•The BaTiO3 particles were coated by La2O3 and SiO2 using a double-coating approach.•BaTiO3@La2O3@SiO2 particles with a multi-level core-shell structure were obtained.•Fine-grained BaTiO3@La2O3@SiO2 ceramics met the X8R specification were prepared.•The prepared ceramics are to be utilized in multi-layer energy storage capacitors.We prepared submicron BaTiO3@La2O3@SiO2 particles with high uniformity and dispersity using a novel double-coating method. The monodispersed submicron BaTiO3 particles (diameter about 240 nm) formed a ferroelectric core that was coated with La2O3 and SiO2 as a modified layer and a layer with high electrical resistance, respectively, and the thickness of two shells was about 20 nm. We then obtained dense, fine-grained BaTiO3-based energy storage ceramics (grain size ≤ 300 nm) with the same particle structure by means of sintering in air at 1240 °C for 2 h. As the amount of SiO2 increased, the content of the tetragonal phase and the densification first increased and then decreased. When the amount of SiO2 exceeded 9.0 wt%, a secondary phase with Ba2TiSi2O8 appeared, and the core-shell structure disappeared. The BaTiO3@La2O3@SiO2 ceramics met the X8R requirements, with a maximum dielectric constant of 3362 at 6.0 wt% SiO2, and a low dielectric loss at room temperature (< 0.020, with a minimum of 0.011). The remnant polarization deceased from 13.80 to 1.21 μC/cm2, while the energy storage density first increased and then decreased as the amount of SiO2 coating increased from 0.0 to 12.0 wt%. The discharged energy storage density was highest (0.54 J/cm3) for samples containing 9.0 wt% SiO2 under a maximum polarization field of 13.6 kV/mm, and the energy storage efficiency of the ceramic was >85%.Download high-res image (229KB)Download full-size image

•CoxFe3−xO4 that is magnetic and microwave absorptive, was designed for drug loading.•We initiated a CTAB-assisted solvothermal method to prepare H-mCoxFe3−xO4 particles.•H-mCoxFe3−xO4 nanocarrier can be used for targeting and microwave controlled release.Facile synthesis and smart designs of multifuctional nanocarriers would make them more potential in the practical application of drug delivery for cancer treatment. In this study, we synthesized hollow-mesoporous cobalt ferrite (H-mCoxFe3−xO4) nanoparticles by a cetyltrimethylammonium bromide (CTAB)-assisted solvothermal method. The resulting monodisperse CoxFe3−xO4 microspheres are 280 nm in diameter with fine uniformity and hollow-mesoporous structure, and they possess a fairly high surface area of 58.03 m2/g, a pore volume of 0.13 cm3/g, an average pore size of 7.21 nm, and are suitable for drug loading. This material has a high magnetization saturation value (42.2 emu/g) for drug targeting and its sodium chloride suspension could raise to 50 °C from room temperature in 180 s. The drug release process shows that the release rate under the microwave irradiation was faster than that under stirring condition, and about 64% VP16 was released after six on/off microwave treatment cycles. So these multifunctional H-mCoxFe3−xO4 nanoparticles with single material are expected to provide the research foundation for using as drug carrier themselves for drug loading, magnetic targeting, and microwave-triggered controllable release.Herein we developed a CTAB-assisted solvothermal process to synthesize hollow-mesoporous structured cobalt ferrite (H-mCoxFe3−xO4) nanoparticles, which also possess the properties of magnetic targeting and microwave-heat transformation. In addition, etoposide (VP16) was used to investigate the drug loading and microwave controlled release.Download high-res image (278KB)Download full-size image

A carrier possessing simple structure and composition, but with microwave-targeted-fluorescence multifunctional properties to precisely control the delivery of the drug was prepared. Herein, we have constructed the multifunctional Fe3O4@ZnAl2O4:Eu3+@mSiO2–APTES core–shell drug-carrier via direct precipitation method and sol–gel process with surfactant-assistance approach. This carrier is a monodisperse microsphere with an average particle size of 325 nm. Fe3O4 in the core has a high saturation magnetization and provides the Fe3O4@ZnAl2O4:Eu3+@mSiO2–APTES with good drug targeting properties. The ZnAl2O4:Eu3+ interlayer has the characteristic of fluorescent luminescence and can be used to monitor the transport of drugs in the body in real time. In addition, the ZnAl2O4:Eu3+ as a dielectric loss microwave absorbing material combines with the high magnetic loss Fe3O4 to form a composite material, which improved the microwave thermal response. Over 78.2% of VP16 molecules were released under microwave trigger. In addition, mesoporous silica nanoparticles in the outer layer improve the drug loading efficiency through organic modification. The results indicated that this multifunctional drug-carrier with simple structure and composition is a potential controlled drug delivery system in cancer therapy.

