Control Of Surface Charge Research Articles

Molecularly Modified Electrodes for Efficient Triboelectric Nanogenerators

The integration of organic molecules into monolayers on triboelectric layers and electrodes has significantly improved the performance of triboelectric nanogenerators (TENGs) in recent years. By modifying surfaces at the molecular level, one can enhance durability, power density, and cost‐efficiency, leading to flexible, lightweight, and more efficient devices. A simple chemistry of organic monolayer formation allows a precise control over orientation, coverage, consistency, and functionality. These monolayers boost surface charge density and output voltage while influencing surface polarization and dipole interactions. This review focuses on recent advances in chemical modification of electrodes for controlling surface charge density and altering surface dipoles, emphasizing the significance of organic monolayers. A new concept of Schottky‐based TENGs is also introduced that explores chemically modified sliding surfaces. Furthermore, the importance of flexoelectricity and its contribution to triboelectricity is discussed. By addressing current challenges and outlining future directions, this review underscores the crucial role of surface chemistry in advancing TENGs.

Mucoadhesive Itraconazole Nanocrystals With Precise Control of Surface Charge Incorporated to Chitosan Films for Buccal Drug Delivery

AbstractDrug delivery to mucosal tissues presents considerable challenges related to the complex nature of the mucus layer protecting such tissues. This aggravates when delivering hydrophobic drugs, often requiring incorporation of drugs to nanoparticles and use of mucoadhesive systems. This paper aimed to develop an antifungal chitosan (CHI)‐based film loading itraconazole (ITZ) nanocrystals (NCs) with precisely controlled surface charge for enhanced mucoadhesion. Cationic and anionic ITZ NCs are prepared using wet media milling with mean particle sizes and zeta potentials of 226.9 ± 1.4 nm and 234.0 ± 2.90 nm, and +15.4 ± 2.8 mV and −16.2 ± 1.3 mV, for the cationic and anionic NCs, respectively. Cationic ITZ‐NCs exhibits a higher affinity to mucin particles. NCs‐loaded films showed stronger mechanical properties and adhesiveness compared with ITZ powder‐loaded films. Physicochemical analysis reveals that crystalline properties of the ITZ are preserved, with no drug‐excipients interaction. A significantly higher amount of ITZ mucosal deposition is obtained from films containing NCs (1360.23 ± 718.73 µg cm−2) compared with that from films containing ITZ powder (58.83 ± 37.45 µg cm−2). This work demonstrates the feasibility of tailoring the NCs surface, with the resultant systems showing potential for the management of fungal infections in mucosal tissues.

Charge-induced aggregation of emulsified oil droplets in water with the presence of functionalized stainless steel felt

Oil-water mixtures, especially the surfactant-stabilized oil-in-water emulsions with high stability, are causing great difficulties in effective separation. In this work, a modification strategy was established to prepare functionalized stainless steel felt for emulsion separation by coating the felt with 3-triethoxysilylpropylamine, followed by the introduction of silica nanoparticles using a sulfur-based three-component coupling reaction. To satisfy the pore size requirement for effective emulsion separation, the developed felt was processed using a compression molding. With special wettability, optimized pore size, and electrostatic demulsification mechanism, the positive charged felt delivered outstanding separation capabilities for oil-in-water emulsions stabilized by various surfactants. Specifically, the flux and COD removal efficiency for the anionic-stabilized emulsion were up to 3911 L m-2h−1 and 95.3 %, while for cationic-stabilized emulsions, which were 1305 L m-2h−1 and 93.1 %. Our comparative results indicated that surface charges played an essential role in governing the separation performance of the felt, and the demulsification arising from the electrostatic attraction demonstrated better separation capability than that caused by the electrostatic repulsion. In addition, the developed felt showed controlled surface charge and anti-fouling performance under cyclic operations. The findings of this study are beneficial for constructing separation material with high separation efficiency and long-term durability for practical applications.

