New inorganic–organic proton conducting membranes based on Nafion and [(ZrO2)·(SiO2)0.67] nanoparticles: Synthesis vibrational studies and conductivity

In this report is described the preparation of six nanocomposite membranes of formula {Nafion/_[(ZrO_2)⋅(SiO_2)0.67]ΨZrO₂}$\{\text{Nafion}/{[(\text{Zr}{\text{O}}_2)\cdot {(\text{Si}{\text{O}}_2)}_{0.67}]}_{{\Psi }_{\text{Zr}{\text{O}}_2}}\}$ with ΨZrO₂${\Psi }_{\text{Zr}{\text{O}}_2}$ ranging from 0 to 1.79 based on Nafion^® and [(ZrO₂)·(SiO₂)_0.67] nanofiller. Morphology investigations carried out by SEM measurements indicate that the composition of membranes is asymmetric. Indeed, with respect to the direction of the films after casting procedure, the top side (A-side) and bottom side (B-side) present a different nanofiller concentration. The concentration of nanofiller increases gradually from A to B side. The membranes present thicknesses ranging from 170 to 350 nm and are studied by FT-IR ATR and micro-Raman measurements.     

The influence of the CO inhibition effect on the estimation of the H2 purification unit surface

The CO inhibition effect on H₂ permeance through commercial Pd-based membranes was analysed by means of permeation measurements at different CO compositions (0–30% molar) and temperatures (593–723 K) with the aim to determine the increase of the membrane area in order to compensate the H₂ flux reduction owing to the CO inhibition effect. The permeance of H₂ fed with carbon monoxide was observed to decrease with respect to the case of pure hydrogen. At 647 K the H₂ permeance of a pure feed of 316 μmol m⁻² s⁻¹ Pa^−0.5 reduces progressively until 275 μmol m⁻² s⁻¹ Pa^−0.5 when 15% or more of CO is present in the system, until it reaches a plateau at 20%. The inhibition effect occurring when CO is present in the feed stream reduces with the progressive temperature increase; the reduction of the permeance decreases exponentially by 23% at 593 K and by 3% at 723 K with 10% of CO. The inhibition effect is seen to be reversible. An H₂ flux profile in a Sieverts' plot shows the effect produced by the increase of the CO composition along the Pd-based membrane length. The H₂ flux profile allows the area of a Pd-based membrane to be evaluated in order to have the same permeate flow rate of H₂ when it is fed with CO or as a pure stream. Moreover, a qualitative comparison between the H₂ flux profiles and a previously proposed model has been carried out.     

Amino‐Functionalized Silica Membranes for Enhanced Carbon Dioxide Permeation

Functionalization of silica membranes is important for enhancing surface interactions with specific chemicals in order to enhance separations. It is important to develop synthesis strategies that allow control over the density and the surface chemistry of the functional group in order to tailor the membrane separation properties. In this paper we investigate the ability of amino functionalization to enhance CO₂ transport in silica membranes. Specifically, we examine three synthesis techniques for functionalizing silica membranes with amino groups that result in different surface chemistries of the silica membranes. Silica membranes are amino‐functionalized by atomic layer deposition (ALD) with aminopropyldimethylethoxysilane (APDMES), ethylenediamine (EDA)‐assisted APDMES ALD, and direct attachment of aminopropyltriethoxysilane (APTES) from the liquid phase. Three different reaction schemes are presented and verified by using Fourier‐transform infrared (FTIR) spectroscopy. The FTIR measurements were performed on silica powders that were processed using the same reaction conditions as the membranes used in this study. The differences in reaction schemes are correlated with changes in the CO₂ facilitation characteristics. It is found that high loadings of amino groups, in which interaction with the silica surface is minimized, promote the highest CO₂ transport.     

