Negatively Charged Research Articles

Therapeutic delivery of siRNA for the management of breast cancer and triple-negative breast cancer.

Breast cancer is the leading cause of cancer-related deaths among women globally. The difficulties with anticancer medications, such as ineffective targeting, larger doses, toxicity to healthy cells and side effects, have prompted attention to alternate approaches to address these difficulties. RNA interference by small interfering RNA (siRNA) is one such tactic. When compared with chemotherapy, siRNA has several advantages, including the ability to quickly modify and suppress the expression of the target gene and display superior efficacy and safety. However, there are known challenges and hurdles that limits their clinical translation. Decomposition by endonucleases, renal clearance, hydrophilicity, negative surface charge, short half-life and off-target effects of naked siRNA are obstacles that hinder the desired biological activity of naked siRNA. Nanoparticulate systems such as polymeric, lipid, lipid-polymeric, metallic, mesoporous silica nanoparticles and several other nanocarriers were used for effective delivery of siRNA and to knock down genes involved in breast cancer and triple-negative breast cancer. The focus of this review is to provide a comprehensive picture of various strategies utilized for delivering siRNA, such as combinatorial delivery, development of modified nanoparticles, smart nanocarriers and nanocarriers that target angiogenesis, cancer stem cells and metastasis of breast cancer.

Lipase-catalyzed synthesis of erythorbyl oleate and its characterization as a multifunctional emulsifier.

Erythorbyl oleate (EO), a novel emulsifier with multifunctional properties, was synthesized via lipase-catalyzed solvent-free esterification between erythorbic acid and oleic acid. The reaction produced EO of 30.75±1.65mM at 60h, monitored by high-performance liquid chromatography (HPLC) analysis. Purified EO was chemically identified as 6-O-oleoyl-erythorbic acid by HPLC-electrospray ionization/mass spectrometry (ESI-MS), 1H nuclear magnetic resonance (NMR), and 13C NMR analyses, and further investigations on its multifunctionalities were conducted. EO displayed antioxidant activity equivalent to erythorbic acid in 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities. Investigation of the antibacterial activity of EO against foodborne pathogens showed MICs of 0.27±0.09 and 0.40mM for Bacillus cereus ATCC 10876 and Staphylococcus aureus ATCC 12692, respectively. EO also displayed interfacial properties, lowering interfacial tension between medium-chain triglyceride oil and water to 3.40±0.04 mN/m with a critical micelle concentration of 2.54±0.03mM. Dynamic light scattering analyses of the emulsion stabilized by EO demonstrated a similar polydispersity index (0.15±0.00) to Tween 80-stabilized emulsion (0.28±0.01), with an average droplet size of 173.2±1.8nm. In addition, the EO-stabilized emulsion exhibited a negative surface charge (-56.83±4.30mV) in zeta potential measurements, indicating sufficient electrostatic repulsion between droplets. These results suggest that EO is a multifunctional emulsifier to simultaneously control oxidative rancidification and bacterial spoilage in emulsion-based foods. Practical Application: EO was synthesized via an enzymatic esterification reaction between erythorbic acid and oleic acid. The synthetic process excluded any use of organic solvent, diminishing potential health hazards or environmental pollution associated with chemical reactions. The interfacial properties of the resultant EO, along with excellent antioxidant and antibacterial activities, propose its potential application in emulsion-based foods. Simultaneous control of bacterial spoilage and oxidative rancidification by EO would fulfill the industrial needs for extending shelf life and enhancing consumer safety.

Bisubstrate inhibitors of 6-hydroxymethyl-7,8-dihydroptein pyrophosphokinase: Toward cell permeability

