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The aquaporin‐4 (AQP4) water channel is abundantly expressed in the glial cells of the central nervous system and facilitates brain swelling following diverse insults, such as traumatic injury or stroke. Lack of specific and therapeutic AQP4 inhibitors highlights the need to explore alternative routes to control the water permeability of glial cell membranes. The cell surface abundance of AQP4 in mammalian cells fluctuates rapidly in response to changes in oxygen levels and tonicity, suggesting a role for vesicular trafficking in its translocation to and from the cell surface. However, the molecular mechanisms of AQP4 trafficking are not fully elucidated. In this work, early and recycling endosomes were investigated as likely candidates of rapid AQP4 translocation together with changes in cytoskeletal dynamics. In transiently transfected HEK293 cells a significant amount of AQP‐eGFP colocalised with mCherry‐Rab5‐positive early endosomes and mCherry‐Rab11‐positive recycling endosomes. When exposed to hypotonic conditions, AQP4‐eGFP rapidly translocated from intracellular vesicles to the cell surface. Co‐expression of dominant negative forms of the mCherry‐Rab5 and ‐Rab11 with AQP4‐eGFP prevented hypotonicity‐induced AQP4‐eGFP trafficking and led to concentration at the cell surface or intracellular vesicles respectively. Use of endocytosis inhibiting drugs indicated that AQP4 internalisation was dynamin‐dependent. Cytoskeleton dynamics‐modifying drugs also affected AQP4 translocation to and from the cell surface. AQP4 trafficking mechanisms were validated in primary human astrocytes, which express high levels of endogenous AQP4. The results highlight the role of early and recycling endosomes and cytoskeletal dynamics in AQP4 translocation in response to hypotonic and hypoxic stress and suggest continuous cycling of AQP4 between intracellular vesicles and the cell surface under physiological conditions. [ABSTRACT FROM AUTHOR]

The osmotic stress imposed on microorganisms by hypotonic conditions is perceived to regulate water and solute flux via cell membranes, which are crucial for survival. Some cells that fail to perceive osmotic stress die because this results in the rupture of the cell membrane. The flux through the membrane is characterized by the membrane permeability, which is measured using a stopped-flow apparatus in response to a millisecond-order osmolarity change. However, the obtained data are an ensemble average of each cell response. Additionally, the measurement of permeability, considering cellular viability, contributes to a more accurate evaluation of osmoadaptation. Here, we present a novel on-chip instantaneous extracellular solution exchange method using an air–liquid interface. The presented method provides a concurrent evaluation at the single-cell level in response to a millisecond-order osmotic shock, considering cellular viability by solution exchange. This method utilizes a liquid bridge with a locally formed droplet on the surface of a micropillar fabricated inside a microchannel. We evaluated a solution exchange time of 3.6 ms and applied this method to Synechocystis PCC 6803 under two different osmolarity conditions. The live/dead ratio of 1 M to 0.5 M osmotic down shock condition was 78.8/21.2% while that of 1 M to 0.25 M osmotic down shock condition was 40.0/60.0%. We evaluated the water permeability of two groups: cells that were still live before and after osmotic shock (hereafter named cell type 1), and cells that were live before but were dead 10 minutes after osmotic shock (hereafter named cell type 2). The results indicated that the water permeability of cell type 2 was higher than that of cell type 1. The results obtained using the presented methods confirmed that the effect of osmotic stress can be accurately evaluated using single-cell analysis. [ABSTRACT FROM AUTHOR]

This study was aimed to develop an efficient tumour-targeted liposome nanobubbles (LNBs) system using ultrasound-targeted nanobubble destruction for enhanced release and transfection of miRNA-199a-3p in hepatocellular carcinoma (HCC) therapy. The prepared LNBs comprised a polyethylene glycol-modified liposome shell and a perfluoropentane (PFP) core. MiRNA-199a-3p was attached to the nanocomposite surface via electrostatic adsorption, while RGD peptide functionalized the LNBs surface for enhanced HCC cell targeting, namely PFP@miR-RGD-LNBs. The LNBs were spherical with a narrow size distribution. The gene-loaded LNBs effectively condensed miR-199a-3p and protected it from enzymatic degradation. Low-intensity focused ultrasound (LIFU) promoted a fast release of miR-199a-3p from the prepared LNBs, thereby enhancing therapeutic effects. The combined application of PFP@miR-RGD-LNBs and LIFU exhibited a more potent inhibitory effect on HepG2 cells than the other groups, potentially due to LIFU promoting rapid and efficient gene release at the target site and increasing cell membrane permeability. Quantitative reverse transcription-polymerase chain reaction analysis revealed significantly increased mRNA expression levels of key apoptosis markers (Bad, Bax, Caspase-9 and Caspase-3) in the PFP@miR-RGD-LNBsþLIFU group compared to other groups. These findings suggest that the prepared LNBs are highly likely to be promising candidates for further exploration of HCC gene delivery and therapy. [ABSTRACT FROM AUTHOR]

The canonical autophagy pathway in mammalian cells sequesters diverse cytoplasmic cargo within the double membrane autophagosomes that eventually convert into degradative compartments via fusion with endolysosomal intermediates. Here, we report that autophagosomal membranes show permeability in cells lacking principal ATG8 proteins (mATG8s) and are unable to mature into autolysosomes. Using a combination of methods including a novel in vitro assay to measure membrane sealing, we uncovered a previously unappreciated function of mATG8s to maintain autophagosomal membranes in a sealed state. The mATG8 proteins GABARAP and LC3A bind to key ESCRT‐I components contributing, along with other ESCRTs, to the integrity and imperviousness of autophagic membranes. Autophagic organelles in cells lacking mATG8s are permeant, are arrested as amphisomes, and do not progress to functional autolysosomes. Thus, autophagosomal organelles need to be maintained in a sealed state in order to become lytic autolysosomes. Synopsis: Mammalian ATG8s (mATG8s) interact with ESCRT‐I components to maintain autophagosomal membranes in a sealed, nonporous state that enables autophagic intermediates to progress into lytic organelles. mATG8s bind and recruit ESCRT components to maintain autophagic membranes in a sealed state impermeable to solutesBoth LC3 and GABARP subsets of mATG8s are requiredThe most widely used marker of autophagy, LC3B, is not involved in these processesAutophagic organelles not maintained in a sealed state are arrested at the amphisomal stage [ABSTRACT FROM AUTHOR]

