Latest ArticlesStructure-efficacy effect of small molecular drug attracts wide attentions, but it has always been ignored in nanomedicine research. To reveal the efficacy modulation of nanomedicine, we developed a new type of paclitaxel (PTX)-conjugated gold nanoparticles (PTX-conjugated GNPs) to investigate the influence of drug position in controlling their in vitro properties and in vivo performance. Two therapeutic ligands (TA-PEG-NH-N=PTX and TA-PTX=N-NH-PEG) were synthesized to conjugate PTX on the surface of GNPs at different positions, locating on the surface of gold conjugate and inserting between GNPs and polyethylene glycol (PEG, molecular weight 1000 Da), respectively. It was found that PEG-PTX@GNPs with PTX located between GNP and PEG exhibited higher aqueous solubility, biocompatibility, and stability. In addition, an acid sensitive hydrazone bond has been inserted between PTX and PEG in both ligands for drug release of PTX and PTX-PEG segment, respectively, at the tumor site. Further release of PTX from PTX-PEG segment is based on the esterase hydrolysis of an ester bond between PTX and PEG. This two-step drug release mechanism offers PEG-PTX@GNPs effective and sustained release behavior for desirable anticancer activity, enhanced therapeutic efficacy, and lower systematic toxicity in Heps-bearing animal models.
Metallic zinc is attractive anode material of rechargeable aqueous Zn-based batteries due to its ambient stability, high volumetric capacity, and abundant reserves. Nonetheless, Zn anodes suffer from issues such as low coulombic efficiency (CE), large polarization and dendrite formation. Herein, uniform Zn electrodeposition is reported on carbon substrates by selective nitrogen doping. Combined experimental and theoretical investigations demonstrate that pyrrolic and pyridinic nitrogen doped in carbon play beneficial effect as zinc-philic sites to direct nucleation and growth of metallic Zn, while negligible effect is observed for graphite nitrogen in Zn plating. The carbon cloth with modified amount of doped pyrrolic and pyridinic nitrogen stabilizes Zn plating/stripping with 99.3% CE after 300 cycles and significantly increases the deliverable capacity at high depth of charge and discharge compared to undoped carbon substrate and Zn foil. This work provides a better understanding of heteroatom doping effect in design and preparation of stable 3D carbon-supported zinc anode.
To date, investigations onto the regulation of reactants mass transfer has been paid much less attention in environmental catalysis. Herein, we demonstrated that by rationally designing the adsorption sites of multi-reactants, the pollutant destruction efficiency, product selectivity, reaction stability and secondary pollution have been all affected in the catalytic chlorobenzene oxidation (CBCO). Experimental results revealed that the co-adsorption of chlorobenzene (CB) and gaseous O2 at the oxygen vacancies of CeO2 led to remarkably high CO2 generation, owning to their short mass transfer distance on the catalyst surface, while their separated adsorptions at Brönsted HZSM-5 and CeO2 vacancies resulted in a much lower CO2 generation, and produced significant polychlorinated byproducts in the off-gas. However, this separated adsorption model yielded superior long-term stability for the CeO2/HZSM-5 catalyst, owning to the protection of CeO2 oxygen vacancies from Cl poisoning by the preferential adsorption of CB on the Brönsted acidic sites. This work unveils that design of environmental catalysts needs to consider both of the catalyst intrinsic property and reactant mass transfer; investigations of the latter could pave a new way for the development of highly efficient catalysts towards environmental pollution control.
Flexible rechargeable Zn-air batteries are considered as one of the most promising battery systems to drive flexible and wearable electronic devices owing to their high safety, high gravimetric energy density, low self-discharge and low cost. One of the key challenges is to develop air electrodes with high performance and high mechanical flexibility. This minireview discusses the recent progress in the design and fabrication of flexible air electrodes. It focuses on the latest innovations in bifunctional oxygen reduction reaction and oxygen evolution reaction electrocatalysts, mainly including carbon-based materials (e.g., heteroatom-doped carbon, metal-nitrogen moieties doped carbon), metal oxides (e.g., spinel oxides, perovskite oxides) and their composites. It aims to provide an insight into the structure-property relationship of bifunctional catalysts. We also discuss the challenges and future perspectives.
With excellent biocompatibility and biodegradability, natural polysaccharides and their derivatives have exhibited great potential in constructing drug delivery vehicles for tissue engineering and therapeutics. Cucurbit[n]uril (CB[n])-mediated reversible crosslinking of polysaccharides possess intrinsic stimuli-responsiveness towards competitive guests and have been extensively investigated to fabricate various particles and hydrogels for multiple stimuli-responsive drug release by incorporation with other stimuli including photo, redox, and enzyme. Through host-guest interactions between CB[6] and aliphatic diamines, functional tags covalently connected with CB[6] can be readily anchored into polysaccharide-based hydrogels, realizing multiple functionalization. The rheological property and drug release profile of polysaccharide-based supramolecular hydrogels can be facilely tuned through CB[8]-mediated dynamic homo or hetero crosslinking of polysaccharides and/or other polymers. In this review, we introduce and summarize recent progress regarding polysaccharide-based supramolecular drug delivery systems mediated via host-guest interactions of CB[6] and CB[8], covering both bulk hydrogels and particular systems. At the end, possible utilization of CB[7]-based host-guest interactions in constructing polysaccharide-based drug delivery systems and future perspectives of this research direction are also discussed.
