Ultrasound (US)-triggered sonodynamic therapy (SDT) that enables noninvasive treatment of large internal tumors has attracted widespread interest. For improvement in the therapeutic responses to SDT, more effective and stable sonosensitizers are still required. Herein, ultrafine titanium monoxide nanorods (TiO1+x NRs) with greatly improved sono-sensitization and Fenton-like catalytic activity were fabricated and used for enhanced SDT. TiO1+x NRs with an ultrafine rodlike structure were successfully prepared and then modified with polyethylene glycol (PEG). Compared to the conventional sonosensitizer, TiO2 nanoparticles, the PEG-TiO1+x NRs resulted in much more efficient US-induced generation of reactive oxygen species (ROS) because of the oxygen-deficient structure of TiO1+x NR, which predominantly serves as the charge trap to limit the recombination of US-triggered electron-hole pairs. Interestingly, PEG-TiO1+x NRs also exhibit horseradish-peroxidase-like nanozyme activity and can produce hydroxyl radicals (•OH) from endogenous H2O2 in the tumor to enable chemodynamic therapy (CDT). Because of their efficient passive retention in tumors post intravenous injection, PEG-TiO1+x NRs can be used as a sonosensitizer and CDT agent for highly effective tumor ablation under US treatment. In addition, no significant long-term toxicity of PEG-TiO1+x NRs was found for the treated mice. This work highlights a new type of titanium-based nanostructure with great performance for tumor SDT.

Ultrafine Titanium Monoxide (TiO1+x) Nanorods for Enhanced Sonodynamic Therapy

Dielectric ceramics are highly desired for electronic systems owing to their fast discharge speed and excellent fatigue resistance. However, the low energy density resulting from the low breakdown electric field leads to inferior volumetric efficiency, which is the main challenge for practical applications of dielectric ceramics. Here, we propose a strategy to increase the breakdown electric field and thus enhance the energy storage density of polycrystalline ceramics by controlling grain orientation. We fabricated high-quality -textured Na0.5Bi0.5TiO3–Sr0.7Bi0.2TiO3 (NBT-SBT) ceramics, in which the strain induced by the electric field is substantially lowered, leading to a reduced failure probability and improved Weibull breakdown strength, on the order of 103 MV m−1, an ~65% enhancement compared to their randomly oriented counterparts. The recoverable energy density of -textured NBT-SBT multilayer ceramics is up to 21.5 J cm−3, outperforming state-of-the-art dielectric ceramics. The present research offers a route for designing dielectric ceramics with enhanced breakdown strength, which is expected to benefit a wide range of applications of dielectric ceramics for which high breakdown strength is required, such as high-voltage capacitors and electrocaloric solid-state cooling devices. The energy density of dielectric ceramic capacitors is limited by low breakdown fields. Here, by considering the anisotropy of electrostriction in perovskites, it is shown that -textured Na0.5Bi0.5TiO3–Sr0.7Bi0.2TiO3 ceramics can sustain higher electrical fields and achieve an energy density of 21.5 J cm−3.

Grain-orientation-engineered multilayer ceramic capacitors for energy storage applications.

Magnetic nanoparticles as versatile carriers for enzymes immobilization: A review.

Metal organic framework-derived Fe/carbon porous composite with low Fe content for lightweight and highly efficient electromagnetic wave absorber

Compared with free enzymes, immobilized enzymes are more robust and resistant to environmental changes. In addition, with enhanced stability, immobilized enzymes can be separated from the reaction mixture and used for repeated cycles. These advantages prompt their applications in various fields. This review outlines the existing methods and easy separated support materials for enzymes immobilization. After a brief introduction on the immobilized enzyme, the immobilization methods of adsorption, entrapment, covalent attachment and cross-linking are discussed. The emphasis is given on the easy separated support materials of magnetic nanoparticles (MNPs), membranes and capillary columns. An outlook on the immobilized enzyme is given at last.

