Inactivation Of Microorganisms Research Articles

Solar-driven strongly coupled plasmonic Au nanoarrays on mesoporous silica nanodisks enable selective fungal and bacterial inactivation in well water

Well water is an important water source in isolated rural areas but easily suffers from microbial contamination. Herein, we anchored periodic Au nanoarrays on mesoporous silica nanodisks (Au-MSN) to fabricate a solar-driven nano-stove for well water disinfection. The solar/Au-MSN process completely inactivated 3.98, 6.55, 7.11 log10 cfu/mL, and 3.37 log10 pfu/mL of Aspergillus niger spores, Escherichia coli, chlorine-resistant Spingopyxis sp. BM1–1, and bacteriophage MS2 within 5 min, respectively. Moreover, the complete inactivation of various microorganisms (even at a viable but nonculturable state) was achieved in the flow-through reactor under natural solar light in real well water matrixes. Thorough characterizations and theoretical simulations verified that the densely anchoring strategy of Au-MSN's nanoarray worked on broadband absorption via the photon confinement effect, and trace amounts of Au can induce strong electromagnetic fields and collective localized heating. The resulting surge of 1O2 and heat synergically destroyed membranes, dysfunction cellular self-defense and metabolic system, induced intracellular oxidative stress, and ultimately inactivated microorganisms. Additionally, the 1O2-dominated oxidation and cell adhesion facilitated the selective disinfection in real well water matrixes. This study provides a cost-effective and practical solution for efficient well water disinfection, which assists isolated rural areas in getting safe drinking water.

Effects of Nitro-Oxidative Stress on Biomolecules: Part 1-Non-Reactive Molecular Dynamics Simulations.

Plasma medicine, or the biomedical application of cold atmospheric plasma (CAP), is an expanding field within plasma research. CAP has demonstrated remarkable versatility in diverse biological applications, including cancer treatment, wound healing, microorganism inactivation, and skin disease therapy. However, the precise mechanisms underlying the effects of CAP remain incompletely understood. The therapeutic effects of CAP are largely attributed to the generation of reactive oxygen and nitrogen species (RONS), which play a crucial role in the biological responses induced by CAP. Specifically, RONS produced during CAP treatment have the ability to chemically modify cell membranes and membrane proteins, causing nitro-oxidative stress, thereby leading to changes in membrane permeability and disruption of cellular processes. To gain atomic-level insights into these interactions, non-reactive molecular dynamics (MD) simulations have emerged as a valuable tool. These simulations facilitate the examination of larger-scale system dynamics, including protein-protein and protein-membrane interactions. In this comprehensive review, we focus on the applications of non-reactive MD simulations in studying the effects of CAP on cellular components and interactions at the atomic level, providing a detailed overview of the potential of CAP in medicine. We also review the results of other MD studies that are not related to plasma medicine but explore the effects of nitro-oxidative stress on cellular components and are therefore important for a broader understanding of the underlying processes.

Simultaneous degradation of contaminants of emerging concern and disinfection by solar photoelectro-Fenton process at circumneutral pH in a solar electrochemical raceway pond reactor

Simultaneous contaminants of emerging concern (CECs) removal and wild microorganisms’ inactivation was evaluated by applying solar photoelectro-Fenton (SPEF) process in actual secondary effluent collected from a real municipal wastewater treatment plant (MWWTP). 20 L of a mixture of four CECs was used as model pollutants (200 μg/L of acetaminophen, caffeine, sulfamethazine, and sulfamethoxazole each one). The SPEF process was carried out on fully sunny days, at circumneutral pH using the complex Fe3+-EDDS, in a solar electrochemical – raceway pond reactor (SEC-RPR). Initially, the optimal conditions for CECs degradation were determined using a response surface model based on current density, iron complex concentration and Fe3+-EDDS addition time (to allow previous accumulation of H2O2) as model inputs. A current density of 24.6 mA/cm2, a Fe3+-EDDS complex concentration of 0.089 mM and 3.8 min of previous H2O2 accumulation were the resulting optimum conditions that were afterwards applied for the simultaneous degradation of the CECs synthetic mixture and wild microorganisms inactivation in actual secondary effluent. About 85% CECs removal and complete E. coli inactivation were achieved in 30 min, approximately, while E. faecalis and total coliforms could be inactivated under detection limit in 60 min and 75 min, respectively.

