Inactivation Ability Research Articles

Inactivation of β-coronavirus MHV-A59 by 2.8 GHz microwave.

From the severe acute respiratory syndrome coronavirus in 2003 to the severe acute respiratory syndrome coronavirus 2 in 2019, coronavirus has seriously threatened human health. Electromagnetic waves not only own high penetration and low pollution but also can physically resonate with the virus. Several studies have demonstrated that electromagnetic waves can inactivate viruses efficiently. However, there is still a lack of systemic studies to analyze the potential factors closely associated with the effectiveness of inactivation, such as pH, temperature, and so on. In this study, we evaluated the inactivation ability of a 2.8 GHz microwave (MW) on MHV-A59, a substitute virus for coronavirus. Moreover, the influences of environmental pH and temperature on inactivation abilities were also discussed. The results showed that the viral morphology was destroyed, and the infectivity of MHV-A59 was significantly decreased after exposure to a 2.8 GHz MW at a density of 100 mW/cm2. Furthermore, alteration of pH 8 could produce synergistic effects with MW on virus inactivation. And, it was also proved that MWs could inactivate viruses better at room temperature than that under lower environmental temperatures. These results suggested that electromagnetic wave has great promise to become an effective tool to eliminate coronavirus.

Inactivation of Pseudovirus Expressing the D614G Spike Protein Mutation using Nitric Oxide-Plasma Activated Water.

Variants of concern (VOCs) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) exhibit high infectivity due to mutations, particularly in the spike protein, that facilitate enhanced binding of virus to human angiotensin-converting enzyme 2 (hACE2). The D614G mutation, situated in S1-domain, promotes the open conformation of spike protein, augmenting its interaction with hACE2. Activated water neutralizes pathogens by damaging biological molecules; however, its effect on mutated SARS-CoV-2 or VOCs requires further exploration. Here, the efficacy of nitric oxide (NOx)-plasma activated water (PAW) in inhibiting infections by SARS-CoV-2 pseudovirus expressing D614G-mutated spike protein is investigated, which serves as a model for mutated SARS-CoV-2. Results demonstrated high prevalence of D614G mutation in SARS-CoV-2 and its VOCs. NOx-PAW is non-toxic to cells at high concentration, inhibiting infection by 71%. Moreover, NOx-PAW induced structural changes in S1-domain of spike protein, reducing its binding affinity and lowering clathrin-mediated endocytosis-related gene expression. Additionally, in silico analysis revealed NOx species in NOx-PAW played key role in impairing S1-domain function of the mutated SARS-CoV-2 pseudovirus by interacting directly with it. Collectively, these findings reveal the potent inactivation ability of PAW against mutated SARS-CoV-2 and suggest its potential application in combating emerging variants of SARS-CoV-2 and other viral threats.

Construction of Vine-Inspired Antimicrobial Filter with Multiscale 3D Nanonetwork for High-Efficiency Air Filtration.

Enhancing the antimicrobial activity of high-efficiency particulate air (HEPA) filters while maintaining filtration efficiency and pressure drop is currently an urgent issue for preventing the spread of pathogenic microorganisms. Herein, inspired by vines which can enwind fences to fix as well as decorate them, a flexible antimicrobial chitin nanofiber (ChNF@CuOx) was fabricated and loaded onto the rigid glass fiber (GF) skeleton of a HEPA filter. Through the physical interaction, ChNF@CuOx was spontaneously enwound on GF, and ChNF@CuOx itself interweaved to form a new nanonetwork between the GF skeleton. The obtained antimicrobial air filter (ChNF@CuOx/GF) with a unique nanonetwork increased the filtration efficiency of the HEPA filter. Meanwhile, it possessed excellent inactivation ability against Staphylococcus aureus, Escherichia coli, and Candida albicans due to the urchin-like in situ grown CuOx on the ChNF. In particular, the oxygen vacancies generated unexpectedly in CuOx enabled it to produce reactive oxygen species. After eight cycles of antimicrobial assays, the antimicrobial rates of bacteria were higher than 99.5%, and those of fungi were greater than 98.3%. The successful synthesis of antimicrobial fibers and the construction of multidimensional nanoscale structures through a simple postprocessing method provide a new design mentality for antimicrobial functionalization for HEPA filters.

