Mesoporous Shell Research Articles

Mesoporous silica particles by aerosol spray synthesis; solid core and porous shell structure study

Mesoporous silica core shell particles are materials of high interest especially due to pharmaceutical and catalytic applications. In the current work we presented the synthesis of uniformly porous and solid core porous particles by aerosol spray pyrolysis route according to the principles of EISA, by a one step process. The particles are evaluated morphologically by TEM and by nitrogen adsorption and desorption isotherms for pore size distribution and pore connectivity, validating the effect of synthesis parameters on the core size, surface area and porosity of the uniformly porous and core-shell structures. Three different surfactants Brij-58, CTAB, P123 at various concentrations and combinations as well as three different core type compositions of NaCl, CeO2 and, Ce0.8Zr0.2O2 have been evaluated for the controlled synthesis of silica core-shell particles by a scalable synthesis method.

Osteopontin targeted non-invasive nanoprobes with amplified surface plasmon resonance for photothermally enhanced multimodal precision imaging of vulnerable atherosclerotic plaques

Effective strategies for accurate differentiation of the vulnerable atherosclerosis (AS) plaques at molecular level for clinical diagnosis have yet been developed. Herein, a versatile SAmOCP nanoprobe, is constructed by sealing up the multinuclear gold self-assembled nanospheres by hollow mesoporous silicon shell and then decorating the surfaces with Chlorine e6 (Ce6)-conjugated osteopontin antibody (OPN Ab), followed by filling the internal cavity with perfluoropentane (PFP) for precise in vivo targeting and multi-modal imaging of the vulnerable AS plaques. SAmOCP nanoprobes actively recognize the foam cells and specifically target the vulnerable AS plaques in vivo. Relying on the exceptional photo-to-heat conversion properties resulting from enhanced localized surface plasmon resonance (LSPR) effects of Au self-assembled particles, the encapsulated liquid PFP could transform into abundant microbubbles when AS plaque-rich regions were overheated by 808-nm laser irradiation, enabling hyperthermia-enhanced microbubbles generation, thereby endowing nanoprobes with significantly enhanced ultrasonic imaging capacity. SAmOCP nanoprobes exhibit a triple-modality diagnostic efficacy of ultrasound/fluorescence/photothermal imaging for in vivo precise detection of vulnerable AS plaques at molecular level. Together, SAmOCP nanoprobes overcome the difficulty in identifying the vulnerable AS plaque for clinic practice, holding great promise for vulnerable AS diagnosis.

Al-Doped Core-Shell-Structured Ni@Mesoporous Silica for Highly Selective Hydrodeoxygenation of Lignin-Derived Aldehydes.

Selective deoxygenation of chemicals using non-noble metal-based catalysts poses a significant challenge toward upgrading biomass-derived oxygenates into advanced fuels and fine chemicals. Herein, we report a bifunctional core-shell catalyst (Ni@Al3-mSiO2) consisting of Ni nanoparticles closely encapsulated by the Al-doped mesoporous silica shell that achieves 100% vanillin conversion and >99% yield of 2-methoxy-4-methylphenol under 1 MPa H2 at 130 °C in water. Due to the unique mesoporous core-shell structure, no significant decrease in catalytic activity was observed after 10 recycles. Furthermore, incorporating Al atoms into the silica shell significantly increased the number of acidic sites. Density functional theory calculations reveal the reaction pathway of the vanillin hydrodeoxygenation process and uncover the intrinsic influence of the Al sites. This work not only provides an efficient and cost-effective bifunctional hydrodeoxygenation catalyst but also offers a new synthetic protocol to rationally design promising non-noble metal catalysts for biomass valorization or other widespread applications.

Synthesis of Methotrexate-Loaded Dumbbell-Shaped Titanium Dioxide/Gold Nanorods Coated with Mesoporous Silica and Decorated with Upconversion Nanoparticles for Near-Infrared-Driven Trimodal Cancer Treatment.

