Destruction Of Cell Membrane Research Articles

Alteration of Cell Membrane Permeability by Cetyltrimethylammonium Chloride Induces Cell Death in Clinically Important Candida Species.

The increased incidence of healthcare-related Candida infection has necessitated the use of effective disinfectants/antiseptics in healthcare settings as a preventive measure to decontaminate the hospital environment and stop the persistent colonization of the offending pathogens. Quanternary ammonium surfactants (QASs), with their promising antimicrobial efficacy, are considered as intriguing and appealing candidates for disinfectants. From this perspective, the present study investigated the antifungal efficacy and action mechanism of the QAS cetyltrimethylammonium chloride (CTAC) against three clinically important Candida species: C. albicans, C. tropicalis, and C. glabrata. CTAC exhibited phenomenal antifungal activity against all tested Candida spp., with minimum inhibitory concentrations (MIC) and minimum fungicidal concentrations (MFC) between 2 and 8 µg/mL. The time−kill kinetics of CTAC (at 2XMIC) demonstrated that an exposure time of 2 h was required to kill 99.9% of the inoculums in all tested strains. An important observation was that CTAC treatment did not influence intracellular reactive oxygen species (ROS), signifying that its phenomenal anticandidal efficacy was not mediated via oxidative stress. In addition, sorbitol supplementation increased CTAC’s MIC values against all tested Candida strains by three times (8−32 μg/mL), indicating that CTAC’s possible antifungal activity involves fungus cell membrane destruction. Interestingly, the increased fluorescence intensity of CTAC-treated cells in both propidium iodide (PI) and DAPI staining assays indicated the impairment of cell plasma membrane and nuclear membrane integrity by CTAC, respectively. Additionally, CTAC at MIC and 2XMIC was sufficient (>80%) to disrupt the mature biofilms of all tested spp., and it inhibited the yeast-to-hyphae transition at sub-MIC in C. albicans. Finally, the non-hemolytic activity of CTAC (upto 32 µg/mL) in human blood cells and HBECs signified its non-toxic nature at the investigated concentrations. Furthermore, thymol and citral, two phytocompounds, together with CTAC, showed synergistic fungicidal effectiveness against C. albicans planktonic cells. Altogether, the data of the present study appreciably broaden our understanding of the antifungal action mechanism of CTAC and support its future translation as a potential disinfectant against Candida-associated healthcare infections.

Putative inactivation mechanism and germicidal efficacy of induced electric field against Staphylococcus aureus

Induced electric field (IEF), as an alternative non-conventional processing technique, is utilized to sterilize liquid foods. In this study, the survival and sublethal injury of S. aureus under IEF were investigated in 0.85% normal saline, and the inactivation mechanism of IEF was expounded. The plate count results showed that the sublethal injury rates remained above 90% after IEF treatment for more than 8.4 s, and 7.1 log CFU/mL of S. aureus was completely inactivated after 14 s IEF treatment. Scanning electron microscopy and transmission electron microscope images showed that IEF caused the destruction of cell membrane and internal substructure, and the damage to intracellular substructure was more severe. Altered membrane integrity or permeability was demonstrated through flow cytometry and confocal laser scanning microscope analysis, and the different damage to cells was quantified by propidium iodide & 5-carboxy fluorescein diacetate single and double staining. In addition, IEF treatment also decreased the membrane potential and esterase activity of S. aureus cells. Putative inactivation mechanism of IEF against S. aureus is a complex process, and its apoptosis is the result of the combination of several factors, which provide a basis for understanding the inactivation mechanism of IEF.

Synthesis of CuO and PAA-Regulated Silver-Carried CuO Nanosheet Composites and Their Antibacterial Properties.