Glucose is widely used as an osmotic agent in fluids for peritoneal dialysis. The aim of this work was to study the effect of glucose on the expression of the aquaporin-1 (AQP1) water channel and TonEBP transcription factor, as well as on plasma membrane water permeability of cells in the primary culture of Wistar rat mesenteric mesotheliocytes, using fluorescence microscopy with the intracellular fluorescent dye сalcein. mRNA contents were assessed by real time RT-PCR. Preincubation of cells in a DMEM medium containing glucose (2.3%, 24 h, 37°C, 5% CO2) led to a decrease in the expression of the aqp1 gene by about 60% (control 0.87 ± 0.18; glucose 0.34 ± 0.12, n = 9, p < 0.05) and the tonebp gene by 20% (control 0.37 ± 0.024; glucose 0.3 ± 0.012, n = 9, p < 0.05). A 40% decrease in plasma membrane water permeability of peritoneal mesotheliocytes was also observed after 24-h preincubation with glucose (control 7.3E-3 ± 1.3E-3 (cm/s), n = 27; glucose 4.3E-3 ± 3.8E-4 (cm/s), n = 57, p < 0.01). These results indicate that glucose can exert an inhibitory effect on transport processes in peritoneal mesothelial cells, which, under multiple exposures, may result in structural and functional disorders of the peritoneal membrane. [ABSTRACT FROM AUTHOR]

Composite preparations based on rhamnolipid biosurfactants and N-containing heterocyclic 1,4-naphthoquinone derivatives were obtained. The formation of the compositions was confirmed by UV spectroscopy, dynamic light scattering and changes in the surface tension of the compositions in comparison with the original solutions. Physicochemical and biological properties of composite drugs have been studied. The anticonvulsant effect was assessed using the pentylenetetrazole (PTZ) model. Doses of PTZ for induction of clonictonic seizures (DCTC) and tonic extension (DTE) were calculated relative to control. The effect of rhamnolipid on increasing the permeability of cell membranes for compounds 1a-e was evaluated indirectly by studying anticonvulsant activity. Compound (2-chloro3-((3-(p-tolyl)-1H-pyrazol-5-yl)amino) naphthalene-1,4-dione) (1b) in combination with rhamnolipid was found to have a higher anticonvulsant activity DCTC and DTE averaged 239% and 244%, respectively, which may indicate an improvement of the penetration of the compound when in complex with rhamnolipid into the cell and as a result, an increased anticonvulsant activity of the composite drug. [ABSTRACT FROM AUTHOR]

Peanut sprout (longevity sprout) is one kind of favored food and therapy, due to its crisp taste and unique flavor. The energy, protein, and crude fat content of peanut buds after germination is significantly higher than that of various vegetables. There is a great increase in the content of vitamins, potassium, magnesium minerals, and various amino acids and trace elements required by the human body, especially the content of resveratrol, a polyphenol with important bioactive functions. Among them, resveratrol (chemically known as 3, 4', 5-astragalotriphenol) has the broad-spectrum antibacterial activity as the "plant antitoxin" in recent years. But, there are only a few reports on the effects of peanut bud resveratrol on Salmonella typhimurium. This study was focused on the isolation and purification technique of resveratrol from peanut buds, together with its antibacterial properties. The resins were screened with excellent adsorption and desorption properties for the peanut bud resveratrol compounds, in order to construct the isolation and purification process. The antibacterial efficacy was evaluated to improve the comprehensive utilization of peanut resources. A comparison was made to determine the effects of 16 types of macroporous resins on the separation and purification of arachidonic resveratrol compounds using static adsorption-desorption tests. The LSA-40 was selected as the best adsorption resin for the saturation and plateau in 110 and 90min of static adsorption, respectively. The dynamic adsorption-desorption conditions were optimized as follows. The loading concentration was 120.00 μg/mL, the flow rate was 1.00 mL/min, the pH value was 4.2, and the optimum ratio of loading volume to resin was 8.00 mL/g. The desorption conditions were the 80% ethanol solution, a pH value of 6.6, and a flow rate of 1.00 mL/min. Ultraviolet (UV) spectral analysis showed that the absorption peaks of the purified arachidonic resveratrol and the control were basically the same under the optimized process conditions, where the purity was calculated to be 84.0%. Fourier infrared spectroscopy and ultra-performance liquid chromatography-tandem mass spectrometry were used to identify the components of the purified samples. It was found that the main components of the purified products were resveratrol and the derivatives. The inhibition effect of the purified product on Salmonella typhimurium was evaluated by multiplicative dilution, inhibition growth curve, and cell membrane permeability. The minimum inhibitory concentration of resveratrol-purified product on Salmonella typhimurium was 250 μg/mL. In addition, Salmonella typhimurium treated with resveratrol purification presented a prolonged lag period and a decreased growth rate in the logarithmic phase at the MIC concentration. The cell membrane permeability significantly increased (P < 0.01), according to the growth curve and the protein content of cell contents. The integrity of the cell wall was damaged causing the serious leakage of intracellular proteins, eventually leading to the death of Salmonella typhimurium. This finding can provide some theoretical reference for the comprehensive utilization of peanut resources in natural antibacterial agents. [ABSTRACT FROM AUTHOR]