This study prepared dumbbell-shaped titanium dioxide (TiO2)/gold nanorods (AuNRs) coated with mesoporous silica shells (mS) (AuNRs-TiO2@mS). Methotrexate (MTX) was further loaded into the AuNRs-TiO2@mS, and then upconversion nanoparticles (UCNPs) were decorated to form AuNRs-TiO2@mS-MTX: UCNP nanocomposites. TiO2 is used as an intense photosensitizer (PS) to produce cytotoxic reactive oxygen species (ROS), leading to photodynamic therapy (PDT). Concurrently, AuNRs exhibited intense photothermal therapy (PTT) effects and photothermal conversion efficiency. In vitro results suggested that these nanocomposites can kill oral cancer cells (HSC-3) without toxicity through irradiation of NIR laser, owing to the synergistic effect. The in vivo studies indicated that these nanocomposites exhibited excellent antitumor effects through synergistic PDT/PTT/chemotherapy under a near-infrared (NIR) 808 nm laser irradiation. Thus, these AuNRs-TiO2@mS: UCNP nanocomposites have great potential to undergo deep tissue penetration with enhanced synergistic effects through NIR-triggered light for cancer treatment.

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.

Engineering a Hollow Carbon Sphere-Based Triphase Microenvironment for Enhanced Enzymatic Reaction Kinetics and Bioassay Performance.

Electrochemical bioassays based on oxidase reactions are frequently used in biological sciences and medical industries. However, the enzymatic reaction kinetics are severely restricted by the poor solubility and slow diffusion rate of oxygen in conventional solid-liquid diphase reaction systems, which inevitably compromises the detection accuracy, linearity, and reliability of the oxidase-based bioassay. Herein, an effective solid-liquid-air triphase bioassay system is provided that uses hydrophobic hollow carbon spheres (HCSs) as oxygen nanocarriers. The oxygen stored in the cavity of HCS can rapidly diffuse to the oxidase active sites through the mesoporous carbon shell, providing sufficient oxygen for oxidase-based enzymatic reactions. As a result, the triphase system can significantly improve the enzymatic reaction kinetics and obtain a 20-fold higher linear detection range than the normal diphase system. Other biomolecules can also be determined using this triphase technique, and the triphase design strategy offers a new route to address the gas deficiency problem in catalytic reactions that involve gas consumption.

Monitoring silica core@shell nanoparticle-bacterial film interactions using the multi-parametric surface plasmon resonance technique.

In a healthcare setting, biofilms are a major source of infection and difficult to eradicate once formed. Nanoparticles (NPs) can be designed to effectively penetrate biofilms to more efficiently either deliver antibiotic drugs throughout the biofilm matrix or elicit inherent antibiofilm activity. Antibacterial cerium oxide (CeO2) NPs were employed as core material and coated with a mesoporous silica shell (MSN) to generate cerium oxide coated mesoporous silica NPs (CeO2@MSN). Detailed studies of NP-biofilm interactions are required to rationally develop NP platforms to prevent biofilm-related infections. This work developed and implemented a unique label-free analysis platform for the real-time monitoring of bacterial biofilm formation and then assessed the interactions of antibacterial NPs. An analysis platform which allows bacterial biofilms to grow and develop in situ in flow within the multi-parametric surface plasmon resonance (MP-SPR) instrument was established. This enabled simultaneous monitoring and detection of biofilm growth phases, structure, and interactions between differentially charged CeO2@MSNs and bacterial biofilms. Positively charged antibacterial NPs (polyethyleneimine functionalized CeO2@MSNs) were found to be the most efficient to penetrate the biofilm. The MP-SPR analysis platform was shown to be a powerful tool for monitoring biofilm development in real-time and to analyze biofilm properties and NP-biofilm interactions.

