Latest ArticlesAlthough bone morphogenetic protein (BMP) and WNT signaling play pivotal roles in bone development, homeostasis, and regeneration, the applications of proteins to stimulate corresponding signaling pathways showed limited outcomes in the repair and regeneration of bone defects that might be attributed to the reciprocal interventions of these pathways. In order to satisfy the combinational and sequential activation of BMP and WNT pathways, inspired by the heterogeneous hydrogel-liked structures of Brasenia, heterogeneous alginate/chitosan hydrogels were fabricated and spatially loaded with FK506 and BIO to achieve sustained and sequential release of the activators. Alkaline phosphatase staining, alizarin red staining and qRT-PCR results suggested that FK506 and BIO enhanced osteoblastic differentiation in vitro when used separately. Besides, by mixing and matching the activators and the hydrogel layers, a superior releasing mode that a combination of early FK506 release and following BIO release was identified via both in vitro and in vivo explorations for most efficient bone regeneration. These results suggested that drug-loaded heterogeneous hydrogels possess great potentials in treating bone loss defects for future clinical practice.
Hierarchical NiO nanosheets@nanorods have been rationally designed and constructed for efficient urea electrooxidation in an alkaline solution. The critical synthetic strategy, engaging the one-step anion-competitive reaction, precisely integrates two nickel-based materials into a heterostructure with Ni(OH)2 nanosheets and NiC2O4 nanorods. Benefiting from the hierarchically porous structure and high specific surface area, the NiO NNs can improve the escape efficiency of gas in electrochemical reactions and maintain sustainability. Furthermore, this distinctive structure can expose highly dispersed active sites for enhancing urea molecules' adsorption, surface-dependent redox reactions, and electrical conductivities. As a result, these hierarchical NiO nanosheets@nanorods exhibit superior activity with a low overpotential of 156 mV at 10 mA/cm2, and a slight Tafel slope of 40.7 mV/dec, and high stability with almost no decay of 12,000 s for urea electrooxidation. This work promotes the application of well-designed hierarchical structure in electrooxidizing urea and provides a possibility for highly efficient electrolysis of alkaline urea wastewater.
Co3O4 has been widely explored in electrocatalytic 5-hydroxymethyl-furfural (HMF) oxidation. However, the poor intrinsic ability has seriously limited its electrochemical ability. Heteroatom-doping is an efficient method to enhance the electrocatalytic ability of catalyst by regulating electronic structure. Herein, we have modulated the electronic structure of Co3O4 by high valance Mo6+-doping. With the introduction of Mo6+, the content of Co2+ was increased and metal-oxygen bond was strength. Electrochemical results suggested that the electrocatalytic ability of Co3O4 towards HMF oxidation has been dramatically improved and reaction kinetics has been fasten. Theoretical calculations demonstrated that the surrounding cobalt sites after Mo6+-doping with assembled electron has a strong adsorption ability towards HMF molecule leading to more favourable oxidation of HMF. Post characterizations demonstrated pristine Co3O4 structure was kept after electrolysis cycles and CoOOH active species were formed. This work provides a valuable reference for developing efficient heteroatom-doped electrocatalysts for HMF oxidation.
In this paper, CuO/TiO2 p-n heterojunction was developed as a new surface enhanced Raman scattering (SERS) substrate to magnify Raman signal of 4-mercaptobenzoic acid (4-MBA) molecule. In the heterojunction-molecule system, CuO as an "electron capsule" can not only offer more electrons to inject into the surface state energy level of TiO2 and consequently bring additional charge transfer, but also improve photogenerated carrier separation efficiency itself due to strong interfacial coupling in the interface of heterojunction, which together boost SERS performance of the heterojunction substrate. As expected, owing to the enhanced charge collection capacity and the improvement of photogenerated carrier separation efficiency derived from internal electric field and strong interface coupling provided in the interface of heterojunction, this substrate exhibits excellent SERS detection sensitivity towards 4-MBA, with a detection limit as low as 1 × 10−10 mol/L and an enhancement factor of 8.87 × 106.
Developing sustainable and powerful heterogeneous catalytic systems to convert sulfides into high-value sulfoxide products has become a particularly appealing field and an arduous challenge. In this work, two porous polyoxometalate-pillared metal-organic frameworks, formulated as H3n[Cu3(pidc)2(H2O)2.5]2[PW12O40]n·xH2O (n = 1.5, x = 6 for 1, n = 1, x = 12 for 2; and H3pidc = 2-(3-pyridinyl)-1H-imidazole-4,5-dicarboxylic acid), were consciously manufacture and employed for heterogeneously catalyzed sulfide-sulfoxide transformation. Structural analysis shows that 1 and 2 exhibit similar porous frameworks with nearly identical two-dimensional metal-organic layers further pillared by tetradentate POM ligands with different coordination modes, which also result in the porosity of 1 being almost twice that of 2. In catalyzing the conversion of methyl phenyl sulfide (MPS) to methyl phenyl sulfoxide (MPSO), 1 can convert nearly 100% of MPS into MPSO within 30 min, while 2 achieved the similar results requires 50 min. The higher activity of 1 may be attributed to its larger channel that can provide more active sites and more efficient mass transfer process. Systematic structure-activity analyses and mechanistic studies revealed dual-reaction pathways driven by POM sites and metal sites assisted by the structural microenvironment.