The submicron BaTiO3@YFeO3 particles (diameter about 240 nm) with core–shell structure using a co-precipitation method were prepared. We obtained fine-grained BaTiO3@YFeO3 composite magnetodielectric ceramics (grain size ≤250 nm) with a tetragonal-phase BaTiO3 core and an orthorhombic-phase YFeO3 shell by means of sintering at a low temperature (1180 °C) in air. The temperature coefficient of capacitance characteristic (TCC) of the BaTiO3@YFeO3 ceramics satisfied the X8R specification. As the YFeO3 content increased from 2.0 to 8.0 mol%, the room-temperature permittivity of the samples first increased and then decreased, and the maximum room-temperature permittivity was 2319 at 6.0 mol% YFeO3, and a low dielectric loss at room temperature (<0.020). The saturation magnetization (Ms) and remnant magnetization (Mr) increased as the YFeO3 content increased, reaching values of 2.74 and 1.75 emu/g, respectively, at 8.0 mol% YFeO3. The improved microstructure and properties of BaTiO3@YFeO3 materials indicated that the co-precipitation approach represents a good way to prepare such materials for use in multifunctional devices.

We fabricated an efficient microwave-triggered controlled-release nanocarrier system using Fe3O4@SnO2:Er3+,Yb3+–APTES multifunctional core–shell nanoparticles. We also studied the drug loading and release mechanisms by means of microcalorimetry. The thermodynamic parameter values for loading (ΔH = −42.64 kJ mol−1, ΔS = −452.98 J mol−1 K−1) showed that the main interaction between the nanocarrier and drug molecules is relatively weak hydrogen bonding. The molar enthalpy (ΔH) of the drug-release process was 10.30 kJ mol−1, which indicates an endothermic process. This suggests that drug release can be controlled by microwave heating. When energy provided from the medium rises above the hydrogen bond energy, the hydrogen bond breaks and the nanocarrier begins to release the drug. The release profile can be controlled by the duration and number of cycles of microwave application. Approximately 71% of ibuprofen was released after four cycles. The microwave-stimulated, thermally sensitive, multifunctional nanoparticles therefore represent a new system with potential utility for on-command drug release, and the fluorescence properties allow in situ monitoring.

•Obtained a novel WO3 interlayered Fe3O4@WO3@mSiO2–APTES core-shell drug nanocarrier.•The composites with chemical stability exhibit excellent microwave thermal response.•The nanocarrier was suitable for localized hyperthermia to controlled drug release.We constructed a novel WO3 interlayered Fe3O4@WO3@mSiO2–APTES core-shell structured drug nanocarrier to investigate loading and controllable release properties of etoposide (VP16). This nanocomposite composed of mesoporous silica (mSiO2) shell with magnetic Fe3O4 core, WO3 interlayer. They possesses high surface area of 234.5 m2/g, provides large accessible pore volume of 0.14 cm3/g for adsorption of drug molecules, high magnetization saturation value of 40.54 emu/g for drug targeting under foreign magnetic fields, relatively higher reflection loss of −22.75 dB for controlled release by microwave-triggered which was caused by WO3 interlayer. The VP16 release of over 85.69% under microwave discontinuous irradiation outclasses the 15.88% within 600 min only stirring release. This multifunctional material shows good performance for targeting delivery and WO3 microwave controlled release of anticancer drugs based on all the properties they possess.

