The Hidden Role of the Dielectric Effect in Nanofiltration: A Novel Perspective to Unravel New Ion Separation Mechanisms.

Nanofiltration (NF) membranes play a critical role in separation processes, necessitating an in-depth understanding of their selective mechanisms. Existing NF models predominantly include steric and Donnan mechanisms as primary mechanisms. However, these models often fail in elucidating the NF selectivity between ions of similar dimensions and the same valence. To address this gap, an innovative methodology was proposed to unravel new selective mechanisms by quantifying the nominal dielectric effect isolated from steric and Donnan exclusion through fitted pore dielectric constants by regression analysis. We demonstrated that the nominal dielectric effect encompassed unidentified selective mechanisms of significant relevance by establishing the correlation between the fitted pore dielectric constants and these hindrance factors. Our findings revealed that dehydration-induced ion-membrane interaction, rather than ion dehydration, played a pivotal role in ion partitioning within NF membranes. This interaction was closely linked to the nondeformable fraction of hydrated ions. Further delineation of the dielectric effect showed that favorable interactions between ions and membrane functional groups contributed to entropy-driven selectivity, which is a key factor in explaining ion selectivity differences between ions sharing the same size and valence. This study deepens our understanding of NF selectivity and sheds light on the design of highly selective membranes for water and wastewater treatment.

Roles of Anion-Cation Coupling Transport and Dehydration-Induced Ion-Membrane Interaction in Precise Separation of Ions by Nanofiltration Membranes.

Nanofiltration (NF) membranes are playing increasingly crucial roles in addressing emerging environmental challenges by precise separation, yet understanding of the selective transport mechanism is still limited. In this work, the underlying mechanisms governing precise selectivity of the polyamide NF membrane were elucidated using a series of monovalent cations with minor hydrated radius difference. The observed selectivity of a single cation was neither correlated with the hydrated radius nor hydration energy, which could not be explained by the widely accepted NF model or ion dehydration theory. Herein, we employed an Arrhenius approach combined with Monte Carlo simulation to unravel that the transmembrane process of the cation would be dominated by its pairing anion, if the anion has a greater transmembrane energy barrier, due to the constraint of anion-cation coupling transport. Molecular dynamics simulations further revealed that the distinct hydration structure was the primary origin of the energy barrier difference of cations. The cation having a larger incompressible structure after partial dehydration through subnanopores would induce a more significant ion-membrane interaction and consequently a higher energy barrier. Moreover, to validate our proposed mechanisms, a membrane grafting modification toward enlarging the energy barrier difference of dominant ions achieved a 3-fold enhancement in ion separation efficiency. Our work provides insights into the precise separation of ionic species by NF membranes.

Elucidating the Trade-off between Membrane Wetting Resistance and Water Vapor Flux in Membrane Distillation.

Membrane distillation (MD) has been receiving considerable attention as a promising technology for desalinating industrial wastewaters. While hydrophobic membranes are essential for the process, increasing membrane surface hydrophobicity generally leads to the reduction of water vapor flux. In this study, we investigate the mechanisms responsible for this trade-off relation in MD. We prepared hydrophobic membranes with different degrees of wetting resistance through coating quartz fiber membranes with a series of alkylsilane molecules while preserving the fiber structures. A trade-off between wetting resistance and water vapor flux was observed in direct-contact MD experiments, with the least-wetting-resistant membrane exhibiting twice as high vapor flux as the most wetting-resistant membrane. Electrochemical impedance analysis, combined with fluorescence microscopy, elucidated that a lower wetting resistance (still water-repelling) allows deeper penetration of the liquid-air interfaces into the membrane, resulting in an increased interfacial area and therefore a larger evaporative vapor flux. Finally, we performed osmotic distillation experiments employing anodized alumina membranes that possess straight nanopores with different degrees of wetting resistance, observed no trade-off, and substantiated this proposed mechanism. Our study provides a guideline to tailor the membrane surface wettability to ensure stable MD operations while maximizing the water recovery rate.

Effects of proteoliposome composition and draw solution types on separation performance of aquaporin-based proteoliposomes: implications for seawater desalination using aquaporin-based biomimetic membranes.