The intrinsic liquid interface of Na-K alloy allays concerns about dendrite growth on metal anodes that are thermodynamically within the room temperature (20–22 ℃). Nevertheless, it hinders the formation of a stable electrode structure due to the inferior wettability induced by considerable liquid tension. In addition, the dominant ionic carrier in the Na-K alloy is subject to multiple factors, which is not conducive to customized battery design. This review, based on recently reported frontier achievements on Na-K liquid anodes, summarizes practical strategies for promoting the wettability by high-temperature induction, capillary effect, vacuum infiltration, and solid interface protection. Furthermore, four selection mechanisms of the dominant ionic carrier are presented: (1) ion property dominated, (2) cathode dominated, (3) separator dominated, and (4) solid electrolyte interface dominated. Notably, initial electrolytes in energy storage systems have been unable to play a decisive role in ionic selection. Utilizing a superior wettability strategy and simultaneously identifying the dominant ionic carrier can facilitate the tailored application of dendrite-free Na-K liquid anodes.
In continuation of our efforts toward the discovery of potent HIV-1 NNRTIs with diverse structures, a series of novel S-DACO analogues of 6-(2-cyclohexyl-1-alkyl)-2-(2-oxo-2-phenyl-ethylsulfanyl)pyrimidin-4(3H)-ones were designed, synthesized and evaluated for their antiviral activities in MT-4 cells. Most of these new compounds showed moderate to good activities against wild type HIV-1 with IC50 values ranging from 7.55 μmol/L to 0.018 μmol/L. Among them, compound 5c was identified as the most promising inhibitor against HIV-1 replication with an IC50 = 0.018 μmol/L, CC50 = 194 μmol/L, and SI = 12791, which was much more potent than the reference drugs NVP and DLV and comparable to AZT and EFV. In addition, 5c also exhibited improved activity against double mutant HIV-1 strain RES056 compared to that of the reference drugs NVP/DLV and DB02. The preliminary structure-activity relationship (SAR) and molecular modeling studies were also discussed, which provides some useful indications for guiding the further rational design of new S-DACO analogues.
Using particle swarm optimization (PSO) methodology for crystal structure prediction, we predicted a novel two-dimensional (2D) monolayer of silicide diphosphorus compound: SiP2, which exhibits good stability as examined via cohesive energy, mechanical criteria, molecular dynamics simulation and all positive phonon spectrum, respectively. The SiP2 monolayer is an indirect semiconductor with the band gap as 1.8484 eV (PBE) or 2.681 eV (HSE06), which makes it more advantageous for high-frequency-response optoelectronic materials. Moreover, the monolayer is a relatively hard auxetic material with negative Possion's ratios, and also possesses a ultrahigh carrier mobility (1.069×105 cm2 V-1 s-1) which is approximately four times the maximum value in phosphorene and comparable to the value of graphene and CP monolayers. Furthermore, the effects of strains on band structures and optical properties of SiP2 monolayer have been studied, as well as CO2 molecules can be strongly chemically adsorbed on the SiP2 monolayer. A semiconductor-to-metal transition for -9.5% strain ratio case and a huge optical absorption capacity on the order of 106 cm-1 in visible region present. These theoretical findings endow SiP2 Monolayer to be a novel 2D material holding great promises for applications in high-performance electronics, optoelectronics, mechanics and CO2 capturing material.
Lithium-ion batteries (LIBs) have evolved into the mainstream power source of energy storage equipment by reason of their advantages such as high energy density, high power, long cycle life and less pollution. With the expansion of their applications in deep-sea exploration, aerospace and military equipment, special working conditions have placed higher demands on the low-temperature performance of LIBs. However, at low temperatures, the severe polarization and inferior electrochemical activity of electrode materials cause the acute capacity fading upon cycling, which greatly hindered the further development of LIBs. In this review, we summarize the recent important progress of LIBs in low-temperature operations and introduce the key methods and the related action mechanisms for enhancing the capacity of the various cathode and anode materials. It aims to promote the development of high-performance electrode materials and broaden the application range of LIBs.
Irradiated by visible light, the recyclable (PhTe)2-catalyzed oxidative deoximation reaction could occur under mild conditions. In comparison with the thermo reaction, the method employed reduced catalyst loading (1 mol% vs. 2.5 mol%), but afforded elevated product yields with expanded substrate scope. This work demonstrated that for the organotellurium-catalyzed reactions, visible light might be an even more precise driving energy than heating because it could break the Te-Te bond accurately to generate the active free radical catalytic intermediates without damaging the fragile substituents (e.g., heterocycles) of substrates. The use of O2 instead of explosive H2O2 as oxidant affords safer reaction conditions from the large-scale application viewpoint.
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