Fe3O4@C@MCM41-guanidine core–shell nanostructures as a powerful and recyclable nanocatalyst with high performance for synthesis of Knoevenagel reaction

In this study, preparation, characterization and catalytic application of a novel core–shell structured magnetic with carbon and mesoporous silica shells supported guanidine (Fe3O4@C@MCM41-guanidine) are developed. The Fe3O4@C@MCM41-guanidine was prepared via surfactant directed hydrolysis and condensation of tetraethyl orthosilicate around Fe3O4@C NPs followed by treatment with guanidinium chloride. This nanocomposite was characterized by using Fourier transform infrared spectroscopy, vibrating sample magnetometry, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, thermal gravimetric analysis, wide-angle X-ray diffraction and low-angle X-ray diffraction techniques. This nanocomposite have high thermal, chemical stability, and uniform size. Fe3O4@C@MCM41-guanidine catalyst demonstrated high yield (91–98%) to prepare of Knoevenagel derivatives under the solvent free conditions at room temperature in the shortest time. Also, this catalyst was recovered and reused 10 times without significant decrease in efficiency and stability. Fortunately, an excellent level of yield (98–82%) was observed in the 10 consecutive catalyst cycles.

Rational construction of magnetic core-shell structural carbon Nanotubes@Mesoporous N-doped carbon nanofibers for efficient microwave absorption

Magnetic core-shell structural mesoporous carbon materials have an extensive application prospect in microwave absorption because of their comprehensive merits of magnetic function and distinctive mesoporous structure. Herein, magnetic core-shell structural carbon nanotubes@mesoporous N-doped carbon (CoNi/CNTs@mesoNC) nanofibers are successfully fabricated by combining homogeneous coating of mesoporous polydopamine, surface deposition of CoNi-bimetal metal-organic frameworks (MOFs), and in-situ growth of CNTs and CoNi nanoparticles. The resultant CoNi/CNTs@mesoNC nanofibers possess a well-defined hierarchical structure consisting of CNTs core and mesoporous carbon shell distributed with short CNTs and CoNi nanoparticles, high surface area (∼316 m2 g−1), high nitrogen content (∼5.5 wt%), and large pore size (∼10 nm). As expected, the rational design of multifunctional components and hierarchical structure endows CoNi/CNTs@mesoNC composites with excellent microwave absorption performance. Particularly, the minimum reflection loss can reach −52.1 dB at 13.4 GHz with only 1.7 mm thickness and the corresponding effective absorption bandwidth is up to 5.2 GHz (12.8–18.0 GHz), outperforming most reported microwave absorbing materials. The microwave absorption mechanism of this material has been deeply investigated and systematically clarified. This work provides meaningful reference for the design and fabrication of functional core-shell microwave absorbers with distinctive mesoporous structure.

Construction of Core-shell Sb2 s3 @Cds Nanorod with Enhanced Heterointerface Interaction for Chromium-Containing Wastewater Treatment.

How to collaboratively reduce Cr(VI) and break Cr(III) complexes is a technical challenge to solve chromium-containing wastewater (CCW) pollution. Solar photovoltaic (SPV) technology based on semiconductor materials is a potential strategy to solve this issue. Sb2 S3 is a typical semiconductor material with total visible-light harvesting capacity, but its large-sized structure highly aggravates disordered photoexciton migration, accelerating the recombination kinetics and resulting low-efficient photon utilization. Herein, the uniform mesoporous CdS shell is in situ formed on the surface of Sb2 S3 nanorods (NRs) to construct the core-shell Sb2 S3 @CdS heterojunction with high BET surface area and excellent near-infrared light harvesting capacity via a surface cationic displacement strategy, and density functional theory thermodynamically explains the breaking of SbS bonds and formation of CdS bonds according to the bond energy calculation. The SbSCd bonding interaction and van der Waals force significantly enhance the stability and synergy of Sb2 S3 /CdS heterointerface throughout the entire surface of Sb2 S3 NRs, promoting the Sb2 S3 -to-CdS electron transfer due to the formation of built-in electric field. Therefore, the optimized Sb2 S3 @CdS catalyst achieves highly enhanced simulated sunlight-driven Cr(VI) reduction (0.154 min-1 ) and decomplexation of complexed Cr(III) in weakly acidic condition, resulting effective CCW treatment under co-action of photoexcited electrons and active radicals. This study provides a high-performance heterostructured catalyst for effective CCW treatment by SPV technology.