Oxygen and air cold plasma for the inactivation of Bacillus cereus in low-water activity soy powder

Cold plasma (CP) technology is a promising alternative to thermal treatments for the microbial decontamination of foods with low-water activity. The aim of this work is study the application of low-pressure CP (0.35 mbar) for the inactivation of Bacillus cereus in a soybean powder matrix using O₂ and synthetic air as ionizing gases. The parameters tested were an input power of 100, 200 and 300 W and an exposure time of 10 to 30 min. The excited reactive species formed were monitored by optical emission spectroscopy, and survival data were analyzed using the Weibull mathematical model. Treatments with both gases were effective in inactivating B. cereus. Air plasma resulted in a maximum 3.71-log reduction in bacterial counts at 300 W and 30 min, while O2 plasma showed the strongest inactivation ability, achieving levels higher than 5 log cycles at 300 W and > 25 min. This is likely due to the strong antimicrobial activity of oxygen-derived radicals together with carbon monoxide as an oxidation by-product. In addition, the Weibull distribution function accurately modeled the inactivation of B. cereus. Cold plasma technology is a promising approach for the decontamination of bacteria in low-water activity foods.

Solar/ClO2 system inactivates fungal spores in drinking water: Synergy, efficiency and mechanisms

The risk of fungal pollution in drinking water has been paid attention. Solar/chlorine dioxide (ClO2) combined system is an environment-friendly, economical and efficient disinfection method, especially for countries and regions that are economically backward and still exposed to unsafe drinking water. In this paper, the kinetics, influencing factors, mechanism and regrowth potential of inactivated Aspergillus niger (A. niger) spores by solar/ClO2 were reported for the first time. The inactivation curve can be divided into three stages: instant inactivation within 1–2 min, slow linear inactivation and finally a tail. The synergistic factors produced by solar/ClO2 in terms of log reduction and maximum inactivation rate were 1.194 and 1.112, respectively. The inhibitory effect on the regrowth of A. niger spores inactivated by solar/ClO2 was also stronger than that by ClO2 alone. Strongly oxidizing reactive species produced by solar/ClO2 accelerated the accumulation of endogenic reactive oxygen species (ROS) caused by oxidation stress of A. niger spores, improving the inactivation ability of the system. The inactivation order of A. niger spores was: loss of culturability, accumulation of intracellular ROS, loss of membrane integrity, leakage of intracellular species and change of morphology. The inactivation performance of solar/ClO2 was better than solar/chlor(am)ine according to the comparison of inactivation efficiency and regrowth potential. Results also suggested that solar/ClO2 process was more suitable for the treatment of ground water sources.

The effectiveness of gliding arc discharge plasma in sterilizing artificial seawater contaminated with Vibrio parahaemolyticus

The rapid proliferation of the halophilic pathogen Vibrio parahaemolyticus poses a severe health hazard to halobios and significantly impedes intensive mariculture. This study aimed to evaluate the potential application of gliding arc discharge plasma (GADP) to control the infection of Vibrio parahaemolyticus in mariculture. This study investigated the inactivation ability of GADP against Vibrio parahaemolyticus in artificial seawater (ASW), changes in the water quality of GADP-treated ASW, and possible inactivation mechanisms of GADP against Vibrio parahaemolyticus in ASW. The results indicate that GADP effectively inactivated Vibrio parahaemolyticus in ASW. As the volume of ASW increased, the time required for GADP sterilization also increased. However, the complete sterilization of 5000 mL of ASW containing Vibrio parahaemolyticus of approximately 1.0 × 104 CFU/mL was achieved within 20 min. Water quality tests of the GADP-treated ASW demonstrated that there were no significant changes in salinity or temperature when Vibrio parahaemolyticus (1.0 ×104 CFU/mL) was completely inactivated. In contrast to the acidification observed in plasma-activated water (PAW) in most studies, the pH of ASW did not decrease after treatment with GADP. The H2O2 concentration in the GADP-treated ASW decreased after post-treatment. The NO2-concentration in the GADP-treated ASW remained unchanged after post-treatment. Further analysis revealed that GADP induced oxidative stress in Vibrio parahaemolyticus, which increased cell membrane permeability and intracellular ROS levels of Vibrio parahaemolyticus. This study provides a viable solution for infection with the halophilic pathogen Vibrio parahaemolyticus and demonstrates the potential of GADP in mariculture.