• Heterogeneous multiscale modelling of drug delivery in biological tissues considering the cell membrane permeability. • A permeable interface method based on the central-type finite difference discretization is developed. • Lower solute permeability of the cell membrane decreases the drug penetration. • Drug penetration can be increased with the specific choice of cell shape irrespective of the cell membrane permeability. • Drug penetration can vary with the cell shape even the tissue domain's porosity (ECM volume) remains unchanged. This article presents a finite volume heterogeneous multiscale method (FVHMM-p) to study drug delivery into biological tissues. The FVHMM-p accounts for the passive diffusion across the cell membrane, and the algorithm involves models at two scales: macroscale (tissue scale) and microscale (cell scale). The passive diffusion across membranes is treated in the microscale model which is apparently a three-compartment model; the first compartment involves solute diffusion in extracellular space, the second one includes diffusivity across the cell membrane, and the third one is meant for diffusion in the intracellular space. For the microscale model simulation, a permeable interface method based on central-type finite difference discretization is developed. This model is coupled with the tissue scale model to enforce the cellular (microscale) effects. Furthermore, the effects of cell membrane permeability and drug particle size on distribution and penetration of drug nanoparticles in tissues are investigated by conducting numerical experiments. The cell is considered to be elliptical, and the simulations with different configurations lead to the pronounced effects. The proposed model will be able to identify the optimal strategies in drug delivery. [ABSTRACT FROM AUTHOR]

• R-MnO2 electrodes were used in capacitive system to inactivate microbes successfully. • Bacterial membrane permeability and intracellular ROS levels increase significantly after 5 min capacitance treatment. • Capacitive system was applied as pretreatment for ozonation to reduce O3 dosage and DBPs. • The performance of capacitance-O3 process is proved better than the sum of two individual process efficiencies. • A clean and efficient sequential process was rationally designed for water disinfection. The application of ozone (O 3) disinfection has been hindered by its low solubility in water and the formation of disinfection by-products (DBPs). In this study, capacitive disinfection is applied as a pre-treatment for O 3 oxidation, in which manganese dioxide with a rambutan-like hollow spherical structure is used as the electrode to increase the charge density on the electrode surface. When a voltage is applied, the negative-charged microbes are attracted to the electrodes and killed by electrical interactions. The contact between microbes and capacitive electrodes leads to changes in cell permeability and burst of reactive oxygen species, thereby promoting the diffusion of O 3 into the cells. After O 3 penetrates the cell membrane, it can directly attack the cytoplasmic constituents, accelerating fatal and irreversible damage to pathogens. As a result, the performance of the capacitance-O 3 process is proved better than the direct sum of the two individual process efficiencies. The design of capacitance-O 3 system is beneficial to reduce the ozone dosage and DBPs with a broader inactivation spectrum, which is conducive to the application of ozone in primary water disinfection. [ABSTRACT FROM AUTHOR]

• UV222 suppressed photoreactivation of E. coli by 2-log compared with UV254. • UV222 disinfection damaged multiple cellular targets—DNA, protein, and the cell membrane. • UV222 induced DNA damage at fewer sites than UV254, but the damage was more severe. • UV222 damaged the E. coli cell membrane by photolyzing membrane lipid and protein. • UV222 photolyzed nucleic acid bases and amino acids. Low-pressure mercury lamps emitting at 254 nm (UV254) are used widely for disinfection. However, subsequent exposure to visible light results in photoreactivation of treated bacteria. This study employed a krypton chloride excimer lamp emitting at 222 nm (UV222) to inactivate E. coli. UV222 and UV254 treatment had similar E. coli -inactivation kinetics. Upon subsequent irradiation with visible light, E. coli inactivated by UV254 was reactivated from 2.71-log to 4.75-log, whereas E. coli inactivated by UV222 showed negligible photoreactivation. UV222 treatment irreversibly broke DNA strands in the bacterium, whereas UV254 treatment primarily formed nucleobase dimers. Additionally, UV222 treatment caused cell membrane damage, resulting in wizened, pitted cells and permeability changes. The damage to the cell membrane was mainly due to the photolysis of proteins and lipids by UV222. Furthermore, the photolysis of proteins by UV222 destroyed enzymes, which blocked photoreactivation and dark repair. The multiple damages can be further evidenced by 4.0–61.1 times higher quantum yield in the photolysis of nucleobases and amino acids for UV222 than UV254. This study demonstrates that UV222 treatment damages multiple sites in bacteria, leading to their inactivation. Employing UV222 treatment as an alternative to UV254 could be viable for inhibiting microorganism photoreactivation in water and wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a foodborne bacterial pathogen that seriously threatens dairy product safety and human health, hence effective and available antibacterial agents are urgently needed. This study aims to investigate the antibacterial mechanism of a recombinant enterocin CHQS against L. monocytogenes and its antibacterial effect on pasteurized milk. The minimum inhibitory concentration (MIC) of CHQS was 0.5 μg/mL in both TSB medium and tenfold diluted pasteurized milk. The anti- L. monocytogenes rate of 2 h reached 99.94% with the treatment of the 2 MIC of CHQS in the diluted pasteurized milk. CHQS led to the massive release of proteins and nucleic acids and the significant increase in propidium iodide (PI) uptake, indicating that integrity and permeability of the cell membrane were destroyed. The cell membrane and structure of L. monocytogenes were severely disrupted by observing with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Intracellular reactive oxygen species (ROS) level was increased to 2.18-fold with the 2 MIC CHQS treatment. CHQS at sub-MICs inhibited the biofilm formation and motility of L. monocytogenes in a concentration-dependent manner. In MIC treatment group, the number of L. monocytogenes was 4.55 log 10 CFU/mL fewer than the control group and the bacterial abundance of L. monocytogenes remained a low level (0.22%) on the 12th day of storage at 4 °C in pasteurized milk. The study suggested the antibacterial mechanism of CHQS and its application potentiality in pasteurized milk. • The antibacterial mechanism of a recombinant enterocin CHQS against L. monocytogenes was investigated. • The antibacterial effect of CHQS on pasteurized milk was explored. • CHQS inhibited L. monocytogenes growth by disrupting the integrity and permeability of cell membranes. • CHQS can stimulate ROS generation and inhibit the motility and biofilm formation of L. monocytogenes. [ABSTRACT FROM AUTHOR]

