Nano Research

Constructing composites with heterogeneous structure and dual loss mechanism shows great potential in designing microwave absorbers. In this work, two-dimensional cobalt and nickel alloys@mesoporous carbon (CoNi@MC) composites were constructed via using CoNi layered double hydroxide@mesoporous polydopamine (CoNi LDH@MPDA) as sacrifice template. During the pyrolysis process, the MPDA is transformed into mesoporous carbon coated the surface of CoNi LDH that is further reduced to CoNi alloys. The mesoporous structure is conducive to the multi-reflection of electromagnetic waves and facilitates optimizing impedance matching. Heterogeneous interfaces between CoNi alloys and mesoporous carbon induce interface polarization. Multiple attenuation mechanism promotes the electromagnetic waves conversion. The maximum reflection loss of CoNi@MC composite is −70.86 dB and the widest effective absorption bandwidth is 7.74 GHz covering almost the entire Ku band. This strategy will be a guidance for designing electromagnetic absorbers.

Photodynamic therapy (PDT) is a promising strategy for tumor treatment. Still, its therapeutic efficacy is compromised by the unsatisfactory cytotoxicity to specific subcellular organelles and insidious tumor microenvironment properties like hypoxia and high glutathione levels. Here, we fabricated a novel nanoenzyme that derived from metal-organic framework (MOF) with intrinsic catalase-like activities to decompose H2O2 to O2 and simultaneous glutathione consumption for enhancing PDT efficacy. The obtained Mn3O4 nanoparticle shows a larger pore size and surface area compared to native MOF particles, which can be used to load high dose photosensitizer. When decorated with AS1411 aptamer and polyethylene glycol (PEG), the obtained Mn3O4-PEG@C&A particle exhibits excellent stability and cell nucleus targeting ability. Remarkably, Mn3O4-PEG@C&A particle inhibited the tumor growth in the mouse model with high efficacy without any biotoxicity. This is the first report that applied MOF-derived nanoparticle to nucleus-targeted PDT. It may provide a new approach for designing functional nanoenzyme to subcellular organelles-targeted tumor modulation.

Switchable adhesives have attracted widespread attention due to their strong reusability and adaptability to operate stably in complex environments. However, the simple fabrication of adhesive structures and reliable control of adhesion remain challenging. Here, we developed a neodymium iron boron/polydimethylsiloxane (NdFeB/PDMS) magnetic composite with optimal mechanical and magnetic performance. Then we fabricated lamellar structures and setal arrays using a molding and magnetic field-induced process, imitating the multi-level adhesion system of gecko feet. The lamellar can be deformed under the action of a magnetic field to control the adhesion, and the setal array is used to enhance adhesion and provide self-cleanability to the adhering surface. Switchable adhesion was realized by applying an external magnetic field, where the maximum adhesion strength was 5.1 kPa, and the switchable range was within 40%. Through finite element analysis simulations and experimental verification, it was proved that the adhesion force variation was ascribed to the magnetic field-induced surface deformation. Finally, we installed the adhesive on the end of the robotic arm, realizing the transfer of the target object. This work provides a simple method to fabricate a gecko-like surface and a practical strategy to realize switchable adhesion, which sheds light on broad application potential in production lines, medical products, and more.

The past decade has witnessed a rapid surge of interest in the research and development of non-precious metal-based electrocatalysts for the oxygen reduction reaction (ORR). Until now, the best catalysts in acidic electrolytes have exclusively been Fe-N-C-type materials from high-temperature pyrolysis. Despite the ORR activities of metal phthalocyanine or porphyrin macrocycles having long been known, their durability remains poor. In this work, we use these macrocycles as a basis to develop a novel organic-carbon hybrid material from in-situ polymerization of iron phthalocyanine on conductive multiwalled carbon nanotube scaffolds using a low-temperature microwave heating method. At an optimal polymerto- carbon ratio, the hybrid electrocatalyst exhibits excellent ORR activity with a positive half-wave potential (0.80 V), large mass activity (up to 18.0 A/g at 0.80 V), and a low peroxide yield (<3%). In addition, strong electronic coupling between the polymer and carbon nanotubes is believed to suppress demetallization of the macrocycles, significantly improving cycling stability in acids. Our study represents a rare example of non-precious metal-based electrocatalysts prepared without high-temperature pyrolysis, while having ORR activity in acidic media with potential for practical applications.

