Multiple hydrogen bonding self-assembly tailored electrospun polyimide hybrid filter for efficient air pollution control.

Air pollutions are extremely serious threats to human health and the functional hybrid filter is able to remove complicated pollutants with great potential. However, the stable structure design of hybrid filter to provide efficient filtration and adsorption performance for high temperature applications still remains a challenge. In this study, electrospun polyimide (PI) based hybrid filter was fabricated via multiple hydrogen bonding self-assembly for high-temperature air purification. In particular, Octa(amino-propylsilsesquioxane) (POSS-NH2) was utilized as "bridge" for the surface activation of PI fiber, and then amino-functionalized Zeolitic Imidazolate Framework-8 (NH2-ZIF-8) nanocrystals were anchored on the fiber surface through hydrogen bonding. On account of the synergistic effect of the interception effect of fibers and the electrostatic interaction of NH2-ZIF-8 nanocrystals, the as-obtained PI-POSS@ZIF hybrid filter possessed excellent filtration performance with a high PM0.3 removal efficiency of 99.28% and a low pressure drop of 49.21 Pa at high temperature of 280 °C. Moreover, due to the massive micropore structure, rich open metal sites and functional groups of NH2-ZIF-8, the hybrid filter exhibited prominent VOCs adsorption performance with adsorption capability of 89.95 mg/g for formaldehyde.

Electrospun Wrinkled Porous Polyimide Nanofiber-Based Filter via Thermally Induced Phase Separation for Efficient High-Temperature PMs Capture.

Benefiting from its superior thermal stability, polyimide (PI) fiber-based composites have attracted wide attention in the field of high-temperature filtration and separation. However, the trade-off between filtration efficiency and pressure drop of traditional PI filters with single morphology and structure still remains challenging. Herein, the electrospun PI high-temperature-resistant air filter was fabricated via thermal-induced phase separation (TIPS), employing polyacrylonitrile (PAN) as a template. The PI nanofibers exhibited special wrinkled porous structure, and the filter possessed a high specific surface area of 304.77 m2/g. The removal of PAN changed the chemical composition of the fiber and induced PI molecules to form complex folds on the surface of the fiber, thus forming the wrinkled porous structure. Additionally, the wrinkled porous PI nanofiber filter displayed a high PM0.3 removal efficiency of 99.99% with a low pressure drop of 43.35 Pa at room temperature, and the filtration efficiency was still over 97% after being used for long time. Moreover, the efficiency of the filter could even reach 95.55% at a high temperature of 280 °C. The excellent filtration performance was attributed to the special wrinkled porous surface, which could limit the Brownian motion of PMs and reinforce the mechanical interception effect to capture the particulate matters (PMs) on the surface of the filter. Therefore, this work provided a novel strategy for the fabrication of filters with special morphology to cope with increasingly serious air pollution in the industrial field.

ß-Cyclodextrin-modified hyaluronic acid-based supramolecular self-assemblies for pH- and esterase- dual-responsive drug delivery.

Although some drug-based supramolecular systems have been constructed to overcome multidrug resistance and enhance the bioavailability of chemical drugs, strengthening the specific stimuli-responsive and active targeting ability of these systems is still a major challenge. In this paper, the synthesis and self-assembly behaviour of supramolecular self-assemblies with active targeting ß-cyclodextrin-modified hyaluronic acid (HA-CD) and drug-drug conjugates (curcumin-oxoplatin, Cur-Pt) as building moieties were carefully investigated. Notably, the curcumin was chosen not only as the chemical anti-cancer drug, but also acted as the guest molecule which could be included into CD cavity to form host-guest interaction-based supramolecular assemblies. The obtained self-assemblies exhibited pH- and esterase-responsive drug release behaviours. Furthermore, basic cell experiments were performed to prove their effective cellular toxicity based on A549 cells and PC3 cells with high expression of CD44 receptor but they showed no toxicity to normal LO-2 cells with low expression of CD44 receptor, which suggests their potential application in the targeted drug release field.

Toward high-performance nanofibrillated cellulose/aramid fibrid paper-based composites via polyethyleneimine-assisted decoration of silica nanoparticle onto aramid fibrid.

Flexible paper-based nanocomposites dielectrics are of crucial importance in electrical insulation and advanced electrical power systems. In this work, a novel nanofibrillated cellulose/aramid fibrid (NFC/AF) composite was fabricated by vacuum-assisted filtration process. In order to improve the dielectric property of the composites, carboxylated nano-SiO2 was chemically coated onto aramid fibrid via molecular self-assembly with the aid of phosphoric acid (PA) pretreatment and subsequent polyethyleneimine (PEI) functionalization. It was found that composites prepared by NFC and (PEI/SiO2)-modified AF (after crosslinking) ((PEI/SiO2)-AF) showed dense structure, which was mainly due to enhanced interfacial interaction between AF and NFC. Consequently, NFC/(PEI/SiO2)-AF paper-based composites showed better tensile toughness (∼6 % elongation at break) and mechanical strength (∼36.28 MPa), in comparison with NFC/AF. More importantly, the electrical insulation performance and thermal stability of the composites were significantly improved. Accordingly, this work provides a facile approach to fabricate high-performance dielectric composites especially for high-temperature electrical insulation applications.

Ultrathin MXene/aramid nanofiber composite paper with excellent mechanical properties for efficient electromagnetic interference shielding.

