Free radicals can improve the reaction rate, but most of them are unstable due to unpaired electrons. Simultaneously maintaining their stability and activity is challenging. Herein, taking sulfur (S) radicals as an example, we propose a strategy in which solvated metal complexes constructed by Al(acetylacetonate)3 and different solvents can stabilize high concentrations of S radicals with good activity through ion–dipole interactions. Based on this strategy, it is first demonstrated that S4•− is selectively stabilized by controlling the configurations of the solvated complexes. As a result, the reaction rate of S↔Li2S is increased by 8 times, and the energy efficiency and rate capability of the Li–S batteries are significantly improved, especially the 5-fold increase in cell capacities at a low electrolyte/sulfur ratio. This work provides an important strategy in which solvated metal complexes balance the activity and stability of free radicals to accelerate reactions and their application in various fields.

To improve treatment compliance and reach sustained and controlled drug release in the colon, we developed a hollow mesoporous silica nano-suppository that responded to both pH and redox stimuli. Firstly, we prepared hollow mesoporous silica nanoparticles containing disulfide bonds (HMSN-SS) and loaded them with 5-ASA. Secondly, we modified the surface of HMSN-SS with polydopamine (PDA) and chitosan (CS) and molded the suppository, which we named 5-ASA@HMSN-SS-PDA-CS (5-ASA@HSPC). By administering 5-ASA@HSPC rectally, it acted directly on the affected area. CS helped the nanoparticles adhere to the colon’s surface, while PDA dissociates from HMSN-SS due to protonation in the acidic environment of the ulcerative colon. The disulfide bonds were destroyed by the reducing environment of the colon, leading to a stable and slow release of encapsulated 5-ASA from the pores of HMSN. Finally, in vitro release experiments and in vivo pharmacokinetic and pharmacodynamic experiments had demonstrated that 5-ASA@HSPC exhibited a slow and steady action at the colonic site, with an excellent safety profile. This novel approach showed great potential in the treatment of ulcerative colitis.

To enhance the therapeutic effect of sorafenib (SOR) on liver cancer, we have developed a targeted nanodrug delivery system with glutathione (GSH) downregulation functionality. The preparation process comprises the synthesis of amino-functionalized mesoporous silica nanoparticles (MSN-NH2), surface modification with ethacrynic acid (EA), loading of SOR into the pores, and final surface coating with hyaluronic acid (HA) to obtain SOR@MSN-EA@HA (SMEH) nanoparticles. SMEH nanoparticles specifically enter tumor cells via CD44 receptor-mediated endocytosis. EA binds to GSH to consume it, while SOR is slowly released from the pores to exert antitumor effects while inhibiting GSH production. This results in sustained oxidative stress in the cells, thus enhancing the antitumor efficacy. Both in vitro and in vivo antitumor experiments as well as hemolysis tests have demonstrated that SMEH nanoparticles can accurately target liver cancer cells, effectively downregulate GSH concentration, exhibit good antitumor effects, and possess excellent safety, showing great potential in tumor treatment.

We have developed a targeted nano-drug delivery system that effectively harnesses the anti-tumor properties of trifluoperazine (TFP), while concurrently mitigating its side effects on the central nervous system. The manufacturing process entailed the preparation of mesoporous silica nanoparticles (MSN-NH2), followed by the loading of trifluoperazine into the pores of MSN-NH2 and then surface modification with polyethylene glycol (PEG) and anisamide (AA), resulting in the formation of TFP@MSN@PEG-AA (abbreviated as TMPA) nanoparticles. In vitro and in vivo anti-tumor activity and hemolysis experiments showed that TMPA had an excellent safety profile and a good anti-tumor effect. Importantly, the drug content of the TMPA nanoparticle group was found to be significantly lower than that of the TFP group in the mouse brain tissue as determined by High Performance Liquid Chromatography (HPLC) detection. Therefore, the developed drug delivery system achieved the goal of maintaining TFP's anti-tumor action while avoiding its negative effects on the central nervous system.

A targeted drug delivery system was developed to accumulate specific drugs around tumor cells based on the redox, temperature, and enzyme synergistic responses of mesoporous silica nanoparticles. Mesoporous silica nanoparticles (MSN-NH2) and Doxorubicin (DOX) for tumor therapy were prepared and loaded into the pores of MSN- NH2 to obtain DOX@MSN(DM NPs). Hyaluronic acid (HA) was used as the backbone and disulfide bond was used as the linker arm to graft carboxylated poly (N-isopropylacrylamide)(PNIPAAm-COOH) to synthesize the macromolecular copolymer (HA-SS-PNIPAAm), which was modified to DM NPs with capped ends to obtain the nano-delivery system DOX@MSN@HA-SS-PNIPAAm(DMHSP NPs), and a control formulation was prepared in a similar way. DMHSP NPs specifically entered tumor cells via CD44 receptor-mediated endocytosis; the high GSH concentration (10 mM) of cells severed the disulfide bonds, the hyaluronidase sheared the capped HA to open the pores, and increased tumor microenvironment temperature due to immune response can trigger the release of encapsulated drugs in thermosensitive materials.In vitroandin vivoantitumor and hemolysis assays showed that DMHSP NPs can accurately target hepatocellular carcinoma cells with a good safety profile and have synergistic effects, which meant DMHSP NPs had great potential for tumor therapy.