The Pseudomonas aeruginosa toxin ExoS, secreted by the type III secretion system (T3SS), supports intracellular persistence via its ADP-ribosyltransferase (ADPr) activity. For epithelial cells, this involves inhibiting vacuole acidification, promoting vacuolar escape, countering autophagy, and niche construction in the cytoplasm and within plasma membrane blebs. Paradoxically, ExoS and other P. aeruginosa T3SS effectors can also have antiphagocytic and cytotoxic activities. Here, we sought to reconcile these apparently contradictory activities of ExoS by studying the relationships between intracellular persistence and host epithelial cell death. Methods involved quantitative imaging and the use of antibiotics that vary in host cell membrane permeability to selectively kill intracellular and extracellular populations after invasion. Results showed that intracellular P. aeruginosa mutants lacking T3SS effector toxins could kill (permeabilize) cells when extracellular bacteria were eliminated. Surprisingly, wild-type strain PAO1 (encoding ExoS, ExoT and ExoY) caused cell death more slowly, the time extended from 5.2 to 9.5 h for corneal epithelial cells and from 10.2 to 13.0 h for HeLa cells. Use of specific mutants/complementation and controls for initial invasion showed that ExoS ADPr activity delayed cell death. Triggering T3SS expression only after bacteria invaded cells using rhamnose-induction in T3SS mutants rescued the ExoS-dependent intracellular phenotype, showing that injected effectors from extracellular bacteria were not required. The ADPr activity of ExoS was further found to support internalization by countering the antiphagocytic activity of both the ExoS and ExoT RhoGAP domains. Together, these results show two additional roles for ExoS ADPr activity in supporting the intracellular lifestyle of P. aeruginosa; suppression of host cell death to preserve a replicative niche and inhibition of T3SS effector antiphagocytic activities to allow invasion. These findings add to the growing body of evidence that ExoS-encoding (invasive) P. aeruginosa strains can be facultative intracellular pathogens, and that intracellularly secreted T3SS effectors contribute to pathogenesis. Author summary: While the ADPr domain of the T3SS effector ExoS plays multiple roles in the intracellular lifestyle of P. aeruginosa, ExoS can also be cytotoxic and/or antiphagocytic. Here, we show that when P. aeruginosa enters the cytosol of epithelial cells, cell death is triggered independently of T3SS effector toxins, but ExoS ADPr activity delays this to enable continued intracellular survival and replication. Using rhamnose induction to express the T3SS only after invasion restored this ExoS-dependent phenotype, showing that intracellularly secreted effectors can enable intracellular pathogenesis. ExoS ADPr activity also countered antiphagocytic activity of ExoS and ExoT RhoGAP domains. These results show two additional roles for ExoS ADPr activity in promoting internalization of P. aeruginosa and protecting the intracellular niche, continuing to challenge the notions that P. aeruginosa is exclusively an extracellular pathogen, that it needs to inject T3SS effectors across plasma membranes, and that ExoS is necessarily cytotoxic to host cells. [ABSTRACT FROM AUTHOR]

The potential use of Ligilactobacillus salivarius -derived bacteriocin for the control of L. monocytogenes was investigated. The purpose of the study was to explore the antibacterial action mode of crude bacteriocin C2-1 from Ligilactobacillus salivarius C2-1 against Listeria monocytogenes CICC 21633. The inhibition zone diameter of crude bacteriocin C2-1 was 27.82 ± 0.3 mm against L. monocytogenes CICC 21633, and the minimum inhibitory concentration (MIC) of bacteriocin C2-1was 13.98 μg/mL. Bacteriocin C2-1 significantly inhibited the normal growth of L. monocytogenes CICC21633, is sensitive to proteinase K, trypsin, and pepsin, and has good thermal stability and acid tolerance. The antibacterial mode of bacteriocin C2-1 against L. monocytogenes CICC 21633 was discussed based on changes in cell membrane permeability, integrity, and morphological structure of L. monocytogenes CICC 21633 by measuring the conductivity, UV-absorbing substance content and the observation via scanning electron microscopy, respectively. These results demonstrated that bacteriocin C2-1 affected the cell membrane permeability and integrity of L. monocytogenes CICC 21633, resulting in intracellular material leakage. Furthermore, bacteriocin-producing genes were identified in the genome sequence using antiSMASH and BAGEL4 assays. Bacteriocin C2-1 might be a good biological food preservative to prevent L. monocytogenes infestation. • Bacteriocin C2-1 has antimicrobial activity against Listeria monocytogenes CICC 21633. • Bacteriocin C2-1 can strongly inhibit the normal growth of Listeria monocytogenes CICC 21633. • High heat stability, pH tolerance, and protease sensitivity are all characteristics of bacteriocin C2-1. • The antibacterial action mode of bacteriocin C2-1 was studied against Listeria monocytogenes CICC 21633. • Whole-genome sequencing analysis revealed the presence of bacteriocin biosynthetic gene clusters in Lb. salivarius C2-1. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the dynamics of superoxide anion radical (O•2–) production rate and alterations in DNA content and permeability of cell membranes in etiolated wheat seedlings (Triticum aestivum L. cv. Harmony) as well as those grown under normal daylight regime. The results suggest that the development of etiolated wheat seedlings and those grown under normal daylight is accompanied by the periodic formation of O•2– which leads to alterations in DNA content as well as the permeability of cell membranes. The results also indicate that the first enhancement in the rate of O•2– generation was detected on the sixth and seventh days of development, after which the rate of O•2¯ production reduced in etiolated seedlings and those grown under normal daylight regime. The second maximum of the O•2¯ producing rate in developing and senescent organs occurred on the ninth day of plant development. The lowest values of all studied parameters, such as O•2– producing rate (37%), total genomic DNA concentration (58%) and electrolyte leakage (EL; 18%) were observed in etiolated wheat seedlings. Towards the end of the study period, DNA concentration and EL in organs of wheat seedlings declined, suggesting possible destruction of cellular organelles and the beginning of apoptotic processes. Overall, these results indicate that O•2– generation is decisive for normal morphogenesis, and it is an indispensable element of synchronous growth and development. [ABSTRACT FROM AUTHOR]

