Artificial Macrophage with Hierarchical Nanostructure for Biomimetic Reconstruction of Antitumor Immunity

Artificial cells are constructed from synthetic materials to imitate the biological functions of natural cells. By virtue of nanoengineering techniques, artificial cells with designed biomimetic functions provide alternatives to natural cells, showing vast potential for biomedical applications. Especially in cancer treatment, the deficiency of immunoactive macrophages results in tumor progression and immune resistance. To overcome the limitation, a BaSO4@ZIF-8/transferrin (TRF) nanomacrophage (NMΦ) is herein constructed as an alternative to immunoactive macrophages. Alike to natural immunoactive macrophages, NMΦ is stably retained in tumors through the specific affinity of TRF to tumor cells. Zn2+ as an "artificial cytokine" is then released from the ZIF-8 layer of NMΦ under tumor microenvironment. Similar as proinflammatory cytokines, Zn2+ can trigger cell anoikis to expose tumor antigens, which are selectively captured by the BaSO4 cavities. Therefore, the hierarchical nanostructure of NMΦs allows them to mediate immunogenic death of tumor cells and subsequent antigen capture for T cell activation to fabricate long-term antitumor immunity. As a proof-of-concept, the NMΦ mimics the biological functions of macrophage, including tumor residence, cytokine release, antigen capture and immune activation, which is hopeful to provide a paradigm for the design and biomedical applications of artificial cells.

Rational design of hierarchically nanostructured NiTe@CoxSy composites for hybrid supercapacitors with impressive rate capability and robust cycling durableness

The hierarchically nanostructured NiTe@CoxSy composites are constructed on a foamed nickel substrate by a two-step electrode preparation process. Structural characterization shows the dense growing of CoxSy nanosheets around NiTe nanorods forms a hierarchical nanostructure which possesses synergetic effects from both compositional and structural complementarity, more pathways for ion/electrolyte transport, richer redox active sites, and better conductivity. Thanks to the rational design of this hierarchical structure, NiTe@CoxSy delivers a high areal capacitance of 7.7F cm^-2 at 3 mA cm^-2 and achieves the improved capacitance retention of 97.9% after 10,000 cycles. Of particular importance is the successful fabrication of NiTe@CoxSy//activated carbon hybrid supercapacitors. This hybrid device has a wide operating voltage window, high areal energy density of 0.48 mWh cm^-2 at 2.55 mW cm^-2, impressive rate capability of 62.3% even after a 20-fold increase of the current density, and a 115.1% of initial capacitance retention after 15,000 cycles. Meanwhile, two tandem such hybrid devices can easily drive a pair of mini fans or light up a heart-like pattern assembled by 10 red LEDs. These experimental results not only demonstrate that the hierarchically nanostructured NiTe@CoxSy composites can serve as a prospective candidate electrode; but also develop a novel strategy about how to achieve high-performance stockpile equipment by rationale designing a desirable nanostructures.

Design of reduced graphene oxide coating carbon sub-microspheres hierarchical nanostructure for ultra-stable potassium storage performance

The development of high-performance carbon-based anode materials is still a significant challenge for K-ion storage. In our work, we designed reduced graphene oxide coating carbon sub-microspheres hierarchical nanostructure (CS@RGO) hierarchical nanostructure via a simple freeze-drying and subsequent pyrolysis as anode for K-ion batteries (KIBs), which presented an excellent electrochemical performance for K-ion storage, with a reversible specific capacity of 295 mAh g^-1 after 100 cycles at 100 mAh g^-1. Even at a high current density of 1 A g^-1, our CS@RGO still achieves ultra-stable K-ion storage of 200 mAh g^-1 at 1 A g^-1 after 5000 cycles almost without capacity fade. According to the galvanostatic intermittent titration technique result, the CS@RGO hybrid receives a high average diffusion coefficient of 7.35 × 10^-8 cm² s^-1, contributing to the rapid penetration of K-ion, which facilitates the enhancement of electrochemical performance for KIBs. Besides, we also use Raman spectra to investigate the electrochemical behavior of our CS@RGO hybrid for K-ion storage and confirm the reaction process. We believe that our work will offer the opportunity to enable ultra-stable carbon-based materials by the structure design in the K-ion battery field.