The design of stimuli-responsive controlled drug delivery systems is a promising approach in cancer therapy, but it is still a major challenge to be capable of optimum therapeutic efficacy. Herein, we have elaborately fabricated Fe3O4@ZnO@mGd2O3:Eu (mGd2O3:Eu was short for mesoporous Gd2O3:Eu) multifunction composite nanoparticles by a simple process, with mesoporous Gd2O3:Eu shells as supports to increase the anticancer drug loading and thermally responsive polymer poly[(N-isopropylacrylamide)-co-(methacrylic acid)] (P(NIPAm-co-MAA)) gated mesoporous shells as microwave stimulus gatekeepers. The as-synthesized hybrid nanoparticles show a large accessible pore volume (0.19 cm3 g−1) and a high magnetization saturation value (27.8 emu g−1) for drug loading and targeting. The ZnO shells can effectively absorb and convert microwave to heat upon irradiation with microwaves, as a result of the microwave irradiation P(NIPAm-co-MAA) shrinks to a smaller volume and exposes the pores of the mesoporous luminescent shell, realizing the triggered release of the entrapped etoposide (VP16) drug (under microwave irradiation the VP16 release was about 81.7% within 10 h). In vitro studies show the multifunctional nanocarrier feasibility and advantage for remote-controlled drug release systems.

To meet the needs of future multilayer ceramic capacitors (MLCCs), thinner dielectric layers are necessary. To achieve this goal, the grain size and uniformity of the MLCC particles must be effectively controlled. In this study, we developed a novel precipitation route to control the dispersion and particle size of Ba0.991Bi0.006TiO3 and Ba0.991Bi0.006TiO3@Nb2O5 particles. We confirmed a core–shell particle structure by means of X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The dielectric properties of the ceramics were measured using an LCR meter. We found monodispersed submicron Ba0.991Bi0.006TiO3 particles (∼233 nm) form a core that was coated with a homogeneous Nb2O5 layer (∼7 nm). Dense, fine-grained Ba0.991Bi0.006TiO3-based ceramics (≤250 nm) were obtained by sintering. The ceramics met the X8R requirements, with a Curie temperature of about 140 °C, a maximum dielectric constant of 2336, and a low dielectric loss at room temperature (<2.0%, with a minimum of 0.5%).

We report a 3-aminopropyltriethoxysilane (APTES) functionalized magnetic core–shell structure drug delivery system which is composed of a nonmesporous silica (nSiO2) coated Fe3O4 nanoparticle as the core and mesoporous silica (mSiO2) as the shell (designated Fe3O4@nSiO2@mSiO2-APTES). These spheres have superparamagnetism, high magnetization (39.1 emu/g), a large surface area (222.35 m2/g), uniform accessible mesopores (2.5 nm), and abundant amino groups on the mesoporous shell. We investigated the thermodynamic and kinetic properties for the drug loading and release processes using microcalorimetry for the first time. The drug loading process was exothermal, and the release process was endothermal. A series of thermodynamics parameters ΔH, ΔS, and ΔG for drug loading and release processes was calculated. For drug loading process, the critical value was determined, the kinetics equation dα/dt = 10–3.66(1 – a)1.01, and rate constant k = 10–3.66 s–1 was also obtained. The results show that the interaction between the drug molecule and the nanocarrier is a hydrogen-bond interaction which was derived from the experimental values of the molar enthalpies (ΔH < 0) and molar entropy (ΔS < 0). This method therefore promise to provide a theoretical basis for the interaction between the drug molecule and the nanocarrier, so as to guide an externally controlled drug-delivery system in cancer therapy.

•We constructed Fe3O4@ZnO:Er3 +,Yb3 +@(β-CD) nanoparticles used as a drug carrier.•The nanoparticles have magnetic and up-conversion fluorescence properties.•The nanoparticles have excellent microwave thermal response property.•The nanocomposite could be a controllable drug release triggered by microwave.We constructed a novel core–shell structured Fe3O4@ZnO:Er3 +,Yb3 +@(β-CD) nanoparticles used as drug carrier to investigate the loading and controllable release properties of the chemotherapeutic drug etoposide (VP-16). The cavity of β-cyclodextrin is chemically inert, it can store etoposide molecules by means of hydrophobic interactions. The Fe3O4 core and ZnO:Er3 +,Yb3 + shell functioned successfully for magnetic targeting and up-conversion fluorescence imaging, respectively. In addition, the ZnO:Er3 +,Yb3 + shell acts as a good microwave absorber with excellent microwave thermal response property for microwave triggered drug release (the VP-16 release of 18% under microwave irradiation for 15 min outclass the 2% within 6 h without microwave irradiation release). The release profile could be controlled by the duration and number of cycles of microwave application. This material therefore promises to be a useful noninvasive, externally controlled drug-delivery system in cancer therapy.We functionalized a multifunctional core–shell Fe3O4@ZnO:Er3 +,Yb3 + nanocarriers by adding β-cyclodextrin, which is capable of carrying drug molecules and triggered release of the drug by microwave treatment.