Dopamine: Just the Right Medicine for Membranes

Mussel‐inspired chemistry has attracted widespread interest in membrane science and technology. Demonstrating the rapid growth of this field over the past several years, substantial progress has been achieved in both mussel‐inspired chemistry and membrane surface engineering based on mussel‐inspired coatings. At this stage, it is valuable to summarize the most recent and distinctive developments, as well as to frame the challenges and opportunities remaining in this field. In this review, recent advances in rapid and controllable deposition of mussel‐inspired coatings, dopamine‐assisted codeposition technology, and photoinitiated grafting directly on mussel‐inspired coatings are presented. Some of these technologies have not yet been employed directly in membrane science. Beyond discussing advances in conventional membrane processes, emerging applications of mussel‐inspired coatings in membranes are discussed, including as a skin layer in nanofiltration, interlayer in metal‐organic framework based membranes, hydrophilic layer in Janus membranes, and protective layer in catalytic membranes. Finally, some critical unsolved challenges are raised in this field and some potential pathways are proposed to address them.     

Tough and Self‐Recoverable Thin Hydrogel Membranes for Biological Applications

Tough and self‐recoverable hydrogel membranes with micrometer‐scale thickness are promising for biomedical applications, which, however, rarely be realized due to the intrinsic brittleness of hydrogels. In this work, for the first time, by combing noncovalent DN strategy and spin‐coating method, we successfully fabricated thin (thickness: 5–100 µm), yet tough (work of extension at fracture: 10⁵–10⁷ J m^?3) and 100% self‐recoverable hydrogel membranes with high water content (62–97 wt%) in large size (≈100 cm²). Amphiphilic triblock copolymers, which form physical gels by self‐assembly, were used for the first network. Linear polymers that physically associate with the hydrophilic midblocks of the first network, were chosen for the second network. The inter‐network associations serve as reversible sacrificial bonds that impart toughness and self‐recovery properties on the hydrogel membranes. The excellent mechanical properties of these obtained tough and thin gel membranes are comparable, or even superior to many biological membranes. The in vitro and in vivo tests show that these hydrogel membranes are biocompatible, and postoperative nonadhesive to neighboring organs. The excellent mechanical and biocompatible properties make these thin hydrogel membranes potentially suitable for use as biological or postoperative antiadhesive membranes.     

Promote Intratumoral Drug Release and Penetration to Counteract Docetaxel-Induced Metastasis by Photosensitizer-Modified Red Blood Cell Membrane-Coated Nanoparticle

The red blood cell membrane (RBCm) provides tight protection, lowers the immunogenicity, and prolongs the circulation time of drugs in vivo when acting as the coating of drug delivery systems. However, the cellular uptake and release of drugs are hindered by RBCm. Docetaxel (DTX) is the first-line medicine for treating triple-negative breast cancer (TNBC), but it induces tumor metastasis. To solve these dilemmas, in this study, the photosensitizer 1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide (DiR)-modified RBCm (DM) is prepared, which is coated onto a hybrid micelle consisting of the prodrugs of DTX and the anti-metastasis agent calcitriol (CTL), obtaining a nanoparticle, named HDC-DM. In a 4T1 tumor-bearing mouse model, after injecting HDC-DM, the intratumoral DTX and CTL concentrations are increased by 1.7 and 2.5 times compared with the free drug groups. After irradiating tumors with near-infrared laser, DiR elicits the photothermal effect, triggering the rupture of RBCm and drug release, promoting drug penetration in tumors, and inducing immunogenic cell death. The tumor growth inhibition rate is 77%, and the formation of lung metastases is reduced by 82%, with good biocompatibility. It is suggested that the combination of phototherapy, chemotherapy, and anti-metastatic therapy using HDC-DM is expected to be a powerful strategy for treating TNBC.     

