Highly dispersed amorphous nano-selenium functionalized carbon nanofiber aerogels for high-efficient uptake and immobilization of Hg(II) ions.

Owing to the strong Hg-Se interaction, Se-containing materials are promising for the uptake and immobilization of Hg(II) ions; compared with metal selenides or selenized compounds, elemental Se contains the highest ratio of Se. However, it remains a challenge to fully expose all the potential Se binding sites and achieve high utilization efficiency of elemental Se. Through rational design on the structure, dispersity, and size of materials, Se/CNF aerogels composed of abundant well-dispersed and amorphous nano-Se have been prepared and applied for the high-efficient uptake and immobilization of Hg(II) ions. The well-dispersion of nano-Se increases the exposure of Se sites, the amorphous structure benefits the easy cleavage of Se-Se bonds, the 3D porous networks of aerogels permit fast ions transport and easy operation. Benefiting from the combination effect of strong Hg-Se interaction and sufficient exposure of Se-enriched sites, the Se/CNF aerogels demonstrate strong binding ability (Kd = 3.8 ×105 mL·g-1), high capacity (943.4 mg·g-1), and preeminent selectivity (αMHg > 100) towards highly toxic Hg(II) ions. Notably, the utilization efficiency of Se in Se/CNF aerogels is as high as 99.5%. Moreover, the strong Hg-Se interaction and extraordinary stability of HgSe could minimize the environmental impact of the spent Se/CNF adsorbents after its disposal.

Synergistic Co-N/V-N dual sites in N-doped Co3V2O8 nanosheets: pioneering high-efficiency bifunctional electrolysis for high-current water splitting.

Developing affluent dual-metal active sites bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential to achieve large-scale water electrolysis, whereas still remains challenging. Herein, a novel nitrogen-doped cobalt-vanadium oxide with abundant Co-N and V-N dual active sites supported on nickel foam (N-Co3V2O8@NF) is constructed by a controllable impregnation-thermal nitridation strategy. The staggered nanosheet structure ensures optimal exposure of active sites. More importantly, N doping effectively regulates the electronic structure of the metal centers and induces the formation of Co-N and V-N dual active sites, which is conducive to improving the conductivity and hydrophilicity, thus synergistically enhancing the electrocatalytic efficiency. Consequently, the optimized N-Co3V2O8@NF exhibits prominent HER (63 mV@10 mA cm-2) and OER (256 mV@10 mA cm-2) activities, surpassing most contemporary bifunctional electrocatalysts. In practical application, the assembled N-Co3V2O8@NF(+/-) electrolyzer consistently achieved ultra-low cell voltages of 1.97 and 2.03 V at 500 and 1000 mA cm-2, respectively, superior to the benchmark RuO2@NF(+) || Pt/C@NF(-) and showcasing robust durability. This paves the way for its prospective adoption in industrial water electrolysis applications.

Copper-Nitrogen-Coordinated Carbon Dots: Transformable Phototheranostics from Precise PTT/PDT to Post-Treatment Imaging-Guided PDT for Residual Tumor Cells.

Phototheranostics has attracted considerable attention in the fields of cancer diagnosis and treatment. However, the complete eradication of solid tumors using traditional phototheranostics is difficult because of the limited depth and range of laser irradiation. New phototheranostics enabling precise phototherapy and post-treatment imaging-guided programmed therapy for residual tumors is urgently required. Accordingly, this study developed a novel transformable phototheranostics by assembling hyaluronic acid (HA) with copper-nitrogen-coordinated carbon dots (CDs). In this transformable nanoplatform, named copper-nitrogen-CDs@HA, the HA component enables the specific targeting of cluster determinant (CD) 44-overexpressing tumor cells. In the tumor cells, redox glutathione converts Cu(II) (cupric ions) into Cu(I) (cuprous ions), which confers the novel transformable functionality to phototheranostics. Both in vitro and in vivo results reveal that the near-infrared-light-photoactivated CuII-N-CDs@HA could target CD44-overexpressing tumor cells for precise synergistic photothermal therapy and photodynamic therapy. This study is the first to observe that CuII-N-CDs@HA could escape from lysosomes and be transformed in situ into CuI-N-CDs@HA in tumor cells, with the d9 electronic configuration of Cu(II) changing to the d10 electronic configuration of Cu(I), which turns on their fluorescence and turns off their photothermal properties. This transformable phototheranostics could be used for post-treatment imaging-guided photodynamic therapy on residual tumor cells. Thus, the rationally designed copper-nitrogen-coordinated CDs offer a simple in situ transformation strategy for using multiple-stimulus-responsive precise phototheranostics in post-treatment monitoring of residual tumor cells and imaging-guided programmed therapy.

