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The plasma membrane forms the boundary between a living entity and its environment and acts as a barrier to permeation and flow of substances. Several computational means of calculating permeability have been implemented for molecular dynamics (MD) simulations-based approaches. Except for double bilayer systems, most permeability studies have been performed under equilibrium conditions, in large part due to the challenges associated with creating concentration gradients in simulations utilizing periodic boundary conditions. To enhance the scientific understanding of permeation and complement the existing computational means of characterizing membrane permeability, we developed a non-equilibrium method that enables the generation and maintenance of steady-state gradients in MD simulations. We utilize PBCs advantageously by imposing a directional bias to the motion of permeants so that their crossing of the boundary replenishes the gradient, like a previous study on ions. Under these conditions, a net flow of permeants across membranes may be observed to determine bulk permeability by a direct application of J = P Δ c . In the present study, we explore the results of its application to an exemplary O 2 and POPC bilayer system, demonstrating accurate and precise permeability measurements. In addition, we illustrate the impact of permeant concentration and the choice of thermostat on the permeability. Moreover, we demonstrate that energetics of permeation can be closely examined by the dissipation of the gradient across the membrane to gain nuanced insights into the thermodynamics of permeability. [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 intrinsic pathway of apoptosis is regulated by the Bcl-2 family of proteins. Inhibition of the anti-apoptotic members represents a strategy to induce apoptotic cell death in cancer cells. We have measured the membrane binding properties of a series of peptides, including modified α/β-peptides, designed to exhibit enhanced membrane permeability to allow cell entry and improved access for engagement of Bcl-2 family members. The peptide cargo is based on the pro-apoptotic protein Bim, which interacts with all anti-apoptotic proteins to initiate apoptosis. The α/β-peptides contained cyclic β-amino acid residues designed to increase their stability and membrane permeability. Dual polarisation interferometry was used to study the binding of each peptide to two different model membrane systems designed to mimic either the plasma membrane or the outer mitochondrial membrane. The impact of each peptide on the model membrane structure was also investigated, and the results demonstrated that the modified peptides had increased affinity for the mitochondrial membrane and significantly altered the structure of the bilayer. The results also showed that the presence of an RRR motif significantly enhanced the ability of the peptides to bind to and insert into the mitochondrial membrane mimic, and provide insights into the role of selective membrane targeting of peptides. The membrane binding of two peptides designed to exhibit enhanced membrane permeability to allow cell entry and engagement of Bcl-2 family members shows that an RRR motif significantly enhances peptide binding and insertion into a mitochondrial membrane mimic and provides insights into selective membrane targeting of peptides. [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]

The effect of carbon dots (CDs) on a model blayer membrane was studied as a means of comprehending their ability to affect cell membranes. Initially, the interaction of N-doped carbon dots with a biophysical liposomal cell membrane model was investigated by dynamic light scattering, z-potential, temperature-modulated differential scanning calorimetry, and membrane permeability. CDs with a slightly positive charge interacted with the surface of the negative-charged liposomes and evidence indicated that the association of CDs with the membrane affects the structural and thermodynamic properties of the bilayer; most importantly, it enhances the bilayer's permeability against doxorubicin, a well-known anticancer drug. The results, like those of similar studies that surveyed the interaction of proteins with lipid membranes, suggest that carbon dots are partially embedded in the bilayer. In vitro experiments employing breast cancer cell lines and human healthy dermal cells corroborated the findings, as it was shown that the presence of CDs in the culture medium selectively enhanced cell internalization of doxorubicin and, subsequently, increased its cytotoxicity, acting as a drug sensitizer. [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]

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]

Ultrasound with low frequency (20–100 kHz) assisted drug delivery has been widely investigated as a non-invasive method to enhance the permeability and retention effect of drugs. The functional micro/nanobubble loaded with drugs could provide an unprecedented opportunity for targeted delivery. Then, ultrasound with higher intensity would locally burst bubbles and release agents, thus avoiding side effects associated with systemic administration. Furthermore, ultrasound-mediated destruction of micro/nanobubbles can effectively increase the permeability of vascular membranes and cell membranes, thereby not only increasing the distribution concentration of drugs in the interstitial space of target tissues but also promoting the penetration of drugs through cell membranes into the cytoplasm. These advancements have transformed ultrasound from a purely diagnostic utility into a promising theragnostic tool. In this review, we first discuss the structure and generation of micro/nanobubbles. Second, ultrasound parameters and mechanisms of therapeutic delivery are discussed. Third, potential biomedical applications of micro/nanobubble-assisted ultrasound are summarized. Finally, we discuss the challenges and future directions of ultrasound combined with micro/nanobubbles. [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]

Oxygen on its transport route from lung to tissue mitochondria has to cross several cell membranes. The permeability value of membranes for O2 (PO2), although of fundamental importance, is controversial. Previous studies by mostly indirect methods diverge between 0.6 and 125 cm/s. Here, we use a most direct approach by observing transmembrane O2 fluxes out of 100 nm liposomes at defined transmembrane O2 gradients in a stopped-flow system. Due to the small size of the liposomes intra- as well as extraliposomal diffusion processes do not affect the overall kinetics of the O2 release process. We find, for cholesterol-free liposomes, the unexpectedly low PO2 value of 0.03 cm/s at 35 °C. This PO2 would present a serious obstacle to O2 entering or leaving the erythrocyte. Cholesterol turns out to be a novel major modifier of PO2, able to increase PO2 by an order of magnitude. With a membrane cholesterol of 45 mol% as it occurs in erythrocytes, PO2 rises to 0.2 cm/s at 35 °C. This PO2 is just sufficient to ensure complete O2 loading during passage of erythrocytes through the lung's capillary bed under the conditions of rest as well as maximal exercise. [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]