With the aid of a facile and green aqueous solution approach, a variety of copper oxide (CuO) with different shapes and polyacrylic-acid (PAA)-regulated silver-carried CuO (CuO@Ag) nanosheet composites have been successfully produced. The point of this article was to propose a common synergy using Ag-carried CuO nanosheet composites for their potential antibacterial efficiency against three types of bacteria such as E. coli, P. aeruginosa, and S. aureus. By using various technical means such as XRD, SEM, and TEM, the morphology and composition of CuO and CuO@Ag were characterized. It was shown that both CuO and CuO@Ag have a laminar structure and exhibit good crystallization, and that the copper source and reaction duration have a sizable impact on the morphology and size distribution of the product. In the process of synthesizing CuO@Ag, the appropriate amount of polyacrylic acid (PAA) can inhibit the agglomeration of Ag NPs and regulate the size of Ag at about ten nanometers. In addition, broth dilution, optical density (OD 600), and electron microscopy analysis were used to assess the antimicrobial activity of CuO@Ag against the above three types of bacteria. CuO@Ag exhibits excellent synergistic and antibacterial action, particularly against S. aureus. The antimicrobial mechanism of the CuO@Ag nanosheet composites can be attributed to the destruction of the bacterial cell membrane and the consequent leakage of the cytoplasm by the release of Ag+ and Cu2+. The breakdown of the bacterial cell membrane and subsequent leakage of cytoplasm caused by Ag+ and Cu2+ released from antimicrobial agents may be the cause of the CuO@Ag nanosheet composites' antibacterial action. This study shows that CuO@Ag nanosheet composites have good antibacterial properties, which also provides the basis and ideas for the application research of other silver nanocomposites.

Anti-Fungal Activity of Moutan cortex Extracts against Rice Sheath Blight (Rhizoctonia solani) and Its Action on the Pathogen's Cell Membrane.

Rice sheath blight (RSB) caused by Rhizoctonia solani is one of the most destructive diseases of rice (Oryza sativa). Although chemical fungicides are the most important control methods, their long-term unreasonable application has brought about problems such as environmental pollution, food risks, and non-target poisoning. Therefore, considering the extraction of fungistatic substances from plants may be an alternative in the future. In this study, we found that the Moutan cortex ethanol extract has excellent antifungal activity against R. solani, with a 100% inhibition rate at 1000 μg/mL, which aroused our great exploration interest. In-depth exploration found that the antifungal active ingredients of M. cortex were mainly concentrated in the petroleum ether extract of the M. cortex ethanol extract, which still maintained a 100% inhibition rate with 250 μg/mL, and its effective medium concentration (EC50) was 145.33 μg/mL against R. solani. Through the measurement of extracellular relative conductivity and OD260, the petroleum ether extract induced leakage of intracellular electrolytes and nucleic acids, indicating that the cell membrane was ruined. Therefore, we preliminarily determined that the cell membrane may be the target of the petroleum ether extract. Moreover, we found that petroleum ether extract reduced the content of ergosterol, a component of the cell membrane, which may be one of the reasons for the cell membrane destruction. Furthermore, the increase of MDA content would lead to membrane lipid peroxidation, further aggravating membrane damage, resulting in increased membrane permeability. Also, the destruction of the cell membrane was observed by the phenomenon of the mycelium being transparent and broken. In conclusion, this is the first report of the M. cortex petroleum ether extract exhibiting excellent antifungal activity against R. solani. The effect of the M. cortex petroleum ether extract on R. solani may be on the cell membrane, inducing the disorder of intracellular substances and metabolism, which may be one of the antifungal mechanisms against R. solani.

Alkaline Diuresis as Treatment for 2, 4-D Dimethylamine Herbicide Intoxication: A Case Report

The use of 2, 4-D dimethylamine is expanding as a result of the rise in glyphosate and paraquat resistance in weeds [1]. Instances of 2,4D dimethylamine intoxication have been on the rise. This herbicide exhibits a range of dose-dependent harmful mechanisms, including cell membrane destruction, disruption of acetyl coenzyme A metabolism, and oxidative phosphorylation uncoupling [2]. The neurological system, heart, lungs, liver, muscles, and endocrine system may all be affected by toxic effects [3]. Results in male cases are fatal [2,4]. The usefulness of alkaline diuresis as a life-saving treatment for 2,4-D dimethylamine poisoning with severe symptoms is discussed in this paper. 2, 4-D dimethylamine intoxication can be fatal if not treated promptly. There is no particular antidote and alkaline diuresis shows good result in the patient who present with severe intoxication of 2, 4-D dimethylamine.

Eco-Friendly Green Synthesis of Rubropunctatin Functionalized Silver Nanoparticles and Evaluation of Antibacterial Activity.