Advancements in oral insulin: A century of research and the emergence of targeted nanoparticle strategies

AbstractWith the growing prevalence of diabetes, there is an urgent demand for a user‐friendly treatment option that minimizes side effects related to the use of subcutaneous injections. Scientists have dedicated over a century to developing an oral dosage form of insulin that can be administrated orally. The oral route of administration is the most desirable route for regularly dosed drugs in terms of safety and patient compliance. However, oral delivery of insulin remains a formidable challenge due to its intrinsically limited ability to cross the intestinal epithelium membrane and susceptibility to enzymatic degradation. This article reviews oral insulin research over the past decade, with a particular focus on surface modifications of nanoparticles (NPs). Various strategies involving controlling surface charges, utilizing protective proteins, and targeting specific receptors with ligands have been explored. Notably, surface modifications of the NPs for targeting specific intestinal receptors have shown promise in enhancing insulin oral absorption and bioavailability. Advanced technologies such as oral microneedles and gene therapy have also been developed, but their safety requires further assessment. Despite encouraging preclinical results across numerous strategies, the current clinical evidence is less optimistic. In summary, the present findings highlight the substantial journey that still lies ahead before achieving successful oral delivery of insulin.Practical Applications: This review provides a summary of recent progress in oral insulin delivery, particularly highlighting surface‐modified functional nanoparticles serving as an effective drug delivery system, which offers valuable information to the researchers. Due to the limited effectiveness of oral protein drugs caused by biological barriers, innovative technologies and drug delivery systems have been developed to overcome these obstacles and achieve therapeutic goals. This review concluded that surface modifications to nanoparticles can improve insulin stability and permeability, thereby enhancing oral bioavailability. It could assist researchers in developing more effective and patient‐friendly oral drug delivery systems.

Remotely Controlled Surface Charge Modulation of Magnetoelectric Nanogenerators for Swift and Efficient Drug Delivery.

We have developed a highly efficient technique of magnetically controlled swift loading and release of doxorubicin (DOX) drug using a magnetoelectric nanogenerator (MENG). Core-shell nanostructured MENG with a magnetostrictive core and piezoelectric shell act as field-responsive nanocarriers and possess the capability of field-triggered drug release in a cancerous environment. MENGs generate a surface electric dipole when subjected to a magnetic field due to the strain-mediated magnetoelectric effect. The capability of directional magnetic field-assisted modulation of the surface electrical dipole of MENG provides a mechanism to create/break ionic bonds with DOX molecules, which facilitates efficient drug attachment and on-demand swift detachment of the drug at a targeted site. The magnetic field-assisted drug-loading mechanism was minutely analyzed using spectrophotometry and Raman spectroscopy. The detailed time-dependent analysis of controlled drug release by the MENG under unidirectional and rotating magnetic field excitation was conducted using field-emission scanning electron microscopy, energy-dispersive X-ray, and atomic force microscopic measurements. In vitro, experiments validate the cytocompatibility and magnetically assisted on-demand and swift DOX drug delivery by the MENG near MCF-7 breast cancer cells, which results in a significant enhancement of cancer cell killing efficiency. A state-of-the-art experiment was performed to visualize the nanoscale magnetoelectric effect of MENG using off-axis electron holography under Lorentz conditions.

Peptide-Driven Proton Sponge Nano-Assembly for Imaging and Triggering Lysosome-Regulated Immunogenic Cancer Cell Death.

