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Biliary-stent implantation has become an effective treatment for patients with malignant obstructive jaundice caused by hepatobiliary carcinoma. Stent restenosis due to tumor ingrowth is a common problem. In this study, we assessed a biodegradable form of magnesium (Mg) for its anticancer effect on hepatobiliary carcinoma, compared to the conventional stent material of titanium (Ti). The results showed that a Mg extract inhibited proliferation and induced apoptosis in human cholangiocarcinoma cells, while a Mg plate inhibited cell adhesion and destroyed the cytoskeleton in the process of biodegradation. In animal experiments with H22 tumor-bearing mice, Mg wires implanted in tumors exhibited an inhibitory effect on their growth compared with Ti wires. Fifteen days after implantation of metal wires, the mean tumor volume and weight in the Mg group were significantly smaller than in the Ti group. We observed the dynamic-degradation process of Mg wires in tumors and generation of H2 gas via soft X-ray photography and scanning electron microscopy. Histopathological analyses showed that apoptosis of tumor cells around Mg wires significantly increased, expression of carbonic anhydrase 9 significantly decreased, and the upstream protein hypoxia-inducible factor 1-alpha also decreased to some extent. Taken together, these results indicated that biodegradable Mg had antitumor properties both in vitro and in vivo, suggesting its potential application as a novel material for biodegradable biliary stents.

Polymer film capacitors for energy storage applications at high temperature have shown great potential in modern electronic and electrical systems such as those used in aerospace, automotive, and oil exploration industries. The crosslinking strategy has been regarded as one of the most feasible approaches for polymer dielectrics to meet the high temperature requirements. This article presents recent progress in the field of crosslinked polymer-based materials as high-performance dielectrics at elevated temperature. Self-crosslinking polymers, polymers crosslinked by agents and crosslinked polymer nanocomposites are the focus of materials reviewed. We identify the critical relationships between the crosslinking construction methods and the capacitive energy storage properties of dielectric materials on the molecular scale. An in-depth analysis of challenges and future prospects in this field is also provided. The understanding of the crosslinking strategy enables the rational design of polymer-based materials for high-temperature capacitive energy storage.

A family of poly(vinylidene fluoride-ter-trifluoroethylene-ter-chlorodifluoroethylene) [P(VDF-TrFE-CDFE)] terpolymers was synthesized. The effect of the chlorodifluoroethylene (CDFE) concentration ...

The discovery of relaxor behavior in poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymers plays a crucial role in driving the formation of a morphotropic phase boundary (MPB) near which large enhancements of dielectric and piezoelectric responses are achieved. Here we study the dielectric spectra of P(VDF-TrFE)s near MPB and analyze the relaxor behavior using two different theoretical models. We observe the largest dielectric constant of ∼76 at 1 kHz in morphotropic composition P(VDF-TrFE) 50/50 mol % at around 69 °C. We show that the compositional dependence of dielectric peak temperature changes dramatically in the vicinity of VDF = 49 mol %. Moreover, we find that the parameters (i.e., dielectric relaxation strength) deduced from the fit of the experimental data by different models also changes abruptly at VDF = 49 mol %. These findings clearly signify the destabilization of normal ferroelectric phase occurring at the critical VDF content of 49 mol % and explicitly mark one boundary of ...

Three cross-linked porphyrin-based polyimides (PPBPI-H-CR, PPBPI-Mn-CR, and PPBPI-Fe-CR) were synthesized from 5,10,15,20-tetra(4-aminophenyl)porphyrin (TAPP) and 2,5-bis(3,4-dicarboxyphenoxy)-4′-p...

Significantly enhanced electromechanical responses are inherent to piezoelectric materials at the morphotropic phase boundary (MPB). Here we reveal that conformational competition between the trans-planar and 3/1-helical phases of poly(vinylidene fluoride–trifluoroethylene) P(VDF-TrFE) occurs intramolecularly rather than intermolecularly to induce the formation of MPB. We attribute significantly enhanced piezoelectric properties observed near MPB to the polarization rotation between energetically degenerate trans-planar and 3/1-helical phases. Our results offer design principles to search for new MPB polymers from a molecular perspective.