Insight into the surface discharge cold plasma efficient inactivation of Pseudomonas fluorescens in water based on exogenous reactive oxygen and nitrogen species: Synergistic mechanism and energy benefits

As well known, surface discharge cold plasma has efficient inactivation ability and a variety of RONS are main active particles for inactivation, but their synergistic mechanism is still not clear. Therefore, surface discharge cold plasma system was applied to treat Pseudomonas fluorescens to study bacterial inactivation mechanism and energy benefit. Results showed that energy efficiency was directly proportional to applied voltage and inversely proportional to initial concentration. Cold plasma treatment for 20 min was inactivated by approximately > 4-log10Pseudomonas fluorescens and application of •OH and 1O2 scavengers significantly improved survival rate. In addition, •OH and 1O2 destroyed cell membrane structure and membrane permeability, which promoted diffusion of RONS into cells and affecting energy metabolism and antioxidant capacity, leading to bacterial inactivation. Furthermore, accumulation of intracellular NO and ONOOH was related to infiltration of exogenous RNS, while accumulation of •OH, H2O2, 1O2, O2- was the result of joint action of endogenous and exogenous ROS. Transcriptome analysis revealed that different RONS of cold plasma were responsible for Pseudomonas fluorescens inactivation and related to activation of intracellular antioxidant defense system and regulation of genes expression related to amino acid metabolism and energy metabolism, which promoting cellular process, catalytic activity and other biochemical pathways.

Comparison of chlorine and chlorine dioxide disinfection in drinking water: Evaluation of disinfection byproduct formation under equal disinfection efficiency

Disinfection efficiency and disinfection byproduct (DBP) formation are two important aspects deserving careful consideration when evaluating different disinfection protocols. However, most of the previous studies on the selection of disinfection methods by comparing DBP formation were carried out under the same initial/residual dose and contact time of different disinfectants, and such a practice may cause overdose or underdose of a certain disinfectant, leading to the inaccurate evaluation of disinfection. In this study, a comprehensive and quantitative comparison of chlorine (Cl2) and chlorine dioxide (ClO2) disinfection was conducted with regard to their DBP formation under equal disinfection efficiency. The microbial inactivation models as well as the Cl2 and ClO2 demand models were developed. On such basis, the integral CT (ICT) values were determined and used as a bridge to connect disinfection efficiency and DBP formation. For 3-log10 and 4-log10 reductions of Pseudomonas aeruginosa, ClO2 had 1.5 and 5.8 times higher inactivation ability than Cl2, respectively. In the premise of equal disinfection efficiency (i.e., the ICT ratios of Cl2 to ClO2 = 1.5 and 5.8), the levels of total organic chlorine, total organic bromine, and total organic halogen formed in the Cl2 disinfection were significantly higher than those formed in the ClO2 disinfection. Among the 35 target aliphatic DBPs, trihalomethanes (THMs) and haloacetic acids (HAAs) were the dominant species formed in both Cl2 and ClO2 disinfection. The total THM levels formed in Cl2 disinfection were 14.6 and 30.3 times higher than those in ClO2 disinfection, respectively. The total HAA levels formed in Cl2 disinfection were 3.5 and 5.4 times higher than those in ClO2 disinfection, respectively. Formation of the target 48 aromatic DBPs was much favored in Cl2 disinfection than that in ClO2 disinfection, and the formation levels was dominated by contact time. This study demonstrated that ClO2 had significant advantages over Cl2, especially at higher microorganism inactivation and lower DBP formation requirements.

