Here, we constructed a nanostructured pH/redox dual-responsive supramolecular drug carrier with both aggregation-induced emission (AIE) and Forster resonance energy transfer (FRET) effects, which enabled selective drug release and monitoring drug delivery and release processes. Taking the hyperbranched polyamide amine (H-PAMAM) with intrinsic AIE effects as the core, poly­(ethylene glycol) (PEG) was bridged on its periphery by dithiodipropionic acid. Then, through the host–guest interaction of PEG and α-cyclodextrin, the supramolecular nanoparticles with AIE effects were constructed to load the anticancer drug doxorubicin (DOX). The supramolecular assembly has sufficiently large DOX loading due to the abundant cavities formed by branched structures. The hyperbranched core H-PAMAM has strong fluorescence, and the dynamic track of drug carriers and the dynamic drug release process can be monitored by the AIE and FRET effects between H-PAMAM and DOX, respectively. Furthermore, the introduction of disulfide bonds and the pH sensitivity of H-PAMAM enable the achievement of rapid selective release of loaded DOX at the tumor while remaining stable under normal physiological conditions. In vitro cytotoxicity indicates that the drug-loaded supramolecular assembly has a good therapeutic effect on cancer. In addition, the H-PAMAM core is different from the traditional AIE functional group, which has no conjugated structure, such as a benzene ring, thereby providing better biocompatibility. This technology will have broad applications as a new drug delivery system.

Fischer–Tropsch synthesis (FTS) is a versatile technology to produce high-quality fuels and key building-block chemicals from syngas derived from nonpetroleum carbon resources such as coal, natural gas, shale gas, biomass, solid waste, and even CO2. However, the product selectivity of FTS is always limited by the Anderson–Schulz–Flory (ASF) distribution, and the key scientific problems including selectivity control, energy saving, and CO2 emission reduction still challenge the current FTS technology. Herein, we review recent significant progress in the field of FTS to obtain specific target products including fuels, olefins, aromatics, and higher alcohols with high selectivity. These achievements are enabled by developing highly efficient catalysts and a controlled reaction pathway based on an integrated process. The structural nature of catalytic active sites and established structure–performance relationships are clarified. Moreover, we specially focus on the carbon utilization efficiency, and the efforts to tune the preferential formation of value-added chemicals and strategies to reduce CO2 selectivity are summarized. The challenges and the perspectives for future FTS technology development with high carbon efficiency are also discussed.

No abstract

Cobalt carbide (Co 2 C) nanoprisms derived from CoMn composite oxides exhibit promising catalytic performance for Fischer− Tropsch to olefins (FTO) synthesis via H 2 -lean syngas conversion, but with nearly 45 C% of CO 2 selectivity. The work herein was aimed to investigate the effect of CO 2 in the feed on the structure−performance relationship of Co 2 C-based catalysts during a realistic FTO process. An obvious negative effect of CO 2 was observed on the catalytic performance, and the presence of CO 2 greatly decreased the catalytic activity and olefin formation rate, while it facilitated methane formation. In addition, the product distribution shifted toward light components at increasing CO 2 content, and a typical methanation regime with low selectivity to olefins was observed for CO 2 hydrogenation. A structural characterization suggested that the Napromoted Co 2 C nanoprisms remained stable under FTO working conditions, and weak linearly and bridge adsorbed CO molecules were observed when the temperature reached 250 °C in a flow of CO-containing gas. However, the CO 2 environment hindered CO adsorption, and the strong CO 2 adsorption ability led to decreased CO coverage and a high local H 2 /CO ratio on the catalyst surface. The as-obtained CO-lean and H-rich surface microenvironment gradually changed the morphology of Co 2 C nanostructures from nanoprisms to nanospheres. Some of the Co 2 C was even transformed into metallic Co. The change of the catalyst structure and the surrounding environment inhibited the adsorption of surface intermediates and the subsequent chain growth. This work provides important insights for further catalyst optimization and suggests that CO 2 removal is necessary for recycling the tail gas or using CO 2 -containing feedstocks for industrial FTO processes over Co 2 C-based catalysts.

No abstract

No abstract

Facing the global health crisis caused by drug-resistant bacteria, antimicrobial peptides and their analogues offer exciting solutions to this widespread problem. Without additionally introducing a fluorescent probe, novel nanoengineered peptide-grafted hyperbranched polymers (NPGHPs) are constructed for their combined outstanding antimicrobial activity and sensitive bacterial detection in real time. Hyperbranched polyamide amine (H-PAMAM) that exhibits aggregation-induced emission (AIE) effects is synthesized. Then, NPGHPs are prepared by ring-opening polymerization of α-amino acid N-carboxyanhydrides on the periphery of the H-PAMAM. The NPGHPs exhibit high-efficiency antibacterial properties against a wide spectrum of bacteria, especially against Gram-negative bacteria. On the basis of the AIE effect of NPGHPs, the interaction between NPGHPs and Escherichia coli is explored and the fluorescence intensity of NPGHPs is dependent on the number of E. coli present. Thus, a method for monitoring E. coli concentration is developed, and the detection limit is 1 × 104 CFU mL–1. Furthermore, NPGHPs are used as fluorescent probes to visualize antibacterial process via lighting-up bacteria. NPGHPs can penetrate the membrane of bacteria and cause cell rupture and apoptosis. In addition, the excellent selectivity of NPGHPs toward bacteria over mammalian cells makes them bright prospects for clinical applications.

Syngas conversion serves as a competitive strategy to produce olefins chemicals from nonpetroleum resources. However, the goal to achieve desirable olefins selectivity with limited undesired C1 by-products remains a grand challenge. Herein, we present a non-classical Fischer-Tropsch to olefins process featuring high carbon efficiency that realizes 80.1% olefins selectivity with ultralow total selectivity of CH4 and CO2 (<5%) at CO conversion of 45.8%. This is enabled by sodium-promoted metallic ruthenium (Ru) nanoparticles with negligible water-gas-shift reactivity. Change in the local electronic structure and the decreased reactivity of chemisorbed H species on Ru surfaces tailor the reaction pathway to favor olefins production. No obvious deactivation is observed within 550 hours and the pellet catalyst also exhibits excellent catalytic performance in a pilot-scale reactor, suggesting promising practical applications.