the incorporation of octenidine dihydrochloride (1% and 1.5%), respectively, the antibacterial efficacy against the Streptococcus mutans increased. Time had a significant decrease in the antibacterial effect of OCT.

Innovative application of plasma-activated water in the inactivation of Escherichia coli: Temperature-dependent chemical processes leading to the synergistic microbicidal effect

Plasma-based technologies, including plasma-activated water (PAW), offer the capability to deactivate microorganisms on fruits and vegetables, preserving their sensory and nutritional quality. Although many studies have reported a synergistic microbicidal effect between PAW and mild heating, the underlying chemical processes driving these effects remain unexplored. Our study aims to evaluate the microbicidal capacity of two PAW types, one containing NO2− (PAW-N) and the other H2O2 (PAW-H), as well as their mixture (PAW-M), at different temperatures, and to elucidate the underlying temperature-dependent chemical processes. Using E. coli DH5α as the target microorganism, we measured colony-forming units under varying exposure times for each PAW type and their mixture at 8 and 28 °C. Additionally, we determined the time-dependent concentrations of NO2−, H2O2, and NO3− in the mixture, and calculated the reaction rate constant for peroxynitrous acid generation. The kinetic study revealed a fivefold increase in the reaction constant between H2O2 and NO2− in PAW-M at 28 °C compared to 8 °C, leading to a significant rise in hydroxyl radical production. The microbicidal efficacy of PAW-M exceeded that of individual PAWs or temperatures. Moreover, this effect was significantly enhanced by mild heating, resulting in log reductions of 0.24, 0.34, 2.3 (at 8 °C) and 0.74, 2.3, 3.6 (at 28 °C) for PAW-H, PAW-N, and PAW-M, respectively, after a 10-min exposure. In conclusion, the synergistic effect between PAW and mild heating may be attributed to the accelerated reaction rate of peroxynitrous acid formation in an acidic medium, leading to heightened hydroxyl radical generation.

Microbicidal effect of negative air ion against Penicillium citrinum and quality control of Chinese bayberry

Chinese bayberry is susceptible to decay caused by Penicillium citrinum infection, which will cause food safety problems. Negative air ion (NAI) is a novel type of non-thermal microbicidal technology. This study presented NAI treatment's inhibitory effect and antimicrobial mechanism on P. citrinum isolated from Chinese bayberry fruit. The results indicated that NAI treatment had the optimal inhibitory effect on P. citrinum. P. citrinum cell membrane appeared to have visible wrinkles and damage after NAI treatment, which was observed by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The contents of malondialdehyde (MDA), relative conductivity, soluble protein, soluble carbohydrate, nucleic acid leakage, and lactate dehydrogenase (LDH) in the culture medium increased obviously, which indicated that the membrane permeability of P. citrinum increased. With the laser confocal assay, NAI increased reactive oxygen species (ROS) accumulation and caused oxidative damage to membrane lipids. The membrane lipidomics of P. citrinum hyphae was determined by LC-MS. The results revealed that NAI treatment can hydrolyze the glycerophospholipid into phosphatidic acid (PA) and lysophosphatidylinositol (LPI). Besides, the results of energy metabolism illustrated that NAI treatment reduced the mitochondrial membrane potential (MMP) and energy charge of P. citrinum hyphae. Overall, the microbicidal effect of NAI consisted of two pathways: 1) NAI induced the accumulation of ROS and damaged the membrane structures; 2) NAI reduced mitochondrial membrane potential and caused energy metabolism disorders. In addition, the storage experiment proved that NAI could maintain the quality of Chinese bayberry by inhibiting microbial growth and delaying fruit decay. Hence, NAI hold promises as a potential low-temperature sterilization method for fruit and vegetable storage.