6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is a key enzyme in the folate biosynthesis pathway. It catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP). HPPK is essential for microorganisms but is absent in mammals. Yet, it is not the target of any existing antibiotics. Hence, this enzyme is an attractive target for developing novel antimicrobial agents. A wealth of structural and mechanistic information has provided solid basis for structure-based design of HPPK inhibitors. Our bisubstrate inhibitors were initially created by linking 6-hydroxymethylpterin to adenosine through 2, 3, or 4 phosphate groups (HPnA, n = 2, 3, or 4), among which HP4A exhibited the highest binding affinity (Kd = 0.47 ± 0.04 μM). Further development was carried out based on high-resolution structures of HPPK in complex with HP4A. Replacing the phosphate bridge with a piperidine linked thioether eliminated multiple negative charges of the bridge. Substituting the pterin moiety with 7,7-dimethyl-7,8-dihydropterin improved the binding affinity. Arming the piperidine ring with a carboxyl group and oxidizing the thioether further enhanced the potency, resulting in a druglike inhibitor of HPPK (Kd = 0.047 ± 0.007 μM). None of these inhibitors, however, exhibits bacterial cell permeability. It is most likely due to the lack of active folate transporters in bacteria. Replacing the pterin moiety with a 7-deazagaunine moiety, we have obtained a novel bisubstrate inhibitor (HP-101) showing observable cell permeability toward a Gram-positive bacterium. Here, we report the in vitro activity of HP-101 and its structure in complex with HPPK, providing a framework for structure-based further development.

Structural features of carrot α-tubulin predetermining the natural resistance to dinitroaniline herbicides

Aim. To explain the natural resistance of Daucus carota L. to dinitroaniline herbicides. To clarify features of the carrot α-tubulin that may affect formation of the ligand-protein complex based on the structural and electrostatic analysis of the ligand-binding site. Methods. Reconstruction of the spatial structure of α-tubulin from D. carota and Toxoplasma gondii using profile (Swiss-Model) and de-novo (AlphaFold2) modeling. Molecular dynamics (MD) simulations of the built 3D-models in Gromacs. Analysis of the molecular electrostatics with PDB2PQR/APBS tools. Visualization and analysis of molecular structures in PyMOL. Results. It has been shown that along with the typical positive charge of the dinitroaniline-binding pocket, all isotypes of carrot α-tubulin demonstrate negatively charged regions that may cause conflicts with the nitro-groups of the ligands. Also, the MD-stable negatively charged "bridge" between Cys316 and the aryl-fragment of Phe255 was observed in all α-tubulin isotypes. In our opinion, it not only competes with the cyclic fragment of dinitroanilines, but overall prevent the opening of the site pocket in carrot α-tubulin. Conclusions. It was clarified that natural resistance of D. carota to dinitroaniline herbicides may be associated with steric and electrostatic conflicts observed in in all α-tubulin isotypes. In our opinion, it prevents interaction with dinitroaniline compounds at the stage of primary site recognition on the early stages of protein-ligand complex formation.

Theory of Classical Electrodynamics with Topologically Quantized Singularities as Electric Charges

AbstractA theory of classical electrodynamics, where the only admissible electric charges are topological singularities in the electromagnetic field, is formulated. Charge quantization is accounted by the Chern theorem, such that Dirac magnetic monopoles are not needed. The theory allows positive and negative charges of equal magnitude, where the sign of the charge corresponds to the chirality of the topological singularity. Given the trajectory of the singularity, one can calculate electric and magnetic fields identical to those produced by Maxwell's equations for a moving point charge, apart from a multiplicative constant factor related to electron charge and vacuum permittivity. The theory is based on the relativistic Weyl equation in frequency‐wavevector space, with eigenstates comprising the position, velocity, and acceleration of the singularity, and eigenvalues defining the retarded position of the charge. From the eigenstates, one calculates the Berry connection and the Berry curvatures, and identifies the curvatures as electric and magnetic fields.

In vitro safety profile and phyto-ecotoxicity assessment of the eco-friendly calcium oxide nanoparticles