Aquaporins are a large family of water transport proteins in cell membranes. Their high water permeability and solute rejection make them potential building blocks for high-performance biomimetic membranes for desalination. In the current study, proteoliposomes were prepared using AquaporinZ from Escherichia coli cells, and their separation properties were characterized by stopped-flow measurements. The current study systematically investigated the effect of proteoliposome composition (lipid type, protein-to-lipid ratio (PLR), and the addition of cholesterol) on water permeability and NaCl retention. Among the various lipids investigated, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)-based proteoliposomes were found to have excellent osmotic water permeability and NaCl reflection coefficient values. Increasing the PLR of DOPC proteoliposomes up to 1:200 increased their osmotic water permeability. However, further increase in the PLR reduced the osmotic water permeability probably due to the occurrence of defects in the proteoliposomes, whereas the addition of cholesterol improved their osmotic water permeation likely due to defects sealing. The current study also investigated the effect of major dissolved ions in seawater (e.g., Mg(2+) and SO(4)(2-)) on the stability of proteoliposomes, and design criteria for aquaporin-based biomimetic membranes are proposed in the context of desalination.

Immobilization of poly-L-lysine brush via surface initiated polymerization for the development of long-term antibacterial coating for silicone catheter.

Bacterial colonization of indwelling catheter remains a major threat in healthcare units worldwide. Developing approaches to prevent catheter-associated infections (CAIs) is, therefore, in great demand. Herein, to endow silicone catheter with long-term antibacterial properties, antimicrobial poly-L-lysine (PLL) brush was developed on the surface of catheter via surface initiated ring open polymerization. Surface characterizations confirmed the successful immobilization of PLL. The PLL-tethered catheter showed potent antibacterial activities against catheter-associated urinary tract infections (CAUTIs) related pathogens. Moreover, after immersing in simulated body fluid for 28 days or incubating at 60 °C for 65 days, the bactericidal properties of PLL-tethered catheter were still retained. Furthermore, the PLL-tethered catheter exhibited good anti-infection activity and biocompatibility in vivo. The PLL-tethered surfaces hold great potential in the development of antibacterial silicone catheter to combat CAIs in clinical applications.

The distinct plastisphere microbiome in the terrestrial-marine ecotone is a reservoir for putative degraders of petroleum-based polymers.

Research into plastic-degrading bacteria and fungi is important for understanding how microorganisms can be used to address the problem of plastic pollution and for developing new approaches to sustainable waste management and bioplastic production. In the present study, we isolated 55 bacterial and 184 fungal strains degrading polycaprolactone (PCL) in plastic waste samples from Dafeng coastal salt marshes, Jiangsu, China. Of these, Jonesia and Streptomyces bacteria also showed potential to degrade other types of petroleum-based polymers. The metabarcoding results proved the existence of plastisphere as a distinct ecological niche regardless of the plastic types where 27 bacterial and 29 fungal amplicon sequence variants (ASVs) were found to be significantly (p < 0.05) enriched, including some belonging to Alternaria (Ascomycota, Fungi) and Pseudomonas (Gammaproteobacteria, Bacteria) that were also mined out by the method of cultivation. Further assembly analyses demonstrated the importance of deterministic processes especially the environmental filtering effect of carbon content and pH on bacteria as well as the carbon and cation content on fungi in shaping the plastisphere communities in this ecosystem. Thus, the unique microbiome of the plastisphere in the terrestrial-marine ecotone is enriched with microorganisms that are potentially capable of utilizing petroleum-based polymers, making it a valuable resource for screening plastic biodegraders.

Artificial intelligence-incorporated membrane fouling prediction for membrane-based processes in the past 20 years: A critical review.

Membrane fouling is one of major obstacles in the application of membrane technologies. Accurately predicting or simulating membrane fouling behaviours is of great significance to elucidate the fouling mechanisms and develop effective measures to control fouling. Although mechanistic/mathematical models have been widely used for predicting membrane fouling, they still suffer from low accuracy and poor sensitivity. To overcome the limitations of conventional mathematical models, artificial intelligence (AI)-based techniques have been proposed as powerful approaches to predict membrane filtration performance and fouling behaviour. This work aims to present a state-of-the-art review on the advances in AI algorithms (e.g., artificial neural networks, fuzzy logic, genetic programming, support vector machines and search algorithms) for prediction of membrane fouling. The working principles of different AI techniques and their applications for prediction of membrane fouling in different membrane-based processes are discussed in detail. Furthermore, comparisons of the inputs, outputs, and accuracy of different AI approaches for membrane fouling prediction have been conducted based on the literature database. Future research efforts are further highlighted for AI-based techniques aiming for a more accurate prediction of membrane fouling and the optimization of the operation in membrane-based processes.

Recent advances in membrane biofilm reactor for micropollutants removal: Fundamentals, performance and microbial communities.