Carboxymethyl β-cyclodextrin grafted hollow copper sulfide@mesoporous silica carriers for stimuli-responsive pesticide delivery

Stimuli-responsive controlled release systems have received extensive attention to improve the pesticide bioavailability and minimize environmental pollution. Herein, a multiple stimuli-responsive IMI@HCuS@mSiO2 @ -ss-CβCD delivery system was constructed using modified carboxymethyl β-cyclodextrin (CβCD-ss-COOH) as sealing materials, hollow copper sulfide nanoparticles with amino-functionalized mesoporous silica shell (HCuS@mSiO2-NH2) as carriers and imidacloprid (IMI) as the model drug. The cavity structure of HCuS@mSiO2-NH2 would provide a large space for pesticide loading. The results revealed that HCuS@mSiO2-ss-CβCD was approximately 230 nm in size and the loading efficiency for IMI was 25.7%, and exhibited better biosafety on bacteria and seed. HCuS carriers were also served as photothermal agent and possessed high photothermal conversion effect (η = 38.4%). IMI@HCuS@mSiO2 @ -ss-CβCD displayed excellent foliage adhesion and multiple stimuli-responsive release properties to pH, α-amylase, GSH, and NIR. The photostability of IMI embedded in CuS@mSiO2 @ -ss-CβCD was approximately 10 times that of IMI solution. This work provides an efficient nanoplatform for realizing pesticide delivery.

Enhanced ferroptosis therapy with a “nano-destructor” by disrupting intracellular redox and iron homeostasis

Ferroptosis is an iron-dependent form of cell death that is also a promising tumor therapeutic modality, however, maintaining redox and iron homeostasis in tumor cells limits the ferroptosis therapeutic effect. Herein, we constructed a GSH-depleting magnetic nanoplatform (D@MOs-P) for enhanced ferroptosis by disruption of redox homeostasis and ferritinophagy-mediated iron disorders. D@MOs-P was constructed by coating disulfide bonds-bridged mesoporous silica shells on magnetic nanoparticles (MNPs) and loaded with dihydroartemisinin (DHA, ROS precursor drug). Upon endocytosis by tumor cells, disulfide bond-mediated glutathione depletion and glutathione peroxidase 4 (GPX4) inactivation will synergize with DHA to disrupt intracellular redox homeostasis. On the other hand, the magnetic hyperthermia generated by D@MOs-P will trigger ferritinophagy to achieve tumor iron dyshomeostasis and enhance ferroptosis. Moreover, the released ferrous ions can activate DHA to produce ROS and further disrupt redox homeostasis. Both in vitro and in vivo results demonstrated that D@MOs-P can significant suppression of tumor growth with minimal side effects through the disturbance of dual homeostasis and the intense ferroptosis of tumor cells. Furthermore, MNPs could also provide excellent T2-weighted MR imaging properties. In this work, magnetic hyperthermia was first proven to trigger autophagy-augmented ferroptosis, and the strategies through multi-pathway intracellular homeostasis disruption described in this article can offer an innovative approach in ferroptosis-based antitumor.

Mesoporous silica shell in a core@shell nanocomposite design enables antibacterial action with multiple modes of action