Triggering lysosome-regulated immunogenic cell death (ICD, e.g., pyroptosis and necroptosis) with nanomedicines is an emerging approach for turning an "immune-cold" tumor "hot"-a key challenge faced by cancer immunotherapies. Proton sponge such as high-molecular-weight branched polyethylenimine (PEI) is excellent at rupturing lysosomes, but its therapeutic application is hindered by uncontrollable toxicity due to fixed charge density and poor understanding of resulted cell death mechanism. Here, a series of proton sponge nano-assemblies (PSNAs) with self-assembly controllable surface charge density and cell cytotoxicity are created. Such PSNAs are constructed via low-molecular-weight branched PEI covalently bound to self-assembling peptides carrying tetraphenylethene pyridinium (PyTPE, an aggregation-induced emission-based luminogen). Assembly of PEI assisted by the self-assembling peptide-PyTPE leads to enhanced surface positive charges and cell cytotoxicity of PSNA. The self-assembly tendency of PSNAs is further optimized by tuning hydrophilic and hydrophobic components within the peptide, thus resulting in the PSNA with the highest fluorescence, positive surface charge density, cell uptake, and cancer cell cytotoxicity. Systematic cell death mechanistic studies reveal that the lysosome rupturing-regulated pyroptosis and necroptosis are at least two causes of cell death. Tumor cells undergoing PSNA-triggered ICD activate immune cells, suggesting the great potential of PSNAs to trigger anticancer immunity.

Green Ambient-Dried Aerogels with a Facile pH-Tunable Surface Charge for Adsorption of Cationic and Anionic Contaminants with High Selectivity.

The fabrication of reusable, sustainable adsorbents from low-cost, renewable resources via energy efficient methods is challenging. This paper presents wet-stable, carboxymethylated cellulose nanofibril (CNF) and amyloid nanofibril (ANF) based aerogel-like adsorbents prepared through efficient and green processes for the removal of metal ions and dyes from water. The aerogels exhibit tunable densities (18-28 kg m-3), wet resilience, and an interconnected porous structure (99% porosity), with a pH controllable surface charge for adsorption of both cationic (methylene blue and Pb(II)) and anionic (brilliant blue, congo red, and Cr(VI)) model contaminants. The Langmuir saturation adsorption capacity of the aerogel was calculated to be 68, 79, and 42 mg g-1 for brilliant blue, Pb(II), and Cr(VI), respectively. Adsorption kinetic studies for the adsorption of brilliant blue as a model contaminant demonstrated that a pseudo-second-order model best fitted the experimental data and that an intraparticle diffusion model suggests that there are three adsorption stages in the adsorption of brilliant blue on the aerogel. Following three cycles of adsorption and regeneration, the aerogels maintained nearly 97 and 96% of their adsorption capacity for methylene blue and Pb(II) as cationic contaminants and 89 and 80% for brilliant blue and Cr(VI) as anionic contaminants. Moreover, the aerogels showed remarkable selectivity for Pb(II) in the presence of calcium and magnesium as background ions, with a selectivity coefficient more than 2 orders of magnitude higher than calcium and magnesium. Overall, the energy-efficient and sustainable fabrication procedure, along with good structural stability, reusability, and selectivity, makes these aerogels very promising for water purification applications.

Enhanced Cell Osteogenesis and Osteoimmunology Regulated by Piezoelectric Biomaterials with Controllable Surface Potential and Charges.

Bone regeneration is a well-orchestrated process involving electrical, biochemical, and mechanical multiple physiological cues. Electrical signals play a vital role in the process of bone repair. The endogenous potential will spontaneously form on defect sites, guide the cell behaviors, and mediate bone healing when the bone fracture occurs. However, the mechanism on how the surface charges of implant potentially guides osteogenesis and osteoimmunology has not been clearly revealed yet. In this study, piezoelectric BaTiO3/β-TCP (BTCP) ceramics are prepared by two-step sintering, and different surface charges are established by polarization. In addition, the cell osteogenesis and osteoimmunology of BMSCs and RAW264.7 on different surface charges were explored. The results showed that the piezoelectric constant d33 of BTCP was controllable by adjusting the sintering temperature and rate. The polarized BTCP with a negative surface charge (BTCP-) promoted protein adsorption and BMSC extracellular Ca2+ influx. The attachment, spreading, migration, and osteogenic differentiation of BMSCs were enhanced on BTCP-. Additionally, the polarized BTCP ceramics with a positive surface charge (BTCP+) significantly inhibited M1 polarization of macrophages, affecting the expression of the M1 marker in macrophages and changing secretion of proinflammatory cytokines. It in turn enhanced osteogenic differentiation of BMSCs, suggesting that positive surface charges could modulate the bone immunoregulatory properties and shift the immune microenvironment to one that favored osteogenesis. The result provides an alternative method of synergistically modulating cellular immunity and the osteogenesis function and enhancing the bone regeneration by fabricating piezoelectric biomaterials with electrical signals.