Study of the effect of shock wave from a portable pulsed cold air plasma jet device on inactivation of Trichophyton rubrum in nails

This study aimed to apply a portable pulsed cold air plasma jet (PP-CAPJ) device in onychomycosis treatment and investigate its effect and mechanism of action. Based on the characteristics of onychomycosis, we selected Trichophyton rubrum (T. rubrum) for our experiments and explored the inactivation ability of the PP-CAPJ on T. rubrum that grew in nails. We found that the PP-CAPJ could effectively kill T. rubrum in the nails, and for T. rubrum in 1.5 mm thick nails, 300 spark discharges could kill almost all the fungi. The fungicidal mechanism is mainly due to the ability of shock waves from the PP-CAPJ to impose pressure on the nail and destroy the cell membrane of T. rubrum. This work has therefore demonstrated the use of an effective and noninvasive approach for the treatment of onychomycosis.

Investigation of antimicrobial activity of Ultraviolet B radiation and its potential to generate fructose-mediated reactive oxygen species in coconut water

We evaluated the potential antimicrobial activity and inactivation kinetics, photo-reactivation potential and ability to generate reactive oxygen species (ROS) and consequent ascorbic acid degradation in fructose enriched coconut water. UV-B caused 4.5 ± 0.19 log inactivation in E. coli K12 at 0.45 J/cm2 and inactivation kinetics followed Weibull model, compared to log-linear 4 ± 0.05 log reduction at 0.2 J/cm2 dose of UV-C. A lower extent of UV-A (360 nm) induced photo-reactivation was observed in UV-B treated samples compared to UV-C. UV-B mediated microbial inactivation was largely caused by DNA damage and impaired metabolic activity of E. coli. UV-B treatment did not cause membrane damage, or thiol oxidation. Compared to UV-C, UV-B produced lower concentration of ROS from fructose. At a dose required for 4 log reduction of E. coli K12 by UV-B, only 8% ascorbic acid degraded. These results show that UV-B is an attractive alternative to UV-C treatment. Industrial relevanceUV-C irradiation is a cost-effective measure to ensure food safety. However, for fructose-rich products fruit juices, UV-C exposure to photo-sensitive compounds like fructose generates reactive oxygen species that can deteriorate the quality of fructose-rich products. In this context, UV-B provides comparable, albeit slower, antimicrobial effect but provokes milder fructose mediated oxidative stress than UV-C. This study highlights the potential for using UV-B as an alternative to UV-C light treatment for liquid foods.

AIEgen orthopalladated hybrid polymers for efficient inactivation of the total coliforms in urban wastewater

Monitorable AIE polymers with a bioactive pattern are employed in advanced biomedical applications such as functional coatings, theranostic probes, and implants. After the global COVID-19 pandemic, interest in developing surfaces with superior antimicrobial, antiproliferative, and antiviral activities dramatically increased. Many formulations for biocide surfaces are based on hybrid organic/inorganic materials. Palladium (II) complexes display relevant activity against common bacteria, even higher when compared to their uncoordinated ligands. This article reports the design and synthesis of two series of orthopalladated polymers obtained by grafting a cyclopalladated fragment on two different O, N chelating Schiff base polymers. Different grafting percentages were examined and compared for each organic polymer. The fluorescence emission in the solid state was explored on organic matrixes and grafted polymers. DFT analysis provided a rationale for the role of the coordination core. The antibacterial response of the two series of hybrid polymers was tested against the total coliform group of untreated urban wastewater, revealing excellent inactivation ability.