Nucleic-acid-base photofunctional cocrystal for information security and antimicrobial applications

Cocrystal engineering is an efficient and simple strategy to construct functional materials, especially for the exploitation of novel and multifunctional materials. Herein, we report two kinds of nucleic-acid-base cocrystal systems that imitate the strong hydrogen bond interactions constructed in the form of complementary base pairing. The two cocrystals studied exhibit different colors of phosphorescence from their monomeric counterparts and show the feature of rare high-temperature phosphorescence. Mechanistic studies reveal that the strong hydrogen bond network stabilizes the triplet state and suppresses non-radiative transitions, resulting in phosphorescence even at 425 K. Moreover, the isolation effects of the hydrogen bond network regulate the interactions between the phosphor groups, realizing the manipulation from aggregation to single-molecule phosphorescence. Benefiting from the long-lived triplet state with a high quantum yield, the generation of reactive oxygen species by energy transfer is also available to utilize for some applications such as in photodynamic therapy and broad-spectrum microbicidal effects. In vitro experiments show that the cocrystals efficiently kill bacteria on a tooth surface and significantly help prevent dental caries. This work not only provides deep insight into the relationship of the structure-properties of cocrystal systems, but also facilitates the design of multifunctional cocrystal materials and enriches their potential applications.

Semen enhances transmitted/founder HIV-1 infection and only marginally reduces antiviral activity of broadly neutralizing antibodies.

Topically applied microbicides may play a critical role in preventing sexual transmission of human immunodeficiency virus type 1 (HIV-1); however, their efficacy can be compromised by amyloid fibrils present in semen, which significantly increase HIV-1 infectivity. This phenomenon may have contributed to the failure of most microbicide candidates in clinical settings. Understanding the impact of semen on microbicide effectiveness is thus crucial. In our study, we evaluated the influence of semen on the neutralizing activity of broadly neutralizing antibodies (bNAbs), including PG16, PGT121, 10-1074, 3BNC117, and VRC01, which are potential microbicide candidates. We found that semen enhances infection of HIV-1 transmitted/founder viruses but only marginally affects the neutralizing activity of tested antibodies, suggesting their potential for microbicide application. Our findings underscore the need to consider semen-mediated enhancement when evaluating and developing microbicides and highlight the potential of incorporating HIV-1 bNAbs in formulations to enhance efficacy and mitigate HIV-1 transmission during sexual encounters.IMPORTANCEThis study examined the impact of semen on the development of microbicides, substances used to prevent the transmission of HIV-1 during sexual activity. Semen contains certain components that can render the virus more infectious, posing a challenge to microbicide effectiveness. Researchers specifically investigated the effect of semen on a group of powerful antibodies called broadly neutralizing antibodies, which can neutralize a large spectrum of different HIV-1 variants. The results revealed that semen only had a minimal effect on the antibodies' ability to neutralize the virus. This is promising because it suggests that these antibodies could still be effective in microbicides, even in the presence of semen. Understanding this interaction is crucial for developing better strategies to prevent HIV-1 transmission. By incorporating the knowledge gained from this study, scientists can now focus on creating microbicides that consider the impact of semen, bringing us closer to more effective prevention methods.

Physico-Chemical Investigation and Antimicrobial Efficacy of Ozonated Oils: The Case Study of Commercial Ozonated Olive and Sunflower Seed Refined Oils.

Drug resistance represents one of the great plagues of our time worldwide. This largely limits the treatment of common infections and requires the development of new antibiotics or other alternative approaches. Noteworthy, the indiscriminate use of antibiotics is mostly responsible for the selection of mutations that confer drug resistance to microbes. In this regard, recently, ozone has been raising interest for its unique biological properties when dissolved in natural oils. Ozonated oils have been reported to act in a non-specific way on microorganisms hindering the acquisition of advantageous mutations that result in resistance. Here, we focused on the antimicrobial effect of two commercial olive (OOO) and sunflower seeds (OSO) oils. Nuclear magnetic resonance spectroscopy and thermal analysis showed the change in the chemical composition of the oils after ozonation treatment. Different ozonated oil concentrations were then used to evaluate their antimicrobial profile against Candida albicans, Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli by agar diffusion and broth dilution methods. Cytotoxicity was also evaluated in keratinocytes and epithelial cells. Overall, our results revealed that both OOO and OSO showed a potent microbicidal effect, especially against C. albicans (IC50 = OOO: 0.3 mg/mL and OSO: 0.2 mg/mL) and E. faecalis (IC50 = OOO: 0.4 mg/mL and OSO: 2.8 mg/mL) albeit exerting a certain effect also against S. aureus and E. coli. Moreover, both OOO and OSO do not yield any relevant cytotoxic effect at the active concentrations in both cell lines. This indicates that the ozonated oils studied are not toxic for mammalian cells despite exerting a potent antimicrobial effect on specific microorganisms. Therefore, OOO and OSO may be considered to integrate standard therapies in the treatment of common infections, likely overcoming drug resistance issues.

