Core-shell Nanospheres Research Articles

Room-temperature sensing performance of Pt nanoparticles modified In2O3@ZnS core-shell hollow nanospheres to n-butanol

Room-temperature detection is a great pursuit of goal for semiconductor sensors, aiming to lower energy consumption, prolong the lifetime of sensors, and mitigate safety risks. In this study, room-temperature sensing materials, made of novel Pt nanoparticles modified In2O3@ZnS core-shell hollow nanospheres (Pt-In2O3@ZnS CSHNs), were synthesized by simple hydrothermal and in-situ reduction methods without using any surfactants or toxic organic solvents. The effects of the morphology and composition on gas sensing performance were systematically investigated by adjusting the content of Pt nanoparticles. These materials exhibited excellent sensing performance towards n-butanol at (near) room temperature (~25 °C). The optimal working temperature of Pt-In2O3@ZnS CSHNs (50 °C) was decreased by 210 °C than that of In2O3@ZnS (1:1) CSHNs (260 °C) towards 100 ppm of n-butanol. In particular, the 5% Pt-In2O3@ZnS CSHNs showed an excellent sensing response towards different concentrations of n-butanol at room temperature. The highest sensing response of Pt-In2O3@ZnS CSHNs was up to 7.1 (at 50 °C) and 6.2 (at 25 °C) for 100 ppm n-butanol with a short response time. Further studies demonstrated that such enhanced performances were possibly owing to the “catalytic sensitization” effect driven by Pt NPs and the “electronic sensitization” effect triggered through the formation of Pt-ZnS Schottky junction and In2O3/ZnS n-n heterojunction. This study may shed light on promising gas sensing materials to achieve the room-temperature detection of n-butanol in practical application.

Gradient Hierarchically Porous Structure for Rapid Capillary-Assisted Catalysis.

Synthesis of hierarchically porous structures with uniform spatial gradient and structure reinforcement effect still remains a great challenge. Herein, we report the synthesis of zeolite@mesoporous silica core-shell nanospheres (ZeoA@MesoS) with a gradient porous structure through a micellar dynamic assembly strategy. In this case, we find that the size of composite micelles can be dynamically changed with the increase of swelling agents, which in situ act as the building blocks for the modular assembly of gradient mesostructures. The ZeoA@MesoS nanospheres are highly dispersed in solvents with uniform micropores in the inner core and a gradient tubular mesopore shell. As a nanoreactor, such hierarchically gradient porous structures enable the capillary-directed fast mass transfer from the solutions to inner active sites. As a result, the ZeoA@MesoS catalysts deliver a fabulous catalytic yield of ∼75% on the esterification of long-chain carboxylic palmitic acids and high stability even toward water interference, which can be well trapped by the ZeoA core, pushing forward the chemical equilibrium. Moreover, a very remarkable catalytic conversion on the C-H arylation reaction of large N-methylindole is achieved (∼98%) by a Pd-immobilized ZeoA@MesoS catalyst. The water tolerance feature gives a notable enhancement of 26% in catalytic yield compared to the Pd-dendritic mesoporous silica without the zeolite core.

MXene-wrapped ZnCo2S4 core–shell nanospheres via electrostatic self-assembly as positive electrode materials for asymmetric supercapacitors

MXene-wrapped ZnCo2S4 core–shell nanospheres via electrostatic self-assembly as positive electrode materials for asymmetric supercapacitors

A photoelectrochemical biosensor for detecting Cytokeratin-19 fragments based on CdS/Ni(OH)2 core-shell nanosphere composites amplified by CdSe@MoSe2