Phototheranostics involving both fluorescence imaging and photodynamic therapy has been recognized to be potentially powerful for cancer treatment by virtue of various intrinsic advantages. However, the state-of-the-art materials in this area are still far from ideal toward practical applications, ascribed to their respective and collective drawbacks, such as inefficient imaging quality, inferior reactive oxygen species (ROS) production, the lack of subcellular-targeting capability, and dissatisfactory delivery. In this paper, these shortcomings are successfully addressed through the integration of finely engineered photosensitizers with aggregation-induced emission (AIE) features and well tailored nanocarrier systems. The yielded AIE NPs simultaneously exhibit broad absorption in the visible-light region, bright near-infrared fluorescence emission, high ROS generation, as well as tumor lysosomal acidity-activated and nucleus-targeted delivery functions, making them promising for precise and efficient phototheranostics. Both in vitro and in vivo evaluations show that the presented nanotheranostic systems bearing good photostability and appreciable biosecurity perform well in fluorescence imaging-guided photodynamic cancer therapy. This study thus not only extends the application scopes of AIE nanomaterials but also offers useful insights into constructing advanced cancer phototheranostics.

A composite foam consisting of foamed cross-linking polystyrene (c-PS) and boron nitride nanosheets (BNNSs) was synthesized, which shows a higher thermal conductivity (TC) than the corresponding solid counterparts. The BNNS fillers are found to be aligned along the cell wall as a result of the biaxial stress field from cell expansion during the formation of three-dimensional interconnectivity in the foams, resulting in an enhanced TC of 1.28 W/m K, nearly two and four times those of its solid counterpart and pure c-PS, respectively. It is found that the foaming-assisted formation of the filler network is an efficient strategy to improve the TC at low filler loadings in the composites. Furthermore, the composite foams exhibit low density, rather low dielectric constants and dissipation factors at wide frequency and temperature ranges. The present work provides a novel approach to design and prepare lightweight heat conductive polymers with low filler loadings as low-density heat management materials for potential applications in aeronautics and aerospace components.

Aiming to achieve versatile phototheranostics with the integrated functionalities of multiple diagnostic imaging and synergistic therapy, the optimum use of dissipated energy through both radiative and nonradiative pathways is definitely appealing, yet a significantly challenging task. To the best of the knowledge, there have been no previous reports on a single molecular species effective at affording all phototheranostic modalities including fluorescence imaging (FLI), photoacoustic imaging (PAI), photothermal imaging (PTI), photodynamic therapy (PDT), and photothermal therapy (PTT). Herein, a simple and highly powerful one-for-all phototheranostics based on aggregation-induced emission (AIE)-active fluorophores is tactfully designed and constructed. Thanks to its strong electron donor-acceptor interaction and finely modulated intramolecular motion, the AIE fluorophore-based nanoparticles simultaneously exhibit bright near-infrared II (NIR-II) fluorescence emission, efficient reactive oxygen species generation, and high photothermal conversion efficiency upon NIR irradiation, indicating the actualization of a balance between radiative and nonradiative energy dissipations. Furthermore, the unprecedented performance on NIR-II FLI-PAI-PTI trimodal-imaging-guided PDT-PTT synergistic therapy is demonstrated by the precise tumor diagnosis and complete tumor elimination outcomes. This study thus brings a new insight into the development of superior versatile phototheranostics for practical cancer theranostics.

To achieve efficient and precise design of fluorescent probes, unraveling the intrinsic mechanism of their selectivity on different subcellular organelles in cell imaging is important. Using a theoretical protocol combining large-scale molecular dynamics simulations and the hybrid QM/MM model, we explored the mechanism of the strikingly different fluorescence imaging behaviors of two amphiphilic AIEgens with quite similar chemical structures. We proposed that the hydrophobic moiety and the pyridine group of AIEgens manipulate the emission behaviors, and the charged headgroups control the permeation ability through the cell membrane. Therefore, we proposed a molecular design strategy of AIEgen-based fluorescent probes to selectively target the cell membrane or mitochondria, and designed and synthesized four AIEgens. The cell imaging experimental results successfully confirmed the theoretical prediction, which would open an efficient shortcut to design AIEgen-based fluorescent probes to selectively target the cell membrane or mitochondria and lays a solid foundation for the rational design of advanced cell imaging materials.