The occurrence of micropollutants (MPs) in water and wastewater imposes potential risks on ecological security and human health. Membrane biofilm reactor (MBfR), as an emerging technology, has attracted much attention for MPs removal from water and wastewater. The review aims to consolidate the recent advances in membrane biofilm reactor for MPs removal from the standpoint of fundamentals, removal performance and microbial communities. First, the configuration and working principles of MBfRs are reviewed prior to the discussion of the current status of the system. Thereafter, a comprehensive review of the MBfR performance for MPs elimination based on literature database is presented. Key information on the microbial communities that are of great significance for the removal performance is then synthesized. Perspectives on the future research needs are also provided in this review to ensure the development of MBfRs for more cost-effective elimination of MPs from water and wastewater.

Clinical application of a double-modified sulfated bacterial cellulose scaffold material loaded with FGFR2-modified adipose-derived stem cells in urethral reconstruction.

BACKGROUND: Urethral stricture and reconstruction are one of the thorny difficult problems in the field of urology. The continuous development of tissue engineering and biomaterials has given new therapeutic thinking to this problem. Bacterial cellulose (BC) is an excellent biomaterial due to its accessibility and strong plasticity. Moreover, adipose-derived stem cells (ADSCs) could enhance their wound healing ability through directional modification. METHODS: First, we used physical drilling and sulfonation in this study to make BC more conducive to cell attachment and degradation. We tested the relevant mechanical properties of these materials. After that, we attached Fibroblast Growth Factor Receptor 2 (FGFR2)-modified ADSCs to the material to construct a urethra for tissue engineering. Afterward, we verified this finding in the male New Zealand rabbit model and carried out immunohistochemical and imaging examinations 1 and 3 months after the operation. At the same time, we detected the potential biological function of FGFR2 by bioinformatics and a cytokine chip. RESULTS: The results show that the composite has excellent repairability and that this ability is correlated with angiogenesis. The new composite in this study provides new insight and therapeutic methods for urethral reconstruction. The preliminary mechanism showed that FGFR2 could promote angiogenesis and tissue repair by promoting the secretion of Vascular Endothelial Growth Factor A (VEGFA) from ADSCs. CONCLUSIONS: Double-modified sulfonated bacterial cellulose scaffolds combined with FGFR2-modified ADSCs provide new sight and treatments for patients with urethral strictures.

Graphene films with large domain size by a two-step chemical vapor deposition process.

The fundamental properties of graphene are making it an attractive material for a wide variety of applications. Various techniques have been developed to produce graphene and recently we discovered the synthesis of large area graphene by chemical vapor deposition (CVD) of methane on Cu foils. We also showed that graphene growth on Cu is a surface-mediated process and the films were polycrystalline with domains having an area of tens of square micrometers. In this paper, we report on the effect of growth parameters such as temperature, and methane flow rate and partial pressure on the growth rate, domain size, and surface coverage of graphene as determined by Raman spectroscopy, and transmission and scanning electron microscopy. On the basis of the results, we developed a two-step CVD process to synthesize graphene films with domains having an area of hundreds of square micrometers. Scanning electron microscopy and Raman spectroscopy clearly show an increase in domain size by changing the growth parameters. Transmission electron microscopy further shows that the domains are crystallographically rotated with respect to each other with a range of angles from about 13 to nearly 30°. Electrical transport measurements performed on back-gated FETs show that overall films with larger domains tend to have higher carrier mobility up to about 16,000 cm(2) V(-1) s(-1) at room temperature.

Efficacy of electrochemical membrane bioreactor for virus removal from wastewater: Performance and mechanisms.

Wastewater treatment facilities play pivotal roles in preventing the transmission of water-borne viruses and protecting human health. In this study, a new electrochemical membrane bioreactor (EMBR) was proposed to achieve a long-lasting and efficient removal of virus from wastewater. Results showed that applying a low electric field (2.0 V) in EMBR system could achieve ~100% removal efficiency at both batch tests and continuous flow experiments. In contrast, the control MBR, without the exertion of electric field, exhibited a very low removal efficiency (19.8% on average). Moreover, the fouling in EMBR was significantly mitigated, which enabled its operation duration almost 3 times longer than that of the control. Further explorations suggested that the reactive oxidants generated on electrodes in the EMBR system were mainly responsible for MS2 removal. This study demonstrated the potential of utilizing the EMBR process to achieve an enhanced virus disinfection efficiency during the wastewater treatment process.

Transfer of large-area graphene films for high-performance transparent conductive electrodes.