Essential Oils and Their Combination with Lactic Acid Bacteria and Bacteriocins to Improve the Safety and Shelf Life of Foods: A Review.

The use of plant extracts (e.g., essential oils and their active compounds) represents an interesting alternative to chemical additives and preservatives applied to delay the alteration and oxidation of foods during their storage. Essential oils (EO) are nowadays considered valuable sources of food preservatives as they provide a healthier alternative to synthetic chemicals while serving the same purpose without affecting food quality parameters. The natural antimicrobial molecules found in medicinal plants represent a possible solution against drug-resistant bacteria, which represent a global health problem, especially for foodborne infections. Several solutions related to their application on food have been described, such as incorporation in active packaging or edible film and direct encapsulation. However, the use of bioactive concentrations of plant derivatives may negatively impact the sensorial characteristics of the final product, and to solve this problem, their application has been proposed in combination with other hurdles, including biocontrol agents. Biocontrol agents are microbial cultures capable of producing natural antimicrobials, including bacteriocins, organic acids, volatile organic compounds, and hydrolytic enzymes. The major effect of bacteriocins or bacteriocin-producing LAB (lactic acid bacteria) on food is obtained when their use is combined with other preservation methods. The combined use of EOs and biocontrol agents in fruit and vegetables, meat, and dairy products is becoming more and more important due to growing concerns about potentially dangerous and toxic synthetic additives. The combination of these two hurdles can improve the safety and shelf life (inactivation of spoilage or pathogenic microorganisms) of the final products while maintaining or stabilizing their sensory and nutritional quality. This review critically describes and collects the most updated works regarding the application of EOs in different food sectors and their combination with biocontrol agents and bacteriocins.

Nanostructured N/S doped carbon dots/mesoporous silica nanoparticles and PVA composite hydrogel fabrication for anti-microbial and anti-biofilm application

Regarding the convergence of the worldwide epidemic, the appearance of bacterial infection has occasioned in a melodramatic upsurge in bacterial pathogens with confrontation against one or numerous antibiotics. The implementation of engineered nanostructured particles as a delivery vehicle for antimicrobial agent is one promising approach that could theoretically battle the setbacks mentioned. Among all nanoparticles, silica nanoparticles have been found to provide functional features that are advantageous for combatting bacterial contagion. Apart from that, carbon dots, a zero-dimension nanomaterial, have recently exhibited their photo-responsive property to generate reactive oxygen species facilitating to enhance microorganism suppression and inactivation ability. In this study, potentials of core/shell mesoporous silica nanostructures (MSN) in conjugation with carbon dots (CDs) toward antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli have been investigated. Nitrogen and sulfur doped CDs (NS/CDs) conjugated with MSN which were cost effective nanoparticles exhibited much superior antimicrobial activity for 4 times as much as silver nanoparticles against all bacteria tested. Among all nanoparticles tested, 0.40 M NS/CDs@MSN showed the greatest minimal biofilm inhibitory at very low concentration (< 0.125 mg mL−1), followed by 0.20 M NS/CDs@MSN (0.5 mg mL−1), CD@MSN (25 mg mL−1), and MSN (50 mg mL−1), respectively. Immobilization of NS/CDs@MSN in polyvinyl alcohol (PVA) hydrogel was performed and its effect on antimicrobial activity, biofilm controlling efficiency, and cytotoxicity toward fibroblast (NIH/3 T3 and L-929) cells was additionally studied for further biomedical applications. The results demonstrated that 0.40 M NS/CDs-MSN@PVA hydrogel exhibited the highest inhibitory effect on S. aureus > P. aeruginosa > E. coli. In addition, MTT assay revealed some degree of toxicity of 0.40 M NS/CDs-MSN@PVA hydrogel against L-929 cells by a slight reduction of cell viability from 100% to 81.6% when incubated in the extract from 0.40 M NS/CDs-MSN@PVA hydrogel, while no toxicity of the same hydrogel extract was detected toward NIH/3 T3 cells.