In order to solve the problems of rubropunctatin insoluble in water and its low bioavailability, and explore the synthesis method of green silver nanoparticles, rubropunctatin was used as reducing agent and blocking agent, rubropunctatin-functionalized silver nanoparticles (R-AgNPs) were successfully synthesized. The distinctive absorption peak at 410 nm confirmed the formation of R-AgNPs. Zeta potential measurement showed excellent stability of R-AgNPs with negative values of -29.81 ± 0.37 mV. The results of TEM and XRD showed that the prepared R-AgNPs were round, well dispersed and crystallized with average particle size of 13.54 ± 0.42 nm. FT-IR and XPS studies show that functional groups are involved in R-AgNPs synthesis. The antibacterial activity of R-AgNPs was compared with commercial silver nanoparticles (AgNPs) by microdilution method. The results showed that R-AgNPs (MIC 7.81 μg/mL) has stronger antibacterial activity than commercial AgNPs. The bacteria morphology was observed by the live and dead (SYTO 9/PI) staining assay and SEM showed that the antibacterial effect of R-AgNPs was caused by the destruction of the bacterial cell membrane. Cytotoxicity of rubropunctatin-functionalized silver nanoparticles and commercial silver nanoparticles on mouse fibroblast 3T3 cells was assessed by CCK-8 assay. The results showed that the toxicity of rubropunctatin-functionalized silver nanoparticles to 3T3 cells was lower than that of commercial silver nanoparticles. In summary, synthesis of silver nanoparticles using rubropunctatin is a green synthesis method, and R-AgNPs is a potential antibacterial agent.

Inhibition of Fusarium Graminearum Growth and Deoxynivalenol Biosynthesis by Phenolic Compounds

AbstractPhytopathogenic fungi infections have become a major threat to reduce crop yields and dampen human health globally. The mycelium growth inhibition method was adopted to evaluate the antifungal activity of commercially available natural and natural‐like phenols, bioassay results showed that most phenolic compounds exhibited excellent fungicidal activity against Fusarium graminearum, Rhizoctonia solani, Botrytis cinerea, Fusarium oxysporum f. sp. Vasinfectum, Sclerotinia sclerotiorum, and Magnaporthe oryzae. Particularly, compound Z‐5 exhibited an excellent inhibition rate of 100.00 % at 100 μg/mL and EC50 value of 3.20 μg/mL against Fusarium graminearum. In addition, compound Z‐5 displayed the best efficacy and superior fungicidal activity compared to azoxystrobin (EC50=9.78 μg/mL) based on mycelial growth and spore germination. Significantly, compound Z‐5 at 200 μg/mL reduced 4‐deoxynivalenol production by over 98 % compared to the control, through down‐regulation of the gene expression of Tri5 and Tri6. Preliminary mechanism studies revealed that compound Z‐5 might exert its fungicidal activity by inducing accumulation of reactive oxygen species and lipid peroxidation, and causing cell membrane destruction and DNA synthesis interference. This study demonstrated the potent fungicidal activity of the natural‐like phenolic compound Z‐5 and highlighted its potential as an alternative agent to control F. graminearum.

Rational Design of RN15m4 Cathelin Domain-Based Peptides from Siamese Crocodile Cathelicidin Improves Antimicrobial Activity.

Antimicrobial peptides are becoming a new generation of antibiotics due to their therapeutic potential and ability to decrease drug-resistant bacteria development. Cathelicidins are known as effective peptides of vertebrate immunity that play crucial roles in the defensive strategy against pathogens. To improve its potency, the RN15 antibacterial peptide derived from the cathelin domain of Crocodylus siamensis cathelicidin has been modified and its antimicrobial properties investigated. Peptides were derived by template-based and physicochemical designation. The RN15 derivative peptides were predicted through their structure modeling, antimicrobial potency, and peptide-membrane calculation. The antimicrobial and cytotoxic activities of candidate peptides were investigated. Simultaneous consideration of physicochemical characteristics, secondary structure modeling, and the result of antimicrobial peptide tools prediction indicated that RN15m4 peptide was a candidate derivative antimicrobial peptide. The RN15m4 peptide expresses antimicrobial activity against most Gram-positive and Gram-negative bacteria and fungi with a lower minimum inhibition concentration (MIC) than the parent peptide. Besides, the time-killing assay shows that the designed peptide performed its ability to quickly kill bacteria better than the original peptide. Scanning electron microscopy (SEM) displayed the destruction of the bacterial cell membrane caused by the RN15m4 peptide. In addition, the RN15m4 peptide exhibits low hemolytic activity and low cytotoxic activity as good as the template peptide. The RN15m4 peptide performs a range of antimicrobial activities with low cell toxicity. Our study has illustrated the combination approach to peptide design for potent antibiotic peptide discovery.