Fluorescence-based theranostics provides a powerful platform for effective diagnosis and therapy. In particular, luminogens with aggregation-induced emission (AIE) characteristics have triggered state-of-the-art developments in theranostics, thanks to their intrinsic properties, including high signal-to-noise ratios, high photostability and capability as photosensitizing agents. However, the development of AIE luminogens for biological applications mostly stays at rational design and preparation through organic synthesis, which may give rise to high cost, environmental destruction and potential cytotoxicity. Actually, with easy access and good biocompatibility, it would be of great interest to employ AIE-active natural agents from herbs in theranostics and pharmacodynamics studies through fluorescence imaging. In this work, the use of berberine chloride, an AIE-active natural product from herbal plants, as a theranostic agent towards both cancer cells and bacteria is investigated. Through fluorescence bio-imaging, berberine chloride selectively targets cancer cells over normal cells and discriminates Gram-positive against Gram-negative bacteria. Furthermore, light-driven organelle-targeting migration of berberine chloride from mitochondria to the nucleus was discovered. Therapeutic evaluation shows that berberine chloride can efficiently ablate cancer cells over normal cells, and kill Gram-positive bacteria through both in vitro and in vivo photodynamic therapy. This work thus provides a blueprint for the next generation of theranostics using natural AIE luminogens.

Two sets of thermal stable nanocomposites were fabricated by using engineering plastics poly(ether sulfone) (PES) as a matrix and phthalocyanine molecules (CuPc) or hyperbranched phthalocyanine (HCuPc)-coated barium titanate (BT) nanoparticles as fillers for high electric field and high-temperature dielectric applications. By side-by-side comparison, the hyperbranched coating is finely addressed for enhancing the dielectric response and breakdown strength of the composites. Specifically, BT–HCuPc/PES exhibits 40% lower dielectric loss and about 110% larger breakdown strength than BT–CuPc/PES. The addition of hyperbranched phthalocyanine may enhance the compatibility and dispersion of the ceramic fillers in the polymer matrix and reduces the charge carrier between the filler and matrix. Meanwhile, high dielectric constant, high breakdown, and low dielectric loss are well-maintained in the composites filled with hyperbranched phthalocyanine-modified BT from room temperature to 150 °C. The discharged energy ...

A novel ultrafiltration membrane is developed by incorporating in situ self-assembled polymeric nanoparticles into the membrane matrix. The chemical stability of the nanoparticles in regard to pH and temperature is explored via a rational method. The result indicates that the electrostatic interaction strength between the two polyelectrolytes can withstand a broad pH range (pH 1–11) and a relatively high temperature (80 °C). Meanwhile, the nanoparticle size and distribution in the membranes are investigated by scanning electron microscopy (SEM), which are proved to be affected by the polyelectrolyte concentration and molecular weight. The contact angle values of the prepared membranes show that the membrane hydrophilicity is improved by adding polymeric nanoparticles. Furthermore, the molecular weight cut-off and pore size of the membranes are increased with added nanoparticle loading. More importantly, the mixed matrix membranes exhibit simultaneous increases in permeability and rejection of contaminants compared with the pristine PES membrane, which is ascribed to the appropriate pore size and enhanced hydrophilicity of the membranes. Especially, the composite membrane mixed with 3 wt% polymeric nanoparticles displays the highest pure water flux (460 L m−2 h−1), which is 3 times that of the pristine PES membrane, and 97.6% rejection of BSA. This work provides a new strategy for preparing flexible polymeric nanoparticles and developing high-performance mixed matrix membranes for water treatment.