The present study aims to evaluate the toxicity of the green calcium oxide nanoparticles (CaO-NPs) from golden linseed extract (Linum usitatissimum L.) by phytotoxicity in seeds (Daucus carota, Beet shankar, Lactuca sativa and Brassica oleracea), in vitro safety profile and soil toxicity for CaO-NPs solutions from 12.5 to 100 μg mL−1. Ecotoxicity analysis of the soil was conducted using XRD diffractograms, which revealed characteristic peaks of the nanoparticles at 37.35° (12.5, 25, 50, and 100 μg mL−1), as well as a peak at 67.34° (25 and 100 μg mL−1). Additionally, the in vitro safety assessment indicated favorable cell specification and regulation within the first 24 h, demonstrating reductions of 15.9 ± 0.2%, 17.9 ± 0.2%, 17.6 ± 0.2%, and 32.9 ± 0.2% to 12.5, 25, 50, and 100 μg mL−1, respectively. The dsDNA assay revealed initial protection and controlled release within the cells for 48 h. However, after 72 h, there was an increase of 20 ± 0.2%, 16 ± 0.2%, 32 ± 0.2%, and 43 ± 0.2% to 12.5, 25, and 50 μg mL−1. The analysis of ROS generation demonstrated a reduction of 40 ± 0.2%, 33 ± 0.2%, 20 ± 0.2%, and 9 ± 0.2% to 12.5, 25, 50, and 100 μg mL−1, respectively, within 72 h. When compared to the negative control (NC), there was an increase of 50 ± 0.2%, 56 ± 0.2%, 77 ± 0.2%, and 92 ± 0.2% at the same concentrations, suggesting that the nanoparticles generated free radicals, leading to cellular inflammation. This was attributed to the positive surface charge of the nanoparticles, resulting in reduced interaction with the cell membrane and the subsequent release of hydroxyl (•OH), which caused inflammatory processes in the cells. Therefore, CaO-NPs exhibited a low phytotoxicity and high cytocompatibility, while also promoting plant germination and growth.

Transport of reduced PBAT microplastics in saturated porous media: Synergistic effects of enhanced surface energy and roughness

Microplastic (MP) pollution presents significant global environmental challenges, exacerbated by reduction aging processes in anoxic environments, thereby increasing environmental risks and potential threats to human health. However, the mechanisms underlying the transport of reduced MPs remain poorly understood. In this study, laboratory-scale column experiments were conducted to investigate the transport behavior of polybutylene adipate terephthalate (PBAT), a common biodegradable MPs, and its reduced products obtained through the aging process mediated by two typical reducing agents, NaBH4 and Na2S, under varying conditions (ionic strength (IS), divalent cations, and low molecular weight organic acids (LMWOAs)). The results indicated that reduction aging improved the hydrophilicity of PBAT by increasing the surface roughness (roughness factor increased from 1.300 to 1.642) and surface energy (from 51.80 to 107.03 mN m−1), thereby increasing the mobility of reduced PBAT (with recovery rate increased from 53.77 % to 63.18 %). Increased IS decreased the mobility of reduced PBAT by decreasing the surface negative charge density. Divalent cations inhibited the mobility of both pristine and reduced PBAT in porous media, with pristine PBAT, containing more oxygen functional groups, exhibiting stronger inhibition. Furthermore, LMWOAs promoted the retention of reduced PBAT in porous media, which was dependent on the type of LMWOAs. This study revealed the alterations in MPs properties caused by reduction aging and their effects on transport mechanisms, offering new insights into the transport behavior and environmental risks of reduced MPs.

Improving multifunctional properties of the polyvinylidene fluoride (PVDF) membrane with crosslinked dialdehyde-starch (DAS) and polyethyleneimine (PEI) coating

Dialdehyde-soluble starch (DAS) and polyethyleneimine (PEI) were used to coat the polyvinylidene fluoride (PVDF) membrane for improving its antifouling and multifunctional properties through a combination of dip-coating and spray-coating techniques. The resulting membrane demonstrated excellent hydrophilicity and underwater oleophobicity due to hydrophilic DAS and PEI on its surface. The membrane achieved an impressive oil removal rate of 99.8 % and a flux 1420.8 ± 26.5 L·m−2·h−1 when it was used for oil-water emulsion separation. The hydration layer formed by the DAS and PEI greatly enhanced the membrane antifouling property, and its flux recovery rate was up to 96.6 % in BSA filtration experiments. The positive charge PEI and the negative charge DAS contributed to high separation efficiency of 99.1 % for the anion dye MO with the membrane D10P20, and high separation efficiency of 88.3 % for the cation dye RhB with the membrane P5D20. In addition, the coating layer was stable due to the cross-linked DAS and PEI. This research contributes greatly to the preparation of antifouling and multifunctional membrane using environmentally friendly material including polysaccharide derivatives and water soluble polymer.