Photocatalytic Antimicrobials: Principles, Design Strategies, and Applications.

Nowadays, the increasing emergence of antibiotic-resistant pathogenic microorganisms requires the search for alternative methods that do not cause drug resistance. Phototherapy strategies (PTs) based on the photoresponsive materials have become a new trend in the inactivation of pathogenic microorganisms due to their spatiotemporal controllability and negligible side effects. Among those phototherapy strategies, photocatalytic antimicrobial therapy (PCAT) has emerged as an effective and promising antimicrobial strategy in recent years. In the process of photocatalytic treatment, photocatalytic materials are excited by different wavelengths of lights to produce reactive oxygen species (ROS) or other toxic species for the killing of various pathogenic microbes, such as bacteria, viruses, fungi, parasites, and algae. Therefore, this review timely summarizes the latest progress in the PCAT field, with emphasis on the development of various photocatalytic antimicrobials (PCAMs), the underlying antimicrobial mechanisms, the design strategies, and the multiple practical antimicrobial applications in local infections therapy, personal protective equipment, water purification, antimicrobial coatings, wound dressings, food safety, antibacterial textiles, and air purification. Meanwhile, we also present the challenges and perspectives of widespread practical implementation of PCAT as antimicrobial therapeutics. We hope that as a result of this review, PCAT will flourish and become an effective weapon against pathogenic microorganisms and antibiotic resistance.

Peroxymonosulfate based in situ chemical oxidation: An efficient strategy for mitigation of membrane fouling in real seawater reverse osmosis desalination

Persulfate based advanced oxidation processes (AOPs) is an emerging method to assist the pretreatment to prevent membrane fouling for seawater desalination. However, the present strategies which adopt activators (e.g., UV, heat, Fe) to generate kinds of free radicals, are energy-consuming and enhance the concerns of disinfection by-products (DBPs). Here, peroxymonosulfate (PMS) is adopted as a green, effective and economical pretreatment chemical for simultaneous microorganic pollutants degradation and microorganism inactivation in seawater reverse osmosis (SWRO) desalination without any external energy input. After adding into the seawater, 53% PMS could be activated by Cl- in situ to generate HClO at most with no other active species generated, which is verified by stoichiometric analysis and quenching experiments. Benefited from the residual PMS, not only could up to 89.6% of total organic carbon be removed in the real seawater, but also nearly 80% of DBPs could be degraded by simply adjusting pH from neutral to alkaline conditions. Meanwhile, all bacteria could be killed completely and hardly any regrowth appeared, which further proved the anti-fouling ability of the PMS/Cl- system. Consequently, the addition of PMS could maintain the flux for a long time in the practical SWRO application with significantly reducing the RO membrane fouling. Moreover, the operating cost of PMS is only 0.024 $/ton, which is comparable to NaClO. This study demonstrated the excellent performance of PMS in SWRO pretreatment, supplying a promising scheme in practical desalination processes.

Application of gaseous ozone and its aqueous solution for inactivation of pathogenic microorganisms: A literature review

Due to its potent oxidising properties, ozone presents itself as a promising disinfectant and may serve as a substitute for conventional techniques. The purpose of this study was to analyse the literature on the effectiveness of gaseous ozone and its aqueous solution against pathogenic and opportunistic microorganisms or their surrogates. More than 150 English-language sources have been studied, of which 72 have been selected for this review. To illustrate the effectiveness of ozone against bacteria, bacterial biofilms and viruses, data from selected publications are summarised in tables for the respective groups of disinfectant targets. In cases where data were presented in the form of kinetic curves in the reviewed publications, the maximum inactivation values were chosen. It was shown that both gaseous ozone and its aqueous solution are widely used due to their powerful bactericidal properties. The study noted that ozone is an effective oxidant that neutralises gram-negative, gram-positive, and spore-forming microorganisms, the biofilms they form, as well as fungi, protozoa, viruses, and prions. Among the industries that have implemented or may implement ozone applications are medicine (including dentistry and pharmacy), as well as the food industry and recreation. One of the notable advantages of using ozone is its relatively short half-life, with conversion to non-toxic oxygen. It was also noted that ozone treatment is non-thermal, which allows it to be used for processing fresh fruit and vegetables. The main disadvantages and challenges for safe implementation are ozone toxicity at exceeding the maximum permissible concentration in the air, corrosiveness, and explosiveness at high concentrations