Evaluation of bioaerosol inactivation ability of chitosan-based biohybrid nanofibers loaded with aloe vera mediated silver nanoparticles: Sustainable material for environmental protection

Development of multifunctional polymer-nanofibers with long-lasting antibacterial efficacy is significant to control the biohazards associated with airborne pathogenic microorganisms for sustainable environmental protection. Hence, in the present study biohybrid-nanofibers based on chitosan biopolymer embedded with green-synthesized silver-nanoparticles (AgNPs) were fabricated through electrospinning technique. The pathway of formation of AgNPs with an average size of 50 nm involves in the reduction of AgNO3 by aloe vera leaves extract, which acts as both reducing and capping agent. Morphological examination confirmed the uniform structure of the scaffolds (diameter varied from 32.3 to 273.1 nm) without considerable beads and furthermore, AgNPs play an important role in controlling their average diameter. Fibers with nanosilver exhibited adequate surface area (15.6–83.1 m2/g) for releasing the essential functional groups to prevent the broad spectrum of microbes. No evidence of cytotoxicity of these scaffolds was observed in the cell-viability test, suggesting their biocompatible nature. Porosity measurement of various surface-layer of these fibers by Image-J analysis exhibited their controlled porous structure, favorable for filtration applications. Microbial interaction with these fibers resulted in an excellent inhibition on the growth of the pathogens and fibers entrapped with maximum content of AgNPs proved to have enhanced antimicrobial action, which further confirmed by flow-cytometric analysis. Novel approach based on the application of green electrospinning technique for the formation of cost-effective scaffolds loaded with plant-mediated nanosilver, with a view on mechanistic aspect on their antimicrobial action and, further exploring their reliability in filtration applications, paving the way for innovation in the field of material research.

Study on the Properties and Synergistic Antioxidant Effects of Novel Bifunctional Fusion Proteins Expressed Using the UTuT6 System.

Important antioxidant enzymes, glutathione peroxidase (GPx) and superoxide dismutase (SOD), are involved in maintaining redox balance. They can protect each other and result in more efficiently removing excessive reactive oxygen species (ROS), protecting cells against injury, and maintaining the normal metabolism of ROS. In this study, human cytosolic GPx (hGPx1) and human phospholipid hydroperoxide GPx (hGPx4) genes were integrated into the same open reading frame with human extracellular SOD active site (SOD3-72P) genes, respectively, and several novel fusion proteins were obtained by using the UTuT6 expression system for the first time. Among them, Se-hGPx1UAG-L4-SOD3-72P is the bifunctional fusion protein with the highest GPx activity and the best anti-hydrogen peroxide inactivation ability thus far. The Se-hGPx4UAG-L3-SOD3-72P fusion protein exhibits the strongest alkali and high temperature resistance and a greater protective effect against lipoprotein peroxidation damage. Se-hGPx1UAG-L4-SOD3-72P and Se-hGPx4UAG-L3-SOD3-72P fusion proteins both have good synergistic and antioxidant abilities in H2O2-induced RBCs and liver damage models. We believe that this research will help with the development of novel bifunctional fusion proteins and the investigation of the synergistic and catalytic mechanisms of GPx and SOD, which are important in creating novel protein therapeutics.

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.

Effect of different process conditions on the physicochemical and antimicrobial properties of plasma-activated water

The physicochemical properties of plasma-activated water (PAW) generated under different process conditions were investigated, and their changes under different storage conditions were also studied. The results showed that increasing the processing time and power, and decreasing generated water volume, could cause an increase in the redox potential, conductivity, and temperature of PAW, and a decrease in its pH. A slower dissipation of the reactive oxygen and nitrogen species in PAW was found on storage at 4 °C in a sealed conical flask than on storage at room temperature. The inactivation ability of plasma-activated lactic acid (LA) to Listeria monocytogenes (L. monocytogenes) and Pseudomonas aeruginosa (P. aeruginosa) was higher than that of PAW or LA alone under the same experimental conditions. The results of this study may provide theoretical information for the application of PAW as a potential antimicrobial agent in the future.

QSAR and Chemical Read-Across Analysis of 370 Potential MGMT Inactivators to Identify the Structural Features Influencing Inactivation Potency.