Advances on methods and easy separated support materials for enzymes immobilization

Nanoscale porous metal–organic frameworks and related materials have received considerable attention in recent years due to their widespread applications. However, the effective synthesis of magnetic core–shell MOFs still remains a significant challenge. In this article, a Fe3O4@ZIF-8 core–shell nanostructure with unique morphology, a large specific surface area, excellent thermal stability, and superparamagnetic properties is reported. Additionally, instead of using organic surfactants, a surfactant-free and facile synthesis route is successfully developed. The ZIF-8 shell thickness can be precisely controlled by altering the number of growth cycles. Fe3O4@ZIF-8 shows good adsorption properties for MB, with maximum adsorption capacity of 20.2 mg g−1.

Surfactant-free synthesis of a Fe3O4@ZIF-8 core–shell heterostructure for adsorption of methylene blue

Currently, bismuth-based perovskite-type ceramics are considered as promising species in energy storage applications because of easy phase- and micro/macro-structure modulations and high performances. In this work, the composition dependent phase structure and ferroelectric properties of novel Bi0.5K0.5TiO3–Ba(Mg1/3Nb2/3)O3 (BKT–BMN) ceramics are studied. Relaxor properties are gradually enhanced with increasing BMN content. The BKT–0.15BMN composition is selected to further explore energy storage performance via the hot-pressing (HP) technique. The results show that the recoverable energy storage density (WR = 3.14 J cm−3) for the HP sample is more than two times larger than that of the conventional sintering (CS) one. The outstanding WR also exhibits super stability against temperature and frequency variations. Besides, the energy storage efficiency (η) is up to 83.7% for the HP sample. In particular, the stored energy can be released in a very short time of ∼0.12 μs at room temperature, indicating a fast discharging speed for the HP sample. The enhanced performance is due to the decrease of grain size and the increase of grain boundaries, the mechanism underlying the microstructure effect on the breakdown strength (BDS) value is disclosed by numerical simulations (COMSOL). This work not only enriches the bismuth-based ceramic systems in pulsed power applications, but also deepens the understanding of the intrinsic mechanism of a refined microstructure that boosts energy storage performance.

Fine-grain induced outstanding energy storage performance in novel Bi0.5K0.5TiO3–Ba(Mg1/3Nb2/3)O3 ceramics via a hot-pressing strategy

Energy storage performance of Na0.5Bi0.5TiO3-SrTiO3 lead-free relaxors modified by AgNb0.85Ta0.15O3

The complex dielectric properties for ceramic samples of TbMnO3 were investigated as functions of temperature (100K⩽T⩽360K) and frequency (100Hz⩽f⩽100kHz). Two thermally activated dielectric relaxations were found with the activation energies of 0.30 and 0.22eV for the high- and low-temperature relaxations, respectively. By means of complex impedance analysis the high-temperature relaxation was identified to originate from the internal barrier-layer capacitor effects related to the grain boundaries, and the low-temperature relaxation was ascribed to the dipolar effects induced by charge-carrier-hopping motions inside the grains.

Dielectric properties of TbMnO3 ceramics

Dielectric properties of high-purity (4N degree) rutile TiO2 ceramics were investigated over a wide temperature (100–1073 K) and frequency (20 Hz–10 MHz) ranges. X-ray photoemission spectroscopy measurement revealed the sample possesses mixed-valent states of Ti3+/Ti4+. Four thermally activated relaxations were observed. The lowest temperature relaxation (R1) features two Arrhenius segments with activation energy of 30 and 80 meV for the low- and high-temperature segments, respectively. This relaxation was argued to be a polaron relaxation due to electrons hopping between Ti3+ and Ti4+ ions. The second relaxation (R2) appears around room temperature showing activation energy of 0.68 eV is believed to be a Maxwell-Wagner relaxation. The high-temperature relaxations R3 and R4 with activation energy of 0.84 and 1.26 eV were ascribed to the conduction process due to the hopping motions of singly and doubly charged oxygen vacancies, respectively.

Chunchang Wang

Papers

Surfactant-free synthesis of a Fe3O4@ZIF-8 core–shell heterostructure for adsorption of methylene blue

Fine-grain induced outstanding energy storage performance in novel Bi0.5K0.5TiO3–Ba(Mg1/3Nb2/3)O3 ceramics via a hot-pressing strategy

Energy storage performance of Na0.5Bi0.5TiO3-SrTiO3 lead-free relaxors modified by AgNb0.85Ta0.15O3

Dielectric properties of TbMnO3 ceramics

Dielectric Relaxations in Rutile TiO2