Hollow Mesoporous Nanospheres Research Articles

Mass transfer-enhanced platform for heterogeneous dual organocatalysis to boost yield and diastereoselectivity in enantioselective Michael/benzoin cascade reaction

Mass transfer limitation and tedious anchoring of multiple expensive chiral organocatalysts are the key bottlenecks in heterogeneous asymmetric cascade/tandem reactions, leading to high-cost processes with low catalytic performances. In this paper, two chiral organocatalysts, including (S)-diphenylprolinoltrimethylsilyl ether (ProTMS) and N-heterocyclic carbenes (NHC), are simultaneously immobilized to hollow mesoporous polystyrene nanospheres (HMPNs) in one-pot via Friedel-Crafts alkylation to afford supported dual organocatalysts (ProTMS&NHC@HMPNs) at low cost. The catalyst possesses the spherical morphology with a hollow interior and a thin mesopore-abundant shell, providing suitable environments for reactants to quickly access to the catalytic sites of NHC and ProTMS. The side reactions caused by limited mass transfer are effectively suppressed, and superior yields (70–92 %) and diastereoselectivities (dr = 3:120:1) to homogeneous catalysis are achieved in heterogeneous Michael/benzoin cascade reaction. Overall, the mass transfer-enhanced platform for efficient heterogeneous dual organocatalysis is developed to boost yield and diastereoselectivity in asymmetric cascade reactions.

Heterogeneous organo/metal cooperative catalysis: One-pot immobilization of Pd(PPh3)4 and chiral phosphoric acid to hollow mesoporous polystyrene nanospheres for efficient asymmetric α-allylation of aldehydes

The widely used combinations of palladium catalysts and chiral phosphoric acids face with the problems of cooperative catalysis and low-cost immobilization of binary catalysts in heterogeneous catalysis, due to the significant decline in the freedom of anchored catalysts. In this paper, the one-pot immobilization of both chiral phosphoric acid (TRIP) and Pd(PPh3)4 to hollow mesoporous polystyrene nanospheres (HMPNs) via Friedel-Crafts alkylation is developed to fabricate HMPNs-supported dual organo/metal catalysts (Pd(PPh3)4#TRIP@HMPNs) at a low cost. The efficient cooperative catalysis of anchored TRIP and Pd(PPh3)4 with good to excellent yields (8993 %) and enantioselectivities (8087 % ee) is achieved in the direct asymmetric α-allylation of aldehydes with allylic alcohols. The higher molar ratio of TRIP to Pd(PPh3)4 and a lower crosslinking degree of HMPNs are beneficial to the cooperative catalysis of the anchored catalysts. Overall, this paper showcases a success in solving the key problems in heterogeneous asymmetric metal/oragano catalysis.

Glutathione-responsive abamectin-loaded hollow mesoporous organosilicon nanospheres for their intelligent controlled release

The development of stimulus-responsive controlled-release formulation is an ideal selection to enhance the effective utilization and minimize the excessive use of pesticides in agriculture. In this work, a glutathione-responsive pesticide delivery systems using hollow mesoporous organosilicon nanospheres fortified with thioether-bonded shell (HMS-ss) as carriers were developed for controlling abamectin release. The results demonstrated the loading capacity of abamectin@HMS-ss for abamectin was approximately 11.65% and the HMS-ss could protected the abamectin effectively from UV-induced degradation. The cumulative release rate of abamectin from abamectin@HMS-ss reached 84% with the addition of glutathione (96 h), which indicated that the disulfide-bridged structure of nanoparticles could be decomposed and consequently release of the abamectin on demand when nanoparticles were metabolized by glutathione. Furthermore, the survival rate of aphid with treatment of abamectin@HMS-ss treatment (50 mg L−1) was about 21.67%, which is lower than that of abamectin suspension. The bioactivity survey confirmed that abamectin@HMS-ss had a longer duration in controlling aphid compared to abamectin suspension. In consideration of the superior insecticidal activity and simplicity of preparation, this target-specific pesticide release system has promising potential in pest management.