Microwave-assisted synthesis of hierarchically porous Co3O4/rGO nanocomposite for low-temperature acetone detection

Acetone sensors with high response and excellent selectivity are of enormous demand for monitoring the diabetes. This paper has reported a novel porous 3D hierarchical Co₃O₄/rGO nanocomposite synthesized by a microwave-assisted method, by which Co₃O₄ nanoparticles are rapidly and uniformly anchored on rGO nanosheets. The phase composition, surface morphology of the Co₃O₄/rGO composites and the effect of rGO on their acetone-sensing performance were systematically investigated. The results show that the sample with an optimized content of rGO (Co₃O₄/rGO-1) achieves the highest stability and response to acetone (0.5 ~ 200 ppm) at a relatively low temperature (~160 °C). Also, the Co₃O₄/rGO-1 exhibits a high acetone-sensing selectivity against the gases (or vapors) of H₂S, H₂, CH₄, HCHO, CH₃OH, C₃H₈O and C₂H₅OH. The enhanced acetone-sensing performance of the Co₃O₄/rGO composite can be attributed to the Co₃O₄/rGO p-p heterojunction and the Co³⁺-C coupling effect between Co₃O₄ and rGO, improving transport of carriers. In addition, the unique 3D hierarchically porous structure and large surface areas are favorable to adsorption and desorption of gas molecules. This facile microwave-assisted method provides a charming strategy to develop smart rGO-based nanomaterials for real-time detection of harmful gases and rapid medical diagnosis.

Robust, rapid, and ultrasensitive colorimetric sensors through dye chemisorption on poly-cationic nanodots

Colorimetric sensors were fabricated by incorporation of anionic colorimetric probes on a hierarchical nanofibrous membrane containing poly-cationic nanodots through intense electrostatic interaction. Unique poly-cationic nanodots were covalently grown on poly (4-vinylpyridine)/polyacrylonitrile nanofibrous membrane through a self-propagation reaction of 2-diethylaminoethyl chloride (DEAE-Cl). The nanodots on the nanofiber surfaces possess strong adsorption affinity and high adsorption capacity toward anionic probes, which contributed to excellent detection sensitivity and sensor stability compared with the co-electrospun sensor. As a proof-of-concept study, phenol red was selected to functionalize the as-fabricated substrate (polyDEAE@P4VP/PAN NFM) to a colorimetric sensor, which shows responses to alkaline vapors. The as-fabricated sensor showed rapid color changes to ammonia and triethylamine (response time < 10 s), whose detection limits reached 1 ppm and 5 ppm, respectively. The sensor can be repeatedly used for at least 20 cycles by regenerating it in air for 1 min. Taking advantage of the intense attractive force between poly-cationic nanodots and anionic probes, polyDEAE@P4VP/PAN NFM is a promising media to be used for the development of robust, rapid, and ultrasensitive colorimetric sensors.

Controllable syngas production on gold nanowires/nickel foam electrode in non-aqueous system

A hierarchical electrode is prepared with Au nanowires grown on nickel foam. With large specific active surface area, it is used for producing syngas (H₂/CO) with controllable ratio, through electrochemical process in DMF. The synthetic innovation lies in the use of 3-cyanopropyltriethoxysilane, to achieve the adsorption of appropriate amount of Au seeds for the one-dimensional growth of ultrathin Au nanowires (d ≈ 5 nm). With the nanowires forest on the three-dimensional porous nickel foam substrate, syngas is produced by electro-catalysis with high overall Faradic efficiency and tunable H₂/CO ratios. This synthetic strategy opens a facile way to synthesize the hierarchical nanostructured materials, and broaden the choice of the catalysts for electrochemical applications.