Graphene, a two-dimensional monolayer of sp(2)-bonded carbon atoms, has been attracting great interest due to its unique transport properties. One of the promising applications of graphene is as a transparent conductive electrode owing to its high optical transmittance and conductivity. In this paper, we report on an improved transfer process of large-area graphene grown on Cu foils by chemical vapor deposition. The transferred graphene films have high electrical conductivity and high optical transmittance that make them suitable for transparent conductive electrode applications. The improved transfer processes will also be of great value for the fabrication of electronic devices such as field effect transistor and bilayer pseudospin field effect transistor devices.

Recovery of dissolved methane from anaerobically treated food waste leachate using solvent-based membrane contactor.

The difficulty of dissolved methane recovery remains a major hurdle for mainstream anaerobic wastewater treatment processes. We recently proposed solvent-based membrane contactor (SMC) for high (>90%) methane recovery over a wide temperature range and net-energy production. Here, we investigate the methane recovery efficacy of the SMC process by using an AnMBR effluent from treating food waste leachate. We observed almost identical methane transfer kinetics to the process employing foulant-free methane-saturated feed solutions, with >92% methane recoveries, showing that organic foulants have insignificant impacts on the methane transport in the SMC. We then performed two different membrane contactor experiments: direct-contact membrane-distillation (DCMD, with transmembrane water vapor flow) and SMC (no water vapor flow). From the negligible fouling observed in the SMC experiment, opposite to the DCMD, we elucidate that the absence of water vapor flow renders the SMC process intrinsically robust to membrane fouling. With the low fouling propensity of the SMC process under highly fouling environments, our study highlights the feasibility of SMC processes to enhance the energy production in mainstream anaerobic wastewater treatment processes.

Enhanced removal of pharmaceuticals and personal care products from real municipal wastewater using an electrochemical membrane bioreactor.

A novel electrochemical membrane bioreactor (EMBR) was developed for enhancing PPCPs removal from real municipal wastewater. Compared to the control MBR (CMBR) without applying electric field, EMBR exhibited higher removal efficiencies for 14 PPCPs among all investigated PPCPs, including 3 fluoroquinolones, 2 macrolides, 6 sulfonamides and 3 anti-inflammatory drugs, while no significant difference was observed for the rest 8 PPCPs. The enhanced removal of 14 PPCPs was mainly attributed to electrooxidation by the direct anodic oxidation and reactive oxygen species-mediated indirect oxidation. Moreover, membrane fouling rates of EMBR (0.55 ± 0.10 kPa/d) were significantly reduced compared with CMBR (0.99 ± 0.09 kPa/d). Microbial activities and community analyses demonstrated that the applied electric field had no noticeable adverse impact on microbial viabilities, richness and diversity. These findings demonstrated that this EMBR enhanced pollutant removal and mitigated membrane fouling simultaneously, highlighting the potential of the novel technology to be used for removing PPCPs from wastewater.

Comparative proteomics of rat liver and Morris hepatoma 7777 plasma membranes.

Plasma membranes from normal rat liver and hepatocellular carcinoma Morris hepatoma 7777 were selectively solubilized by use of different reagents. After selective solubilization, proteins were identified by nano-HPLC-electrospray ionization tandem mass spectrometry (LC-ESI MS/MS). Using simple software, the patterns of proteins identified in membrane solubilizates from liver and hepatoma were compared. Proteins identified in Morris hepatoma 7777 and not in the corresponding membrane solubilizate from liver, mostly members of the annexin and heat shock protein families, are discussed as potential candidate markers for hepatocellular carcinomas.

Using targeted magnetic arsenic trioxide nanoparticles for osteosarcoma treatment.

The present study was to investigate the therapeutic efficacy of the magnetic arsenic trioxide (ATO) nanoparticles against osteosarcoma in vivo tumor models. ATO was incorporated in the magnetic nanoparticles and encapsulated by poly lactic acid. Human MG-63 osteosarcoma cells were injected subcutaneously into the nude mice. After 15 days, the mice were randomly assigned to the four groups (n=6 mice): group 1: control, saline only (10 mL kg(-1) day(-1), intravenously (i.v.)); group 2: ATO alone (5 mg kg(-1) day(-1), i.v.); group 3: magnetic ATO nanoparticles at a dose equivalent to 50% of the ATO alone, with an external magnetic field on the tumor; group 4: CDDP, cisplatin (5 mg kg(-1) day(-1), i.v.). The mice were sacrificed after 21 days. In vitro release profiles showed that ATO was released rapidly from the nanoparticles. The magnetic ATO evaluation indicated that the magnetic nanoparticles might localize under the magnet in vivo. The tumor volume examination showed that the treatment with magnetic ATO nanoparticles achieved the similar inhibition effect on osteosarcoma as that of CDDP or ATO alone. Electron microscopic features typical of apoptosis were identified in the tumor tissue with the three-drug treatment. This "magnetic ATO targeting" offers an opportunity to treat osteosarcoma with a lower dose.