One-step synthesis of hollow and yolk-shell mesoporous organosilica nanospheres for efficient separation of lead ions

In this work, we demonstrate that monodispersed hollow mesoporous organosilica nanospheres (MONs) and yolk-shell MONs possessing controlled core cavity and mesoporous shell is successfully synthesized through a one-pot approach, which involves co-condensation of 3-aminopropyltriethoxysilane and 1,2-bis(triethoxysilyl)ethane templated by lauryl sulfonate betaine and sodium dodecyl benzenesulfonate. The MONs present an open mesoporosity, hollow cavity with a morphology tailored by the various core templates, and high surface area (328 m2/g). In addition, the composition of the hollow MONs could be further tuned through the same approach. The as-prepared hollow MONs as adsorbent deliver an enormous adsorption capacity (414 mg/g) towards the removal of Pb2+ from water solution. Importantly, the prepared hollow MONs present acceptable recycling and stability, since the performance in Pb2+ removal from water remains above 80 % even after 5 consecutive cycles. The adsorption of Pb2+ on hollow MONs follows the pseudo-second-order mechanics and Langmuir isotherm models. The results confirm hollow MONs exhibit considerable promise for the remarkably efficient separation of Pb2+ ions in water solution.

Cooperative regulation of hard template and emulsion self-assembly to the synthesis of N/O co-doped mesoporous hollow carbon nanospheres for supercapacitors

Hollow carbon nanospheres have attracted more and more attention as supercapacitor materials due to their excellent electrical conductivity, high theoretical surface area, high accumulation and rapid ion transfer and diffusion. In this work, we employed the Stöber method to create silica as a template, and then applied self-assembly and dopamine polymerization on the surface of the template to form SiO2@TMB-F127-PDA micelles. Then the nitrogen-doped mesoporous hollow carbon nanospheres (N-MHCNs) were prepared by carbonization and etching on the formed carbon precursors. The effect of dopamine amount on the structure and properties of N-MHCNs was systematically studied. Microstructural characterization results reveal that the morphology of N-MHCNs can be changed from sheet to sphere, and the particle size of N-MHCNs can be 33.8–225.7 nm, the specific surface area is distributed in the range of 175.9–430.1 m2 g−1. Due to the N,O heteroatomic co-doping and Porous spherical structure (with a small particle size of 33 nm, and a large specific surface area of 430.1 m2 g−1), typical sample N-MHCNS-2 shows excellent electrochemical performance in supercapacitors. And it has the highest specific capacitance (241 F g−1) at 0.5 A g−1 current density, excellent rate performance (capacity retention rate of 79 % when current density increases from 0.5 to 10 A g−1) and good cycling ability (capacity retention rate of 90.4 % after 3000 cycles), indicating that it shows great potential in energy storage. This approach provides new opportunities for the controllable synthesis of hollow mesoporous nanospheres and it can be extended to other systems such as hollow metals, metal oxide nanomaterials and carbon-based hybrids.

Construction of hollow mesoporous zirconia nanospheres with controllable particle size: Synthesis, characterization and adsorption performance

Organic dyes are difficult to remove effectively in water because of their stable physical and chemical properties. In this study, hollow mesoporous zirconia nanospheres with controllable particle sizes were successfully prepared by in-situ deposition of Zr(OH)4 on the surface of SiO2. The adsorption performance for malachite green (MG) and methylene blue (MB) were tasted. The adsorption removal rates for MG and MB could reach as high as 99 % and 98 %, respectively. The adsorption process could be explained by pseudo-second-order kinetic model and Langmuir isotherm model, and the maximum adsorption capacities for MG and MB were calculated by Langmuir model as 1354.24 and 24.63 mg/g, respectively. Thermodynamic study indicated that the adsorption process of MG and MB were spontaneous endothermic and spontaneous exothermic, respectively. The adsorption mechanism of hollow zirconia nanospheres for MG and MB mainly includes electrostatic interaction, hydrogen bonding and π-π interaction. The results of co-existence ions study demonstrated that the presence of Mg2+ and Ca2+ obviously reduced the removal rates of MB. Desorption-regeneration study showed that the adsorbents can be used for multiple cycles.