O6-methylguanine-DNA methyltransferase (MGMT) constitutes an important cellular mechanism for repairing potentially cytotoxic DNA damage induced by guanine O6-alkylating agents and can render cells highly resistant to certain cancer chemotherapeutic drugs. A wide variety of potential MGMT inactivators have been designed and synthesized for the purpose of overcoming MGMT-mediated tumor resistance. We determined the inactivation potency of these compounds against human recombinant MGMT using [3H]-methylated-DNA-based MGMT inactivation assays and calculated the IC50 values. Using the results of 370 compounds, we performed quantitative structure-activity relationship (QSAR) modeling to identify the correlation between the chemical structure and MGMT-inactivating ability. Modeling was based on subdividing the sorted pIC50 values or on chemical structures or was random. A total of nine molecular descriptors were presented in the model equation, in which the mechanistic interpretation indicated that the status of nitrogen atoms, aliphatic primary amino groups, the presence of O-S at topological distance 3, the presence of Al-O-Ar/Ar-O-Ar/R..O..R/R-O-C=X, the ionization potential and hydrogen bond donors are the main factors responsible for inactivation ability. The final model was of high internal robustness, goodness of fit and prediction ability (R2pr = 0.7474, Q2Fn = 0.7375-0.7437, CCCpr = 0.8530). After the best splitting model was decided, we established the full model based on the entire set of compounds using the same descriptor combination. We also used a similarity-based read-across technique to further improve the external predictive ability of the model (R2pr = 0.7528, Q2Fn = 0.7387-0.7449, CCCpr = 0.8560). The prediction quality of 66 true external compounds was checked using the "Prediction Reliability Indicator" tool. In summary, we defined key structural features associated with MGMT inactivation, thus allowing for the design of MGMT inactivators that might improve clinical outcomes in cancer treatment.

Combined treatment of ε-polylysine and thermosonication to inactivate Bacillus cereus and their application in pasteurized milk

At present, most liquid milk products use high-temperature short-time heat treatment (HTST). However, HTST treatment cannot completely inactivate the bacteria in milk, which seriously affects the quality, safety, and shelf life of the product. Therefore, exploring the combined use of HTST and other technologies is of great importance to the production of high-quality pasteurized milk. In this study, we compared thermosonication (TS), ε-Polylysine (ε-PL), ε- PL combined with TS (ε-PL-TS), and HTST to inactivate B. cereus in pasteurized milk. Based on this comparison, we further discussed the inactivation ability and potential mechanism of ε-PL-TS treatment on B. cereus. The experimental result indicated that ε-PL-TS treatment had an obvious inactivation impact on B. cereus. The cell architecture was damaged by ε-PL-TS treatment, causing the leakage of proteins and DNA from the cell. ε-PL-TS treatment caused metabolic disorders by reducing the activities of key enzymes such as succinate dehydrogenase (SDH) (72.5%), malate dehydrogenase (MDH) (70.5%), and ATPase (80.3%). Meanwhile, the activity of CAT and POD decreased by 42.5% and 48.7%, respectively, suggesting that oxidative stress may be involved in the bactericidal mechanism. In addition, the combined treatment effectively inhibits microbial proliferation of pasteurized milk during storage at 4 °C. Therefore, ε-PL-TS treatment can be used as a potential new inactivated microorganism technology that is helpful to obtain high-quality pasteurized milk with a long shelf life.

Preparation and application of novel poly-tetrahydropyrimidine modified-mesoporous silica microspheres

Mesoporous silica microspheres, a multifunctional material with high specific surface area, pore size, and mechanical properties, are widely used as separation and support materials. Mesoporous silica, has been relatively studied as LC column packing material for separation and detection. In this research, we prepared mesoporous silica microspheres by a simple synthesis method, and the antibacterial modification of mesoporous silica was carried out by adding synthesized PTHP. Excellent test results have been exhibited, the PTHP-SiO2 mesoporous has the same structure and morphology as the SiO2 microspheres, but shows excellent bacterial inactivation ability, and better separation as LC column packing material, thus can be applied as a multifunctional material.