Influence of SiC/Epoxy Coating on Surface Charging Phenomenon at DC Voltage—Part I: Charge Accumulation

Surface charge accumulation on silicon carbide (SiC)/epoxy coatings with different contents of SiC filler, 3, 5, 7, and 10 wt%, is investigated using flat samples of epoxy substrate. In the experiments, a pair of finger-shaped electrodes was attached to the sample’s surface using direct pressing and conductive adhesive providing two different types of contacts and, respectively, surface charging methods. The electrodes were energized by applying dc voltage for various time intervals and resulted surface charge distributions between the electrodes were measured. It was found that depending on the contact type, charging duration, and filler content, different patterns of homocharge or heterocharge appeared on the material surface. Physical reasons for the observed effects are analyzed based on the calculated electric field distributions in the experimental setup, results of the auxiliary tests on material charging in a limited air volume, and surface trap energy distributions measured by utilizing the isothermal surface potential decay (ISPD) method. Application of SiC/epoxy coating for controlling surface charge accumulation is discussed.

Tailoring the Electrical Characteristics of MoS2 FETs through Controllable Surface Charge Transfer Doping Using Selective Inkjet Printing.

Surface charge transfer doping (SCTD) has been regarded as an effective approach to tailor the electrical characteristics of atomically thin transition metal dichalcogenides (TMDs) in a nondestructive manner due to their two-dimensional nature. However, the difficulty of achieving rationally controlled SCTD on TMDs via conventional doping methods, such as solution immersion and dopant vaporization, has impeded the realization of practical optoelectronic and electronic devices. Here, we demonstrate controllable SCTD of molybdenum disulfide (MoS2) field-effect transistors using inkjet-printed benzyl viologen (BV) as an n-type dopant. By adjusting the BV concentration and the areal coverage of inkjet-printed BV dopants, controllable SCTD results in BV-doped MoS2 FETs with elaborately tailored electrical performance. Specifically, the suggested solvent system creates well-defined droplets of BV ink having a volume of ∼2 pL, which allows the high spatial selectivity of SCTD onto the MoS2 channels by depositing the BV dopant on demand. Our inkjet-printed SCTD method provides a feasible solution for achieving controllable doping to modulate the electrical and optical performances of TMD-based devices.

Surface charge control of poly(methyl methacrylate-co-dimethyl aminoethyl methacrylate)-based membrane for improved fouling resistance