Insights into the fate and properties of organic halamines during ultraviolet irradiation: Implications for drinking water safety

Organic halamines compounds present a significant threat to the safety of drinking water due to their potential toxicity and stability. While Ultraviolet (UV) disinfection is commonly used for water treatment, its specific effects on organic halamines and the underlying mechanisms remain poorly understood. In this study, we investigated eight amino acid-derived organic chlor- and bromamines as representative compounds. Our findings revealed that organic halamines have a slow hydrolysis rate (<10−3 M−1 s−1) and can persist in water for extended periods (30–2000 min). However, their disinfection efficacy against Staphylococcus aureus and their ability to degrade micropollutants like carbamazepine were found to be limited. Interestingly, under UV irradiation, the N-X bonds in organic halamines were observed to break, leading to accelerated decomposition and the generation of abundant free radicals. These free radicals synergistically facilitated the removal of micropollutants and the inactivation of pathogenic microorganisms. It is worth noting that this transformation of organic halamines during UV disinfection resulted in a slight increase in the concentrations of nitrogenous disinfection byproducts. These findings shed light on the behavior and characteristics of organic halamines during UV disinfection processes, providing crucial insights for effectively managing drinking water quality impacted by these compounds. By understanding the implications of organic halamines, we can refine water treatment strategies and ensure the safety of drinking water supplies.

Overview of methods and considerations for the photodynamic inactivation of microorganisms for agricultural applications.

Antimicrobial resistance in agriculture is a global concern and carries huge financial consequences. Despite that, practical solutions for growers that are sustainable, low cost and environmentally friendly have been sparse. This has created opportunities for the agrochemical industry to develop pesticides with novel modes of action. Recently the use of photodynamic inactivation (PDI), classically used in cancer treatments, has been explored in agriculture as an alternative to traditional chemistries, mainly as a promising new approach for the eradication of pesticide resistant strains. However, applications in the field pose unique challenges and call for new methods of evaluation to adequately address issues specific to PDI applications in plants and challenges faced in the field. The aim of this review is to summarize in vitro, ex vivo, and in vivo/in planta experimental strategies and methods used to test and evaluate photodynamic agents as photo-responsive pesticides for applications in agriculture. The review highlights some of the strategies that have been explored to overcome challenges in the field.

Study of coaxial-dual-gap dielectric barrier discharge based on capillary: discharge characteristics and Escherichia Coli decontamination.

The medical capillary catheters occupy a high proportion of medical diagnosis, monitoring and treatment devices, and will cause serious cross-infection without being disinfected adequately. This paper presents a new plasma structure for efficient inactivation of harmful microorganisms in medical capillaries. An innovative coaxial-dual-gap dielectric barrier discharge (CDG-DBD) reactor powered by nanosecond-pulsed power supply was designed for disinfection of Escherichia Coli (E. coli) inside and outside medical capillary catheters in this work. Atmospheric helium plasma (AHP) and atmospheric air plasma (AAP) were successfully obtained inside and outside capillary (0.6mm inner diameter and 1.0mm outer diameter), respectively. The electrical and optical characteristics of AHP and AAP were investigated. As the threshold of applied voltage amplitude (Uamp) was below 7.0kV, only one helium glow discharge was generated inside the capillary at the rising and falling stages of pulse voltage. As the Uamp exceeded the threshold, two helium glow discharges were generated that further caused generation of air discharge. Under the Uamp of 9.0kV, the production of AHP lowered the breakdown voltage in air gap, resulting in the formation of high-volume and uniform AAP, which was conducive to the realization of full inactivation. The inactivation rates of E. coli reached 98.13% and 99.99% by 2min AHP and 0.5min AAP treatment, respectively. The electrical stress of AHP and the reactive oxygen and nitrogen species (RONS) produced by AAP were contributed to the inactivation of E. coli. The results of SEM show that plasma treatment can destroy the cellular structure of E.coli.