•The stable γ-Fe2O3 magnetic nanoparticles are favored as magnetic core.•The fluorescer agent of YPO4:Tb3+, Ce3+ has excellent fluorescence properties.•The nanocomposites are further applied to load and release of cisplatin drugs.Multifunctional γ-Fe2O3@Ca3(PO4)2@YPO4:Tb3+,Ce3+ nanocomposites were synthesized using an easy direct-precipitation method. The nanocomposites had a monodispersed spherical morphology with a narrow size distribution, and dispersed well in water. The nanocomposites showed the characteristic emission peaks of Ce3+ (5d–4f) and Tb3+ (5D4–7F3 to 5D4–7F6). Magnetism measurements revealed that the samples were nearly superparamagnetic. The multifunctional nanocomposites were used for in vitro drug delivery tests under ambient conditions, and we discuss the influence of different media on the release of cisplatin (cis-diamminedichloroplatinum). We assessed the loading and release performance for cisplatin by means of UV–visible spectrophotometry. Our findings will provide guidance for engineering similar multifunctional nanocomposites for use in future drug delivery applications.

In this paper, we constructed a novel core–shell structured nanocarrier used as a drug carrier to investigate the storage and controllable release properties of the cancer chemotherapeutic drug etoposide (VP16). The new composite nanocomposite composed of a mesoporous silica shell with magnetic Fe3O4 core and ZnO interlayer with a core–shell structure was prepared by a simple process. The mesoporous nanocarrier possesses high surface area (643.9 m2/g), provides large accessible pore volume (0.32 cm3/g) for the adsorption of drug molecules, and has a high magnetization saturation value (56.8 emu/g) for drug targeting under foreign magnetic fields, and the ZnO interlayer acts as a good microwave absorber with excellent microwave thermal response property for microwave-triggered drug release (the VP16 release of over 85% under microwave discontinuous irradiation outclasses the 14% within 10 h only stirring release). This multifunctional system shows a good performance for targeting delivery and controllable release of anticancer drugs based on all the properties they possess.

In this study, we synthesized γ-Fe2O3@SiO2@TiO2–Ag nanocomposites with a core–shell structure using a hydrothermal method and a sol–gel method. Transmission electron microscope images showed that the γ-Fe2O3@SiO2@TiO2–Ag nanocomposites had a core–shell structure. Photocatalytic examination of the γ-Fe2O3@SiO2@TiO2–Ag was carried out using methyl orange solution under UV irradiation. The γ-Fe2O3@SiO2@TiO2–Ag nanocomposites showed stronger photocatalytic activity than pure TiO2. With γ-Fe2O3@SiO2@TiO2–Ag, about 84% of the methyl orange was decomposed after 1 h of UV irradiation, versus 49% for pure TiO2. The antibacterial activity of γ-Fe2O3@SiO2@TiO2–Ag nanocomposites was remarkably greater than that of bare TiO2 nanoparticles. The introduction of silver nanoparticles into the TiO2 matrix facilitates charge separation by trapping photo-generated electrons, thereby enhancing biological activity and photoactivity.Graphical abstractTEM images of the γ-Fe2O3@SiO2@TiO2–Ag with different amount of the Ti(OC4H9)4: (a) 0 g, (b) 0.75 g, (c) 1.5 g and (d) 2.25 g the γ-Fe2O3@SiO2@TiO2–Ag nanoparticles have a particle size ranging from 230 to 300 nm and that the particles retain a spherical morphology, non-aggregation, and a rough surface at all TiO2 contents. As the amount of Ti(OC4H9)4 increased, the thickness of the TiO2–Ag layer increased.Highlights► γ-Fe2O3@SiO2@TiO2–Ag have been synthesized by hydrothermal method and sol–gel method. ► γ-Fe2O3@SiO2@TiO2–Ag showed the photocatalytic activity higher than the pure TiO2. ► γ-Fe2O3@SiO2@TiO2–Ag showed the antibacterial activity higher than the pure TiO2.