The content of Cytokeratin-19 fragments (CYFRA21–1) is correlated with the metastasis and survival status of patients with lung cancer, and the expression level is higher in the serum of nearly half of non-small cell lung cancer patients. Using CYFRA21–1 as the detection target, a sandwiched photoelectrochemical (PEC) immunosensor based on CdS/Ni(OH)2 was designed and constructed successfully. Herein, due to the matched energy band structure, the Ni(OH)2 modified CdS nanorods made up for the shortcomings of CdS photogenerated electrons and holes that were easy to recombine quickly. In addition, the Z-type heterojunction composite material CdSe@MoSe2 was used as a label to improve the sensitivity of the sensor. On the one hand, MoSe2, with excellent resistance to light corrosion, could absorb and utilize near-infrared light due to its narrow band gap, which expanded the light source available for the sensor. On the other hand, the photo-generated charge on CdSe@MoSe2 would be transferred to the CdS/Ni(OH)2, thereby enhancing the photocurrent of the sensor. The detection limit of this sensor was as low as 0.027 pg mL−1 due to the above advantages, and the sensor’s detection range was from 0.100 pg mL−1 to 500 ng mL−1. Additionally, the sensor showed good stability, selectivity and reproducibility, which provided a feasible method for the detection of such tumor markers.

Effective Combination of Isoniazid and Core-Shell Magnetic Nanoradiotherapy Against Gastrointestinal Tumor Cell Types.

IntroductionRadiotherapy is a conventional treatment for gastrointestinal tumors. However, its therapeutic effect might not be satisfactory because of factors such as radio-resistance of tumor cells and dose reduction applied to avoid damage to normal tissues. We developed a novel combination therapy involving the use of isoniazid (INH) and core-shell magnetic nanospheres (NPs) to enhance the efficacy of radiotherapy.MethodsMagnetic core-shell NPs were synthesized. The shell manganese dioxide (MnO2) reacted with intracellular glutathione to produce Mn2+, which decomposed hydrogen peroxide (H2O2) to hydroxyl radicals (·OH) in the presence of INH to produce sufficient amount of reactive oxygen species. In addition to this chemodynamic therapy, MnO2 catalyzed H2O2 to O2, which alleviated hypoxia in tumors and thus enhanced the effect of radiotherapy. In addition, iron oxide (Fe3O4) and reduced Mn2+ were potential candidates for T1–T2 dual-mode magnetic resonance imaging (MRI) with remarkable magnetic targeting ability.ResultsNPs exhibited efficient tumor targeting performance under the magnetic field and improved T1/T2 dual-mode MRI, which elevated oxygen levels without toxicity to the mice to achieve remarkable therapeutic outcomes, reaching a tumor inhibition rate of 93.2%. Moreover, chemodynamic therapy mediated by INH and NPs enhanced the therapeutic effect of radiotherapy both in vivo and in vitro.ConclusionThe results demonstrated that the combination of INH and NPs could be a novel strategy for radiosensitization with clinical potential.

Mesoporous Core-Shell Pd@Pt Nanospheres as Oxidase Mimics with Superhigh Catalytic Efficiency at Room Temperature.

Mesoporous Pt-Pd bimetallic core-shell nanospheres (mPd@Pt NSs) with palladium-rich cores and platinum-rich shells were synthesized via a simple, two-step, wet chemical strategy mediated by nitrogen-doped carbon dots. The BET surface area of mPd@Pt NSs was found to be 210.4 m2·g-1, which is significantly higher than the currently reported unsupported Pt-based nanomaterials. Because of the large active surface area, the as-prepared mPd@Pt NSs show superhigh oxidase activity and exhibit excellent oxidase-like catalytic efficiency with a catalytic constant (Kcat) as high as 2.1 × 103 s-1 at room temperature, which is of the same order of magnitude as the natural horseradish peroxidase (HRP) (Kcat = 4.3 × 103 s-1) at 37 °C and five-fold greater than the reported Kcat values of oxidase-like nanozyme obtained at 30 °C.

Metal-Organic Framework-Derived Core-Shell Nanospheres Anchored on Fe-Filled Carbon Nanotube Sponge for Strong Wideband Microwave Absorption.