Multipodal mesoporous silica hollow spheres: Branched hierarchical nanostructure by region-selective self-assembly

HYPOTHESIS

Hollow nanostructures, known as nanocapsules, have been the preferable candidates in the drug-delivery and control-release applications. To enhance the adherence and penetration into biological hosts for efficient drug delivery, constructing multiple pods on the hollow structure to form a tribulus-like branched architecture has been proven an effective strategy. However, the synthesis is challenging due to the simultaneous control of the branched podal morphology, the hollow architecture and the mesophase structures at the nanometer scale.

EXPERIMENTS

Polymer spheres with surface carboxyl moieties were first prepared by emulsion polymerization, which were partly coated by a type of basic silane. The left carboxyl moieties formed some seperated acid spots on the surface of polymer spheres, which could lead to the subsequent self-assembly of surfactant and silica within these acidic spots to grow a branched nanostructure.

FINDINGS

Radiolarian-like organic-inorganic hybrid hollow architecture with branched ordered mesoporous pods were obtained after removing the organic templates of the polymer spheres and surfactants by calcination. The ordered cylindrical mesoporous channels were along the central axis direction of the hexagonal-prism-like pods, which connected inside and outside of the hollow spheres. The number of the branched pods could be easily tuned at the range of one to four.

Hierarchical assembly of manganese dioxide nanosheets on one-dimensional titanium nitride nanofibers for high-performance supercapacitors

MnO₂ has attracted considerable attention for use in supercapacitors. Nevertheless, its low electrical conductivity greatly hinders its potential application. Here, we demonstrate the fabrication of a high-performance electrode material via facile coating of hierarchical MnO₂ nanosheets onto highly electrically conductive one-dimensional (1D) TiN nanofibers for use in supercapacitors. The TiN nanofibers are prepared through nitridation electrospinning of TiO₂ nanofibers via ammonia annealing. The obtained TiN@MnO₂ composites exhibit enhanced electrochemical properties, such as high specific capacitance of 386 F/g at a current density of 1 A/g, and long cycle stability of ∼111.7% capacity retention after 4000 cycles at 6 A/g. The unique nanostructure and significant synergistic effect between TiN and MnO₂ are responsible for its good electrochemical performance.

Activated Carbon Fibers with Hierarchical Nanostructure Derived from Waste Cotton Gloves as High-Performance Electrodes for Supercapacitors

One of the most challenging issues that restrict the biomass/waste-based nanocarbons in supercapacitor application is the poor structural inheritability during the activating process. Herein, we prepare a class of activated carbon fibers by carefully selecting waste cotton glove (CG) as the precursor, which mainly consists of cellulose fibers that can be transformed to carbon along with good inheritability of their fiber morphology upon activation. As prepared, the CG-based activated carbon fiber (CGACF) demonstrates a surface area of 1435 m2 g-1 contributed by micropores of 1.3 nm and small mesopores of 2.7 nm, while the fiber morphology can be well inherited from the CG with 3D interconnected frameworks created on the fiber surface. This hierarchically porous structure and well-retained fiber-like skeleton can simultaneously minimize the diffusion/transfer resistance of the electrolyte and electron, respectively, and maximize the surface area utilization for charge accumulation. Consequently, CGACF presents a higher specific capacitance of 218 F g-1 and an excellent high-rate performance as compared to commercial activated carbon.