•New X8R-type BaTiO3−K0.5Na0.5NbO3−(Li2O–Bi2O3−B2O3) dielectric ceramics was reported.•BaTiO3−K0.5Na0.5NbO3−(Li2O–Bi2O3–B2O3) dielectric ceramics can be densified well at a low temperature of 980 °C.•Permittivity of X8R-type dielectric ceramics was extremely enhanced to 5585.BaTiO3 ceramics doped with 3 wt% K0.5Na0.5NbO3 content and different Li2O–Bi2O3–B2O3 frit as the sintering aids were prepared by the conventional solid state ceramic route. The effects of the Li2O–Bi2O3–B2O3 frit on the phase composition, microstructure and dielectric properties of BaTiO3 ceramics were investigated. Results show that the BaTiO3 pellet has pure tetragonal crystal structure. And the dielectric ceramic with high permittivity of 5585 and excellent densification were obtained at a sintering temperature of 980 °C, meeting X8R specifications. The results also suggest that the developed BaTiO3 based X8R ceramics may serve as a promising candidate for fabricating cheap multilayer capacitors with base metal as inner electrode.

Nb-doped BaTiO3 nanocrystalline powders and ceramics were prepared by a simple sol–gel process, which used H3[Nb(O2)4] as a precursor. The powders and ceramics were characterized by methods of XRD, SEM and TEM, while dielectric properties of the ceramics were also determined. The results indicated that the powders synthesized by sol–gel process were in nanometer scale, which were mainly composed of cubic BaTiO3 with small amount of BaCO3. After sintering, only BaTiO3 phase could be found and there was no evidence of a second phase. Compared to the traditional solid-state method, the sintering temperature of the ceramics prepared by sol–gel route was reduced obviously due to the good sinterability of nanopowders. And doped niobium could make Curie temperature shift to low temperature. Nb-doped BaTiO3 ceramics calcined at 1000 °C for 2 h and sintered at 1250 °C for 2 h had a regular microstructure with the maximal dielectric constant of 10,298. The methodology is a simple process with low cost, by which materials of BaTiO3 powders doped with high concentration of niobium, even up to 10 mol%, can be prepared.

The Co-doped BaTiO3 nanosized powders and ceramics were prepared via the sol–gel process. The powders and ceramics were characterized by methods of XRD, SEM and TEM. The dielectric properties of the ceramics were also determined by these methods. The influence of sintering temperature, sintering time and Co concentration on the microstructure and dielectric properties was discussed. The results revealed that the powders were in nanometer scale (30–50 nm) and were mainly composed of cubic BaTiO3 phase and small amount of BaCO3. After sintering, both the cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3. The sintering temperatures of the Co-doped BaTiO3 ceramics decreased (about 100 °C) and the Curie temperatures of the ceramics were then moved to lower temperature. In addition, the dielectric constant of the ceramics doping with Co was higher than that of the pure BaTiO3 ceramics. The dielectric constant was increased first, and then decreased as the concentration of Co increased.

The design of stimuli-responsive controlled drug delivery systems is a promising approach in cancer therapy, but it is still a major challenge to be capable of optimum therapeutic efficacy. Herein, we have elaborately fabricated Fe3O4@ZnO@mGd2O3:Eu (mGd2O3:Eu was short for mesoporous Gd2O3:Eu) multifunction composite nanoparticles by a simple process, with mesoporous Gd2O3:Eu shells as supports to increase the anticancer drug loading and thermally responsive polymer poly[(N-isopropylacrylamide)-co-(methacrylic acid)] (P(NIPAm-co-MAA)) gated mesoporous shells as microwave stimulus gatekeepers. The as-synthesized hybrid nanoparticles show a large accessible pore volume (0.19 cm3 g−1) and a high magnetization saturation value (27.8 emu g−1) for drug loading and targeting. The ZnO shells can effectively absorb and convert microwave to heat upon irradiation with microwaves, as a result of the microwave irradiation P(NIPAm-co-MAA) shrinks to a smaller volume and exposes the pores of the mesoporous luminescent shell, realizing the triggered release of the entrapped etoposide (VP16) drug (under microwave irradiation the VP16 release was about 81.7% within 10 h). In vitro studies show the multifunctional nanocarrier feasibility and advantage for remote-controlled drug release systems.