Local recurrence has become the main problem of tumor thermal ablation for hepatocellular carcinoma (HCC). Nanotechnology could potentially aid in improving the situation. MoS₂ nanomaterials, as ideal photothermal therapy (PTT) agents, have gathered great interest due to their excellent surface plasmon resonance features, high photothermal conversion efficiency, good biocompatibility and low cost. In this work, we synthesized layered MoS₂ hollow spheres (LMHSs; diameter ∼300 nm) via the solvent-controlled ultrasonic nebulization method. Compared to LMHSs previously synthesized by our group (approx. 600 nm), the current ones showed better efficacy, as well as enhanced permeability and retention, due to their ideal size. In addition, the LMHSs are developed with both layered and hollow structures, which are extremely suitable for loading anticancer agents. In this study, doxorubicin (DOX) was loaded into the nanoparticles (NPs) using the vacuum negative pressure loading method, and the drug loading capacity was as high as 32.5%. Therefore, the efficacy of cancer cell killing by photothermal ablation was markedly enhanced by DOX released from the LMHSs. As we expected, the as-made DOX@MoS₂ NPs exhibited excellent photothermo-chemotherapy effect, both in vitro and in vivo. Tumor cell viability was inhibited up to 73% at the power density of 1.2 W cm-2, and tumors in mice models achieved complete response, with no recurrence. The PTT with DOX@MoS₂ NPs had a much better synergistic therapeutic efficacy than each individual treatment, showing great promise for HCC treatment.

In this study, a polymeric composite with high-k, low dielectric loss, and high electrical energy storage has been developed by dispersing tetra-amido-phthalocyanine zinc (ZnPc) coated acidified multi-walled carbon nanotubes (a-MWCNT) within the sulfonated poly (ether ether ketone) (SPEEK) polymer matrix. The ZnPc-MWCNT/SPEEK composites exhibited better dielectric properties than pure polymer matrix, with a dielectric constant of 14.0 and a dielectric loss of 0.042 at 1 kHz (with 12 wt% ZnPc-MWCNT). Furthermore, the discharged energy density of ZnPc-MWCNT/SPEEK composites (4 wt% ZnPc-MWCNT) is 68% higher than that of the pure polymer.

High-temperature ceramic/polymer nanocomposites with large energy density as the reinforcement exhibit great potential for energy storage applications in modern electronic and electrical power systems. Yet, a general drawback is that the increased dielectric constant is usually achieved at the cost of decreased breakdown strength, thus leading to moderate improvement of energy density and even displaying a marked deterioration under high temperatures and high electric fields. Herein, a new strategy is reported to simultaneously improve breakdown strength and discharged energy density by a step-by-step, controllable dual crosslinking process, which constructs a strengthened interface as well as reduces molecular chains relaxation under elevated temperatures. Great breakdown strength and discharged energy density is achieved in the dual crosslinked network BT-BCB@DPAES nanocomposites at elevated temperatures when compared to noninterfacial-strengthened, BT/DPAES composites, i.e., an enhanced breakdown strength and a discharged energy density of 442 MV m-1 and 3.1 J cm-3 , increasing by 66% and 162%, and a stable cyclic performance over 10 000 cycles is demonstrated at 150 °C. Moreover, the enhancement through the synergy of two crosslinked networks is rationalized via a comprehensive phase-field model for the composites. This work offers a strategy to enhance the electric storage performances of composites at high temperatures.

Relaxor ferroelectrics exhibit outstanding dielectric, electromechanical and electrocaloric properties, and are the materials of choice for acoustic sensors, solid-state coolers, transducers and actuators1-4. Despite more than five decades of intensive study, relaxor ferroelectrics remain one of the least understood material families in ferroelectric materials and condensed matter physics5-14. Here, by combining X-ray diffraction, atomic force microscope infrared spectroscopy and first-principles calculations, we reveal that the relaxor behaviour of ferroelectric polymers originates from conformational disorder, completely different from classic perovskite relaxors, which are typically characterized by chemical disorder. We show that chain chirality is essential to the formation of the disordered helix conformation arising from local distortions of gauche torsional angles, which consequently give rise to relaxor properties in polymers. This study not only sheds light on the fundamental mechanisms of relaxor ferroelectrics, but also offers guidance for the discovery of new ferroelectric relaxor organic materials for flexible, scalable and biocompatible sensor and energy applications.