MXenes, new two-dimensional compounds with hydrophilic surfaces and high metallic conductivity, have attracted significant interest in the electromagnetic interference shielding field in recent years. Nevertheless, poor mechanical properties and brittle nature are bottlenecks for their commercial application. Herein, one-dimensional ANFs were designed as the intermolecular cross-linker between d-Ti3C2Tx flakes and MXene (d-Ti3C2Tx)/aramid nanofiber (ANF) composite paper with a multi-layered structure was fabricated via the vacuum-assisted filtration approach. Further investigation revealed that the ANFs and MXene displayed good combination by hydrogen bonding, and MXene/ANF composite papers exhibited excellent mechanical properties and superior electrical conductivity. The MXene/ANF composite paper possessed a favorable shielding effectiveness (SE) which reached ∼28 dB in 8.2-12.4 GHz (X band) with an ultra-thin thickness ∼17 µm and showed potential application prospects as an advanced composite in sensitive electronic products.

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB2-type host-guest-conjugated amphiphilic molecules for controlled drug delivery.

Although stimuli-responsive supramolecular self-assemblies have been constructed, the controlled drug delivery induced by morphology transitions of these supramolecular self-assemblies on the basis of host-guest-conjugated monomers (HGCMs) are few reported. In this paper, the self-assembly behaviors of AB2-type HGCMs, e.g., ß-cyclodextrin-benzimidazole2 (ß-CD-BM2), were investigated at neutral and acidic pH conditions, respectively. Specifically, ß-CD-BM2 first self-assembled into fan-shaped supramolecular self-assemblies with a hydrodynamic diameter of 163 nm at neutral pH, whereas they were further dissociated into spherical supramolecular self-assemblies with a size of 52 nm under acidic conditions. This morphology transition process was utilized to conduct a two-stage DOX delivery under neutral and acidic pH. Basic cell experiments demonstrated that the drug-loaded ß-CD-BM2-based supramolecular self-assemblies with varied morphology could inhibit cancer cell proliferation, indicating their potential application in the field of drug delivery.

Construction of ß-cyclodextrin-based supramolecular hyperbranched polymers self-assemblies using AB2-type macromonomer and their application in the drug delivery field.

Despite some efforts have been made in the research of supramolecular hyperbranched polymers (SHPs) self-assemblies, the study which has not been consideration to date is the influence of incoming stimuli-responsive polymer chain on their self-assembly property undergo outer stimuli. The introduction of stimuli-responsive segments which could maintain their hydrophilic property are expected to affect the self-assembly behaviour of SHPs and expand their further biomedical application. In this paper, AB2-type macromolecular monomer, LA-(CD-PDMA)2, which consisted one lithocholic acid (LA) and two ß-cyclodextrin terminated poly(2-(dimethylamino)ethyl methacrylate) segments (CD-PDMA) was synthesized. LA-(CD-PDMA)2 based SHP were obtained based on the host-guest inclusion interactions of CD/LA moietes and with PDMA as pH-responsive hydrophilic chains. As a control to study the influence of incoming PDMA chains, both LA-(CD-PDMA)2 based SHPs-1 and LA-CD2 based SHPs-2 self-assemblies were comparatively investiged through 2D 1H NMR ROESY, transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results suggested that except for the higher drug loading efficiency LA-(CD-PDMA)2 based SHPs-1 pocessing, the release rates of SHPs-1 increased notably at pH 5.0 than that of pH 7.4 due to the repulsion and stretch of protonated PDMA chains while the release rates of SHPs-2 showed no obvious difference. Finally, basic cell experiments demonstrated that the SHPs based self-assemblies can be internalized into cancer cells, indicating their potential application in the drug delivery field.

Photo- and pH- Dual-Responsive ß-Cyclodextrin-Based Supramolecular Prodrug Complex Self-Assemblies for Programmed Drug Delivery.

Despite the fact that progress has been made in the application of supramolecular prodrug self-assemblies to enhance the functionality of drug-delivery systems, corresponding research on multi-responsive supramolecular prodrug self-assemblies for programmed drug delivery is still limited. In this paper, the synthesis and self-assembly behavior of supramolecular prodrug complexes (SPCs) with ß-cyclodextrin-acylhydrazone-doxorubicin (ß-CD-hydrazone-DOX) and the targeting of azobenzene-terminated poly[2-(dimethylamino)ethyl methacrylate] (Azo-PDMA-FA) as a building block were investigated. The obtained SPCs could also form self-assemblies on the basis of their amphiphilic nature. Next, SPC-based multi-compartment vesicles and complex micelles, which were confirmed by transmission electron microscopy and dynamic/static light scattering, were obtained with good reversibility under alternative visible light or UV irradiation. Furthermore, three-stage programmed drug-delivery behavior was observed from dual-responsive SPC-based self-assemblies by utilizing UV and pH stimuli. Specifically, the SPCs first self-assembled into multicompartmental vesicles, which was accompanied by a slow release of DOX. Next, UV-light irradiation induced the dissociation of ß-CD/Azo, which led to morphology transition and a slight increase in the rate of release of DOX. Upon transferring the self-assemblies to phosphate-buffer solution (pH 5.0), the release rates increased notably as a result of the broken acylhydrazone bond. Finally, basic cell experiments further demonstrated that the SPC-based self-assemblies could be internalized into cancer cells, which suggests their promise for applications in cancer therapy.