Analysis of the synergistic antifungal mechanism of small molecular combinations of essential oils at the molecular level

The bacteriostatic concentration of essential oil (EO) in practical application is usually higher than the flavor threshold, resulting in a lack of balance between bacteriostatic concentration and flavor, which has become the bottleneck of its application in the field of agriculture products. One of the effective ways to solve this problem is the synergistic antibacterial effect of the active components of EO. In this paper, molecular docking , independent gradient model (IGM) and symmetric matching perturbation theory (SAPT) are combined for the first time to investigated the molecular mechanism of eugenol and citral small molecules (E AC ) against Aspergillus niger . The results show that E AC can combine with β-(1,3)-glucan synthase and chitin synthase proteins, and then destroy the integrity of cell wall, in which the trans -citral has the best affinity with these two enzyme proteins. In addition, E AC can bind to tryptophan , tyrosine and phenylalanine in cell membrane. The binding of citral small molecules to these three amino acids is mainly hydrogen bond, while the binding force of eugenol to them is mainly van der Waals force or π-π interaction. Finally, the synergistic antifungal effect of E AC was confirmed by the damage of membrane proteins and the leakage of cell contents. In this combination, citral binds to the cell wall, which promotes the interaction between eugenol and cell membrane, and finally leads to the serious destruction of cell membrane. The above results show that E AC has the potential to be developed into a new type of agriculture products preservative with synergistic antifungal effect. • Eugenol and citral (E AC ) can combine with chitin synthase and β-(1,3)-glucan synthase to destroy the integrity of cell wall. • Trans-Citral has the best affinity with chitin synthase and β-(1,3)-glucan synthase. • Static electricity is the main contribution to the stability of essential oils molecules and amino acids. • The E AC could cause damages to Aspergillus niger cell membrane that led to a loss of cell viability.

Green synthesis of silver nanoparticles from Mahonia fortunei extracts and characterization of its inhibitory effect on Chinese cabbage soft rot pathogen.

The pathogenic bacterium Pectobacterium carotovorum causes soft rot in cabbage and significantly reduces plant yield. In this study, we employed Mhonia fortunei extracts to synthesis silver nanoparticles (Mf-AgNPs) and investigated their functions against P. carotovorum. The results showed that the surface plasmon resonance (SPR) peak of AgNP was 412 nm under optimal synthesis conditions. Furthermore, the results of Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS) and High-resolution transmission electron microscopy (HR-TEM) revealed that the Mf-AgNPs had a spherical structure with an average diameter of 13.19 nm and the content of Ag0 ions accounted for 82.68% of the total elemental content. The X-Ray diffraction (XRD) results confirmed that AgNPs had a face-centered cubic (FCC) crystal structure, while Fourier transform infrared spectroscopy (FTIR) results indicated the presence of various biomolecules as reducing and stabilizing agents on the AgNP surface. Antibacterial activity was first evaluated by an inhibitory zone test, which revealed that 500 μg ml-1 of AgNPs had antibacterial activity against P. carotovorum and four model bacteria including Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa, respectively with an antibacterial function comparable to 1 mM AgNO3 solution. The Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for P. carotovorum were 8 μg ml-1, respectively. Furthermore, AgNPs at 8 μg ml-1 completely inhibited the growth of P. carotovorum, decreased their tolerance to 0.25 mM H2O2 as well as considerably reduced colony formation after 1 h of treatment and thereafter. Treatment with Mf-AgNPs resulted in bacterial cell membrane destruction and biofilm formation inhibition, respectively. With an FIC (fractional inhibitory concentration) index of 0.174, AgNP and zhongshengmycin showed a significant synergistic effect. The infection of P. carotovorum to cabbage explants was significantly inhibited in vitro by a combination of 2 μg ml-1 Mf-AgNP and 5 μg ml-1 zhongshengmycin. In conclusion, the synthesized Mf-AgNP exhibited significant antibacterial activity against P. carotovorum.