Metal-organic frameworks (MOFs) are booming as a promising precursor for constructing lightweight, high-efficiency microwave absorbing (MA) material. However, it is still a challenge to rationally design three-dimensional (3D), porous MOF-derived MA materials with a stable structure and strong and wideband MA performance. Herein, a 3D hybrid nanostructure (CNT/FeCoNi@C) comprising MOF-derived magnetic nanospheres and Fe-filled carbon nanotube (CNT) sponge has been controllably fabricated to enhance the absorption ability and broaden the effective absorption bandwidth (EAB). The magnetic nanospheres are uniformly anchored on the CNT skeleton, forming hybrid network structures, which enhance interface polarization, electron transportation, and impedance matching. The minimum reflection loss (RL) and EAB of the as-prepared CNT/FeCoNi@C sponges reach -51.7 dB and 6.0 GHz, respectively, outperforming most reported MOF-based wave absorbers. This work provides not only a novel design of MOF-derived 3D nanostructures but also an effective guide for the optimization of electromagnetic properties and absorbing performance in MA material.

A smartphone-based ratiometric fluorescent sensing system for on-site detection of pyrethroids by using blue-green dual-emission carbon dots

Exploring the high-performance fluorescence strategy for on-site monitoring of pyrethroids is of great significance to the protection of the ecological environment and human health. Aiming at attaining precise onsite analysis, blue-green dual-emission carbon dots (CDs) were used as well-resolved optosensing centers, and an innovative ratiometric fluorescence core-shell nanosphere was constructed using molecular imprinting in this study. The ratiometric fluorescent signal of the CDs was used by the nanospheres to realize on-site quantitative detection of pyrethroids with excellent selectivity. The detection range of this ratiometric sensing platform was 1–150 μg/L and the limit of detection (LOD) was obtained, as low as 0.048 μg/L. Importantly, the core-shell nanospheres exhibited fluorescence changes on exposure to pyrethroids under UV irradiation. A smartphone application was used to output the color channel values of the captured images. The smartphone-based ratiometric sensing system was used for the quantitative detection of pyrethroid with a sensitive LOD of 0.61 μg/L, which could meet the needs of real analytical samples. This sensing platform showed great application potential for the on-site detection of pesticide residues in agriculture food and pollution control in resource-limited environments.

Iron oxide-Palladium core-shell nanospheres for ferromagnetic resonance-based hydrogen gas sensing

Interfaces of ferromagnetic transition metals such as Iron, Cobalt, and Nickel with non-magnetic palladium are of interest due to their unique magnetic and spintronic properties. These interfaces enable ferromagnetic resonance (FMR) based sensing of hydrogen gas. In the present work, we synthesized Fe3O4–Pd core-shell nanospheres via a one-pot synthesis method using the thermal decomposition of Fe3+ acetylacetonate in the presence of a reducing agent to produce the Fe3O4 core, followed by the reduction of a Pd2+ precursor to form the pure Pd shell. We found that our in-situ synthesized core-shell nanostructure is magnetically active and shows excellent H2 gas sensing properties. The effect of reversible hydrogen gas absorption on the magnetism of Fe3O4–Pd core-shell nanospheres was investigated. The hydrogen-induced ferromagnetic-resonance (FMR) peak shift amounted to 30% of the peak linewidth for the virgin state of the sample. In addition, in the presence of hydrogen gas, we observed a fully reversible decrease in the FMR peak linewidth by about two times. This was accompanied by a nearly doubling of the FMR peak height. Response and recovery times of about 2 and 50 s, respectively, were extracted from the measurements. All the data was collected using a mix of just 3% hydrogen in a nitrogen carrier gas.

Preparation of biomimetic non-iridescent structural color based on polystyrene-polycaffeic acid core-shell nanospheres.

Caffeic acid (CA), as a natural plant-derived polyphenol, has been widely used in surface coating technology in recent years due to its excellent properties. In this work, caffeic acid was introduced into the preparation of photonic band gap materials. By controlling the variables, a reasonable preparation method of polystyrene (PS) @polycaffeic (PCA)–Cu(ii) core–shell microspheres was achieved: 1 mmol L−1 cupric chloride anhydrous (CuCl2), 3 mmol L−1 sodium perborate tetrahydrate (NaBO3·4H2O), 2 mmol L−1 CA and 2 g L−1 polystyrene (PS) were reacted at 50 °C for 10 min to prepare PS@PCA–Cu(ii) core–shell microspheres through rapid oxidative polymerization of CA coated PS of different particle diameters. The amorphous photonic crystal structure was self-assembled through thermal assisted-gravity sedimentation, resulting in structural color nanomaterials with soft and uniform color, no angle dependence, stable mechanical fastness and excellent UV resistance.