Identification of members of the annexin family in the detergent-insoluble fraction of rat Morris hepatoma plasma membranes.

For proteomic analysis, plasma membranes of rat hepatocellular carcinoma Morris hepatoma 7777 were selectively solubilized according to the previously developed method [D. Josic, K. Zeilinger, Methods Enzymol. 271 (1996) 113-134]. If the Triton X100 insoluble pellet is subsequently extracted, several proteins can be solubilized. These proteins can be classified in two groups according to their molecular size. The proteins with apparent molecular weights in SDS-PAGE between 70 and 75 kDa belong to the first group. Smaller proteins, with apparent molecular weights between 30 and 45 kDa, are members of the second group. The main protein of higher molecular weight was also found in the Triton X100 insoluble extract from normal rat liver plasma membranes. This protein was identified as Annexin A6. The proteins from the second group are practically absent in the Triton X100 insoluble extract from rat liver. These proteins are present in relatively high concentrations in plasma membranes of Morris hepatoma 7777. Both groups of detergent-insoluble proteins from Morris hepatoma 7777 were further analyzed with SELDI-TOF and LC electrospray ionization mass spectrometry. From the first group, Annexin A6, together with two other integral plasma membrane proteins, was identified. In the second group of proteins with apparent molecular weights between 30 and 45kDa, further members of the annexin family, Annexins A1, A2, A4, A5 and A7 were identified. The possible role of these low molecular size annexins as potential cancer biomarkers is discussed.

Fusion behaviour of aquaporin Z incorporated proteoliposomes investigated by quartz crystal microbalance with dissipation (QCM-D).

Aquaporin-based biomimetic membranes have potential as promising membranes for water purification and desalination due to the exceptionally high water permeability and selectivity of aquaporins. However, the design and preparation of such membranes for practical applications are very challenging as the relevant fundamental research is rather limited to provide guidance. Here we investigated the basic characteristics and fusion behaviour of proteoliposomes incorporated with aquaporin Z (AqpZ) on to solid surfaces. This study is expected to offer a better understanding of the properties of proteoliposomes and the potential of the vesicle fusion technique. Our results show that after incorporation of AqpZ, the size and surface charge density of the proteoliposomes change significantly compared with those of liposomes. Although the liposome could easily form a supported lipid bilayer on silica via vesicle rupture, it is much more difficult for proteoliposomes to fuse completely into a bilayer on the same substrate. In addition, the fusion of proteoliposomes is further hindered as the density of incorporated AqpZ is increased, suggesting that proteoliposome with more proteins become more robust. However, both the liposome and proteoliposome have difficulty forming supported lipid bilayers on the surface of a polyelectrolyte layer even though it carries an opposite charge, indicating that the polymer may play an important role in stabilising vesicles. It was also observed that a high concentration of AqpZ could be incorporated into the 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) liposome even though its permeability decreased. These findings may provide some useful guidance for preparing such biomimetic membranes.

Anti-biofouling properties of amphiphilic phosphorylcholine polymer films.

Surfaces of amphiphilic phosphorylcholine polymer (PC1036) prepared by spin-coating were characterized by spectroscopic ellipsometry, water contact angle and atomic force microscopy. The antifouling properties of the PC1036 films to marine benthic diatom Nitzschia closterium MMDL533 were also investigated. The results showed that the dry PC1036 film promoted the adhesion of N. closterium MMDL533 because the hydrophobic lauryl groups were present in the film surface. The 2 h-swelled PC1036 films had excellent anti-fouling properties with extremely low attachment densities and retention densities no matter what the annealing temperature was. The thickness of the coated films lower than 147 Å had a profound effect on the film anti-fouling properties. Otherwise, when the film thickness was higher than that value, there was no more improvement of diatom cell reduction observed. The annealing temperature had only a little effect on the film resistant to diatom adhesion, which might be attributed to two factors including the PC group packing densities in the outer PC layer and the equilibrated water volume fraction in the 2 h-swelled PC1036 films.

Topochemical approach to efficiently produce main-chain poly(bile acid)s with high molecular weights.

Based on a topochemical approach, a strategy for efficiently producing main-chain poly(bile acid)s in the solid state was developed. This strategy allows for facile and scalable synthesis of main-chain poly(bile acid)s not only with high molecular weights, but also with quantitative conversions and yields.