Cell membrane permeability is one of the main indicators of cytotoxicity and related to many critical biological pathways. Here, we determined the Cd2+-induced membrane permeability of human MCF-7 cells using ferrocene methanol molecular probes based on scanning electrochemical microscopy (SECM). The cell height and topography were examined with an impermeable Ru(NH3)6Cl3 probe. The membrane permeability exhibited no significant changes when the Cd2+ incubation time was less than 2 h and its concentration was less than 40 μM. The permeability increased when the Cd2+ concentration was greater than 60 μM, or when the incubation time was longer than 3 h. From the combined 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and cytoskeleton imaging experiments, it was found that the changes occurred because the cells exhibited a defensive mode and their membranes contracted when treated with a low concentration of Cd2+ for a short time. However, the cell membranes were irreversibly damaged when the cytoskeleton structures were destroyed, and the cell activities decreased at high concentrations over long periods. Interestingly, through the comparison with an x-scan study, it was found that DPV technology shows a higher performance in the detection of changes in the membrane permeability. Using a combination of cytoskeleton fluorescence imaging and cell-viability tests, the effect of the cadmium metal on the cell membrane permeability can be explored deeper and more comprehensively. This study provides a new idea for exploring the changes in the cell membrane permeability and may be helpful for rapid evaluation of cytotoxicity. [ABSTRACT FROM AUTHOR]

Photodynamic therapy has always been an antibacterial tool for solving multi-drug resistant bacteria problem, but the side effects and the low efficiency due to the high aggregation and low solubility of photosensitizers limit its application. Due to the anti-inflammatory effect of caffeic acid, two novel photosensitizers (CA-1-TBO, CA-TBO) were synthesized by conjugating caffeic acid with toluidine blue O (TBO). The structures have been characterized by 1HNMR and high-resolution mass spectrometry. The UV–vis absorption, fluorescence spectra and the octanol-water partition coefficient of two photosensitizers were measured to evaluate their photophysical properties and hydrophilic/hydrophobic properties. Compared with parent TBO, the two modified photosensitizers have shown a higher quantum yield and kinetics constants of singlet oxygen, which has been supported by the simulation results of density functional theory. As drug-resistant representatives of gram-positive and gram-negative bacteria, respectively, S. aureus and P. aeruginosa have been used for in vitro antibacterial experiments. The sterilization efficiencies of the two modified photosensitizers far exceed that of parent TBO. The results of the octanol-water partition coefficient and fluorescence quantification showed that modified photosensitizers CA-1-TBO and CA-TBO could be more accumulated than parent TBO. Based on scanning electron microscopy images, protein gel electrophoresis, and the conductivity of the bacterial solution, the possible mechanism of improved antibacterial photodynamic efficiencies could be induced by membrane permeability due to the caffeic acid effect. The findings demonstrate the significant potential of natural phenolic compounds in the development of photosensitizer molecules with characteristics such as more efficient, biocompatible and less side effects. • Novel photosensitizers from caffeic acid and toluidine blue O have been prepared. • CA-1-TBO and CA-TBO can penetrate bacterial membranes. • CA-1-TBO and CA-TBO could accumulate efficiently into bacterial cells. • CA-1-TBO and CA-TBO showed the enhanced aPDT efficiency. • CA-1-TBO and CA-TBO could target intracellular proteins. [ABSTRACT FROM AUTHOR]

Phospholipase A1 (PlaA) plays a pivotal role in diverse applications within the food and biochemical medical industries. Herein, we investigate the impact of the accessory protein encoded by plaS from Serratia marcescens on PlaA activity in Escherichia coli. Notably, PlaS demonstrates the ability to enhance PlaA activity while concurrently exhibiting inhibitory effects on the growth of E. coli BL21 (DE3). Our study revolves around probing the inhibitory action of PlaS on E. coli BL21 (DE3). PlaS exhibits a propensity to heighten both the permeability of outer and inner cell membranes, leading to concomitant reductions in membrane fluidity and surface hydrophobicity. This phenomenon is validated through scanning electron microscopy (SEM) analysis, which highlights PlaS's capacity to compromise membrane integrity. Moreover, through a comprehensive comparative transcriptomic sequencing approach, we identify four down-regulated genes (galM , ybhC , ldtC , and kdpB) alongside two up-regulated genes (rbsB and degP). These genes are intricately associated with processes such as cell membrane synthesis and modification, energy metabolism, and transmembrane transport. Our investigation unveils the intricate gene-level mechanisms underpinning PlaS-mediated growth inhibition and membrane disruption. Consequently, our findings serve as a significant reference for the elucidation of membrane protein mechanisms, shedding light on potential avenues for future exploration. • The accessory protein PlaS located on cell membranes • PlaS damage the integrity of cell membrane and inhibit the growth of E. coli. • PlaS affect the permeability, fluidity and hydrophobicity of E. coli. • Comparative transcriptomic analysis the mechanism of PlaS [ABSTRACT FROM AUTHOR]