• P(MMA-co-DMAEMA) was synthesized and blended with polysulfone UF membrane. • Blend PSF-PMD membrane was quaternized to increase surface positive charge. • Membrane was grafted with 2-carboxyethyl acrylate for surface neutralization. • Neutralization resulted in comprehensive anti-fouling smooth membrane surface. • Surface charge control is simple and effective to mitigate membrane fouling. In this study, a new poly(methyl methacrylate-co-dimethyl aminoethyl methacrylate) (P(MMA-co-DMAEMA))-based membrane was fabricated and modified to control surface charge in order to improve fouling resistance. The positively-charged P(MMA-co-DMAEMA) copolymer was first synthesized from the free radical polymerization of methyl methacrylate (MMA) and dimethylamino-2-ethyl methacrylate (DMAEMA). The copolymer was blended with polysulfone and cast into a membrane via nonsolvent-induced phase separation. The membrane was then quaternized using iodomethane and neutralized by grafting 2-carboxylethyl acrylate via UV irradiation. The membrane surface charge, composition, morphology, hydrophilicity, and anti-fouling properties were evaluated. Surface charge control of the membrane resulted in outstanding antibacterial activity and fouling resistance against model protein foulants. While the incorporation of P(MMA-co-DMAEMA) in the membrane and its quaternization greatly improved the surface hydrophilicity of the membrane and endowed positive surface charge as well. Neutralization of the blend membrane endowed a smooth and electroneutral surface layer on the membrane surface, which led to not only excellent anti-bacterial activity and comprehensive resistance against charged foulants, but also high flux retention after simple membrane washing. Dynamic filtration using protein and bacterial foulants revealed the ability of the membrane with almost zero net surface charge to regulate fouling even in practical filtration applications. The results in this study exhibit a simple and effective method for mitigation of membrane fouling propensity for practical application.

Titanium Carbide‐Based Adsorbents for Removal of Heavy Metal Ions and Radionuclides: From Nanomaterials to 3D Architectures

AbstractHeavy metal ions (HMIs) and radionuclides pose serious threats to food safety, human health, and marine ecosystems. Titanium carbides are advantageous owing to their good hydrophilicity, controllable surface charge, specific active groups, and high radiation stability, which make them effective candidates for removing toxic HMIs and radionuclides from wastewater. Recently, a lot of research is conducted to discover new methods for preparing functional titanium carbide composite materials to enhance the adsorption performance and overcome the shortcomings of conventional nanomaterials. Since 2011, the titanium carbide‐based adsorbents have undergone a developmental process from a single 2D nanosheet to a wide range of composite materials and 3D architectures. In this review, the development and progress in the design and synthesis methods of various titanium carbide‐based adsorbents are summarized. These methods are practical, scalable, and controllable in terms of structure and surface chemistry. The application of these surface‐modified composite materials in the adsorption of HMIs and radionuclides is also discussed, and the adsorption mass transfer mechanism of the adsorbates on titanium carbide‐based adsorbents is analyzed. Finally, the challenges and prospects of titanium carbide composite materials for future applications in the domain of metal ion adsorption are discussed.

Surface charge control of hierarchical ceria/silica hybrid shells for enhanced dispersion stability

Although ceria particles are currently receiving great interest with their unique catalytic and optical properties, the problem of agglomeration is yet to be overcome, which is caused by their high density and surface energy, consequently hampering the practical applications. Herein, a novel method of preparing hierarchical shells of ceria (CeO2) and silica (SiO2) on a polystyrene (PS) core is introduced to control the shape and surface charge of the particle, which give rise to different dispersion conditions. The PS/CeO2/SiO2 hybrid core–shell microspheres provide a wide spectrum of surface charge via adjustment of the thickness of the outermost silica shell from 20 to 40 nm, which sets the isoelectric point (IEP) in the range of 5.1–8.6. Subsequently, the silica shell significantly extends the product’s stability and utilization windows due to the controlled surface charge and affinity between the particle surface and the dispersion medium. The developed multilayered core–shell microspheres and the method of synthesis have great potential for various applications that require sophisticated control of surface properties.

Polyelectrolyte Substrate Coating for Controlling Biofilm Growth at Solid–Air Interface