Temperature dependence of the AB lines and optical properties of the carbon–antisite-vacancy pair in 4H−SiC

Defects in semiconductors have in recent years been revealed to have interesting properties in the venture towards quantum technologies. In this regard, silicon carbide has shown great promise as a host for quantum defects. In particular, the ultrabright AB photoluminescence lines in 4H−SiC are observable at room temperature and have been proposed as a single-photon quantum emitter. These lines have previously been studied and assigned to the carbon–antisite-vacancy (CAV) pair. In this paper, we report on new measurements of the AB lines’ temperature dependence, and carry out an in-depth computational study on the optical properties of the CAV defect. We find that the CAV defect has the potential to exhibit several different zero-phonon luminescences with emissions in the near-infrared telecom band, in its neutral and positive charge states. However, our measurements show that the AB lines only consist of three nonthermally activated lines instead of the previously reported four lines; meanwhile, our calculations on the CAV defect are unable to find optical transitions in full agreement with the AB-line assignment. In light of our results, the identification of AB lines and the associated room-temperature emission require further study. Published by the American Physical Society 2024

Polyelectrolyte-modified covalent organic framework membranes for multivalent cation removal

Covalent organic framework (COF) has become a promising membrane material in chemical separations. However, the application of COF membranes for ion separation is still challenging, due to the mismatch between the pore size of COFs (1–5 nm) with the diameter of hydrated ions (<1 nm). Herein, a cationic polyelectrolyte surface modification strategy of COF membranes was proposed, by assembling a cationic polyelectrolyte (PEI, PDDA, PAH) layer on the surface of an anionic COF (TpPa-SO3H) membrane via dip coating. The cationic polyelectrolytes on the membrane surface offered abundant positive charges and reduced the surface pore size, leading to the synergistic enhancement of the size sieving and the electrostatic repulsion. Accordingly, effective rejection of multivalent cations was realized with a significantly increased rejection rate of 97.1 % for MgCl2, compared to that of TpPa-SO3H membrane (10.3 %). Furthermore, the polyelectrolyte-modified COF membrane exhibited desirable separation performance for heavy metal ions in water. The rejection rates for heavy metal salts, including CrCl3, CdCl2, CuCl2, PbCl2 and NiCl2, reached 98.5 %, 97.3 %, 97.0 %, 96.2 %, and 96.0 %, respectively, and remained above 95 % during the 7-day long-term operation test.

Uniformly dispersed FeOOH nanoparticles supported on alumina-carbon nanosheets for Cr(VI) removal

The mesoporous alumina-carbon nanosheets supported FeOOH nanoparticles were prepared by a facile and cost-effective hydrothermal synthesis for Cr(VI) removal in the wastewater, based on the affinity and selectivity of FeOOH and the accelerated mass transfer of nanosheet structure. The prepared nanoparticles with a small size of 2–5 nm were uniformly dispersed over the alumina-carbon nanosheets, attributed to the metal interaction and mesoporous confinement. The acid property after the introduction of alumina induced a positive charge on the surface of the adsorbent, which could enhance the adsorption of negatively charged metal ions. The Cr(VI) removal efficiency with the Al/Fe ratios showed a similar volcano curve. When Al/Fe ratio was around 3.3 and pHpzc was about 7.1, the adsorbent exhibited the best Cr(VI) removal efficiency of 99.4 %, owing to a large specific surface area, and small nanoparticle size, combined with abundant moderate-strong acid content of 294.5 μmol NH3 g−1.The Langmuir model could describe the adsorption process well, and the kinetic data was consistent with Pseudo-second-order. The thermodynamics revealed that the reaction process was spontaneous and endothermic. The adsorbent maintained a high removal efficiency of more than 80 % after running for five cycles and kept over 95 % under ionic co-existence and natural water conditions. Therefore, this study provides a new insight into the rational construction of efficient adsorbents with low-cost Cr(VI) removal.

Chameleon‐Inspired, Dipole Moment‐Increasing, Fire‐Retardant Strategies Toward Promoting the Practical Application of Radiative Cooling Materials

AbstractToward addressing the aesthetic demand, IR emissivity, and fire hazards of radiative cooling materials in the practical application, chameleon‐inspired is tactfully employed, dipole moment‐increasing, and fire‐retardant strategies to manufacture an advanced polyurea‐based composite coating through incorporating thermochromic microcapsules, boron nitride nanosheets, and montmorillonite nanosheets. The chameleon‐inspired thermochromic microcapsules and admirable IR emissivity (supported by the original IR emittance spectra) realized by the increasing dipole moment allow the composite coatings to spontaneously adjust the solar absorption and reflection during hot daytime, while enabling high‐efficiency radiative cooling throughout the day. The IR emissivity higher than most literature is attributed to the strong interfacial interactions within polyurea composite coatings which improve the dipole moment of C─O─C, Si─O, and B─N bonds by increasing the distance between the centers of positive and negative charges, thus producing more IR emissions. Furthermore, the thermally melted montmorillonite nanosheets can form a ceramic protective layer enhanced by boron nitride nanosheets, further suppressing combustion behavior to improve the fire safety performance of polyurea coatings. The integration of thermochromic functionality, high fire safety, and admirable IR emissivity not only contribute to promoting the practical application of radiative cooling materials, but also provide a precious reference route to design high IR emissivity.