Cracking enabled unclonability in colloidal crystal patterns authenticated with computer vision.

Colloidal crystals with iridescent structural coloration have appealing applications in the fields of sensors, displays, anti-counterfeiting, etc. A serious issue accompanying the facile chemical self-assembly approach to colloidal crystals is the formation of uncontrolled and irregular cracks. In contrast to the previous efforts to avoid cracking, the unfavorable and random micro-cracks in colloidal crystals were utilized here as unclonable codes for tamper-proof anti-counterfeiting. The special structural and optical characteristics of the colloidal crystal patterns assembled with monodisperse poly(styrene-methyl methacrylate-acrylic acid) core-shell nanospheres enabled multi-anti-counterfeiting modes, including angle-dependent structural colors and polarization anisotropy, besides the physically unclonable functions (PUFs) of random micro-cracks. Moreover, by using the random cracks in the colloidal crystals as templates to guide fluorescent silica nanoparticle deposition, an fluorescent anti-counterfeiting mode with PUFs was introduced. To validate the PUFs of the fluorescent micro-cracks in the colloidal crystals, a novel edge-sensitive template matching approach based on a computer vision algorithm with an accuracy of ∼100% was developed, enabling ultimate security immune to forgery. The computer-vision verifiable physically unclonable colloidal crystals with multi-anti-counterfeiting modes are superior to conventional photonic crystal anti-counterfeiting materials that rely on angle-dependent or tunable structural colors, and the conventional PUF labels in the aspect of decorative functions, which will open a new avenue for advanced security materials with multi-functionality.

Ultrahigh Adsorption by Regenerable Iron-Cobalt Core-Shell Nanospheres and Their Synergtic Effect on Nanohybrid Membranes for Removal of Malachite Green Dye

Ultrahigh Adsorption by Regenerable Iron-Cobalt Core-Shell Nanospheres and Their Synergtic Effect on Nanohybrid Membranes for Removal of Malachite Green Dye

The effect of TiO2@CoAl-LDH nanosphere on early hydration of cement and its photocatalytic depollution performance under UV–visible light

A new core–shell nanosphere TiO2@CoAl-LDH was synthesized and applied to prepare a photocatalytic cementitious composite. The photocatalytic performance of the photocatalytic cementitious composite was evaluated by the real-time degradation of NOx and methylene blue under continuous UV–visible light irradiation. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), isothermal calorimetry, Vickers microhardness, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and thermal gravimetry (TG) were employed to analyze the effects of TiO2@CoAl-LDH on early cement hydration, localized morphology, and microscopic mechanical properties of the photocatalytic cementitious composites. The results showed that the newly synthesized core–shell nanosphere TiO2@CoAl-LDH can achieve a significant utilization of solar light in the whole wavelength range and thus exhibit an overall better photocatalytic performance compared to the traditional photocatalyst TiO2, particularly when an appropriate mix dosage was applied in cementitious composite.

Synthesis and application of CdS nanoparticles-decorated core–shell Ag@Ni nanohybrids for visible-light spectrophotometric assay of sulfide in aqueous sample