Core@shell structured nanocomposites have received significant attention for their synergistic mode of antibacterial action. Identification of the accommodated unit’s function in the core@shell nanostructure is necessary in order to determine whether antibacterial synergism against bacterial cell growth that is provided within the same core@shell structure. Herein, a novel nanostructure(s) composed of a cerium oxide core and a porous silica shell (CeO2@pSiO2) accomodating curcumin and lectin was prepared, and the antibacterial synergism provided by the nanocomposite was identified. The resulting spherical-shaped CeO2@pSiO2 nanostructure allowed accommodation of curcumin loading (9 w/w%) and a lectin (concanavalin A) coating (15 w/w%). The antibacterial synergism was tested using a minimal inhibitory concentration assay against an Escherichia coli Gram-negative bacterial strain. Furthermore, the mechanisms of bacterial cell disruption induced by the curcumin-loaded and concanavalin A-coated CeO2@pSiO2 core@shell structure, namely the nanoantibiotic (nano-AB) and its design components, were identified. Our findings reveal that the mesoporous silica shell around the CeO2 core within the nano-AB design aids the accommodation of curcumin and concanavalin A and promotes destruction of bacterial cell motility and the permeability of the inner and outer bacterial cell membranes. Our findings strongly indicate the promising potential of a mesoporous silica shell around nanoparticles with a CeO2 core to provide synergistic antibacterial treatment and attack bacterial cells by different mechanisms of action.

Bifunctional MOFs with robust mesoporous armors and superionic conduction

Metal-organic frameworks (MOFs) have raised extensive attention for ionic conduction; however, the inferior ionic conductivity and weak mechanical strength of semi-solid MOF electrolytes have limited their further development. Here, bifunctional MOFs (BF-MOFs) with a yolk-shell structure have been designed to realize superionic conduction and high mechanical stiffness. In the BF-MOFs, the mesoporous shells work as robust armors for suppressing dendrite growth, and simultaneously provide perfect pathways for rapid and uniform ionic transport; the large gaps between the mesoporous shells and the MOF cores can store more Li ions for superionic conduction. In addition, the MOF cores function as ionic rectifiers for uniform Li deposition. As a result, the electrolyte with BF-MOFs delivers a high ionic conductivity of 1.27 × 10-3 S cm−1 at 30 °C and a high Li+ transference number of 0.74. An ultralong life of 4500 cycles with capacity retention of 96.5% is obtained in LiFePO4//Li cells. Furthermore, LiNi0.8Co0.1Mn0.1O2//Li cells are also fabricated, displaying remarkable durability with capacity retention of 92.2% after 800 cycles.

Mesoporous colloidal silica cubes with catalytically active cores

Preparation methods of cubic core-shell particles with specific functionality are limited. Here we demonstrate the possibility to transform cuprous oxide cubes coated with mesoporous silica into functional core-shell particles, while retaining their cubic shape. Cuprous oxide nanocubes are coated with mesoporous silica using cetyltrimethylammonium bromide as a template, after which the cuprous oxide core is transformed using liquid phase calcination and galvanic replacement. Nitrogen physisorption and electron microscopy confirm that mesoporous silica coatings are obtained with tuneable thickness. The successful transformation of cuprous oxide into gold and silver is assessed via UV–VIS spectroscopy and energy dispersive X-ray spectroscopy. Particles with a silver core and a cubic mesoporous silica shell are demonstrated to be catalytically active in the degradation of the dye Congo red.Graphical abstract

Molecular-Weight-Dependent Infiltration and Adsorption of Polymers into Nanochannels.

The mesoporous silica shell coating hydrogenolysis nano-catalysts alters the molecular weight distributions of cleaved polymer chains compared to catalysts without a shell. The shell, composed of radially aligned narrow cylindrical nanopores, reduces the formation of low-valued gaseous products and increases the median molecular weight of the product, thus enhancing the value of the products for polymer upcycling. To understand the role of the mesoporous shell, we have studied the spatial distribution of polystyrene chains, used as a model polymer, in the nanochannels in both the melt phase and solution phase. In the melt, we observed from small-angle X-ray scattering experiments that the infiltration rate of the polymer into the nanochannels is inversely proportional to the molecular weight, which is consistent with theory. In theta solution experiments using UV-vis spectroscopy, we found that the shell significantly enhances polymer adsorption compared to nanoparticles without pores. In addition, the degree of polymer adsorption is not a monotonic function of molecular weight but initially increases with the molecular weight before eventually decreasing. The molecular weight for the peak adsorption increases with the pore diameter. This adsorption behavior is rationalized as resulting from a balance between the mixing entropy gain by surface adsorption and the conformational entropy penalty incurred by chains confined in the nanochannels. The spatial distribution of polymer chains in the nanochannels is visualized by energy-dispersive X-ray spectroscopy (EDX), and inverse Abel-transformed data reveals a less uniform polymer distribution along the primary pore axis for longer chains.