Homogenous Sono-Fenton reaction can trigger long term bactericidal effect against Acinetobacter baumannii due to residual stress induced by reactive oxygen species

Gastrointestinal diseases caused by microbial contamination of water has been one of the enduring public health challenges of the mankind, wherefore demands continual innovation in the contemporary water treatment techniques. Here, a systematic study was carried out to elucidate the bactericidal mechanism of ultrasound assisted Fenton reaction (Sono-Fenton: SF) against multidrug resistant Acinetobacter baumannii. Inactivation of ≈5 × 106 CFU/mL of A. baumannii was achieved within 90 min of SF under weak acidic conditions using 20 mg L-1 of H2O2 and 2 mg L-1 of Fe2+. Having more than 99 % inactivation efficiency, no reactivation of the bacteria was observed for 96 h. After SF, a combination of ultrasound and H2O2 was found to be more efficient although complete inactivation was not achieved within the same time frame. Experimental evidence suggests the generation of multiple reactive oxygen species (ROS) such as H2O2, •OH and O2•–. The synergistic effect of ROS and ultrasound may have resulted in the membrane damage of the bacteria as evident from the electron microscopy analysis. Interestingly, our data also suggests that the residual stress associated with SF could have long term bactericidal effect and is influenced by incubation temperature. Comparative transcriptomic analysis showed that NirD/YgiW/YdeI family stress tolerance protein, KGG domain containing proteins, and PspC domain containing proteins, all known to control the stress induced responses in bacteria was significantly upregulated after SF treatment. Additionally, genes regulating transcription (GntR) and translation (rpsQ) have been downregulated which may induce a nutrient and metabolite limiting conditions in the bacterial cell. The bacterial inactivation ability of SF process was further validated with real water samples collected from natural systems and therefore, advocate the possible real-world applications.

Bacterial Sterilization Using Non-Thermal Plasma Method Surface Dielectric Barrier Discharge (SDBD): Effect of Treatment Duration on Colony Count, DNA, Protease Enzymes, and Cell Morphology

The ability of Escherichia coli to become increasingly resistant to sterilization has resulted in high cases of this bacterial infection. To overcome this problem, a new method is needed. The circuit design uses 2 parallel plates of copper material. The first plate is HV electrode and second plate is ground electrode which is separated by a dielectric layer. Non-thermal plasma with surface dielectric barrier discharge is generated using a 20 VDC voltage source and then transformed into a high voltage source to generate plasma. Distance between plasma source and fixed sample is 3 mm. OES is used to observe reactive species produced in plasma indicated by magnitude of intensity at certain wavelengths. SDBD non-thermal plasma could be used to inactivate bacteria depending on treatment time. The longer treatment time, greater inactivation ability. For the number of colonies after being treated for 120 s, namely 4.33×107 CFU/mL, it was much lower than control, which was 409×107 CFU/ml. For DNA after being treated for 120 s, results of genome from Escherichia coli were no longer visible or faded, marked by a DNA concentration of 8.18 ng/ul, far lower than the control DNA concentration of 124.44 ng/ul. For the activity of the protease enzyme, the time variation of 105 s had the smallest activity value of the protease enzyme, namely 35.375 U/mL compared to control, which was 52.307 U/mL whereas for cell morphology after 120 s treatment showed increasingly severe cell damage observed using SEM. Non-thermal plasma SDBD configurations can be used to inactivate or kill bacteria. Effectiveness or capability of non-thermal plasma also depends on the treatment time. SDBD nonthermal plasma ability increases with the longer treatment time. HIGHLIGHTS In this research, a non-thermal plasma method of surface dielectric barrier discharge (SDBD) for Escherichia coli sterilization was developed. The results of research on inactivation of Escherichia coli bacteria using non-thermal plasma SDBD showed that the configuration of non-thermal plasma SDBD could be used to inactivate or kill bacteria. The effectiveness or capability of non-thermal plasma also depends on the treatment time. SDBD non-thermal plasma capability increases with longer treatment time. GRAPHICAL ABSTRACT