Novel Ag@Ni nanosphere decorated with CdS NPs (Ag@Ni-CdS NCs) was synthesized by one step chemical synthesis method. The fabricated NCs were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), fourier transfer infra-red spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), zeta sizer and particle size analyzer. TEM and XRD confirmed the Ag in core and Ni in shell for the effective formation of Ag@Ni core shell nanosphere. EDAX and XPS spectra of NCs confirms the formation of Ag@Ni-CdS NCs. Zeta potential and particle size of the NCs was found to be 29.5 ± 1.5 mV and 24 ± 1 nm respectively. The complete loss in the peak intensity of Ag@Ni-CdS NCs (localized surface plasmon resonance (LSPR)) at ∼410 nm in presence of S2− ions was observed which indicates its selective detection towards S2− ions. The sulfide ion sensing by Ag@Ni-CdS NCs was due to the successive oxidation of Ag results in the formulation of Ag2+ ions in the system, which causes the diminishing of LSPR band of NCs. The limit of detection (LOD) of S2− ions by Ag@Ni-CdS NCs was calculated to be of 2.66 nM. The combination of CdS NPs with core–shell Ag@Ni nanosphere guides a promising strategy for S2− ions detection from environmental polluted samples.

In-situ growth of TiO2@B-doped g-C3N4 core-shell nanospheres for boosts the photocatalytic detoxification of emerging pollutants with mechanistic insight

The photocatalysts charge transportation and separation abilities are two critical factors for the efficient detoxification of organic and pharmaceutical hazards. This study demonstrated an in-situ hydrothermal synthesis method to develop unique core-shell nanospheres, TiO2@B-doped g-C3N4 (TOBCN (1-3)) Z-scheme photocatalyst. The TOBCN were characterized by using X-ray powder diffraction, FT-IR, SEM, TEM, EDX with mapping analysis, XPS and UV-DRS. In particular, under optimized ratio, synthesized TOBCN (2) photocatalyst showed an excellent detoxification ability of both toxic organic (rhodamine-B (Rh-B)) and pharmaceutical levofloxacin (LF) via synergistic interfacial effects of TiO2 core with BCN shell. At the same time, lower detoxification results were also observed when compared with TOBCN (1), TOBCN (3), pure TiO2 and BCN in terms of the efficiency and kinetic rate constant. The BET, photoluminescence, photocurrent and impedance analysis also revealed an improved surface area of active sites, efficient charge separation and subsequent charge transfer of photocatalyst, respectively. Further, the photo detoxification mechanisms, generated reactive species and stability of the photocatalyst were also elucidated and discussed in detail. This work emphasized that the prepared core (metal oxide)-shell (carbon) material has great potential as an efficient photocatalysts for detoxification of hazards and beyond.

Uniform H-CdS@NiCoP core–shell nanosphere for highly efficient visible-light-driven photocatalytic H2 evolution

Constructing highly efficient and cost-effective photocatalyst system has been a big challenge for photocatalysis. Herein, CdS nanosphere (N-CdS), hollow CdS (H-CdS) and a series of H-CdS@NiCoP core–shell nanospheres have been successfully prepared via a facile hydrothermal method. The activity test showed that H-CdS exhibited higher photocatalytic activity (3.34 mmol g-1h−1) compared with N-CdS (0.99 mmol g-1h−1) under visible light irradiation (λ ≥ 420 nm), suggesting that hollow structure could effectively improve photocatalytic activity. Moreover, the H-CdS@NiCoP-7 wt% displayed a maximum photocatalytic H2 evolution rate of 13.47 mmol g-1h−1, which was about 4 times and 2.5 times higher than that of pristine H-CdS and H-CdS@Pt-3 wt%, respectively. Furthermore, H-CdS@NiCoP-7 wt% exhibited a good stability during 20 h test. The physicochemical properties were characterized by XRD, SEM, TEM, XPS, UV–vis DRS, PL and photoelectrochemical technique. The results showed that NiCoP addition can construct p-n junction with H-CdS and effectively promote the charge transfer from CdS to NiCoP, which improved the photocatalytic hydrogen evolution activity. This work revealed that NiCoP could react as an excellent co-catalyst for enhancing H-CdS photocatalytic activity.