Hierarchical nanostructured noble metal/metal oxide/graphene-coated carbon fiber: in situ electrochemical synthesis and use as microelectrode for real-time molecular detection of cancer cells

We report the design and fabrication of a new type of nanohybrid microelectrode based on a hierarchical nanostructured Au/MnO2/graphene-modified carbon fiber (CF) via in situ electrochemical synthesis, which leads to better structural integration of different building blocks into the CF microelectrode. Our finding demonstrates that wrapping CF with graphene nanosheets has dramatically increased the surface area and electrical conductivity of the CF microelectrode. The subsequent template-free electrodeposition of MnO2 on graphene-wrapped CF gives rise to a porous nanonest architecture built up from twisted and intersectant MnO2 nanowires, which serves as an ideal substrate for the direct growth of Au nanoparticles. Owing to the structural merit and synergy effect between different components, the hierarchical nanostructured noble metal/metal oxide/graphene-coated CF demonstrates dramatically enhanced electrocatalytic activity. When used for nonenzymatic H2O2 sensing, the resultant modified microelectrode exhibits acceptable sensitivity, reproducibility, stability, and selectivity, which enable it to be used for real-time tracking H2O2 secretion in human cervical cancer cells. Graphical abstract A schematic illustration of preparation of hierarchical Au/MnO2/ERGO/CF nanohybrid electrode for real-time molecular detection of cancer cells.

Fabrication of macro-mesoporous titania/alumina core-shell materials in oil/water interface

A series of macro-mesoporous TiO2/Al2O3 nanocomposites with different morphologies were synthesized. The materials were calcined at 723 K and were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscope (TEM), N2 adsorption/desorption, Infrared Emission Spectroscopy (IES), X-ray photoelectron spectroscopy (XPS) and UV-visible spectroscopy (UV-visible). A modified approach was proposed for the synthesis of 1D (fibrous) nanocomposite with higher Ti/Al molar ratio (2:1) at lower temperature (<100°C), which makes it possible to synthesize such materials on industrial scale. The performance-morphology relationship of as-synthesized TiO2/Al2O3 nanocomposites was investigated by the photocatalytic degradation of a model organic pollutant under UV irradiation. The samples with 1D (fibrous) morphology exhibited superior catalytic performance than the samples without, such as titania microspheres.

Rapid and selective detection of acetone using hierarchical ZnO gas sensor for hazardous odor markers application

Hierarchical nanostructured ZnO dandelion-like spheres were synthesized via solvothermal reaction at 200°C for 4h. The products were pure hexagonal ZnO with large exposure of (002) polar facet. Side-heating gas sensor based on hierarchical ZnO spheres was prepared to evaluate the acetone gas sensing properties. The detection limit to acetone for the ZnO sensor is 0.25ppm. The response (Ra/Rg) toward 100ppm acetone was 33 operated at 230°C and the response time was as short as 3s. The sensor exhibited remarkable acetone selectivity with negligible response toward other hazardous gases and water vapor. The high proportion of electron depletion region and oxygen vacancies contributed to high gas response sensitivity. The hollow and porous structure of dandelion-like ZnO spheres facilitated the diffusion of gas molecules, leading to a rapid response speed. The largely exposed (002) polar facets could adsorb acetone gas molecules easily and efficiently, resulting in a rapid response speed and good selectivity of hierarchical ZnO spheres gas sensor at low operating temperature.

Rapid and selective detection of acetone using hierarchical ZnO gas sensor for hazardous odor markers application

Hierarchical nanostructured ZnO dandelion-like spheres were synthesized via solvothermal reaction at 200°C for 4h. The products were pure hexagonal ZnO with large exposure of (002) polar facet. Side-heating gas sensor based on hierarchical ZnO spheres was prepared to evaluate the acetone gas sensing properties. The detection limit to acetone for the ZnO sensor is 0.25ppm. The response (Ra/Rg) toward 100ppm acetone was 33 operated at 230°C and the response time was as short as 3s. The sensor exhibited remarkable acetone selectivity with negligible response toward other hazardous gases and water vapor. The high proportion of electron depletion region and oxygen vacancies contributed to high gas response sensitivity. The hollow and porous structure of dandelion-like ZnO spheres facilitated the diffusion of gas molecules, leading to a rapid response speed. The largely exposed (002) polar facets could adsorb acetone gas molecules easily and efficiently, resulting in a rapid response speed and good selectivity of hierarchical ZnO spheres gas sensor at low operating temperature.