Fischer-Tropsch synthesis: Osmium promoted Co@HCS catalysts

Little attention has been given to the use of osmium as a promoter for Fischer-Tropsch Synthesis (FTS). In previous studies, Os has proven to be a poor FT catalyst, but its use as a catalyst promoter has not been studied. In this study, the synthesis and use of Os nanoparticles supported on/in Co@HCS (HCS = hollow carbon sphere) FT catalysts are reported. The hollow morphology of the HCSs was exploited to study the influence of Os promoter nanoparticle location relative to the Co3O4 nanoparticles (dCo = 3.5–12.5 nm) and on the effect of Os on the reduction behaviour and activity of the Co FT catalyst. Os (0.1, 0.5 and 1 wt%) nanoparticles were loaded both inside and outside the HCSs, while the Co3O4 particles (Co 10 wt%) were loaded inside of the HCSs to give CoOs@HCS and Os/(Co@HCS). Electron microscopy, in situ PXRD, PDF, TGA, BET, and TPR studies revealed that both catalysts were successfully synthesized. The use of ex-situ PXRD, PDF and TPR studies provided information on the Co phases and reduction pathways of the Co3O4 metal catalyst and the spillover effect from Os to Co. Co3O4 and CoO phases were observed for the CoOs@HCS and Os/(Co@HCS) catalysts. More interesting was the observation of the Co fcc phase in the OsCo@HCS catalysts, indicating the importance of the Os-Co interaction. The catalyst with Co and Os close together (primary spillover process) gave a higher Fischer-Tropsch activity (38.5–46.4 × 10−6 molCO/gCo.s) and higher C5+ production than both the unpromoted catalyst (27.8 × 10−6 molCO/gCo.s), and the catalysts where Os and Co were separated (25.1–36.4 × 10−6 molCO/gCo.s) by the mesoporous carbon shell (secondary spillover effect). The studies on both CoOs@HCS and Co/(Os@HCS) catalysts have indicated for the first time the effect of Os on Co catalysts, with particular reference to FTS.

Green water-etching synthesized La-MIL-101(Fe)-NH2@SiO2 yolk-shell nanocomposites with superior pH stability for efficient and selective phosphorus recovery

Although MIL-101(Fe) has a homogeneous distribution of active metal sites, the relatively low stability of its coordination bonds limits its potential for application, especially in harsh environments. Here, a novel lanthanum-doped MIL-101(Fe)-NH2@mesoporous SiO2 yolk-shell (LMFN-YS) material, synthesized by green water-etching, has effectively improved the adsorption capacity and stability of MIL-101(Fe)-NH2. Compared to traditional acid-base etching methods, water etching offered a more co-friendly and cost-effective approach to producing yolk-shell structures. Due to the mesoporous protective shell of mesoporous SiO2 and more exposed active sites, the yolk-shell materials showed a faster adsorption rate (30 min) and a larger uptake capacity (240.0 mg P/g) than those of MIL-101. The material also exhibited broad range of pH stability from 2 to 10 and displayed good cyclic regeneration ability, with a removal efficiency of 75.9 % after three cycles. Additionally, it demonstrated excellent selectivity towards various coexisting anions such as Cl−, NO3−, SO42−, CO32− and HCO3− at diverse ionic strengths ranging from 0.001 to 1 M. The superior performance of L1MFN-YS (yolk-shell materials of La: Fe = 1:1) was attributed to a combination of factors, including ligand exchange between La(Fe)-OH and phosphates, Lewis acid-base interaction and electrostatic attraction. Additionally, high phosphate removal performance was observed in the real petrochemical wastewater (initial concentrations of 5.48 mg P/g) with a residual effluent concentration of 0.05 mg P/L, which was below the A-level standard of phosphate effluent in China (0.5 mg/L). This work provides a green method for preparing yolk-shell materials with improved ability to treat phosphate wastewater.