Nonlinear optical properties of Au@Ag coreshell nanospheres excited by femtosecond laser

The nonlinear optical properties and ultrafast dynamics process of Au@Ag coreshell nanospheres (NSs) are reported in this paper. We researched the optical nonlinear absorption property of Au@Ag coreshell NSs excited by 800 nm laser at different energies by open-aperture Z-scan technology. The experimental results demonstrated that the Au@Ag coreshell NSs exhibited two-phone absorption (TPA) behavior, the degree of which was intensity-dependent. The TPA coefficients of Au@Ag coreshell NSs excited by different energies were obtained by fitting. By using pump-probe technology, we studied the ultrafast dynamics process of Au@Ag coreshell NSs. The results indicated that the relaxation process contained a fast and a slow process, which depended strongly on the laser intensity. By numerical fitting, we got the relaxation times of the sample excited at different laser powers.

Europium(III) Complex-Functionalized SiO2@mTiO2 Nanospheres for Al3+-Modulated Multicolor Emission.

A europium(III) hybrid material Eu(tta)3bpdc-SiO2@mTiO2 (Htta = 2-thenoyltrifluoroacetone, H2bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid) was successfully designed and synthesized by the covalent grafting complex Eu(tta)3bpdc to SiO2@mTiO2 core–shell nanosphere. The FT-IR, PXRD, XPS, TEM, HRTEM, SAED, TGA and PL were performed to characterize these materials. The results indicate that core–shell nanosphere structure and anatase crystallites of SiO2@mTiO2 are retained well after grafting the europium complex. Hybrid material Eu(tta)3bpdc-SiO2@mTiO2 displays uniform nanosphere structure, bright red color and long lifetime, which can serve as a multicolor emission material modulated by using Al3+ ions via the cation exchange approach under a single-wavelength excitation. To the best of our knowledge, this work is the first multicolor emissive sensor for Al3+ ions based on the lanthanide hybrid material.

Gas-sensing performance of In2O3@MoO3 hollow core-shell nanospheres prepared by a two-step hydrothermal method

Core-shell semiconductor nanostructures can be suitable for high-performance gas sensors due to their unique structural features. In this study, In2O3@MoO3 core-shell hollow spheres were synthesized by a facile two-step solvo-thermal method, followed by post-heat treatment. The synthesis results in 20-nm thick MoO3 shells coated on In2O3 hollow spheres (200-nm diameter). The effects of the morphology and composition on gas sensing performance were systematically investigated by adjusting the molar ratio of In to Mo. The sensing tests suggest that the core-shell structure with the In to Mo molar ratio of 1:1 exhibits the highest sensing response (28.1) towards 100-ppm n-butylamine at the optimized working temperature of 300 °C. This response is two times higher than that of the In2O3 & MoO3 binary mixture (11.1) and five times than that of the pristine In2O3 hollow spheres (4.8). The sensing performance is a result of the unique core-shell structures including both the catalytic reaction mechanism of MoO3 and the co-catalytic properties of the In2O3 hollow spheres. This study may shed light on the design of practical, high-performance amine gas sensors in the future.

3D carbonized wood-based integrated electrochemical immunosensor for ultrasensitive detection of procalcitonin antigen

This work presents a novel 3D carbonized wood-based integrated electrochemical immunosensor for ultrasensitive detection of procalcitonin (PCT) antigen at picogram level, achieving a wide linear detection range for PCT concentrations range from 0.05 to 90 pg mL−1 with a low detection limit of 0.014 pg mL−1 (S/N = 3), outperforming the previous reports. 3D carbonized wood as a new immunosensor matrix is used for electrochemical PCT biosensing, improving the stability of electrode and overcoming the disadvantages of traditional glassy carbon electrode (GCE). It obtained an excellent detection result, due to it has abundant mutual crisscross microchannels that promote the reactants and electrons transfer, greatly amplify the current signal. This novel sandwich-type electrochemical immunosensor is composed of 3D carbonized wood, carboxylic multi-walled carbon nanotube (cMWCNT), Au@Co3O4 core-shell nanosphere and Au/single layer nitrogen-doped graphene (Au/SL-NG), when it is applied for PCT detection in real clinical samples, it exhibits high accuracy same as enzyme-linked immunosorbent assay (ELISA) method.