Adsorption of Se(IV) on kaolinite and montmorillonite in the presence of fulvic acid

This study investigates the influence of fulvic acid, a representative of aquatic natural organic matter (NOM), on the pH-dependent adsorption of Se(IV) on kaolinite and montmorillonite. Given their negative charges in aqueous solutions, Se(IV) and fulvic acid compete for the limited and identical adsorptive sites of clay minerals, particularly in neutral to alkaline environments. This competition was most pronounced under acidic conditions, where both Se(IV) and fulvic acid adsorption are favored. At pH 3, the presence of 20–80 mg·L−1 fulvic acid reduced the Se(IV) adsorption by up to half on both clay adsorbents. However, in near-neutral to alkaline pH regions (pH 6 to 10), the competitive interaction between Se(IV) and fulvic acid was less pronounced, since the adsorption of both fulvic acid and Se(IV) decreased. In particular for kaolinite, a rise in Se(IV) adsorption was evident at lower fulvic acid concentrations (20 mg·L−1). This phenomenon arises from the absence of aqueous complexes between Se(IV) and fulvic acid under acidic conditions, contrasting with their strong interaction under alkaline conditions as observed in the ATR-FTIR spectra. This study sheds light on the influence of NOM on the mobility of Se(IV) in natural waters, an aspect yet to be thoroughly explored.

RNA Interference Unleashed: Current Perspective of Small Interfering RNA (siRNA) Therapeutics in the Treatment of Neuropathic Pain.

Neuropathic pain (NP) is one of the debilitating pain phenotypes that leads to the progressive degeneration of the central as well as peripheral nervous system. NP is often associated with hyperalgesia, allodynia, paresthesia, tingling, and burning sensations leading to disability, motor dysfunction, and compromised psychological state of the patients. Most of the conventional pharmacological agents are unable to improve the devastating conditions of pain because of their limited efficacy, undesirable side effects, and multifaceted pathophysiology of the diseased condition. A rapid rise in new cases of NP warrants further research for identifying the potential novel therapeutic modalities for treating NP. Recently, small interfering RNA (siRNA) approach has shown therapeutic potential in many disease conditions including NP. Delivery of siRNAs led to potential and selective downregulation of target mRNA and abolished the pain-related behaviors/pathophysiological pain response. The crucial role of siRNA in the treatment of NP by considering all of the pathways associated with NP that could be managed by siRNA therapeutics has been discussed. However, their therapeutic use is limited by several hurdles such as instability in systemic circulation due to their negative charge and membrane impermeability, off-target effects, immunogenicity, and inability to reach the intended site of action. This review also emphasizes several strategies and techniques to overcome these hurdles for translating these therapeutic siRNAs from bench to bedside by opening a new avenue for obtaining a potential therapeutic approach for treating NP.

Protonated polyethyleneimine enables synchronous crosslinking of polyimide nanofiltration membranes for dye desalination

Dye recovery and desalination are of great significance in the treatment of printing and dyeing wastewater. Nanofiltration (NF) has been proved an effective method for dye desalination. As organic solvents are usually coexisted, there is a great demand for organic solvent nanofiltration (OSN) membranes. Compared to thin film composite (TFC) membranes prepared by interfacial polymerized (IP), integrally skinned asymmetric (ISA) membranes with relatively thicker selective layer may present better separation stability in harsh solvent and cleaning reagent. In this work, polyethyleneimine-b-polyethersulfone (PEI-PES) is synthesized and added to PI solution directly, the crosslinking reaction proceeds along with phase conversion process. The PEI chains endow the membrane with good hydrophilicity and high positive charge. PEI-PES/PI membranes show stable permeability in organic solvents such as N, N-dimethylformamide (DMF), ethanol (EtOH) and toluene, etc. The rejections of dyes such as Congo Red (CR), Janus Green B, and Sunset Yellow are over 95 % in EtOH, while the rejections of salts like MgSO4 and Na2SO4 are around 20 %. After 200 h separation test, the rejection for CR remains around 92 % in DMF and 96 % in EtOH with a stable flux. The simple and cost-effective preparation process can accelerate the progress of the positively charged OSN membranes.