Values of cell membranes permeability coefficients for water and molecules of cryoprotective agents (CPAs) are the necessary characteristics for developing physical-mathematical models describing mass transfer processes through cell membranes in order to predict optimal cell cooling rates. We carried out a comparative analysis of the permeability coefficients of mouse oocyte membranes for molecules of water, ethylene glycol (EG), propane-1,2-diol (1,2-PD) and dimethyl sulfoxide (Me 2 SO), determined by applying the classical Kedem-Katchalsky model, which considers only the penetration of non-electrolyte molecules (water and CPA) through the membrane, and the model developed by us, which takes into account the transmembrane transfer of ions and the associated changes in the transmembrane electric potential. We shown that calculations based on the developed modified model provide lower values of the permeability coefficients of the oocyte membrane for water and CPA molecules. What is important that the obtained by our modified model permeability coefficients for water molecules do not depend on the type of cryoprotectant, while the application of the classical model both in our studies and works of other authors always gave different values of these coefficients in solutions with different cryoprotectants. Our modified model also makes it possible to determine the dynamics of the transmembrane electric potential of the cell under the conditions of transmembrane mass transfer and the duration of the membrane being influenced by the changes in electric potential, that is a parameter that can directly affect the viability of cells. • The physical-mathematical model for determining of cell's permeability coefficients considering transmembrane ion transfer. • Modified model makes it possible to determine the dynamics of the transmembrane potential during cryoprotectant penetration. • Maximum change in the transmembrane potential depend on the rate of the cryoprotectant penetration into the cell. • Our model provides values of permeability coefficients for water that do not depend on the type of cryoprotectant. [ABSTRACT FROM AUTHOR]

The aims of this study were to use metagenomics to reveal the fates of antibiotic resistance genes (ARGs) during composting under the regulation of peroxydisulfate and clarify the relationship between ARGs and cell membrane permeability. Results showed that peroxydisulfate increased cell membrane permeability by effectively regulating the expression of outer membrane protein and lipopolysaccharide related genes. Besides, it reduced polysaccharides and proteins in extracellular polymer substances by 36% and 58%, respectively, making it easier for intracellular ARGs (i-ARGs) to reach the extracellular environment, among which the absolute intracellular abundance of mphK , Erm(31) , and tet(44) decreased to 1.2, 1.0, and 0.89 fold of the control, respectively. Finally, variation partitioning analysis showed that i-ARGs dominated the removal of ARGs. These results revealed that the removal of i-ARGs by activated peroxydisulfate was the key to the removal of ARGs and increased cell membrane permeability played a key role for peroxydisulfate to remove i-ARGs during composting. [Display omitted] • The fates of ARGs in response to peroxydisulfate were revealed by metagenomics. • Peroxydisulfate promoted the degradation of extracellular polymeric substances. • Peroxydisulfate increased the permeability of cell membranes. • Increased membrane permeability led to more i-ARGs to extracellular environment. • The removal of i-ARGs dominated the removal of ARGs. [ABSTRACT FROM AUTHOR]

As a common polymer, poly (dimethylaminoethyl methacrylate) (PDMAEMA) is mainly used to synthesize medical materials. However, there are few reports about the related polymer fluorescent probes. Moreover, as far as we know, no one has studied the effect of its molecular weight on the performance of polymer probes. In this work, polymer probes (NapNH 2 (1) -PDM (4) , NapNH 2 (1) -PDM (9) , NapNH 2 (1) -PDM (23) , NapNH 2 (1) -PDM (34) ) with different molecular weights were accurately constructed based on 1,8-naphthalimide fluorophore and poly(N , N -dimethylaminoethyl methacrylate) and their photophysical properties were systematically studied. The test results showed that they all showed good photophysical properties. Moreover, the polymer probe NapNH 2 (1) -PDM (23) , which had the best self-assembly effect and good cell permeability, was successfully screened by confocal fluorescence imaging technology. Not only that, the probe NapNH 2 (1) -PDM (23) could also label lysosomes in cells quickly and accurately. Therefore, this work provided important reference to construct relevant polymer probes with good cell permeability in the future. [Display omitted] • A series of polymer probes with different molecular weights were accurately constructed by simple synthesis method. • A series of polymer probes exhibited good photophysical properties. • The polymer probe NapNH 2 -PDM-C could perfectly self-assemble into nanoparticles in water. • The influence of different molecular weights on the cell permeability of polymer probe was studied. • The polymer probe NapNH 2 (1) -PDM (23) could realize rapid and accurate targeted imaging of lysosomes in cancer cells. [ABSTRACT FROM AUTHOR]

The interaction between Ras and SOS1 is an attractive and promising target in discovering candidate drugs for the Ras-driven cancers. Synthesized hydrocarbon-stapled peptides simulate αH helix structure of SOS1, improve proteolytical stability and enhance cell permeability. SSOSH-5 inhibited the proliferation of pan-Ras-mutated cancer cells and induce cell apoptosis. SSOSH-5 could regulate downstream signaling pathway, such as Ras-RAF-MEK-ERK and Ras-PI3K-AKT-mTOR. [Display omitted] • Ras is the most frequently mutated gene family in numerous cancers. • The interaction between Ras and SOS1 is an attractive and promising target in discovering candidate drugs for the Ras-driven cancers. • Synthesized hydrocarbon-stapled peptides simulate αH helix structure of SOS1, improve proteolytical stability and enhance cell permeability. • SSOSH-5 inhibited the proliferation of pan-Ras-mutated cancer cells and induce cell apoptosis. • SSOSH-5 could regulate downstream signaling pathway, such as Ras-RAF-MEK-ERK and Ras-P110-AKT-mTOR. Blocking the interaction between Ras and Son of Sevenless homolog 1 (SOS1) has been an attractive therapeutic strategy for treating cancers involving oncogenic Ras mutations. K-Ras mutation is the most common in Ras-driven cancers, accounting for 86%, with N -Ras mutation and H-Ras mutation accounting for 11% and 3%, respectively. Here, we report the design and synthesis of a series of hydrocarbon-stapled peptides to mimic the alpha-helix of SOS1 as pan-Ras inhibitors. Among these stapled peptides, SSOSH-5 was identified to maintain a well-constrained alpha-helical structure and bind to H-Ras with high affinity. SSOSH-5 was furthermore validated to bind with Ras similarly to the parent linear peptide through structural modeling analysis. This optimized stapled peptide was proven to be capable of effectively inhibiting the proliferation of pan-Ras–mutated cancer cells and inducing apoptosis in a dose-dependent manner by modulating downstream kinase signaling. Of note, SSOSH-5 exhibited a high capability of crossing cell membranes and strong proteolytic resistance. We demonstrated that the peptide stapling strategy is a feasible approach for developing peptide-based pan-Ras inhibitors. Furthermore, we expect that SSOSH-5 can be further characterized and optimized for the treatment of Ras-driven cancers. [ABSTRACT FROM AUTHOR]