Polymer dielectrics are ubiquitous in advanced electric energy storage systems. However, the relatively low operating temperature significantly menaces their widespread application at high temperatures, such as for hybrid vehicles and aerospace power electronics. Spider silk, a natural nanocomposite comprised of biopolymer chains and crystal protein nanosheets combined by multiple interfacial interactions, exhibits excellent mechanical properties even at elevated temperatures. Inspired by the hierarchical nanostructure of spider silk, poly(aryl ether sulfone) is anchored to the surface of wide bandgap artificial nanosheets to prepare the nanocomposites with nanoconfinement effect. The bioinspired strategy successfully improves the mechanical and electrical performances of the nanocomposite. Owing to the structural-enabled enhancements, the nanocomposites exhibit excellent breakdown strength and electrical energy storage performance at high temperatures. In detail, giant discharged energy density (2.7 J cm-3 ) and high charge-discharge efficiency (>90%) are simultaneously achieved at 150 °C and 400 MV m-1 . Notably, under 500 MV m-1 , the discharged energy density reaches 4.2 J cm-3 , which is the record high discharged energy density among polymer-based dielectrics at 150 °C. This work demonstrates a viable strategy to design high-temperature polymer dielectrics by constructing nanoconfinement in the nanocomposites.

Construction of single component theranostic agent with one-for-all features to concurrently afford both multi-modality imaging and therapy is an appealing yet significantly challenging task. Herein, a type of luminogens with aggregation-induced emission (AIE) characteristics are tactfully designed and facilely synthesized. These AIE luminogens (AIEgens) exhibit long emission wavelengths, good photostability, remarkable biocompatibility, good reactive oxygen species (ROS) generation performance and excellent photothermal conversion efficiency, which allow them to be powerfully utilized for in vitro and in vivo cancer phototheranostics. The results show that one of the AIEgens is capable of precisely diagnosing solid tumors of mice by means of combined near-infrared-I/II (NIR-I/II) fluorescence-photoacoustic imaging, meanwhile this AIEgen can activate photodynamic and photothermal synergistic therapy (PDT-PTT) upon laser irradiation, resulting in excellent tumor elimination efficacy with only once injection and irradiation. This study thus provides a versatile platform for practical cancer theranostics.

Photodynamic therapy (PDT) has long been recognized to be a promising approach for cancer treatment. However, the high oxygen dependency of conventional PDT dramatically impairs its overall therapeutic efficacy, especially in hypoxic solid tumors. Exploration of distinctive PDT strategy involving both high‐performance less‐oxygen‐dependent photosensitizers (PSs) and prominent drug delivery system is an appealing yet significantly challenging task. Herein, a precise nuclear targeting PDT protocol based on type‐I PSs with aggregation‐induced emission (AIE) characteristics is fabricated for the first time. Of the two synthesized AIE PSs, TTFMN is demonstrated to exhibit superior AIE property and stronger type‐I reactive oxygen species (ROS) generation efficiency owing to the introduction of tetraphenylethylene and smaller singlet–triplet energy gap, respectively. With the aid of a lysosomal acid‐activated TAT‐peptide‐modified amphiphilic polymer poly(lactic acid)12k–poly(ethylene glycol)5k–succinic anhydride‐modified TAT, the corresponding TTFMN‐loaded nanoparticles accompanied with acid‐triggered nuclear targeting peculiarity can quickly accumulate in the tumor site, effectively generate type‐I ROS in the nuclear region and significantly suppress the tumor growth under white light irradiation with minimized systematic toxicity. This delicate “Good Steel Used in the Blade” tactic significantly maximizes the PDT efficacy and offers a conceptual while practical paradigm for optimized cancer treatment in further translational medicine., A precise nuclear targeting photodynamic therapy (PDT) protocol based on tactfully designed type‐I photosensitizers with aggregation‐induced emission characteristics is fabricated for the first time with the aid of a lysosomal acid‐activated TAT‐modified nuclear delivery system, which can significantly maximize the PDT efficacy. ​