Development of self-healing sol-gel anticorrosion coating with pH-responsive 1H-benzotriazole-inbuilt zeolitic imidazolate framework decorated with silica shell

Zeolitic imidazolate framework-8 (ZIF-8)-based pH-responsive nanocontainers present a new pathway to endowing sol-gel anticorrosion coatings with self-healing ability. The organic nature of the ZIF-8-based nanocontainers, however, makes them less compatible with the inorganic sol-gel coating matrix, thus ineffective in protection against corrosion. In this paper, a novel pH-responsive corrosion inhibitor release system (BTA-ZIF-8@SiO2) based on ZIF-8 for self-healing sol-gel anticorrosion coating was reported. A facile one-step self-assembly procedure was used to create the 1H-benzotriazole (BTA)-encapsulated ZIF-8 core, on which a layer of silica was subsequently coated using a standard sol-gel method. The silica shell can provide better compatibility of the nanocontainers with the sol-gel matrix, thus improving the overall corrosion protection. Characterizations of the BTA-ZIF-8@SiO2 nanocontainers via X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer−Emmett−Teller, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy confirmed the successful synthesis of ZIF-8-based nanocontainers with high loading content of BTA and mesoporous SiO2 shell. Inhibitor release studies revealed the pH-responsive smart release of inbuilt BTA at both acidic and alkaline media. The anticorrosion performance of sol-gel coating incorporating the nanocontainers was investigated by electrochemical impedance spectroscopy, scanning Kelvin probe, and salt spray test, and the results indicated that BTA-ZIF-8@SiO2 could effectively enhance the corrosion protection properties of the coating and exhibit excellent self-healing performance, in which the |Z|0.01Hz was >2 orders of magnitude higher and coating resistance and oxide layer resistance were >3 orders of magnitude higher than these of pure sol-gel coating after 28 d of immersion. This could be attributed to the synergistic effect of enhanced passive protection, improved nanocontainer compatibility with the sol-gel matrix, and corrosion inhibitor film formed on metal surface.

Wnt3a Loaded Hydroxyapatite Nanowire@Mesoporous Silica Core-Shell Nanocomposite Promotes the Regeneration of Dentin-Pulp Complex via Angiogenesis, Oxidative Stress Resistance and Odontogenic Induction of Stem Cells.

Pulp exposure often leads to pulp necrosis, root fractures and ultimate tooth loss. The repair of exposure site with pulp capping treatment is of great significance to preserve pulp vitality, but its efficacy is impaired by the low bioactivity of capping materials and cell injuries from the local accumulation of oxidative stress. This study develops a Wnt3a loaded hydroxyapatite nanowire@mesoporous silica (Wnt3a-HANW@MpSi) core-shell nanocomposite for the pulp capping treatments. The ultralong and highly flexible hydroxyapatite nanowires provide the framework for the composites, and the mesoporous silica shell endows the composite with the capacity of efficiently loading/releasing Wnt3a and Si ions. Under the in vitro investigation, Wnt3a-HANW@MpSi not only promotes the oxidative stress resistance of dental pulp stem cells (DPSCs), enhances their migration and odontogenic differentiation, but also exhibits superior property of angiogenesis in vitro. Revealed by the transcriptome analysis, the underlying mechanisms of odontogenic enhancement by Wnt3a-HANW@MpSi are closely related to multiple biological processes and signaling pathways toward pulp/dentin regeneration. Besides, an animal model of subcutaneous transplantation demonstrates the significant reinforcement of the formation of dentin-pulp complex-like tissues and blood vessels by Wnt3a-HANW@MpSi in vivo. These results indicate promising potential of Wnt3a-HANW@MpSi in treatments of dental pulp exposure. This article is protected by copyright. All rights reserved.