Bacterial infection has become a global health issue. The misuse of antibiotics has been resulting in increased drug resistance and bioaccumulation. Therefore, developing a highly safe antibacterial agent, with high antibacterial performance is demanding. Inspired by the natural motors performing automated tasks in complicated living environments, we demonstrate tadpole-like nanoparticles (TNPs) with several functions, including high photothermal conversion efficiency, peroxidase-like catalytic activity, glutathione peroxidase-like activity, and catalase-like activity. TNPs produce hydroxyl radical (•OH) at an extremely low concentration of hydrogen peroxide of 0.006%, which can damage bacterial cell membranes, proteins, and DNA. Moreover, the glutathione peroxidase-like activity disrupts the anti-oxidative mechanism of bacteria and improves the permeability of the cell membranes, consequently enhancing the killing effect of ROS. In addition, TNPs possess tadpole-like asymmetry to overcome Brownian motion, demonstrating strong directional motion propelled by O 2. The in vivo experiments indicate that TNPs could also shorten the inflammatory period and promote angiogenesis, making them a very promising antibacterial agent. [Display omitted] • A tadpole-like NPs with PTT, peroxidase-like catalytic, glutathione peroxidase-like, and catalase-like activity are synthesis. • The glutathione peroxidase-like activity improves the permeability of the cell membranes. • TNPs could also shorten the inflammatory period and promote angiogenesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Unique strategy to produce tunable FRET emission as a function of medium pH. • Maximum sensing efficiency of the biosensor at a particular pH. • Drastic FRET ON-and-OFF behavior in aqueous media. • Conformational change of the drug molecules at elevated pH resulting stable fluorescent exciplex switching off the FRET emission. • Proficient cell permeability of the sensor will help in the controlled drug delivery to tumor cell lines. The present contribution depicts a unique approach to generate tunable Förster resonance energy transfer (FRET) emission with variation of pH of the medium. The pH sensitive absorption of Doxorubicin leads to modification of spectral overlap between emission spectra of donor (Pyrazoline) and absorption spectra of acceptor (Doxorubicin) thereby sensing maximum FRET efficiency in an optimum pH (near pK a of Doxorubicin). This drug molecule exhibits an instantaneous conformation change at a particular pH, which consequences on abrupt ON-and-OFF FRET efficiency. At elevated pH, both the drug molecules exhibit conformational change and form stable fluorescent exciplex, switching off the FRET emission. Confocal fluorescence images of live HepG2 cells imply that the sensor can proficiently go through the cell membrane and can be applied in the controlled delivery of drug to the tumor cell lines. [ABSTRACT FROM AUTHOR]

It is well established that lipid aldehydes (LAs) are able to increase the permeability of cell membranes and induce their rupture. However, it is not yet clear how LAs are distributed in phase-separated membranes (PSMs), which are responsible for the transport of selected molecules and intracellular signaling. Thus, we investigate here the distribution of LAs in a PSM by coarse-grained molecular dynamics simulations. Our results reveal that LAs derived from mono-unsaturated lipids tend to accumulate at the interface between the liquid-ordered/liquid-disordered domains, whereas those derived from poly-unsaturated lipids remain in the liquid-disordered domain. These results are important for understanding the effects caused by oxidized lipids in membrane structure, properties and organization. [Display omitted] • Liquid-ordered (Lo) and liquid-disordered (Ld) phases coexist in cell membranes (lipid rafts). • The interface between the Lo/Ld domains is more susceptible to pore formation. • Lipid aldehydes (LAs) derived from mono-unsaturated lipids tend to accumulate at the interface between the Lo/Ld domains. • LAs derived from poly-unsaturated lipids remains in the Ld domain. [ABSTRACT FROM AUTHOR]

The gap between the current serious soil heavy metal (HM) contamination and the low efficiency of soil remediation threatens human health. The aim of this study was to propose a method to improve the efficiency of phytoremediation by exogenous rutin application and explain the potential mechanism. A series of rutin treatments were designed to evaluate the biomass, cadmium (Cd) accumulation and physiological and biochemical responses of Amaranthus hypochondriacus under different Cd stresses. The results showed a decline in cell membrane damage with rutin application, and more Cd ions were immobilized in the cell wall than in the vacuole, resulting in an increase in Cd tolerance in plants. The addition of rutin caused significant effects on the synthesis of glutathione (GSH), including the advancement of the conversion of GSH to phytochelatins (PCs). Among them, PC 2 and PC 3 in the leaves contributed the most to the high accumulation of Cd. Overall, the phytoremediation efficiency and phytoextraction amount of Amaranthus hypochondriacus with rutin application were improved maximumly by 219.48% and 260.00%, respectively. This study provides a constructive approach for improving the efficiency of phytoremediation by foliar application of flavonoids and contributes to the further development of soil remediation in Cd-contaminated fields. [Display omitted] • Rutin promoted the excess cadmium accumulation in A. hypochondriacus. • Rutin declined cell membrane damage and increased cell tolerance. • Rutin caused more Cd retention occurred in cell walls. • A predication model of excess Cd accumulation was carried out. • Rutin significantly elevated phytoremediation efficiency. [ABSTRACT FROM AUTHOR]