Antibiofouling Characteristics and Mechanisms in an Anammox Membrane Bioreactor Based on an Optimized Photocatalytic Technology─Photocatalytic Optical Fibers.

As an ecofriendly photocatalytic antifouling technology for membrane bioreactors (MBRs), photocatalytic optical fibers (POFs) can decrease the replacement cost of modified membranes and prevent the proliferation of photosynthetic bacteria caused by direct light illumination. Here, POFs were applied in situ in an anaerobic ammonium oxidation (anammox) MBR for membrane biofouling control. Compared with the control MBR without POFs treatment, the average fouling cycle of the POFs-loaded MBR was extended by 137%, and the energy consumption caused by membrane fouling was saved by 18%. In the antibiofouling process, •OH was the key photocatalytic reactive species. On the fouled POFs-loaded membranes, the membrane-adhered foulant was significantly decreased by photocatalytic degradation of the proteins, polysaccharides and humic substances in the microbial metabolites. The membrane-attached bacteria were inactivated by the POFs by the mechanisms of cell-membrane destruction and cell-membrane permeabilization, which caused bacterial necrosis and apoptosis, respectively. Moreover, the total nitrogen-removal efficiencies of the two MBRs were maintained at 85.3-90.4%, and the abundance of anammox bacteria increased from 21.3% to 46.2% during the 202 days of operation, indicating an efficient anammox process with excellent nitrogen-removal performance, biomass retention, and anammox bacteria enrichment. The systematic insights into the antibiofouling performance and mechanisms of POFs in anammox MBRs will promote application and development of membrane-filtration technology in wastewater treatment using environmentally friendly and energy-efficient antifouling strategies.

Pharmacokinetics and pharmacodynamics of isopropoxy benzene guanidine against Clostridium perfringens in an intestinal infection model.

This study aimed to evaluate the antibacterial activity of isopropoxy benzene guanidine (IBG) against C. perfringens based on pharmacokinetics/pharmacodynamics (PK/PD) modeling in broilers. The PK parameters of IBG in the plasma and ileal content of C. perfringens-infected broilers following oral administration at 2, 30, and 60 mg/kg body weight were investigated. in vivo PD studies were conducted over oral administration ranging from 2 to 60 mg/kg and repeated every 12 h for 3 days. The inhibitory Imax model was used for PK/PD modeling. Results showed that the MIC of IBG against C. perfringens was 0.5–32 mg/L. After oral administration of IBG, the peak concentration (Cmax), maximum concentration time (Tmax), and area under the concentration-time curve (AUC) in ileal content of broilers were 10.97–1,036.64 mg/L, 2.39–4.27 h, and 38.31–4,266.77 mg·h/L, respectively. After integrating the PK and PD data, the AUC0 − 24h/MIC ratios needed for the bacteriostasis, bactericidal activity, and bacterial eradication were 4.00, 240.74, and 476.98 h, respectively. For dosage calculation, a dosage regimen of 12.98 mg/kg repeated every 12 h for 3 days was be therapeutically effective in broilers against C. perfringens with MIC ≤ 2 mg/L. In addition, IBG showed potent activity against C. perfringens, which may be responsible for cell membrane destruction. These results can facilitate the evaluation of the use of IBG in the treatment of intestinal diseases in broilers caused by C. perfringens.

Two-dimensional NbS2 nanosheets with hyperthermia for killing bacteria to promote infected wound healing

Antibiotic resistance and bacteria-related infections pose a threat to lives around the globe, which calls for urgent development of advanced therapy to curb this menace. Although photothermal therapy (PTT) is promising, most photothermal agents lack good photothermal conversion performance which restrains their application. Transition metal dichalcogenides (TMDs) nanosheets can exhibit many advantages in antibacterial applications due to their unique two-dimensional structure with larger specific surface area and higher near-infrared (NIR) absorption. Here, we prepared two-dimensional NbS2 nanosheets (NbS2 NSs) with good biological stability and high biocompatibility through a high-temperature reduction reaction. NbS2 NSs exhibited excellent and stable photothermal properties, which were capable of killing Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) under 5 min of 808 nm laser irradiation. In addition, the morphological characterization of bacteria showed bacterial cell membrane destruction. Furthermore, NbS2 NSs under NIR irradiation inhibited the formation of biofilms and quickly eradicated S. aureus from an infected wound to promote wound healing through a hyperthermia effect. Overall, this work provides an attractive strategy for synthesizing and applying two-dimensional NbS2 NSs with significant implications for bacterial eradication and future biomedical applications.