Direct covalent immobilizaion of chiral phosphine oxide: Hollow mesoporous polystyrene nanospheres as a platform for efficient heterogeneous enantioselective reductive aldol reaction

The heterogeneous catalysis of expensive chiral phosphine oxides suffers from multi-step tedious immobilization and limited mass transfer due to its bulky volume. In this paper, a simple and direct strategy for covalently anchoring (S)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl dioxide (BINAPO) to hollow mesoporous polystyrene nanospheres (HMPNs) is developed to fabricate HMPNs-supported BINAPO (HMPNs@BINAPO) via one-pot Friedel-Crafts alkylation. HMPNs@BINAPO possesses a nanoscale and spherical morphology with a thin and mesoporous shell suitable for fast mass transfer of reactants and products. In the asymmetric reductive aldol reaction of α, β-unsaturated ketones and benzaldehydes with HSiCl3, HMPNs@BINAPO shows the comparable good to excellent catalytic performances to homogeneous BINAPO and good reusability without an obvious decrease in diastereoselectivity and enantioselectivity.

Mass transfer-based heterogeneous photocatalysis: Hollow porous polystyrene nanospheres as a platform for efficient energy transport of iridium (III) complex

Heterogeneous photocatalysis of iridium (III) complexes faces two major bottle-necks: limited mass/energy transfer and tedious immobilization. In this work, fac-Ir(ppy)3 is directly anchored to hollow mesoporous polystyrene nanospheres (HMPNs) via one-pot F-C alkylation, achieving the covalent immobilization of fac-Ir(ppy)3 at a low-cost. The thin shell, pores, hollow interior, and swelling property of HMPNs enable reactants to quickly access to fac-Ir(ppy)3, effectively avoiding energy loss in energy transport from excited fac-Ir(ppy)3* to reactants. The mass transfer of reactants and optical properties of fac-Ir(ppy)3 such as quantum yield, luminescent lifetime and band gap energy closely depend on the cross-linking degree of polystyrene. The anchored fac-Ir(ppy)3 exhibits comparable catalytic activity to homogeneous fac-Ir(ppy)3 in heterogeneous [2 + 2] photodimerization of olefins with a good reusability without a significant decrease in yields over ten recycles. This work develops a strategy for fabricating efficient heterogeneous photocatalysts using available non-conjugated polymer as support based on the concept of fast mass transfer of reactants.

Investigation of hollow mesoporous NiFe2O4 nanospheres fabricated via a template-free solvothermal route as pH-responsive drug delivery system for potential anticancer application

A novel magnetic-targeted pH-responsive intelligent drug carrier based on hollow mesoporous structured NiFe2O4 nanospheres was designed and developed for potential anticancer treatment in the present study. The hollow mesoporous NiFe2O4 nanospheres were fabricated through a template-free solvothermal approach and the possible formation mechanism of this structure was proposed. The products were investigated comprehensively for their morphology, microstructure, composition and magnetic properties using a wide series of characterization methods. The NiFe2O4 nanospheres were demonstrated to possess a well-defined spherical morphology, homogeneous particle size distribution, large hollow cavities and abundant mesopores, unique superparamagnetic behavior, high saturation magnetization as well as good biocompatibility. Due to these desirable physicochemical properties, the hollow mesoporous NiFe2O4 nanospheres were expected to be employed as a potential vehicle for loading and delivering anticancer drug of doxorubicin hydrochloride (DOX). Drug release behavior was evidenced to be controllable and pH-responsive with effective DOX release of 73.1% and 58.8% in acidic conditions (pH 4.0 and 5.5), whereas insufficient drug release of 44.7% at a neutral atmosphere (pH 7.4) within 48 h. More importantly, the DOX-loaded NiFe2O4 nanospheres displayed significant anti-proliferation and apoptosis effects on human breast cancer cells (MCF-7), which further indicated the promising potential application of constructed drug delivery nanocarriers in the field of cancer therapy.