In order to make the drug specifically aggregate at the tumor site, we had developed a targeted drug delivery system based on pH responsive mesoporous silica nanoparticles. Mesoporous silica nanoparticles (MSN-COOH) were prepared and doxorubicin (DOX) was loaded into the pores of MSN-COOH, and then polyethyleneimine (PEI) and anisamide (AA) were modified on the surface of mesoporous silica, named DOX@MSN-PEI-AA(DMPA). DMPA specifically entered tumor cells through AA-mediated receptor endocytosis; PEI dissociated from the surface of the MSN in the acidic environment of cellular lysosomes/endosomes due to protonation of PEI, resulting in steady release of the encapsulated DOX from the pores of MSN in the cytoplasm of the target cells. In vitro and in vivo anti-tumor experiments and hemolytic experiments indicated that DMPA can accurately target breast cancer cells and show excellent safety at the same time, showing great potential for tumor therapy.

The shuttle effect is one of the most notable challenges in the fundamental research and practical use of lithium-sulfur (Li-S) batteries, especially within high-polarity electrolytes containing enriched polysulfides. Herein, we demonstrate a proof-of-concept study showing that the issue can be resolved by constructing a liquid-state/quasi-solid-state (LS/QSS) two-phase interface that is composed of a high-polarity QSS electrolyte and a weak-polarity LS one. The weak-polarity electrolyte shows negligible solubility to polysulfides and good compatibility to Li metal, resulting in the substantially improved cyclic stability of the Li anode for more than 1400 h in Li∣Li symmetrical cells. Moreover, over 300 cycles were achieved in the Li-S battery with the polysulfide-enriched LS/QSS electrolyte. This finding indicates that the LS/QSS electrolyte can effectively suppress the chemical reaction between electrolyte components and lithium metal. The concept of LS/QSS two-phase electrolyte provides a new strategy for the application of high-polarity solvents in energy conversion/storage devices.

Metal/nitrogen co-doped carbon (M-N-x/C) materials have shown their good catalytic activity for electrochemical/chemical reactions in energy conversion devices and organics synthesis. However, the preparation of M-N-x/C materials usually involves a high-temperature pyrolysis step, it generates not only active M-N-x sites but also inactive metal-based aggregates that restrict their activity. How to prepare the M-N-x/ C materials with high density of M-N-x sites and specific nanostructure remains a challenge. Herein, we report a general method of "self-assembly induced metal ionic polymer" for preparing M-N-x/C precursors, which can not only preferentially generate M-N-x sites by inhibiting metal aggregation during pyrolysis, but also produce advanced nanostructure for catalysis. Taking the preparation of Fe-N-x/C as an example, the self-assembled nanosheets of [Fe(CN)(6)](4)center dot{[C6H4-(NH3)(2)](2)}(4+) compounds are used as prefabricated materials, which effectively induce the formation of metal ionic-polymer nanowires and nanoparticles. They are applied to synthesize the Fe-N-x/C nanowires and nanoparticles with single metal atoms, respectively. The Fe-N-x/C nanowires exhibit the excellent oxygen reduction reaction activity with the half-wave potentials of 0.82 and 0.92 V under acidic and alkaline conditions, respectively. The proposed strategy can be a general method to prepare the M-N-x/C catalyst precursors with the special morphology and high thermal stability. (C) 2020 Elsevier Inc. All rights reserved.

Metal and nitrogen codoped carbon (M-Nx/C) materials with good metal dispersion in a carbon matrix have attracted great attention because they can efficiently catalyze various kinds of chemical/electrochemical reactions. However, the existing strategies for preparing M-Nx/C materials still face the challenge of metal site aggregation when the carbon skeleton in the precursor is substantially lost during pyrolysis. Herein, we propose a general strategy that the increase of metal site density and inhibition of metal aggregation could be realized by separating M-N4 units in metal-organic frameworks (MOFs). The metal sites can be well separated and distributed in carbon materials during the pyrolysis of a metal-coordinated block copolymer, one of the specific MOFs. The strategy can be widely applicable for the synthesis of M-Nx/C materials with dense metal sites, such as Fe-, Mn-, Ni-, and Co-Nx/C materials, which are potentially used as the efficient catalysts for various kinds of reactions. Taking Fe-Nx/C as a model oxygen reduction reaction (ORR) electrocatalyst, it shows the ORR half-wave potentials of 0.90 and 0.81 V vs RHE in alkaline and acidic electrolytes, respectively.