Households Water Purification Using Solar Water Disinfection (SODIS) in Gombe Metropolis, Gombe State, Nigeria

Assessment of water quality has been an important issue nowadays as the available water supply is severely polluted and can be the cause of waterborne diseases like cholera, diarrhea and dysentery. Solar disinfection (SODIS) is an efficient, low technology and cost-effective method for inactivation of pathogenic microorganisms in low-income communities where clean drinking water is limited or absent. The study was designed to assess the information about sanitation behavior at the household level using a structured questionnaire and to provide cost-effective method for its treatment. The result of the bacteriological analysis shows that all the water samples were found to harbour coliforms organisms in numbers greater than the required WHO/FAO/NSDWQ standards. The isolated organisms were identified to be Enterobacter aerogenes, species. SODIS was proven to be a more environmentally friendly and low-cost method to disinfect water against the conventional methods of water treatment that require high technology and it is time-consuming. In addition, the chemical used in the treatment process might be toxic. Providing the community with simple water treatment techniques using the SODIS method, and intensive health education and sanitation practices for the community are highly recommended.

Evaluation of new photochemical systems for water disinfection by the integration of particle tracking into kinetic models for microbial inactivation

This work presents the development of a novel methodology for the simulation of photochemical processes for water disinfection using computational fluid dynamics (CFD). A new approach was implemented to calculate and visualise the disinfection performance as the microorganisms move along the photoreactor. Hydrodynamics and microorganism's statistical trajectories were computed using the discrete phase model, which also provides the distribution of microbial residence times. The distribution of radiation in the reactor was calculated using the discrete ordinate method. The local values of incident radiation were integrated over each statistical trajectory path to get the accumulated dose received for each microbial particle. The coupling in situ of the cumulative radiation dose with the inactivation kinetics allows monitoring of the disinfection process concurrently with the particle tracking. This methodology introduces significant advantages over the traditional estimation of the microorganism inactivation sequentially after calculating the dose histograms estimated from the statistical trajectories. The developed tool enables evaluating the photoreactor efficiency in each reactor position, a useful capability for optimising and scaling up complex geometries. It also allows the easy, intuitive visualisation of microbial inactivation trajectories, improving the understanding of the influence of the reactor features on the disinfection process. Application of this computational approach to two different photoreactor geometries using a virus as a representative target microbe is presented.

Inactivation of airborne pathogenic microorganisms by plasma-activated nebulized mist

The airborne microorganisms in the aerosols are one main transmission way of pathogenic microorganisms and therefore inactivation of microorganisms in aerosols could effectively prevent the transmission of pathogenic microorganisms to control epidemics. The mist nebulized by plasma-activated air could effectively inactivate bacteria and could be developed for the sterilization of microorganisms in aerosols. In this study, the plasma-activated nebulized mist (PANM) was applied for the inactivation of microorganisms in aerosols and efficiently inactivated the bacteria, yeast, and viruses in aerosols after 2-min treatment. The PANM treatment caused morphologic changes and damage to the bacteria cells in aerosols. The PANM could also inactivate the microorganisms attached to the surface of the treatment chamber and the bacteria attached to the skin of mice within 6-min treatment. The biosafety assays demonstrated that the PANM treatment exhibited no effects on the behavior, hematological and serum biochemical parameters of blood, and organs from the mice. This study would supply an efficient, broad-spectrum, and safe aerosol sterilization strategy based on plasma technology to prevent the transmission of airborne microorganisms.