Morphology controllable fabrication of arch-like covalent triazine framework nanosheets for high-rate and high energy density zinc-ion hybrid supercapacitors

Covalent triazine frameworks (CTFs) are a class of N-rich porous organic polymers with high chemical and thermal stabilities, showing enormous potential in Zn-ion energy storage devices. However, irregular block-shaped morphology of traditional CTFs hinders ion transport and electron transfer in frameworks and thus limits their specific capacity and rate-performance. Here, a morphology controllable fabrication strategy has been developed to prepare CTFs nanosheets using bisnitrile derivative-grafted hollow mesoporous SiO2 nanospheres (HMSN-CN2) as the precursor for the first time. After ZnCl2-mediated cyclotrimerization at the optimal temperature and removing HMSN template, arch-like O-bridged CTF nanosheets (namely, CTFO-NS-700) were successfully obtained. The arch-like 2D nanosheet morphology and hierarchically porous structure with an appropriate mesopore size (2–10 nm) effectively shorten the ion diffusion paths and reduce the ion migration barriers. The CN and COC groups offer abundant active centers for Zn-ion adsorption, which have been verified by ex-situ characterizations and theoretical calculations. As an advanced cathode for zinc-ion hybrid supercapacitors (ZHSCs), CTFO-NS-700 deliver a high capacity of 164.7 mAh/g (296.5F g−1) at current density of 1.0 A/g, superior-rate performance (retain 82.5 mAh/g, 148.5F g−1 at a high current density of 50 A/g), and a high energy density of 162.5 Wh kg−1, as well as long cycling life. In addition, CTFO-NS-700 based flexible ZHSCs also displays satisfactory capacity, excellent flexibility and nice anti-freezing property.

Hollow mesoporous structured MnFe2O4 nanospheres: A biocompatible drug delivery system with pH-responsive release for potential application in cancer treatment

In this paper, a novel pH-responsive drug delivery system based on hierarchical hollow mesoporous MnFe2O4 nanospheres was developed for potential application in cancer treatment. The well-defined hollow mesoporous MnFe2O4 nanospheres were directly fabricated via a facile one-step solvothermal approach without the involvement of additional templates. A mechanism of inside-out Ostwald ripening was suggested to account for the formation of hollow mesoporous nanostructures. The morphology, crystal structure, chemical composition, magnetic properties, thermal stability and mesoporous characteristics of the fabricated MnFe2O4 nanospheres were comprehensively assessed based on various analysis techniques. The resulting hollow mesoporous MnFe2O4 nanospheres with a high biocompatibility were able to be served as a nanocarrier for loading and delivering of anticancer drug doxorubicin (DOX). In vitro drug release study revealed that DOX release from DOX-loaded MnFe2O4 nanospheres was significantly restrained in pH 7.4 phosphate buffer solution (PBS), while it was markedly accelerated in pH 4.5 PBS. The results of cytotoxicity assay and inverted biological microscopy demonstrated that the DOX-loaded MnFe2O4 nanospheres were more cytotoxic against HepG2 cells than MnFe2O4 nanospheres due to the evident inhibition effect of released DOX from the constructed drug delivery system. Therefore, the developed pH-responsive delivery system will have a great potential for its practical application in cancer treatment.