Advanced lithium extraction nanofiltration membrane with fast transport channels via competitive diffusion and reaction of rigid electropositive phenylbiguanide molecules

The utilization of nanofiltration membranes for lithium extraction from Salt-Lake holds the potential to address lithium resource scarcity and drive energy transformation. Nevertheless, the trade-off effect between water permeability and Mg2+/Li+ separation selectivity poses a challenge in the application of these membranes. In this work, rigid-flexible interpenetration and competitive diffusion reaction strategies were proposed to regulate the pore structure and charge density of the functional layer, thus enhancing the overall separation performance of nanofiltration membrane. Phenylbiguanide (PBG) possessing rigid structure, high positive charge density, and low energy transfer barrier was embedded into flexible polyethyleneimine-based polyamide network. This integration facilitated the formation of continuous and semi-permanent microcavities with rigid-flexible coupled structure, and meanwhile, elevated the density of positive charges. Consequently, the modification extended the water molecular transport channels within the functional layer, leading to a notable enhancement in pure water flux, from 7.40 to 26.43 L m−2h−1. In addition, due to the faster diffusion of PBG than polyethyleneimine with high molecular weight (70000 Da, as aqueous monomer in this work), it could react with excess 1,3,5-trimesoyl chloride (TMC) on the surface of initial membrane to form a new polyamide layer, which repaired the defects in the functional layer and also enhanced the charge density inside pore channels. Therefore, Mg2+/Li+ separation selectivity factor increased from 3.79 of TFC membrane to 22.98 of PBG membrane, i.e., by about 6 times. This study provided an effective strategy to develop nanofiltration membranes with both good water permeability and Mg2+/Li+ selectivity.

Mechanically activated and deactivated ion transport across nanopores with heterogeneous surface charge distributions

To mimic the intricate and adaptive functionalities of biological ion channels, electrohydrodynamic ion transport has been studied extensively, albeit mostly, across uniformly charged nanochannels. Here, we analyze the ion transport under coupled electric field and pressure across heterogeneously charged nanopores with oppositely charged sections on their lateral surface. We only consider such pores with symmetric hourglass-like and cylindrical shapes to focus on the effects of the non-uniform surface charge distribution. Finite-element simulations of a continuum model demonstrate that a pressure applied in either direction of the pore-axis equally suppresses or amplifies the ionic conductance, depending on the electric field polarity, by distorting the quasi-static distribution of ions in the pore. The resulting anomalous mechanical deactivation and activation of ionic current under opposite voltage biases exhibit the functional modularity of our setup, while their intensities are highly tunable, substantially greater than those of analogous behaviors in other nanochannels, and fundamentally correlated to ionic current rectification (ICR) in our pores. A detailed study of ICR subsequently reveals its counterintuitive non-monotonous variations, in the pores, with the magnitude of applied voltage and the pore length, that can help optimize their diode-like behavior. We further illustrate that while the hourglass-shaped nanopores yield the more efficient mechanical suppressors of ion transport, their cylindrical analogs are the superior rectifiers and mechanical amplifiers of ion conduction. Therefore, this article provides a blueprint for the strategic design of nanofluidic circuits to attain a robust, modular, and tunable control of ion transport under external electrical and mechanical stimuli.