AbstractBecause bacteria–surface interactions play a decisive role in bacteria adhesion and biofilm spreading, it is essential to understand how biofilms respond to surface properties to develop effective strategies to combat them. Polyelectrolyte coating is a simple and efficient way of controlling surface charge and energy. Using polyelectrolytes of various types, with different molecular weights and polyelectrolyte solutions of various pH provides a unique approach to investigate the interactions between biofilms and their substrate. Here, the formation of Escherichia coli biofilms at a solid–air interface is explored, whereby charge and interfacial energy are tuned using polyelectrolyte coatings on the surface. Cationic coatings are observed to limit biofilm spreading, which remain more confined when using high molecular weight polycations. Interestingly, biofilm surface densities are higher on polycationic surfaces despite their well‐studied bactericidal properties. Furthermore, the degree of polyelectrolyte protonation also appears to have an influence on biofilm spreading on polycation‐coated substrates. Finally, altering the interplay between biomass production and surface forces with polyelectrolyte coatings is shown to affect biofilm 3D architecture. Thereby, it is demonstrated that biofilm growth and spreading on a hydrogel substrate can be tuned from confined to expanded, simply by coating the surface using available polyelectrolytes.

Förster resonance energy transfer in surface plasmon coupled color conversion processes of colloidal quantum dots.

Förster resonance energy transfer (FRET) from a green-emitting quantum dot (GQD) into a red-emitting quantum dot (RQD) is an important mechanism in a multiple-color conversion process, particularly under the surface plasmon (SP) coupling condition for enhancing color conversion efficiency. Here, the dependencies of FRET efficiency on the relative concentrations of GQD and RQD in their mixtures and their surface molecule coatings for controlling surface charges are studied. Also, the SP coupling effects induced by two kinds of Ag nanoparticles on the emission behaviors of GQD and RQD are demonstrated, particularly when FRET is involved in the coupling process. FRET efficiency is reduced under the SP coupling condition. SP coupling can enhance the color conversion efficiency of either GQD or RQD. The combination of SP coupling and FRET can be used for controlling the relative converted light intensities in a multiple-color conversion process.

Zwitterionic surface charge regulation in ionic covalent organic nanosheets: Synergistic adsorption of fluoroquinolone antibiotics

The effective removal of zwitterionic fluoroquinolone (FQ) antibiotics with high water solubility in wastewater is a key environmental challenge due to the inefficacy of conventional methods of wastewater treatment. In this work, zwitterionic covalent organic frameworks (Tp-MTABs) were synthesized through a solvothermal route using 5,5′,5″-methanetriyltris(2-aminobenzenesulfonic acid) (MTABs) as a zwitterionic linker and 1,3,5-triformylphloroglucinol (Tp) as neutral knots for efficient uptake of FQ antibiotics. Tp-MTABs compose of regular distributions of sulfonic acids and amines that produce zwitterionic binding sites, which produce complementary ion-pair interactions with zwitterionic FQ antibiotics. The charge on Tp-MTABs facilitates its initial self-exfoliation to few-layered ionic covalent organic nanosheets (iCONs) with controlled surface charge, which exposes more surface ionic sites and phenyl groups toward FQ antibiotics, improving ion-pair and π–π interactions between iCONs and FQ antibiotics. These iCONs with multiple active sites highly facilitated the process of antibiotics adsorption, boosting the adsorption kinetics and improving the selectivity towards FQ antibiotics. Tp-MTABs endows ultrafast adsorption rate (<30 s) of FQ antibiotics (average over 99%). In addition, Tp-MTABs exhibit high selectivity to the removal of FQs in complex systems containing multiple competing organic compounds and high-salinity natural seawater. This work explored the structural and functional design of iCONs for the removal of organic molecules in environmental remediation.

Surface-Charge-Assisted Microdroplet Generation on a Superhydrophobic Surface.

The ability to generate and manipulate droplets down to microscales has attracted great attention in a variety of applications, such as in printing, microreactors, and biological assays. However, the production of microdroplets is often limited by special equipment or the size of needles. Here, an unexplored and facile approach is demonstrated; microdroplets can be generated and trapped yet not pinned on a micro-nano-structured superhydrophobic surface by controllable surface charge during drop impact. Tiny droplets with a size at a scale of tens of microns to millimeters are generated by simply changing the impacting velocity, the size of the impact drop, or impact frequency. Theoretical analysis suggests the generation of the microdroplet as a result of the surface-charge-regulated adhesion, competing with liquid dynamic and interfacial energy. The distribution of surface charge which determines the size and the location of the microdroplet is at the top of the micro-nano-structured surface and dependent on the pressure field applied on the surface during the drop impact. The mobility of the resulting microdroplet that can be easily manipulated without liquid retention is also shown, by taking advantage of the shielding property of the surface charge. This facile yet effective method provides a promising candidate for the realization of tiny droplet-generating and -manipulating applications.