Dimensionality and orientation of hexagonal boron nitride (h-BN) nanosheets are promising to create and control their unique properties for diverse applications. However, low-temperature deposition of vertically oriented h-BN nanosheets is a significant challenge. Here we report on the low-temperature plasma synthesis of maze-like h-BN nanowalls (BNNWs) from a mixture of triethylamine borane (TEAB) and ammonia at temperatures as low as 400 °C. The maze-like BNNWs contained vertically aligned stacks of h-BN nanosheets. Wavy h-BN nanowalls with randomly oriented nanocrystalline structure are also fabricated. Simple and effective control of morphological type of BNNWs by the deposition temperature is demonstrated. Despite the lower synthesis temperature, thermal stability and oxidation resistivity of the maze-like BNNWs are higher than for the wavy nanowalls. The structure and oxidation of the nanowalls was found to be the critical factor for their thermal stability and controlled luminescence properties. Cytotoxic study demonstrated significant antibacterial effect of both maze-like and wavy h-BN nanowalls against E. coli. The reported results reveal a significant potential of h-BN nanowalls for a broad range of applications from electronics to biomedicine.

Nanomaterials are increasingly used for biomedical applications; thus, it is important to understand their biological effects. Previous studies suggested that magnetic iron oxide nanoparticles (IONPs) have tissue-repairing effects. In the present study, we explored cellular effects of IONPs in mesenchymal stem cells (MSCs) and identified the underlying molecular mechanisms. The results showed that our as-prepared IONPs were structurally stable in MSCs and promoted osteogenic differentiation of MSCs as whole particles. Moreover, at the molecular level, we compared the gene expression of MSCs with or without IONP exposure and showed that IONPs upregulated long noncoding RNA INZEB2, which is indispensable for maintaining osteogenesis by MSCs. Furthermore, overexpression of INZEB2 downregulated ZEB2, a factor necessary to repress BMP/Smad-dependent osteogenic transcription. We also demonstrated that the essential role of INZEB2 in osteogenic differentiation was ZEB2-dependent. In summary, we elucidated the molecular basis of IONPs’ effects on MSCs; these findings may serve as a meaningful theoretical foundation for applications of stem cells to regenerative medicine.

Although metal-organic frameworks have been heavily tested as the anode materials for lithium-ion batteries (LIBs), the poorer conductivity, easy collapse of frameworks, and serious volume expansion limit their further application in LIBs. Herein, we report a facile approach to obtain MXene-encapsulated porous Ni-naphthalene dicarboxylic acid (Ni-NDC) nanosheets by hybridizing ultrathin Ti3C2 MXene and three-dimensional (3D) Ni-NDC nanosheet aggregates. In the structure of Ni-NDC/MXene hybrids, the interlayer hydrogen-bond interaction between Ni-NDC and MXene can effectively increase the interlayer spacing and further inhibit the oxidation of pure MXene. Hence, the introduction of MXene (a conductive matrix) could further improve the conductivity of Ni-NDC, avoid self-agglomeration, and buffer the volume expansion of Ni-NDC nanosheets. Benefiting from the synergistic effects between Ni-NDC and MXene, Ni-NDC/MXene hybrid electrode exhibits a reversible discharge capacity (579.8 mA·h·g−1 at 100 mA·g−1 after 100 cycles) and good long-term cycling performance (310 mA·h·g−1 at 1 A·g−1 after 500 cycles).