Universal one-pot strategy for fabricating supported chiral organocatalysts via direct covalent immobilization upon hollow mesoporous polystyrene nanospheres

Heterogeneous asymmetric organocatalysis is severely limited by two problems: mult-step energy- and time-consuming covalent immobilization of expensive organocatalysts and difficulty in controlling the morphology and porous structure of supported organocatalysts. Herein, a universal strategy is presented for the direct covalent immobilization of structurally different chiral organocatalysts upon hollow mesoporous organic polystyrene nanospheres (HMOPNs) via a one-pot tandem reaction. Owing to the steric confinement and fast mass transfer originating from their hollow interior, thin shell thickness and abundant mesopores, these supported chiral organocatalysts show excellent catalytic performances in the stereo-controlled steps of the synthesis of natural products and pharmaceuticals in good to high yields (76–96%) with excellent enantioselectivities (93–99% ee). This one-pot immobiliza- tion strategy paves a universal way for direct covalent immobilization of chiral organocatalysts bearing phenyl/aryl moiety to fabricate supported chiral organocatalysts with good long-term performances, achieving the low-cost production of chiral molecules.

Dual nanoenzymes loaded hollow mesoporous organotantalum nanospheres for chemo-radio sensitization.

Chemo-radiotherapy has been extensively used in clinics, displaying substantial advantages in treatment and prognosis. Stimuli-responsive biodegradable nanoagents that can achieve not only delivery and controlled release of chemotherapeutics, but also hypoxia alleviation to enhance chemoradiotherapy therefore has tremendous potential. Herein, glutathione (GSH)-responsive, biodegradable, doxorubicin-carrying hollow mesoporous organotantalum nanospheres modified with Au and Pt dual nanoenzymes (HMOTP@Pt@Au@Dox) were constructed for chemo-radio sensitization. Degradation of HMOTP@Pt@Au@Dox can be self-activated through GSH stimulation and on-demand release packaged Dox owing to the disulfide bond in the hybrid framework of organotantalum nanospheres. Au and Pt nanoenzymes triggered cascade catalytic reactions that could alleviate hypoxia by utilizing β-d-glucose and H2O2, thereby sensitizing ROS-based chemoradiotherapy with synergistic starving therapy. Given the radiosensitization of high-Z elements (Ta, Pt, Au), nanoenzymes induced cascade catalytic reaction for hypoxia relief, and the depletion of the predominant antioxidant GSH, desirable tumor suppression could be achieved both in vitro and in vivo, indicating that HMOTP@Pt@Au@Dox is a promising nanoagent to boost chemo-radiotherapy.

Synthesis of Dual-Response MnO2 Nanospheres as Multifunctional Drug Carriers

Recently, hollow structures have attracted much attention due to their high specific surface area, clear interior space, low density and good permeability. Among them, manganese dioxide (MnO2) hollow structure has also been widely studied for catalysis, drug delivery and energy storage. Based on the characteristics of low pH and high GSH concentration in tumor microenvironment, it is possible to develop an intelligent drug delivery system with pH/GSH response based on hollow mesoporous MnO2 nanospheres. In addition, the excellent physical and chemical properties of MnO2 nanomaterials provide conditions for its synergistic photothermal therapy. For example, Mn2+ released after manganese dioxide reacts with GSH can enhance T1-MAGNETIC resonance (MR) imaging. Meanwhile, manganese dioxide can also react with H2O2 in tumor microenvironment to release oxygen and alleviate tumor hypoxia. In order to prevent drug loss during delivery, a GSH-responsive hollow mesoporous manganese dioxide microsphere was selected as the drug carrier in this paper, and a series of studies were carried out on the performance of the carrier. Hollow mesoporous MnO2 nanospheres with particle size below 100 nm were prepared by hydrothermal method, and their response to tumor microenvironment was simulated in vitro. It has been proved that hollow mesoporous MnO2 nanospheres can be desorbed at low pH and GSH response, and can be used to deliver drugs or photothermal agents, as well as for collaborative cancer imaging and treatment.