Particularity of environmental biotic factors impact on mammal’s organism

This article explores ecological significance of animal venom as a stressful biotic factor and its role in disruption of homeostatic processes in mammal’s organism. The variety of venomous species of animals and their widely distribution in the world forces other species of animals to adapt to the coexistence with them. Thus, venom toxins have an important ecological significance, because they act as stressors and appreciably impact on the biotic interaction between organisms. According to scientists’ estimates, 220.000 species of animals, or 15% of the world’s biodiversity, are venomous, and there are 3.709 species of venomous snakes. The increase of snakebites cases is not only related to geographical distribution of snakes, but also to climate changes (high humidity and an increase of average annual temperature), which contributes to the reproduction of snakes and a shift of their natural habitats. Every year, around 5.4 million people are bitten by snakes worldwide. This leads to heavy social and economic costs in many countries of the world and it is the reason for constant attention to this problem. Among the variety of venomous animals, snakes have attracted the greatest attention of scientists due to peculiarities of the composition of their venom, its biochemical properties and the possibility of use in pharmacology and medicine. However, despite annual large-scale studies of the composition of snake toxins, the specifics of their effects on animals and human is not fully indentified. It has been established that among venomous snakes only vipers are common in Ukraine. Among them there are two subspecies of the common adder (Vipera berus Linnaeus, 1758): Vipera b. berus, which can be found in Polissia, Forest Steppe and the Carpathians, and Nikolsky’s viper (Vipera berus nikolskii Vedmederja, Grubant et Rudaeva, 1986), which occurs mainly in the Left Forest Steppe. Their bites can be very painful, but are rarely fatal for adults. Vipera berus venom has hemolytic, proteolytic and cytotoxic properties due to its composition: phospholipase A2, serine proteases, metallo proteases, amino acid L-oxidase, hemorrhagic factors and blood coagulation inhibitors, vasoactive peptides, cysteine-rich secretory protein. The composition of Vipera b. berus and Vipera b. nikolskii venom and mechanism of its action in victim’s organism were analyzed too. It is known that among the components of Nikolsky viper’s venom (Vipera b. nikolskii) the most part belongs to various enzymes. Of all enzymes, phospholipase A2 reached about 65% of the dry weight, serine proteases — 19%. Experiments on mammals (mice) showed that Nikol­sky’s viper (Vipera b. nikolskii) venom cause both local symptoms — swelling, pain, lymphangitis, and systemic symptoms — hypotension, mild neurotoxic effect. In addition, there are reports of damage to the cranial nerves and progressive paralysis of the limbs in mice. The components of Vipera b. berus viper venom have mainly a hemotoxic effect due to variety of enzymes from the metalloproteinase family, serine proteases, L-amino acid oxidases and C-type lectinlike proteins and cause enhanced blood coagulation. It is known that L-amino acid oxidases block the neuromuscular transmission of impulses and cause the destruction of cell membranes. The venom of this viper also contains several proteins that have a neurotoxic effect. A comprehensive and thorough analysis of experimental research data testify that the composition of toxins of various animal species, including vipers, is extremely diverse. Plenty of studies state about the hemovasotoxic and neurotoxic effects of these venoms. There are also reports of damage to the cardiovascular, urinary, respiratory, and digestive systems. It is noted that not all targets of viper toxins in mammal’s organism have been identified yet, and not all mechanisms of its action are understood, so further research is relevant.