Bipolar cancellation is the phenomenon in which the permeability of cell membranes subjected to high intensity short pulsed electric field (ns-μs range) is reduced or eliminated when the system is subjected to bipolar instead of monopolar pulses. Although several studies have tried to explain bipolar cancellation, the underlying mechanisms remain unclear. Very few articles study bipolar cancellation by means of molecular dynamics (MD) simulation. In this paper, we investigated the molecular mechanisms underlying the difference in electroporation induced by bipolar and monopolar picosecond electric pulses (EPs) using MD simulation. The electric field gradients and electric forces on water molecules of the two pulses were analyzed in detail for the first time. For a certain pulse width, when the field intensity is relatively small, the direction of bipolar electric force on the interfacial water molecule reverses as the bipolar EPs reverse, while the electric force on interfacial water molecules of the cathode side remains in the same direction as that of applied monopolar EPs. The bipolar electric force reversal delays the water protrusion and increases the pore formation time. Therefore, this phenomenon could correspond to bipolar cancellation. When the field intensity is relatively large, although the bipolar electric force direction still reverses, half of the total time of the monopolar EPs has no electric fields. The electric forces of monopolar no-field half-cycles are much smaller than those of the bipolar EPs. Therefore, the pore formation time of bipolar EPs reduces, and this phenomenon is called bipolar enhancement. The occurrence of bipolar cancellation or bipolar enhancement depends on conditions such as the width and intensity of the pulse. [Display omitted] • Hypotheses about the molecular mechanism involved in bipolar cancellation • Hypotheses about the molecular mechanism involved in bipolar enhancement • Molecular mechanisms of electroporation induced by bipolar and monopolar pulse trains [ABSTRACT FROM AUTHOR]

[Display omitted] The formation of transient pores in their membranes is a well-known mechanism of permeabilization of cells exposed to high-intensity electric pulses. However, the formation of such pores is not able to explain all aspects of the so-called electroporation phenomenon. In particular, the reasons for sustained permeability of cell membranes, persisting long after the pulses' application, remain elusive. The complete resealing of cell membranes takes indeed orders of magnitude longer than the time for electropore closure as reported from molecular dynamics (MD) investigations. Lipid peroxidation has been suggested as a possible mechanism to explain the sustainable permeability of cell membranes. However, theoretical investigations of membrane lesions containing excess amounts of hydroperoxides have shown that the conductivities of such lesions were not high enough to account for the experimental measurements. Here, expanding on these studies, we investigate quantitatively the permeability of cell membrane lesions that underwent secondary oxidation. MD simulations and free energy calculations of lipid bilayers show that such lesions provide a better model of post-pulse permeable and conductive electropermeabilized cells. These results are further discussed in the context of sonoporation and ferroptosis, respectively a procedure and a phenomenon, among others, in which, alike electroporation, substantial lipid oxidation might be triggered. [ABSTRACT FROM AUTHOR]

[Display omitted] Bacteria have developed a wealth of strategies to avoid and resist the action of antibiotics, one of which involves pathogens invading and forming reservoirs within host cells. Due to the poor cell membrane permeability, stability and retention of conventional antibiotics, this renders current treatments largely ineffective, since achieving a therapeutically relevant antibiotic concentration at the site of intracellular infection is not possible. To overcome such challenges, current antibiotics are 'repurposed' via reformulation using micro- or nano-carrier systems that effectively encapsulate and deliver therapeutics across cellular membranes of infected cells. Bioinspired materials that imitate the uptake of biological particulates and release antibiotics in response to natural stimuli are recently explored to improve the targeting and specificity of this 'nanoantibiotic' approach. In this review, the mechanisms of internalization and survival of intracellular bacteria are elucidated, effectively accentuating the current treatment challenges for intracellular infections and the implications for repurposing conventional antibiotics. Key case studies of nanoantibiotics that have drawn inspiration from natural biological particles and cellular uptake pathways to effectively eradicate intracellular pathogens are detailed, clearly highlighting the rational for harnessing bioinspired drug delivery strategies. [ABSTRACT FROM AUTHOR]

DNA nanotechnology offers to build nanoscale structures with defined chemistries to precisely position biomolecules or drugs for selective cell targeting and drug delivery. Owing to the negatively charged nature of DNA, for delivery purposes, DNA is frequently conjugated with hydrophobic moieties, positively charged polymers/peptides and cell surface receptor-recognizing molecules or antibodies. Here, we designed and assembled cholesterol-modified DNA nanotubes to interact with cancer cells and conjugated them with cytochrome c to induce cancer cell apoptosis. By flow cytometry and confocal microscopy, we observed that DNA nanotubes efficiently bound to the plasma membrane as a function of the number of conjugated cholesterol moieties. The complex was taken up by the cells and localized to the endosomal compartment. Cholesterol-modified DNA nanotubes, but not unmodified ones, increased membrane permeability, caspase activation and cell death. Irreversible inhibition of caspase activity with a caspase inhibitor, however, only partially prevented cell death. Cytochrome c-conjugated DNA nanotubes were also efficiently taken up but did not increase the rate of cell death. These results demonstrate that cholesterol-modified DNA nanotubes induce cancer cell death associated with increased cell membrane permeability and are only partially dependent on caspase activity, consistent with a combined form of apoptotic and necrotic cell death. DNA nanotubes may be further developed as primary cytotoxic agents, or drug delivery vehicles, through cholesterol-mediated cellular membrane interactions and uptake. [ABSTRACT FROM AUTHOR]