Mesoporous hollow nanospheres with amino groups for reverse osmosis membranes with enhanced permeability

Aiming at enhancing the permeability of reverse osmosis (RO) membranes, polyaniline-co-polypyrrole hollow mesoporous nanospheres (PPHMNs) were synthesized with aniline and pyrrole monomers via a simple and rapid one-step method, and then added to the aqueous phase of interfacial polymerization to fabricate thin-film nanocomposite (TFN) membranes. Hollow cores of the PPHMNs embedded in polyamide layers could reduce the interior transfer resistance of the membrane and shorten the transmission pathway of water molecules. Mesoporous shell of PPHMNs provided more channels for rapid transmission of water molecules. Moreover, amino groups in PPHMNs originated from the monomer of aniline could not only be bonded to polyamide (PA) layer by reacting with acyl chloride groups to prevent the leakage but also improve hydrophilicity of the membrane. Water flux of TFN membrane doped with PPHMNs (TFN-Ps) of 0.005 wt% addition concentration was 34.1 L·m−2·h−1 which is 76.7% higher than that of thin-film composite (TFC) membrane, and the NaCl rejection all kept over 99.0%. The TFN-Ps also showed excellent long-term stability, chlorine resistance and anti-fouling performance. This work opens an avenue for application of mesoporous hollow nanospheres with amino groups synthesized by simple and time-saving methods in developing TFN membranes with improved water flux.

A “Closed‐Loop” Therapeutic Strategy Based on Mutually Reinforced Ferroptosis and Immunotherapy

AbstractThe immunosuppression and immune escape of current immunotherapy result in low efficacy, and ferroptosis is greatly restricted by the low reactive oxygen species (ROS) production efficiency. Here, for the first time a “closed‐loop” therapy based on photothermal enhancement of ferroptosis and immunotherapy stimulated by each other on a multifunctional nanoplatform is reported. This platform is composed of copper silicate and iron silicate mesoporous hollow nanospheres, followed by in situ growth of Au nanoparticles and loading of an immune adjuvant resiquimod R848. The laser irradiation‐mediated heat and the introduction of copper ions significantly enhance ROS generation, leading to the simultaneous depletion of glutathione peroxidase 4 (GPX4) and glutathione (GSH). The onset of ferroptosis in tumor cells is thus enhanced and an immune response with immunogenic cell death (ICD) is triggered, promoting the dendritic cells (DCs) maturation and T cell infiltration. Interferon γ (IFN‐γ) released from CD8+ T cells downregulates the expression of SLC7A11 and GPX4, which in turn enhances ferroptosis expression, thus constituting a “closed‐Loop” therapy. Importantly, this system is effective in both killing the primary tumor and inhibiting tumor metastasis. The proposed “closed‐loop” therapeutic strategy may provide a guidance for the design of future antitumor nanoplatforms.

A light-activated TiO2@In2Se3@Ag3PO4 cathode for high-performance Zn-Air batteries

Zn-air batteries (ZABs) require a small discharging voltage and large charging voltage. In this work, mesoporous hollow nanospheres of titanium dioxide@indium selenide@silver phosphate (TiO2@In2Se3@Ag3PO4) are designed and synthesized. The three-layer structure consists of TiO2 as the inner layer, In2Se3 as the middle layer, and Ag3PO4 as the outer layer. When TiO2@In2Se3@Ag3PO4 is irradiated with light, In2Se3 serves as the sensitizer to enhance light absorption and in the three-layer architecture, the photogenerated electrons and holes migrate in opposite direction in the near surface to minimize recombination. Hence, the three monomeric materials produce synergistic effects upon light illumination. The excited electrons are mainly concentrated in the conduction band (CB) of In2Se3 to promote the oxygen reduction reaction (ORR) and also increase the output voltage during discharging. On the other hand, holes are primarily concentrated in the valence band (VB) of Ag3PO4 to promote the oxygen evolution reaction (OER) and decrease the input voltage during charging. During light illumination, the discharging and charging voltages of the ZABs are 1.82 V and 0.64 V, respectively. The novel materials design reveals an effective strategy to harvest photo energy for electrochemical storage devices.