Influence of cold atmospheric pressure plasma treatment of Spirulina platensis slurry over biomass characteristics

Cold atmospheric pressure plasma (CAPP) technique is an innovative non-thermal approach for food preservation and decontamination. This study aimed to evaluate the effect of CAPP power density on microorganism inactivation and quality of Spirulina platensis (S. platensis) slurry. 91.31 ± 1.61% of microorganism were inactivated within 2.02 ± 0.11 min by 26.67 W/g CAPP treatment under 50 ℃. Total phenolic, Chlorophyll-a (Chl-a), and carotenoids contents were increased by 20.51%, 63.55%, and 70.04% after 20.00 W/g CAPP treatment. Phycobiliproteins (PBPs), protein, intracellular polysaccharide, and moisture content of S. platensis was decreased, while vividness, lightness, color of yellow and green, antioxidant activity, Essential Amino Acid Index were enhanced after CAPP treatment. The nutrient release and filaments breakage of CAPP-treated S. platensis improved its bio-accessibility. The findings provided a deep understanding and insight into the influence of CAPP treatment on S. platensis, which were meaningful for optimizing its sterilization and drying processing condition.

Pyrogenic carbon accelerates iron cycling and hydroxyl radical production during redox fluctuations of paddy soils

Carbon materials (e.g., pyrogenic carbon (PyC)) are widely used in agricultural soils and can participate in various biogeochemical processes, including iron (Fe) cycling. In soils, Fe(II) species have been proposed as the main active contributor to produce reactive oxygen species (ROS), which are involved in various biogeochemical processes. However, the effects of PyC on the transformation of different Fe species in soils and the associated production of ROS are rarely investigated. This study examined the influence of PyC (pyrolyzed at 300–700 °C) on Fe(II)/Fe(III) cycling and hydroxyl radical (·OH) production during redox fluctuations of paddy soils. Results showed that the reduction of Fe(III) in soils was facilitated by PyC during anoxic incubation, which was ascribed to the increased abundance of dissimilatory Fe(III)-reducing microorganisms (biotic reduction) and the electron exchange capacity of PyC (abiotic reduction). During oxygenation, PyC and higher soil pH promoted the oxidation of active Fe(II) species (e.g., exchangeable and low-crystalline Fe(II)), which consequently induced higher yield of ·OH and further led to degradation of imidacloprid and inactivation of soil microorganisms. Our results demonstrated that PyC accelerated Fe(II)/Fe(III) cycling and ·OH production during redox fluctuations of paddy soils (especially those with low content of soil organic carbon), providing a new insight for remediation strategies in agricultural fields contaminated with organic pollutants.Graphical

The simultaneous influence of ultraviolet rays and cold plasma on the physicochemical attributes and shelf life of dried pistachios during the storage period

AbstractThis investigation aimed to assess the simultaneous impact of ultraviolet (UV) and cold plasma (CP) on the quality and microbial attributes of dried pistachios during the storage period. Currently, novel nonthermal technologies exhibit high potential as a low‐cost, efficient, additive‐free, and nonpolluting strategies for fungi deactivation and mycotoxins degradation in foods. Over recent years, the combination of CP with other procedures, such as ultraviolet (UV) irradiation, ultrasound, ozone, and so forth, has been proposed and attracted lots of attention. For this purpose, in this study, the simultaneous effects of ultraviolet rays and cold plasma on dried pistachios artificially contaminated with aflatoxigenic fungi were assessed. The physicochemical attributes and surface morphology of pistachios were evaluated as well. The concentration of aflatoxin produced was investigated via high‐performance liquid chromatography. Artificially contaminated pistachios were treated with cold plasma at 80 W constant power level at both 10 and 15 min. Following the plasma treatment, pistachio samples were treated by ultraviolet rays at 354 nm wavelength and current intensity in 0.25 A at the same time. The results of this study revealed the fungal deactivation rate achieved by UV‐CP treatment was greater than the sum of the deactivation rates of distinct UV and CP treatments, as maximum reduction of Aspergillus oryzae count (3.7 CFU/g) observed after simultaneous UV‐CP treatment for 15 min (p &lt; 0.05). Moreover, no substantial modifications were detected in the investigation of pH and DPPH radical scavenging activity of samples treated with UV‐CP (p &gt; 0.05). The results of this study confirm the effectiveness of the simultaneous application of UV rays and CP in nuts to maintain quality and increase useful life, along with an alternative method for thermal treatments.Practical applicationsUsually, nonthermal procedures lead to their destruction by changing the chemical structure of mycotoxins. Ultraviolet (UV) radiation being a nonthermal technology, the benefits of its usage are various: the least loss of nutrients and sensorial quality of foods, no toxic residues, and low energy consumption compared with other thermal treatments normally applied for food decontamination. The latter is the main purpose of this technique due to its effectiveness in the inactivation of pathogenic microorganisms and spoilage. Besides this, Cold plasma (CP) technology has been displayed to overcome many of the insufficiency of regular decontamination strategies in the food industry, with slight damage to the quality of products and high efficiency. Although several physical procedures have shown acceptable results in the decontamination of fungi and degradation of mycotoxins in many foods, to date there are few published works on the effects of simultaneous application of UV radiation and CP on foods, particularly pistachios in is available. Hence, the intention of this investigation was to assess the effect of combination of UV radiation and CP on the physicochemical attributes and shelf life of dried pistachios during the storage period.