Nanomaterials for Tumor Hypoxia Relief to Improve the Efficacy of ROS-Generated Cancer Therapy.

Given the fact that excessive levels of reactive oxygen species (ROS) induce damage to proteins, lipids, and DNA, various ROS-generating agents and strategies have been explored to induce cell death and tumor destruction by generating ROS above toxic threshold. Unfortunately, hypoxia in tumor microenvironment (TME) not only promotes tumor metastasis but also enhances tumor resistance to the ROS-generated cancer therapies, thus leading to ineffective therapeutic outcomes. A variety of nanotechnology-based approaches that generate or release O2 continuously to overcome hypoxia in TME have showed promising results to improve the efficacy of ROS-generated cancer therapy. In this minireview, we present an overview of current nanomaterial-based strategies for advanced cancer therapy by modulating the hypoxia in the TME and promoting ROS generation. Particular emphasis is put on the O2 supply capability and mechanism of these nanoplatforms. Future challenges and opportunities of design consideration are also discussed. We believe that this review may provide some useful inspiration for the design and construction of other advanced nanomaterials with O2 supply ability for overcoming the tumor hypoxia-associated resistance of ROS-mediated cancer therapy and thus promoting ROS-generated cancer therapeutics.

Mechanisms of Reactive Oxygen Species Generated by Inorganic Nanomaterials for Cancer Therapeutics.

Recently, inorganic nanomaterials have received considerable attention for use in biomedical applications owing to their unique physicochemical properties based on their shapes, sizes, and surface characteristics. Photodynamic therapy (PDT), sonodynamic therapy (SDT), and chemical dynamic therapy (CDT), which are cancer therapeutics mediated by reactive oxygen species (ROS), have the potential to significantly enhance the therapeutic precision and efficacy for cancer. To facilitate cancer therapeutics, numerous inorganic nanomaterials have been developed to generate ROS. This mini review provides an overview of the generation mechanisms of ROS by representative inorganic nanomaterials for cancer therapeutics, including the structures of engineered inorganic nanomaterials, ROS production conditions, ROS types, and the applications of the inorganic nanomaterials in cancer PDT, SDT, and CDT.

A full-spectrum responsive B-TiO2@SiO2-HA nanotheranostic system for NIR-II photoacoustic imaging-guided cancer phototherapy.

The second near-infrared (NIR-II) window (1000-1350 nm) usually offers further improved light penetration, a higher maximum permissible exposure (MPE), and a lower background signal. Development of NIR-II optical diagnosis and phototherapy technologies is of great significance for precise, efficient tumor therapy. In this work, a new type of Ti-based targeting agent (B-TiO2@SiO2-HA) nanotheranostic system with strong NIR-II absorption was designed and fabricated for the first time. Oxygen vacancies were formed in B-TiO2 and its band gap was narrowed, resulting in nanotheranostic systems with full-spectrum responses to stimulation with light. The experimental results showed that B-TiO2@SiO2-HA not only can enable high NIR-II photothermal conversion and provide excellent reactive oxygen species (ROS) production capacity, but also can enable high-resolution photoacoustic imaging (PAI) under NIR-II laser irradiation. Moreover, HA modification gives the nanotheranostic systems the useful ability to target high-CD44-expression tumor cells and tissues. In vitro and in vivo experiments demonstrated that B-TiO2@SiO2-HA exhibited a targeted photothermal/photodynamic (PTT/PDT) effect that produced tumor-cell ablation and apoptosis under the guidance of real-time NIR-II PA imaging. B-TiO2@SiO2-HA exhibits precise nanotheranostic potential for PAI-guided tumor-targeting phototherapy.

An injectable thermosensitive photothermal-network hydrogel for near-infrared-triggered drug delivery and synergistic photothermal-chemotherapy.