Natural day–night temperature variations driving pyrocatalytic wastewater treatment and CO2 reduction based on room-temperature rhombohedral–tetragonal phase transition of lead-free ferroelectric BZT-0.5BCT fibers

Environmental remediation approaches in terms of wastewater treatment and CO2 reduction using environmental energy are highly desirable for an industrialized society. Herein, the pyrocatalytic performance of electrospun lead-free ferroelectric Ba(Ti0.8Zr0.2)O3-x(Ba0.7Ca0.3)TiO3 (BZT-xBCT, x = 0.2, 0.3, 0.4, 0.5, 0.6) micro-nano fibers is investigated, and BZT-0.5BCT is identified as an efficient pyrocatalyst for water pollutants decomposition driven by rhombohedral–tetragonal (R-T) phase transition. Phase changes can induce high pyroelectric coefficients. In response to 0–60 °C thermal cycles, the decomposition ratio of Rhodamine B (RhB) by BZT-0.5BCT fibers after nine thermal cycles is approximately 70%. Moreover, under outdoor day-night temperature fluctuations, about 76% of RhB and 95% of methylene blue (MB) can be degraded after 10 and 7 days respectively because BZT-0.5BCT has an R-T phase change point of around 30 °C. For Cr(VI) (potassium dichromate) and tetracycline (TE), the fibers also show good pyrocatalytic degradation ability. Due to destruction of bacterial cell membranes by superoxide groups, high levels of antimicrobial activity could also be achieved against Escherichia coli (99.99%) and Staphylococcus aureus (92.83%). Furthermore, the pyrocatalytic reduction of CO2 to acetaldehyde by BZT-0.5BCT can reach approximately 382.47 μmol g−1 after 20 thermal cycles of 0–60 °C. Therefore, such outstanding catalytic performance of pyroelectric BZT-0.5BCT fibers enables pyroelectric catalysis as a potential approach for both all-round wastewater treatment and CO2 reduction.

Effect of Pulsed Electric Field Pre-Treatment and the Freezing Methods on the Kinetics of the Freeze-Drying Process of Apple and Its Selected Physical Properties.

The aim of this study was to investigate the effect of application of pulsed electric field (PEF) and different freezing methods (fast, slow and vacuum freezing) on the drying kinetics as well as selected physical properties of freeze-dried apple. The apples were subjected to PEF treatment with range of pulses from 0 to 160 and the intake energy from 0 to 1327 kJ·g−1. Apples with and without PEF treatment were frozen with different rates and the freeze-dried. The water content, water activity and colour attributes of freeze-dried apples were investigated. Regression analysis and fitting procedures showed that among six different models, the Midilli et al. model the best described the drying curves of all dried samples. The highest value of the parameter L* = 71.54 was obtained for freeze-dried sample prepared without PEF pre-treatment and fast frozen. Application of PEF pre-treatment resulted in increase in browning index of freeze-dried apples (BI). The studies confirmed the positive effect of PEF on the freeze drying rate only in the case of the slow or fast freezing of the material after the application of low-energy PEF treatment. However, the increase in drying rate was also observed after application of slow and vacuum freezing of the material without PEF pre-treatment. These technologies can be recommended for optimization of the freeze drying process of apples. The statement that the freeze drying process with application of appropriately selected PEF processing parameters causing only partial destruction of cell membranes can be considered as an innovative contribution to the development of science about the possibilities of PEF application.

The oxidative stress, mitochondrial pathway apoptosis, and the antagonistic effects of chrysophanol in SH-SY5Y cells via DTPP-induced photodynamic therapy

BackgroundTo investigate the susceptibility of SH-SY5Y cells to DTPP-based photodynamic therapy (PDT) and the antagonistic effects of chrysophanol (Chr) on PDT. MethodsPDT photocytotoxicity to cells was quantified and determined by exposing increasing concentrations of DTPP between 2.5 to 20 μg/mL to radiation with energy densities of 1.2–9.6 J/cm2 at 630-nm wavelength. Sodium azide (SA, NaN3) and d-mannitol (DM) were employed to study the reaction type of PDT. The photodynamic stress after PDT was assessed by superoxide dismutase (SOD), malondialdehyde (MDA), and total antioxidative capacity (T-AOC) assays. The apoptosis pathway of SH-SY5Y cells after PDT was studied by the determination of JC-1 and caspase-9/Caspase-3 concentrations. MTT and double fluorescence staining assays were applied to study the effect of Chr on cell survival and apoptosis rate in PDT, respectively. PI was used to detect the effect of Chr on cell membrane integrity after DTPP-PDT treatment. ResultsThe dose-dependent killing effect of high DTPP concentrations and irradiation doses were identified. Cell apoptosis is mediated by a mitochondrial pathway with a total apoptosis rate of 33.8% at 10 μg/mL of DTPP after irradiation with 2.4 J/cm2. Oxidative stress was produced by ROS in PDT and non-reversible cell oxidative damage appeared due to the cells’ modulation of the oxidative stress balance during the PDT response. Chr had a- effect on ROS capture and an inhibitory effect on the PDT-induced destruction of cell membranes. ConclusionsSH-SY5Y cells were susceptible to DTPP-PDT, resulting in a mitochondrial apoptosis pathway. There is an antagonistic effect of Chr on PDT in SH-SY5Y neuroblastoma cells.