Review of Developments in Bioelectrics as an Application of Pulsed Power Technology

The field of bioelectrics lies at the intersection of biomedical engineering, biophysics, pulsed power technology, and bioscience, guided by the underlying theme of using electric pulses of varying waveforms and durations to drive and manipulate desired biological responses and outcomes in cells and tissues. The ever-growing list of applications includes tumor treatment, wound healing, neurostimulation, decontamination and inactivation of microorganisms and pathogens, cardiac ablation for the treatment of arrhythmias, and many more. Here, we present a broad review of the various advances in the field, the state of the hardware that drives the successful implementation of bioelectric systems, and some of the underlying biophysics and modeling efforts that help quantify and unravel the underlying mechanisms for eventual optimization of outcomes and their successful modulation. The primary focus is on the achievements over the past 50 years and the promise for future directions.

Evaluation of pulsed xenon UV irradiation on inactivation of Listeria monocytogenes on stainless-steel surfaces

UV-C disinfection is a safe and effective method for the inactivation of bacteria, viruses, spores, and other microorganisms. Pulsed xenon UV lamps (PX-UV) can provide high intensity UV-C irradiation in a short time. To improve our understanding of which factors affect the disinfection efficacy of PX-UV lamps, a rigorous investigation of the effects of exposure time, frequency, UV fluence, and angle of irradiance on log reduction of Listeria monocytogenes on stainless steel surfaces was characterized. Total UV fluence received proved to be the main determinant of log reduction regardless of pulse frequency, angle, or exposure time. However, 30 s of exposure to UV light at 25 Hz resulted in a 5.59-log reduction which corresponds to a fluence of 151.2 mJ/cm2. Kinetic constants of UV inactivation was determined to allow end users to calculate the required fluence needed to achieve the desired log-reduction. This work confirms that UV-C fluence should be the primary consideration when deploying PX-UV lamps as a no-touch disinfection technology and that operational parameters should be selected to achieve the desired fluence.

CORROSION OF STAINLESS STEELS IN DISINFECTANT SOLUTIONS

Surface disinfection is a relevant measure for the inactivation of microorganisms and viruses. This procedure is used almost everywhere, from water treatment facilities to medical institutions and public facilities. The disadvantage of these measures is the increased corrosion of the contact surfaces, often made of stainless steels and accompanied by the leaching of heavy metals from them. According to WHO recommendations, the largest amount of disinfectants is hypochlorite solutions. The article investigates the corrosive effect of disinfectants on stainless steels of the 300th series. For research, chlorine-containing solutions were used at a concentration of 2 wt.% in terms of hypochlorite ion and ozone-saturated water as an alternative disinfectant solution. The research results showed that solutions of sodium hypochlorite and calcium hypochlorite have the greatest corrosion effect on the studied stainless steels. In this case, the largest amount of leachable metals from the studied steels occurs when using a solution of calcium hypochlorite. The use of water saturated with ozone does not lead to the washing out of heavy metals from all the studied steels.