Near-infrared (NIR)-responsive hydrogels have exhibited remarkable advantages in biomedical applications especially for in situ therapeutic delivery, because of their deep-tissue penetration capacity, minimal invasiveness, and high spatiotemporal selectivity. Nevertheless, conventional NIR-responsive nanocomposite hydrogels suffer from the disadvantages of limited photothermal effect and potential leakage of the physically mixed photothermal nanoagents. To overcome these limitations, we herein designed an injectable thermosensitive photothermal-network hydrogel (PNT-gel) through the host-guest self-assembly of a photothermal conjugated polymers and ɑ-cyclodextrin. The conjugated-polymer backbones can directly convert incident light into heat, endowing the PNT-gel with high photothermal conversion efficiency (η = 52.6%) and enhanced photothermal stability. Meanwhile, the mild host-guest assembly enable the shear-thinning injectability, photothermally-driven and reversible gel-sol conversion of the hydrogel. Consequently, the remotely controlled on-demand release of doxorubicin (DOX) was achieved via photothermal-induced gel-sol transition. Because the backbone of the hydrogel absorbs NIR light and mediates the photothermal conversion itself, the PNT-gel demonstrated the advantage of a prolonged retention time and thus permitting repeatable NIR treatment after a one-time intratumoral injection of this hydrogel. Under repeated NIR laser irradiation (0.15 W cm-2), the synergistic photothermal-chemotherapy mediated by the PNT-gel almost completely eradicated 4T1 breast cancer. This work not only presents a multifunctional therapeutic platform integrated with inherent photothermal characteristic and reversible stimuli responsiveness for on-demand delivery and combinatorial photothermal-chemotherapy, but also provides a new strategy for the development of the next-generation of light-modulated intelligent hydrogels. STATEMENT OF SIGNIFICANCE: The conventional NIR-responsive nanocomposite hydrogels suffer from the disadvantages of limited photothermal effect and possible leakage of the physically mixed photothermal nano-components. To overcome these limitations, we hereby fabricated a NIR-responsive themosensitive photothermal-network hydrogel through the supramolecular assembly of conjugated polymer. The conjugated polymeric backbones of the hydrogel directly convert NIR light to heat, endowing the hydrogel with good photothermal effect and long-term photothermal stability. Meanwhile, the dynamic crosslinkages via supramolecular assembly enabled the shear-thinning injectability and reversible gel-sol transition of the hydrogel, facilitating the photothermal-induced drug release. Our strategy demonstrated the efficacy of using conjugated polymer as the backbone of hydrogel for the construction of a new injectable NIR-responsive hydrogel system with enhanced photothermal capabilities and improved therapy outcomes.

NIR-II light-modulated thermosensitive hydrogel for light-triggered cisplatin release and repeatable chemo-photothermal therapy.

Cisplatin is one of the most effective chemotherapeutic agents, although its clinical use is limited by severe nephrotoxicity. Multifunctional platform for spatiotemporally controlled delivery of cisplatin and multimodal synergistic therapy is highly desirable in antitumor research. Herein, for the first time, an injectable, NIR-II light-modulated and thermosensitive hydrogel is synthesized through supramolecular self-assembly of a conjugated polymer and α-cyclodextrin. This hydrogel intrinsically features NIR responsive characteristics and thermo-responsive properties. The conjugated polymer (poly(N-phenylglycine)) not only tethers the poly(ethylene glycol) chains to enable the hydrogel formation, but also serves as the NIR-absorbing mediators. Accordingly, one particular benefit of this hydrogel is that its building blocks absorb NIR-II light and mediate the photothermal conversion itself, offering the important advantage of a prolonged retention time and thus permitting repeatable treatment upon a single-injection of this hydrogel. Under NIR-II laser irradiation, the localized photothermal effect not only ablates the highly metastatic triple-negative breast cancer (TNBC), but also triggers the on-demand cisplatin release through the thermo-responsive gel-sol transition, thus resulting in enhanced antitumor activity and reduced off-target toxicity. This work not only provides a novel multifunctional platform for NIR-triggered cisplatin release and chemo-photothermal combination therapy, but also presents a promising strategy for the rational design of NIR light-responsive hydrogels for the intervention of highly aggressive cancers.

A near infrared-modulated thermosensitive hydrogel for stabilization of indocyanine green and combinatorial anticancer phototherapy.

Indocyanine green (ICG), a multifunctional near-infrared (NIR) imaging agent approved by the FDA, has been extensively used in clinical cancer theranosis, but limited by its inherent instability, short plasma half-life and lack of targeting ability. Herein, an in situ formed photothermal network based thermosensitive hydrogel (PNT-gel) constructed by using supramolecular cross-linking conjugated polymers was developed for the stabilization of ICG and efficient combinatorial photothermal/photodynamic antitumor therapy. While the conjugated polymeric backbone in PNT-gel anchored the aromatic phototherapeutic agent ICG via π-π stacking interactions to avoid premature leakage, it also directly converted low-dose NIR light to induce localized hyperthermia to enhance the photothermal effect. The PNT-gel shows a reversible gel-to-sol upper critical solution temperature (UCST) that is slightly above body temperature. Therefore, the controlled release of ICG was switched on or off by NIR via photothermal-induced gel-sol transition. In vitro and in vivo antitumor experiments demonstrated that ICG loaded PNT-gel not only efficiently induced the killing of 4T1 cancer cells, but also achieved almost complete eradication of 4T1 cells by one-dose intratumoral injection in combinatorial photothermal/photodynamic therapy under irradiation of a low-dose 808 nm laser (0.14 W cm-2). Additionally, the combinational therapy proved to enhance the effectiveness of photodestruction without tumor recurrence compared with photothermal therapy (PTT) or photodynamic therapy (PDT) treatment alone.