Apoptosis is an exquisitely controlled complex process which plays key roles in maintaining cell homeostasis. Abnormal regulation of apoptosis was directly related to severe diseases including cancer, neurodegenerative diseases, and cardiovascular diseases. Herein, we proposed a chain-engineering strategy for constructing probes to distinguish the different stages of apoptosis. Two fluorescent probes (CPI-2 and CPI-3) with very similar structure were developed to detect the late and early apoptotic stages, respectively. CPI-2 with short chain could not enter live cells due to its poor membrane permeability, and thus exclusively illuminated the nucleolus of late apoptotic cells with damaged plasma membrane. CPI-3 was permeable to biomembranes and stained mitochondria in living cells, which immigrated into the nucleolus during early apoptotic procedure due to the decrease of mitochondrial membrane potential. Furthermore, CPI-2 and CPI-3 were successfully used to monitor the different stages of apoptosis induced by different concentrations of H 2 O 2 , paclitaxel, and rotenone. Particularly, we studied the heavy metals poisoning and detoxification of cysteine by CPI-2 and CPI-3. This work provides a viable strategy for constructing probes to detect the different stages of apoptosis, which is expected to promote the development of probes to monitor apoptosis processes. [Display omitted] • A chain-engineering strategy for probes to detect the early and late apoptosis was proposed. • Two probes with similar chemical structures were developed to distinguish different apoptotic stages. • CPI-2 was impermeable to intact biomembranes which enabled detection of late apoptosis. • CPI-3 exhibited good membrane permeability which could detect early apoptosis via subcellular immigration. • Both probes were used to study heavy metal poisoning and the detoxication of cysteine. [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]

Transwell experiments with Caco-2 or MDCK cells are the gold standard for determining the intestinal permeability of chemicals. The intrinsic membrane permeability (P 0), that can be extracted from these experiments, might be comparable to P 0 measured in black lipid membrane (BLM) experiments and P 0 predicted by the solubility-diffusion model. Unfortunately, the overlap between experimental P 0,Caco-2/MDCK and P 0,BLM data is very small. So far, differences between both approaches have been attributed to the cholesterol and sphingomyelin content of cell membranes, but the database is too sparse to thoroughly test this theory. To create a diverse dataset, we measured P 0,BLM of ten chemicals in BLM experiments using DPhPC and DPhPC/cholesterol/sphingomyelin membranes. The results were compared to predicted BLM data and experimental Caco-2/MDCK data obtained from literature. While P 0,BLM of all chemicals was well predicted by the solubility-diffusion model, P 0,Caco-2/MDCK was only predictable for rather hydrophilic compounds with logarithmic hexadecane/water partition coefficients below −0.5. The effect of cholesterol and sphingomyelin on P 0,BLM was negligibly small. [Display omitted] • Cholesterol and sphingomyelin have no impact on the permeability of DPhPC membranes. • DPhPC membrane permeability is well predicted by the solubility-diffusion model. • Caco-2 permeability of lipophilic compounds differs from solubility-diffusion model. • DPhPC membranes can be used to predict Caco-2 permeability of hydrophilic compounds. [ABSTRACT FROM AUTHOR]

Quercetin is a polyphenolic molecule with a broad spectrum of biological activities derived from its antioxidant property. Its mechanism of action has been explained by its binding and/or interference with enzymes, receptors, transporters and signal transduction systems. Since these important mechanisms generally occur in membrane environments, within and through lipid bilayers, investigating the biophysical properties related to the diversity of lipid compositions of cell membranes may be the key to understanding the role of cell membrane in these processes. In this work, we explored the interaction of quercetin with model membranes of different lipid compositions to access the importance of lipid phases and bilayer homogeneity to the action of quercetin and contribute to the understanding of quercetin multiple activities. Analysis of the influence of quercetin on the morphology and permeability of GUVs, the rigidity of LUVs and affinity to these vesicles showed that quercetin strongly partitions to the more homogeneous environments, but significantly permeates and modifies the more heterogeneous where liquid-disordered, liquid-ordered and solid phases coexist. Our findings support the condensing effect of quercetin, which is observed through a significant rigidifying of bilayers containing 40% cholesterol, but much less evidenced when it is reduced to 20% or in its absence. Nevertheless, the presence of sphingomyelin in the ternary system led to a more heterogeneous bilayer with the formation of micrometric and probably also nanometric domains, which coalesce in the presence of quercetin. This observation together with increased permeability points to an insertion effect. [Display omitted] • Quercetin significantly increases membrane permeability depending on the presence of micrometric lipid domains. • Quercetin rigidifies bilayers, exerting a condensation effect which is cholesterol-content dependent. • Quercetin strongly partitions to the more homogeneous lipid bilayers with a preference for those of higher ld fractions. • Quercetin induces the coalescence of micrometric domains in vesicles containing sphingomyelin. • Lipid domains coalescence and increased permeability point to quercetin interdigitation effect in ternary bilayer. [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]