Complete Prevention of Contact Electrification by Molecular Engineering

Summary Electrostatic charges are easily generated on surfaces during contact electrification. Although these invisible charges have emerged as a new dimension in mediating the functions of surfaces, such as energy conversion, liquid transport, reactivity, and adsorbability, the accumulation of charges on surfaces can also pose many undesirable consequences. Despite notable progress, existing approaches in engineering antistatic surfaces suffer from limitations such as the need to modify bulk materials or for delicate control of patterning on surfaces that rely on the neutralization of generated charges. Herein, we report a general toolbox for designing antistatic coatings by leveraging on chemically heterogeneous components with electron-donating and electron-accepting functions, i.e., N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and 1H,1H,2H,2H-perfluorooctyl trimethoxysilane, to molecularly engineer the surface potential to achieve an electrostatic homogeneity and completely prevent charge generation. Our approach is general, which allows the facile fabrication of antistatic coatings on various materials, even flexible and curved, with good re-writability and transparency.

Ultraselective and Highly Permeable Polyamide Nanofilms for Ionic and Molecular Nanofiltration

AbstractMembranes with ultrahigh ion selectivity and high liquid permeance are needed to produce high‐quality product water with increased recovery and process efficiency in water desalination. The narrow pore size distribution and controlled surface charge in the separation layer of nanofiltration membranes significantly improve the ion selectivity through molecular sieving and Donnan exclusion of co‐ions. Here, the ultraselective and yet highly water permeable polyamide nanofilm composite nanofiltration membranes developed by precisely controlling the kinetics of the interfacial polymerization reaction by maintaining the stoichiometric equilibrium at the interface is reported. The kinetically favorable stoichiometric equilibrium condition prohibits the formation of aggregate pores in the nanofilm and leads to the formation of narrow network pores with a high surface negative charge. Nanofilms are designed with a controlled degree of crosslinking and made as thin as ≈7 nm to achieve increased water permeance. The ultraselective membranes exhibit up to 99.99% rejection of divalent salt (Na2SO4) and demonstrate monovalent to divalent ion selectivity of &gt;4000. The selectivity of these nanofilm composite membranes is beyond the permeance–selectivity upper‐bound line of the state‐of‐the‐art nanofiltration membranes and one to two orders of magnitude higher than the commercially available membranes with pure water permeances of up to 23 L m−2 h−1 bar−1. The fabrication process is scalable for membrane manufacturing.

Tuning the Surface Charge of Self-Assembled Polydiacetylene Vesicles to Control Aggregation and Cell Binding.

Polydiacetylene vesicles of various compositions were assembled using a two-part mixture of 10,12-pentacosadiynoic acid (PCDA) and ethylenedioxy-bis-ethylamine (EDEA)-labeled PCDA in order to control surface charge and stability within a desired pH range. Investigation of the interaction of the vesicles with mammalian cells as a function of surface charge was carried out and identified a clear correlation in cell–vesicle association and corresponding cell death for vesicles with positive surface charge. The binding behavior of the vesicles was found to be tunable by regulating the proportion of anionic PCDA relative to cationic PCDA–EDEA content within vesicles as to control the surface charge as a function of pH. Association of vesicles with cells thus depended on the corresponding charge of the vesicles and cell surface. The prospect of this work may serve as a step toward future vesicle designs to allow triggered uptake of vesicles locally within low pH tumor microenvironments.