A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy.

The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications.

Covalent entrapment of cobalt-iron sulfides in N-doped mesoporous carbon: extraordinary bifunctional electrocatalysts for oxygen reduction and evolution reactions.

To alleviate the kinetic barriers associated with ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) in electrochemical systems, efficient nonprecious electrocatalysts are urgently required. Here we report a facile soft-template mediated approach for fabrication of nanostructured cobalt-iron double sulfides that are covalently entrapped in nitrogen-doped mesoporous graphitic carbon (Co0.5Fe0.5S@N-MC). Notably, with a positive half-wave potential (0.808 V) and a high diffusion-limiting current density, the composite material delivers unprecedentedly striking ORR electrocatalytic activity among recently reported nonprecious late transition metal chalcogenide materials in alkaline medium. Various characterization techniques, including X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, are conducted to elucidate the correlation between structural features and catalytic activities of the composite. Moderate substitution and well-dispersion of iron in bimetallic sulfide composites are believed to have positive effect on the adsorption and activation of oxygen-containing species, thus leading to conspicuous ORR and OER catalytic enhancement compared to their monometallic counterparts. Besides, the covalent bridge between active sulfide particles and mesoporous carbon shells provides facile pathways for electron and mass transport. Beneficially, the intimate coupling interaction renders prolonged electrocatalytic performances to the composite. Our results may possibly lend a new impetus to the rational design of bi- or multimetallic sulfides encapsulated in porous carbon with improved performance for electrocatalysis and energy storage applications.

A superhydrophobic sponge with excellent absorbency and flame retardancy.

Frequent oil spillages and the industrial discharge of organic solvents have not only caused severe environmental and ecological damage, but also create a risk of fire and explosion. Therefore, it is imperative, but also challenging, to find high-performance absorbent materials that are both effective and less flammable. Here we present a superior superhydrophobic sponge that exhibits excellent absorption performance through a combination of its superhydrophobicity, high porosity, and robust stability. More importantly, it inherits the intrinsic flame-retardant nature of the raw melamine sponge, and is thus expected to reduce the risk of fire and explosion when being used as an absorbent for flammable oils and organic compounds. Moreover, the fabrication of this sponge is easy to scale up, since it does not use a complicated process or sophisticated equipment. These characteristics make the sponge a much more competitive product than the commercial absorbent, nonwoven polypropylene fabric.

Controlling the formation of rodlike V2O5 nanocrystals on reduced graphene oxide for high-performance supercapacitors.

Vanadium pentoxide (V2O5) has attracted much attention for energy storage application because of its high Faradaic activity and stable crystal structure, which make it a promising electrode material for supercapacitors. However, the low electronic conductivity and small lithium-ion diffusion coefficient of V2O5 limit its practical applications. To overcome these limitations, a facile and efficient method is here demonstrated for the fabrication of V2O5/reduced graphene oxide (rGO) nanocomposites as electrode materials for supercapacitors. With this method, the reduction of graphene oxide can be achieved in a cost-effective and environmentally friendly solvent, without the addition of any other toxic reducing agent. Importantly, this solvent can control the formation of the uniform rodlike V2O5 nanocrystals on the surface of rGO. Compared to pure V2O5 microspheres, the V2O5/rGO nanocomposites exhibited a higher specific capacitance of 537 F g(-1) at a current density of 1 A g(-1) in neutral aqueous electrolytes, a higher energy density of 74.58 Wh kg(-1) at a power density of 500 W kg(-1), and better stability even after 1000 charge/discharge cycles. Their excellent performances can be attributed to the synergistic effect of rGO and rodlike V2O5 nanocrystals. Such impressive results may promote new opportunities for these electrode materials in high-energy-density storage systems.

Sp2 C-dominant N-doped carbon sub-micrometer spheres with a tunable size: a versatile platform for highly efficient oxygen-reduction catalysts.

A simple, yet versatile strategy to prepare size-controlled and monodisperse carbon sub-micrometer spheres is developed based on the biomolecule dopamine. Unlike traditional carbon materials, the resulting carbon sub-micrometer spheres contain much less sp(3) carbon with high-level electroactive nitrogen. Moreover, metal-carbon hybrid sub-micrometer spheres can be easily obtained, and show highly promising catalytic properties in the oxygen-reduction reaction.