Facile synthesis of the three-dimensional flower-like ZnFe2O4@MoS2 composite with heterogeneous interfaces as a high-efficiency absorber.

Lightweight and high-efficiency microwave absorbers are determined by structure and composition of materials. In this research, a novel core-shell ZnFe2O4@MoS2 composite with a flower-like heterostructure was synthesized successfully by a facile hydrothermal process. The unique 3D heterostructure (porous ZnFe2O4 and MoS2 nanosheets as core and outer shells, respectively) endows the synthesized sample with high-efficiency electromagnetic wave absorption performance. The exploration of microwave absorption properties reveals that the maximum reflection loss displayed by the ZnFe2O4@MoS2 composite is up to -61.8 dB at 9.5 GHz with a filler content of 20 wt%, and the corresponding effective bandwidth (RL exceeding -10 dB) achieves 5.8 GHz (from 7.2 to 13 GHz). The enhanced microwave absorption performance is benefitted by the porous core-shell structure, intense interfacial polarization, multiple reflections, matched impedance and favorable synergistic effect between ZnFe2O4 core and MoS2 shell. Consequently, this strategy provides inspiration for the design of novel microwave absorber with high-performance.

Suppressing the Radiation-Induced Corrosion of Bismuth Nanoparticles for Enhanced Synergistic Cancer Radiophototherapy.

The level of tumor killing by bismuth nanoparticles (BiNPs) as radiosensitizers depends strongly on the powerful particle-matter interaction. However, this same radiation leads to the structural damage in BiNPs, consequently weakening their specific physicochemical properties for radiosensitization. Herein, we studied the radiation-induced corrosion behavior of BiNPs and demonstrated that these damages were manifested by the change in their morphology and crystal structure as well as self-oxidation at their surface. Furthermore, artificial heterostructures were created with graphene nanosheets to greatly suppress the radiation-induced corrosion in BiNPs and enhance their radiocatalytic activity for radiotherapy enhancement. Such a nanocomposite allows the accumulation of overexpressed glutathione, a natural hole scavenger, at the reaction interfaces. This enables the rapid removal of radiogenerated holes from the surface of BiNPs and minimizes the self-radiooxidation, therefore resulting in an efficient suppression of radiation corrosion and a decrease of the depletion of reactive oxygen species (ROS). Meanwhile, the radioexcited conduction band electrons react with the high-level H2O2 within cancer cells to yield more ROS, and the secondary electrons are trapped by H2O molecules to produce hydrated electrons capable of reducing a highly oxidized species such as cytochrome c. These radiochemical reactions together with hyperthermia can regulate the tumor microenvironment and accelerate the onset of cellular redox disequilibrium, mitochondrial dysfunction, and DNA damage, finally triggering tumor apoptosis and death. The current work will shed light on radiosensitizers with an enhanced corrosion resistance for controllable and synergistic radio-phototherapeutics.

Preparation of Lead-free Two-Dimensional-Layered (C8H17NH3)2SnBr4 Perovskite Scintillators and Their Application in X-ray Imaging.

Scintillators, as spectral and energy transformers, are essential for X-ray imaging applications. However, their current disadvantages, including high-temperature sintering and generation of agglomerated powders or large bulk crystals, may not meet the increasing demands of low cost, nontoxicity, and flexible radiation detection. Thus, improved perovskite scintillators are developed in this research. A hybrid perovskite ((C8H17NH3)2SnBr4), which is nontoxic, lead-free, and organic-inorganic, is developed as a scintillator with good emission performance and radioluminescence intensity. These perovskite scintillators are synthesized at low temperatures in an aqueous acid solution, through which they generate a near-unity photoluminescence quantum yield of 98% with the excitation of ultraviolet light. As far as we know, this work is the first to show that the two-dimensional (2D) (C8H17NH3)2SnBr4 perovskite scintillator films prepared by coating a polymer layer can be applied to an X-ray imaging system. The results demonstrate that the low cost X-ray imaging device with good resolution and performance benefits dramatically from this lead-free organic-inorganic hybrid perovskite film. Therefore, this 2D-layered (C8H17NH3)2SnBr4 perovskite scintillator may be a high potential candidate for scintillating material for X-ray imaging techniques.