Microbicidal Effect of Sodium Chlorite in Combination with Caffeine at a Neutral pH

Microbicidal Effect of Sodium Chlorite in Combination with Caffeine at a Neutral pH

Biomechanical aspects of radiation sterilization of composite material “Carbon FC” for medicine

The process of volumetric sterilization by gamma-irradiation of composite cellular material actively used for bone defect replacement in medicine is studied. The purpose of this study is to substantiate the necessary doses of gamma-irradiation for sterilization of highly porous carbon material "Carbon-FC" without reducing its mechanical characteris-tics. The technique of volumetric sterilization of the material under study and its testing for microbiological sterility is described. The results of mechanical tests of samples be-fore and after gamma-irradiation are given. Recommendations on selection of ionizing radiation doses providing microbicidal effect without reduction of strength properties during compression of the material under study are given.

Antimicrobial foam-filter based on commercial support coated with polydopamine and silver nanoparticles for water treatment

Fresh water is a critical resource on the planet and the treatment techniques employed worldwide are often insufficient at removing contaminants, leading to their release in the environment. This work displays the development of a foam-filter based on open-cell polyurethane foams coated with polydopamine and an antimicrobial metal for water treatment processes. A simple coating method is proposed and the resulting tool is characterized. Its antimicrobial activity is assessed on pure water-based cultures of Staphylococcus aureus, Escherichia coli, Legionella pneumophila and Candida albicans in optimal growth conditions. This study also investigates the stability and reusability of the foam-filter. The results show that silver grafting via this one-step original approach (namely OCPUF@PDA/Ag) exhibits a good antimicrobial activity on the selected microorganisms, with a complete microbicidal effect against C. albicans and E. coli after 3 h of contact time (5 and 6 Log decrease, respectively), and after 24 h of contact time for S. aureus. The foam-filter shows great stability and recyclability as it can be reused at least 4 times with the same overall activity, as well as significant antifouling properties. The mechanism of action was partially investigated and shows that reactive oxygen species are generated inside the bacterial cells after contact with the foam. This study gives a starting framework for the development of a bio-inspired polydopamine material with interesting physical, antifouling and antimicrobial properties applicable in water treatment processes.

Direct antimicrobial effects of chemokines on Cryptococcus spp, with special emphasis on a 'CXC' chemokine.

Cryptococcus species are ingenious human pathogens that are widespread globally. They continue to cause over 200,000 deaths per year. Presently due to the rise in resistance and therapy failure, it is necessary to shift the focus to an alternate therapeutic strategy against this pathogen. One promising approach is to emphasize the host defense system in order to develop more precise and customized treatment strategies. In this regard, research has revealed that interferon-γ-inducible CXCL10 chemokine, amongst other chemokines spanning both CXC and CC categories, has a direct killing effect in vitro against Cryptococcus neoformans and Cryptococcus gattii, with a significantly greater microbicidal effect against the former. Moreover, when CXCL10 is used in combination with CCL5, there is a significant reduction in the survival of C. gattii at normal-serum level concentration, indicating a previously unreported synergistic effect of these two chemokines. Confocal and STED microscopic studies have demonstrated that CXCL10 has both cell wall/membrane and intracellular targets against this fungus. These findings present new possibilities for developing chemokine-derived small molecule antifungals and may represent a step forward in creating precision medicine tailored to each patient.

Carbon spheres/polyvinylpyrrolidone doped MnO2 nanorods served as dye degrader and antibacterial activity with evidential molecular docking