Mechanisms determining water permeability and ion selectivity of multilayered glycine-functionalized graphene oxide membranes in saline water reverse osmosis processes: A computational investigation

Non-Equilibrium Molecular Dynamics simulations were performed to examine in detail the mechanisms involved in a reverse osmosis process for the removal of monovalent (Na+, Cl−) and divalent (Mg2+) ions from saline water, using multilayered glycine-functionalized graphene oxide (GO) membranes. We varied parameters such as the degree of functionalization of the GO flakes and the structural flexibility of the membranes and examined their performance in a wide range of applied pressure gradients. In all models examined, water permeability was found to be almost 2 orders of magnitude larger compared to that in conventional reverse osmosis (RO) membranes. High structural flexibility of the membranes was found to increase water permeability due to the formation of additional nanochannels that favor faster water transport. Functionalization of the GO flakes by the glycinate groups resulted in a decrease in water permeability due to the formation of a denser hydrogen-bonding network within the membranes. Three main mechanisms were identified regarding ion selectivity. Due to the overall negative charge of the membranes, the strong adsorption of the Mg2+ ions onto the GO flakes resulted in their full rejection. Weaker adsorption of the Na+ ions led only to their partial rejection. At the same time, the electrostatic repulsion of the Cl− ions by the membranes was found to result in almost full removal levels at high pressure gradients. The rejection of the monovalent ions was found to decrease with the structural flexibility of the membranes and increase with the functionalization of the GO flakes, in response to the changes observed in water permeability on these membrane modifications. The pressure-dependent deformability of the structurally flexible membranes combined with charge accumulation close to the membrane's entrance, resulted in a non-monotonic dependence of the monovalent ion rejection on the applied pressure difference.

Spatial Control of Nickel Vacancies in Colloidal NiMgO Nanocrystals for Efficient and Stable All-inorganic Quantum Dot Light-Emitting Diodes.

Colloidal quantum dot (QD)-based light-emitting diodes (QD-LEDs) have reached the pinnacle of quantum efficiency and are now being actively developed for next-generation displays and brighter light sources. Previous research has suggested utilizing inorganic hole-transport layers (HTLs) to explore brighter and more stable QD-LEDs. However, the performance metrics of such QD-LEDs with inorganic HTLs generally lag behind those of organic-inorganic hybrid QD-LEDs employing organic HTLs. In this study, colloidal NiMgO nanocrystals (NCs) with spatially controlled Mg are introduced as HTLs for realizing efficient and stable all-inorganic QD-LEDs. During the co-condensation of Ni and Mg precursors to produce valence band-lowered NiMgO NCs, incorporating ≈2% Mg into the NiO lattice creates additional Ni vacancies (VNi) within and on the NCs, influencing the hole concentration and mobility of the NiMgO NC films. Passivating the VNi exposed on the surface with magnesium hydroxide allows for tuning the electrical properties of the NiMgO NCs relative to those of an electron transport layer, allowing for a balanced charge supply and suppressed negative charging of the QDs. Optimized all-inorganic QD-LEDs employing NiMgO NCs achieved a peak external quantum efficiency of 16.4%, peak luminance of 269455cdm⁻2, and a half-life of 462690h at 100nit.

Sodium alginate- and chitosan-based hydrogels with different network charges for selective removal of cationic and anionic dyes from water

ABSTRACT The grafting of chitosan (CH) and sodium alginate (SA) biopolymers with glycidyl methacrylate (GMA) and acrylamide (AAm) monomers, combined with graphene oxide (GO), led to the formation of bio-based hydrogels. These hydrogels, named CH -GO -hydrogel (GO/CH-g-poly (AAm-co-GMA)), CH -GO -hydrogel (CH-g-poly (AAm-co-GMA)), SA -GO -hydrogel (GO/SA-g-poly(AAm-co-GMA)), and SA -hydrogel (SA-g-poly(AAm-co-GMA)), were tested as selective dye adsorbents. While the chitosan-based hydrogels exhibited positive zeta potential values ranging from +27.5 to +0.1 mV, alginate-based samples had negative values between −10.4 to −41.7 mV in pH conditions from 3.0 to 9.0. Adding GO nano-fillers reduced the swelling capacity of both hydrogels, with water absorption (WA) values for SA -GO -hydrogel and SA -hydrogel recorded at 10.1 and 22.2 g/g, respectively. The ability of these materials to adsorb dyes, specifically crystal violet (cationic) and Congo red (anionic), was confirmed. Factors such as adsorbent dosage, initial pH, dye concentration, shaking time, and temperature were analyzed to determine dye adsorption capacity. Interestingly, the pristine hydrogels, free of GO, performed better than their nanocomposite counterparts. Adsorption capacities (qm) for crystal violet and Congo red with SA -hydrogel, SA -GO -hydrogel, CH -hydrogel, and CH -GO -hydrogel was 909.1, 714.3, 454.5, and 400.0 mg/g, respectively.