A Soft Resistive Acoustic Sensor Based on Suspended Standing Nanowire Membranes with Point Crack Design

An artificial basilar membrane (ABM) is an acoustic transducer that mimics the mechanical frequency selectivity of the real basilar membrane, which has the potential to revolutionize current cochlear implant technology. While such ABMs can be potentially realized using piezoelectric, triboelectric, and capacitive transduction methods, it remains notoriously difficult to achieve resistive ABM due to the poor frequency discrimination of resistive‐type materials. Here, a point crack technology on noncracking vertically aligned gold nanowire (V‐AuNW) films is reported, which allows for designing soft acoustic sensors with electric signals in good agreement with vibrometer output—a capability not achieved with corresponding bulk cracking system. The strategy can lead to soft microphones for music recognition comparable to the conventional microphone. Moreover, a soft resistive ABM is demonstrated by integrating eight nanowire‐based sensor strips on a soft trapezoid frame. The wearable ABM exhibits high‐frequency selectivity in the range of 319–1951 Hz and high sensitivity of 0.48–4.26 Pa^?1. The simple yet efficient fabrication in conjunction with programmable crack design indicates the promise of the methodology for a wide range of applications in future wearable voice recognition devices, cochlea implants, and human–machine interfaces.     

Cancer Cell Membrane‐Coated Gold Nanocages with Hyperthermia‐Triggered Drug Release and Homotypic Target Inhibit Growth and Metastasis of Breast Cancer

The cell‐specific targeting drug delivery and controlled release of drug at the cancer cells are still the main challenges for anti‐breast cancer metastasis therapy. Herein, the authors first report a biomimetic drug delivery system composed of doxorubicin (DOX)‐loaded gold nanocages (AuNs) as the inner cores and 4T1 cancer cell membranes (CMVs) as the outer shells (coated surface of DOX‐incorporated AuNs (CDAuNs)). The CDAuNs, perfectly utilizing the natural cancer cell membranes with the homotypic targeting and hyperthermia‐responsive ability to cap the DAuNs with the photothermal property, can realize the selective targeting of the homotypic tumor cells, hyperthermia‐triggered drug release under the near‐infrared laser irradiation, and the combination of chemo/photothermal therapy. The CDAuNs exhibit a stimuli‐release of DOX under the hyperthermia and a high cell‐specific targeting of the 4T1 cells in vitro. Moreover, the excellent combinational therapy with about 98.9% and 98.5% inhibiting rates of the tumor volume and metastatic nodules is observed in the 4T1 orthotopic mammary tumor models. As a result, CDAuNs can be a promising nanodelivery system for the future therapy of breast cancer.     

Novel Organic‐Dehydration Membranes Prepared from Zirconium Metal‐Organic Frameworks

Membranes with outstanding performance that are applicable in harsh environments are needed to broaden the current range of organic dehydration applications using pervaporation. Here, well‐intergrown UiO‐66 metal‐organic framework membranes fabricated on prestructured yttria‐stabilized zirconia hollow fibers are reported via controlled solvothermal synthesis. On the basis of the adsorption–diffusion mechanism, the membranes provide a very high flux of up to ca. 6.0 kg m^?2 h^?1 and excellent separation factor (>45 000) for separating water from i ‐butanol (next‐generation biofuel), furfural (promising biochemical), and tetrahydrofuran (typical organic). This performance, in terms of separation factor, is one to two orders of magnitude higher than that of commercially available polymeric and silica membranes with equivalent flux. It is comparable to the performance of commercial zeolite NaA membranes. Additionally, the membrane remains robust during a pervaporation stability test (≈300 h), including exposure to harsh environments (e.g., boiling benzene, boiling water, and sulfuric acid) where some commercial membranes (e.g., zeolite NaA membranes) cannot survive.     

Novel Engineered Ion Channel Provides Controllable Ion Permeability for Polyelectrolyte Microcapsules Coated with a Lipid Membrane

The development of nanostructured microcapsules based on a biomimetic lipid bilayer membrane (BLM) coating of poly(sodium styrenesulfonate) (PSS)/poly(allylamine hydrochloride) (PAH) polyelectrolyte hollow microcapsules is reported. A novel engineered ion channel, gramicidin (bis‐gA), incorporated into the lipid membrane coating provides a functional capability to control transport across the microcapsule wall. The microcapsules provide transport and permeation for drug‐analog neutral species, as well as positively and negatively charged ionic species. This controlled transport can be tuned for selective release biomimetically by controlling the gating of incorporated bis‐gA ion channels. This system provides a platform for the creation of “smart” biomimetic delivery vessels for the effective and selective therapeutic delivery and targeting of drugs.