Piezoelectricity—the direct interconversion between mechanical and electrical energies—is usually remarkably enhanced at the morphotropic phase boundary of ferroelectric materials1–4, which marks a transition region in the phase diagram of piezoelectric materials and bridges two competing phases with distinct symmetries1,5. Such enhancement has enabled the recent development of various lead and lead-free piezoelectric perovskites with outstanding piezoelectric properties for use in actuators, transducers, sensors and energy-harvesting applications5–8. However, the morphotropic phase boundary has never been observed in organic materials, and the absence of effective approaches to improving the intrinsic piezoelectric responses of polymers9,10 considerably hampers their application to flexible, wearable and biocompatible devices. Here we report stereochemically induced behaviour in ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) copolymers, which is similar to that observed at morphotropic phase boundaries in perovskites. We reveal that compositionally tailored tacticity (the stereochemical arrangement of chiral centres related to the TrFE monomers11,12) can lead to intramolecular order-to-disorder evolution in the crystalline phase and thus to an intermediate transition region that is reminiscent of the morphotropic phase boundary, where competing ferroelectric and relaxor properties appear simultaneously. Our first-principles calculations confirm the crucial role of chain tacticity in driving the formation of this transition region via structural competition between the trans-planar and 3/1-helical phases. We show that the P(VDF-TrFE) copolymer with the morphotropic composition exhibits a longitudinal piezoelectric coefficient of −63.5 picocoulombs per newton, outperforming state-of-the-art piezoelectric polymers10. Given the flexibility in the molecular design and synthesis of organic ferroelectric materials, this work opens up the way for the development of scalable, high-performance piezoelectric polymers.

The first water-soluble NIR AIEgen was synthesized and used for ultrafast wash-free cellular imaging and photodynamic cancer cell ablation., The synthesis of water-soluble near-infrared (NIR)-emissive fluorescent molecules with aggregation-induced emission (AIE) characteristics and theranostic functions is highly desirable but remains challenging. In this work, we designed and readily prepared for the first time such a molecule with AIE features, good water-solubility and intense emission in the NIR region. This AIE luminogen (AIEgen) is able to specifically “light up” the cell membrane without the involvement of a washing procedure. Interestingly, the staining process can be performed by simply shaking the culture with cells at room temperature for only a few seconds after the addition of the AIEgen, indicating an ultrafast and easy-to-operate staining protocol. This is the first fluorescent “light-up” probe for cell-imaging that allows the combination of a short staining period (at the second-level) with a wash-free process. Additionally, the presented AIEgen has also been developed to serve as an excellent phototherapeutic agent for high efficiency generation of reactive oxygen species (ROS) upon visible light irradiation, which allows its effective application in the photodynamic ablation of cancer cells, demonstrating its dual role as an imaging and phototherapeutic agent.

With the increase of bacterial infections in clinical practice, it becomes a public health problem which has aroused worldwide attention. Fluorescence imaging-guided photodynamic antibiosis has recently emerged as a promising protocol to solve this problem. However, developing a super powerful fluorescent material allowing facile preparation, long emission wavelength, rapid bacterial discrimination, washing-free staining, and high photodynamic antibacterial efficiency in a single entity, is highly desirable but remains challenging. In this study, we utilize for the first time a water-soluble near-infrared (NIR) emissive luminogen with aggregation-induced emission (AIE) characteristics, namely TTVP, for simultaneous dual applications of Gram-positive bacteria discrimination and photodynamic antibiosis. TTVP is able to selectively target Gram-positive bacteria over Gram-negative bacteria through a washing-free procedure after only 3 s incubation period, which is at least 100-fold shorter than those of previously reported protocols, implying ultrafast bacterial discrimination features. Meanwhile, TTVP exhibits extremely high reactive oxygen species generation efficiency, which is far superior to that of most popularly used photosensitizers, representing one of the best candidates for photodynamic antibiosis. In vitro and in vivo results demonstrate that TTVP provides extraordinary performance on photodynamic antibacterial therapy. This study thus offers a blueprint for the next generation of antibacterial materials.

A polymer that generates large cooling under applied voltage is attractive for many applications. The past decade has witnessed the discovery and advancement in electrocaloric (EC) polymers, which display large electric field induced temperature and entropy changes. However, in contrast to the burgeoning literature on large electrocaloric effects (ECEs) in various ferroelectric materials, there are no EC devices employing these EC polymers, demonstrating a meaningful cooling power. Here, we show that it is the dielectric breakdown, the weakest link problem, in EC materials which poses a critical barrier for transitioning these advanced EC materials to practical EC coolers. Hence, high quality EC films and high performance of EC materials, exhibiting large ECE at low electric fields, are required to overcome this barrier. Here, we show that by expanding the compositions in EC polymers, a relaxor tetrapolymer exhibits a critical end point at low electric fields, leading to large ECE induced at low electric fields.