Antibacterial Activity of Honey in Combination with Cinnamon

Emergence of antimicrobial resistance (AMR) is a major global concern today. High prevalence of multidrug resistant (MDR) bacteria cause the treatments to be less effective or ineffective and finally leads to higher rates of mortality. This situation urges the development of novel antimicrobial agents. Natural products have gained more attention as safe and cost-effective sources of candidate compounds. Honey possesses a potent antibacterial activity against a wide range of bacteria. High osmolarity, acidic pH, hydrogen peroxide production, and presence of nonperoxide compounds provide various mechanisms for honey to act against bacteria. Cinnamon also has the ability to act on a number of bacteria through destruction of cell membranes, anti-quorum sensing effect, ATPase inhibition and membrane porins inhibition. Thus, the combinations of honey and cinnamon have shown important interactions such as synergistic, additive and antagonistic effects due to the interactions among various constituents in them. Their combined action varies depending on the honey type, cinnamon plant species, cinnamon extract type, etc. Therefore, both honey and cinnamon can be considered as good candidates for developing new antimicrobial agents. Further studies are required to isolate and identify bioactive compounds and to clarify their exact mechanisms of action, antibacterial spectrum, and toxicities.

Disinfection effect and mechanism of neutral electrolyzed water on Staphylococcus albus

To evaluate the disinfection efficacy and mechanism of neutral electrolyzed water(NEW) on Staphylococcus albus. The bactericidal effect of NEW was observed through suspension quantitative bactericidal test. In addition, to analyze the mechanism of NEW, the leakage of bacterial contents and enzyme activity were tested, and the damage of bacterial protein and DNA were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis and agarose gel electrophoresis. After treated with NEW for 1 min, staphylococcus albus in suspension(2.07×10~7 CFU/mL)were reduced to below the detection limit(<10 CFU/mL), with killing rate >99.999% and killing log value >5. NEW could destroy the integrity of the cell membrane, resulting in the leakage of Ca~(2+), K~+, protein and nucleic acid, and change the activity of superoxide dismutase(SOD), peroxidase(POD), catalase(CAT) and other enzymes, it could also damage protein and DNA. NEW can effectively kill Staphylococcus albus in suspension, and its mechanism involves the destruction of cell membrane, bacterial protein and nucleic acid, and the change of enzyme activity.

Novel functionalized selenium nanowires as antibiotic adjuvants in multiple ways to overcome drug resistance of multidrug-resistant bacteria.

Methicillin-resistant Staphylococcus (MRS) is a multi-drug resistant bacteria that pose a serious threat to human health. Antibacterial nanomaterials are becoming a promising antibiotic substitute or antibiotic adjuvants. In this work, selenium nanowires were modified with nano‑silver (Ag NPs) with antibacterial activity and [Ru(bpy)2dppz]2+ with fluorescent labeling of DNA (SRA), and the antibacterial activity, antibacterial mechanism and biological toxicity of SRA synergistic antibiotics were studied. In vitro, antibacterial results show that SRA (12μg/mL) improves the antibacterial activity of various antibiotics against resistant bacteria and significantly slows the development of bacterial resistance to antibiotics. Studies on antibacterial mechanisms have shown that SRA synergistic antibiotics destroy drug-resistant bacteria through a combination of physical (physical damage) and chemical pathways (destruction of biofilm, membrane depolarization, cell membrane destruction, adenosine triphosphate consumption and reactive oxygen species production). Transcriptomics analysis found that SRA affects bacterial activity by affecting bacterial biosynthesis, ATP synthesis and biofilm formation. Furthermore, SRA synergistic antibiotics can accelerate wound healing of bacterial infection by reducing the inflammatory response. The toxicity evaluation results show that SRA has extremely low cellular and in vivo toxicity. SRA has the potential of clinical application as multiple antibiotic adjuvants to deal with resistant bacterial infections.