Two triphenylamine-based star-type push-pull chromophores (T1, T2) were designed and synthesized. Triphenylamine serves as the central core and acts as an electron-donating group surrounded by electron-withdrawing pentafluorobenzene or N, N-dimethyl substituted tetrafluorobenzene, which are connected by ethylene bridges. Single-crystal X-ray diffraction confirmed the structures and molecular arrangement of two chromophores. The systematic photophysical research of T1 and T2 absorption characteristics was carried out to gain a better understanding of how structure-property relationships affect the observed nonlinear optical absorption phenomenon. Complementary calculations based on density functional theory (DFT) further confirmed the experimental results. Both chromophores exhibited excellent two-photon absorption (TPA) properties in CH2Cl2. Notably, T2 has more remarkable nonlinear optical absorption effects with the TPA cross-section up to 4.24 × 107 GM. By adjusting the electronic structures of the chromophores through introducing pentafluorobenzene or N, N-dimethyl as functional groups with different electron-donating or withdrawing behaviors, the TPA performance of the small organic molecule could be greatly enhanced. These molecular structures with push-pull systems were excellent candidates for different two-photon applications.
Diabetic patients often have problems such as residual tumor and wound infection after tumor resection, causing severe clinical problems. It is urgent to develop effective therapies to reach oncotherapy/anti-infection/promotion of wound healing combined treatment. Herein, we propose CS/MnO2-GOx (CMGOx) nanocatalysts for the specific catalytic generation of •OH to inhibit tumors and bacteria in a hyperglycemic environment. The good biocompatible chitosan (CS), as a carrier for the catalyst, exhibits excellent antibacterial effect as well as promotes wound healing. Glucose oxidase (GOx) is loaded on the surface of CS nanoparticles to generate H2O2 and gluconic acid by consuming glucose (starvation therapy, ST) and O2. The MnO2 depletes glutathione (GSH) to produce Mn2+, amplifying oxidative stress and further promoting the activity of Mn2+-mediated Fenton-like reaction to produce •OH (chemodynamic therapy, CDT) in weak acidic environment. Moreover, the produced gluconic acid lowers the pH of the environment, enhancing chemodynamic therapy (ECDT). The tumor cells and bacteria are efficiently eliminated by the synergistic effect of ST and ECDT. The MnO2 nanoparticles at neutral environment decomposes H2O2 into O2, which cooperate with CS to promote healing. The self-enhanced cascade reaction of CMGOx in situ exhibits excellent effects of antitumor/antibacterial therapy and promotion of wound healing, offering a promising integrated treatment for diabetic patients after tumor surgical resection.
Long afterglow organic-inorganic hybrid materials have attracted much attention in recent years and are widely used in information security, biological imaging and many other fields. Since up-conversion long-persistence materials are promising for bio-optical imaging due to their high penetration depth and elimination of autofluorescence background, it is highly desirable to combine down-conversion and up-conversion pathways to obtain smart materials with excitation-dependent tunable room-temperature phosphorescence properties. In this work, a metal-organic framework (Zn-DCPS-BIMB), consisting of divalent zinc ions, o-bis(imidazol-1-ylmethyl)benzene and 4,4′-dicarboxydiphenylsulfone, is designed to stabilize triplet excitons, coordinate the emission of different ligands, and endow materials with tunable emission color and up-conversion properties via heavy atoms effects promoting single-triplet orbital coupling and intersystem crossing.
Fe-Nx sites have been identified as core descriptors for Fe-N/C based oxygen reduction reaction catalysts. However, the low density and less utilization of Fe-Nx sites render these catalysts with inefficient catalytic performance. Herein, we develop an organic carboxylate-assisted engineering to construct Fe, N co-doped porous carbon interlinked carbon nanotubes (Fe/N-CCNTs) with high-density and sufficiently exposed Fe-Nx sites based on self-catalyzed effect. The existing forms of Fe include Fe-imidazole configuration and coordination with unsaturated Zn sites via organic carboxylate as linkers, leading to high-density Fe-Nx sites after pyrolysis. Besides, hexatomic carbon rings of organic carboxylate lower cyclization energy barrier for CNT formation, resulting in CNTs interlinked with separated active sites through "active point-conductive line-active point" connections. The optimal sample (Fe-BOAc-PNC) exhibits the onset potential of 0.93 V (vs. RHE) and half-wave potential of 0.84 V in alkaline solution. The liquid-state Zn-air battery (ZAB) employing Fe-BOAc-PNC generates large power density (160 mW/cm2) and stability over 160 h. Moreover, the assembled flexible ZAB displays superb power density of 93 mW/cm2 with robust flexibility. This work provides an insightful perspective for designing Fe-N/C catalysts with high-density and sufficiently exposed active sites for energy storage application.
Lithium-sulfur (Li-S) batteries have been regarded as the candidate for the next-generation energy storage system due to the high theoretical specific capacity (1675 mAh/g), energy density (2600 Wh/kg) and the abundance of elemental sulfur, but the application of Li-S batteries is impeded by a series of problems. Recently, all-solid-state Li-S batteries (ASSLSBs) have drawn great attention because many drawbacks such as safety issues caused by metallic lithium anodes and organic liquid electrolytes can be overcome through the use of solid-state electrolytes (SEs). However, not only the problems brought by sulfur cathodes still exist, but more trouble arouses from the interfaces between SEs and cathodes, hampering the practical application of ASSLSBs. Therefore, in order to deal with the problems, enormous endeavors have been done on ASSLSB cathodes during the past few decades, including engineering of cathode active materials, cathode host materials, cathode binder materials and cathode structures. In this review, the electrochemical mechanism and existing problems of ASSLSBs are briefly introduced. Subsequently, the strategies for developing cathode materials and designing cathode structures are presented. Then there follows a brief discussion of SE problems and expectations, and finally, the challenges and perspectives of ASSLSBs are summarized.
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