The present study synthesized carbon sphere (CS) and polyvinylpyrrolidone (PVP) doped MnO2 nanorods via co-precipitation technique. Using a systematic approach, this research investigates the deliberate doping of carbon spheres at 2 and 4 wt.% concentrations into a predetermined quantity of PVP-doped MnO2 nanorods (NRs). The motive of this work was to reduce the recombination rate and inhibit the dimension of NRs that caused to increase in the catalytic reduction of methylene blue and microbicidal action of MnO2 NRs confirmed by molecular docking analysis. Several characterization techniques were utilized to check the effect of doping agents (CS and PVP) on the structural, morphological and optical characteristics of MnO2. The XRD pattern evidenced that MnO2 had an orthorhombic framework, and incorporating PVP and CS reduced the crystallinity of NRs. The electronic spectra revealed the blue shift, assigned to increase band gap energy by the addition PVP and CS. TEM analysis confirmed the formation of a network of MnO2 nanorods and decreased size with the integration of dopants. CS and PVP-doped MnO2 NRs significantly improved their microbicidal effectiveness towards Escherichia coli (E. coli) measured in an inhibitory zone mm and catalytic performance. The enigma behind these bactericidal effects was recently unraveled by in silico assertions regarding these doped NRs for targeted enzymes (i.e., DNA gyrase and β-lactamase).

Inactivation of E. coli O157:H7, Salmonella enterica, and L. monocytogenes through semi-continuous superheated steam treatment with additional effects of enhancing initial germination rate and salinity tolerance

Superheated steam (SHS) is a powerful technology used to reduce bacteria on food surfaces while causing less damage to the underlying sublayer of food compared to conventional heating treatments. In this study, a semi-continuous SHS system was developed to inactivate foodborne pathogens within 1 s (Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes) on radish seed surfaces and to enhance the seeds’ salinity tolerance, which is vital for adapting to arid and semi-arid regions. The temperature of the SHS was set to 200 °C and 300 °C, with flow rates of 5 m/s and 7 m/s, and treatments were cycled either once or three times. As a result, increased temperature (200 °C–300 °C) and number of treatments (1 time to 3 times) led to a significantly larger microbial reduction on the surface of radish seeds. E. coli O157:H7, S. enterica, and L. monocytogenes were reduced by 4.42, 4.73, and 3.95 log CFU/g (P < 0.05), respectively, after three SHS treatments at 300 °C and 7 m/s. However, due to the ongoing potential for recovery of residual microorganisms, further research involving combinations is essential to enhance the microbicidal effect. Water imbibition showed significantly higher values in the SHS-treated group up to 30 min, indicating faster germination rates in the SHS-treated group (71.3–81.3%) compared to the control group (52.7%) on the second day, indicating a significant enhancement in germination rate. In addition, the salinity resistance of the radish seeds increased after SHS treatment. When moisturized with 0.5% NaCl solution, more radish seeds germinated after treatment with SHS (40%) than controls (22.7%) (P < 0.05). The results of this study, the first to apply semi-continuous SHS to seeds, are expected to serve as a cornerstone for future pilot-scale investigations aiming to implement the system within the seed industry.

Vitamin K3 (Menadione) is a multifunctional microbicide acting as a photosensitizer and synergizing with blue light to kill drug-resistant bacteria in biofilms.

Cutaneous bacterial wound infections typically involve gram-positive cocci such as Staphylococcus aureus (SA) and usually become biofilm infections. Bacteria in biofilms may be 100-1000-fold more resistant to an antibiotic than the clinical laboratory minimal inhibitory concentration (MIC) for that antibiotic, contributing to antimicrobial resistance (AMR). AMR is a growing global threat to humanity. One pathogen-antibiotic resistant combination, methicillin-resistant SA (MRSA) caused more deaths globally than any other such combination in a recent worldwide statistical review. Many wound infections are accessible to light. Antimicrobial phototherapy, and particularly antimicrobial blue light therapy (aBL) is an innovative non-antibiotic approach often overlooked as a possible alternative or adjunctive therapy to reduce antibiotic use. We therefore focused on aBL treatment of biofilm infections, especially MRSA, focusing on in vitro and ex vivo porcine skin models of bacterial biofilm infections. Since aBL is microbicidal through the generation of reactive oxygen species (ROS), we hypothesized that menadione (Vitamin K3), a multifunctional ROS generator, might enhance aBL. Our studies suggest that menadione can synergize with aBL to increase both ROS and microbicidal effects, acting as a photosensitizer as well as an ROS recycler in the treatment of biofilm infections. Vitamin K3/menadione has been given orally and intravenously worldwide to thousands of patients. We conclude that menadione/Vitamin K3 can be used as an adjunct to antimicrobial blue light therapy, increasing the effectiveness of this modality in the treatment of biofilm infections, thereby presenting a potential alternative to antibiotic therapy, to which biofilm infections are so resistant.