Constructing zigzag-like hollow mesoporous nanospheres MoO2/C with superior lithium storage performance

Hollow mesoporous nanospheres MoO2/C are successfully constructed through metal chelating reaction between molybdenum acetylacetone and glycerol as well as the Kirkendall effect induced by diammonium hydrogen phosphate. MoO2 nanoparticles coupled by amorphous carbon are assembled to unique zigzag-like hollow mesoporous nanosphere with large specific surface area of 147.7 m2 g−1 and main pore size of 8.7 nm. The content of carbon is 9.1%. As anode material for lithium-ion batteries, the composite shows high specific capacity and excellent cycling performance. At 0.2 A g−1, average discharge capacity stabilizes at 1092 mAh g−1. At 1 A g−1 after 700 cycles, the discharge capacity still reaches 512 mAh g−1. Impressively, the composite preserves intact after 700 cycles. Even at 5 A g−1, the discharge capacity can reach 321 mAh g−1, exhibiting superior rate capability. Various kinetics analyses demonstrate that in electrochemical reaction, the proportion of the surface capacitive effect is higher, and the composite has relatively high diffusion coefficient of Li ions and fast faradic reaction kinetics. Excellent lithium storge performance is attributed to the synergistic effect of zigzag-like hollow mesoporous nanosphere and amorphous carbon, which improves reaction kinetics, structure stability and electronic conductivity of MoO2. The present work provides a new useful structure design strategy for advanced energy storage application of MoO2.

Facile fabrication of hollow mesoporous bioactive glass spheres: From structural behaviour to in vitro biology evaluation

Bone defects accompanied by infection or inflammation can significantly delay the healing process. To simultaneously achieve controlled release of local antibiotics for infection control and bone healing, bone-implantable delivery systems have been considered as a promising strategy. This study aims to improve drug loading capacity of bone-implantable delivery systems by introducing hollow structure mesoporous bioactive glass nanospheres (HMBGs) through a sol–gel process. Particularly, such core–shell bimodal-porous structured nanoparticles were prepared through a sacrificing template using cetyltrimethylammonium bromide (CTAB) as surfactant. It was found that varying the amount of CTAB during the synthesis process is a simple and effective approach for tuning the particle size, morphology, and structure of HMBGs. For in vitro drug release, HMBGs could sustain storage and release of vancomycin hydrochloride (VAN) via diffusion-controlled mechanism, thereby inhibiting the bacteria growth in the subsequent bacterial study. Moreover, HMBGs incorporated with VAN provided a biomimetic microenvironment favored by cell adhesion and proliferation. These findings support the compatibility of HMBG nanoparticles with antibiotics and their potential application in the treatment of infectious bone defects.

Template-free construction of hollow mesoporous Fe3O4 nanospheres as controlled drug delivery with enhanced drug loading capacity

Monodisperse hollow mesoporous Fe3O4 nanospheres have been successfully synthesized via a template-free one-pot solvothermal method under the existence of iron chloride hexahydrate, polyvinylpyrrolidone and urea. A proposed gas-bubble-assisted Ostwald ripening mechanism was allowed to explain the possible fabrication of hollow nanostructures. The formed Fe3O4 nanospheres possessed a narrow particle size distribution with a average hydrodynamic diameter of 392 nm, superparamagnetic characteristics with high saturation magnetization of 74.9 emu/g, as well as the typical mesoporous structures with specific surface area of 27.3 m2/g. Furthermore, it was found that the bare hollow mesoporous Fe3O4 nanospheres showed an insignificant cytotoxicity, but exhibited obvious cytotoxic effects towards HeLa cells after being loaded with the anti-cancer drug of DOX, which could be recommended as a promising and effective drug delivery system with high drug loading capacity and pH-responsive feature. The determined maximum drug loading capacity of DOX on this kind of hollow mesoporous Fe3O4 nanospheres was as high as 0.36 ± 0.04 g/g, which can store and deliver effectively the anticancer drugs to induce death of cancer cells.