Latest ArticlesNovel peptide-fentanyl analogue conjugates were synthesized by the covalent coupling of carfentanyl derivatives to the C-terminus or N-terminus of the conformationally constrained dermorphin tetrapeptide BVD03 via a chemical linker. The carfentanyl-related analogues displayed distinct binding and functional activities at µ/δ opioid receptors (MOR/DOR) and antinociceptive effects when conjugated to the peptide. The most potent compound, SW-LJ-11, displayed mixed MOR/DOR agonist properties in the low nanomolar range and significant analgesic efficacy in vivo in four classic mouse models of pain. Interestingly, SW-LJ-11 did not exhibit any physical dependence or respiratory depression, in contrast to an equipotent analgesic dose of morphine or BVD03, indicating that the use of opioid peptide–fentanyl analogue conjugates as dual MOR/DOR agonists may be a promising strategy for obtaining safer opioids.
Organic room temperature phosphorescent (ORTP) materials provide an exciting research direction for phosphorescent oxygen (O2) sensors due to their high sensitivity and rapid response to O2. However, most pure ORTP materials are tightly-packed aromatic compound crystals in a face-to-face manner, which largely prohibits effective O2 diffusion for sensing. Thus, how to solve this contradiction still faces huge challenges. Here, the use of organic phosphorescent indicator carbon dots (CDs), inorganic matrix layered double hydroxides (LDHs) and polymers (PVA) successfully prepared an ultra-long RTP composite film whose phosphorescence decay intensity is linearly related to O2 concentration. More importantly, the use of the abundant O2 defects (Vo) on the surface of the inorganic matrix LDHs to adsorb O2, which further accelerates the phosphorescence quenching of the thin film and improves the O2 response. This strategy will provide the possibility to develop high-sensitivity phosphorescent O2 sensors from a new perspective.
Red emissive carbon dots (CDs) are highly desired for biological applications. However, serious luminescence quenching of red emissive CDs in aqueous solution greatly hinders their application in high performance biological imaging. Herein, we reported a facile strategy to realize enhanced red emission of CDs in aqueous solution by surface modification with polyetherimide (PEI) via microwave heating method. High photoluminescence quantum yield (PLQY) of 25% was realized from the PEI functionalized CDs (CDs@PEI) in aqueous solution. The proposed PEI functionalization strategy not only protects the red emission against water molecules quenching, but also reverses the surface charges from negativity to positivity to promote cellular uptake of CDs, leading to clear cell imaging in red fluorescence region. More important, CDs@PEI exhibits much better photostability than commercial red emissive dye (MitoTracker red) in cell fluorescent imaging. Potential application of CDs@PEI on fast staining of cells for clonogenic assay has also been demonstrated.
The uncontrolled growth of lithium dendrites and accumulation of "dead lithium" upon cycling are among the main obstacles that hinder the widespread application of lithium metal anodes. Herein, an ionic liquid (IL) consisting of 1-methyl-1-propylpiperidinium cation (Pp13+) and bis(fluorosulfonyl)imide anion (FSI−), was chosen as the additive in propylene carbonate (PC)-based liquid electrolytes to circumvent the shortcoming of lithium metal anodes. The optimal 1% Pp13FSI acts as the role of electrostatic shielding, lithiophobic effect and participating in the formation of solid electrolyte interface (SEI) layer with enhanced properties. The in-situ optical microscopy records that the addition of IL can effectively inhibit the growth of lithium dendrites and the corrosion of lithium anode. This study delivers an effective modification to optimize electrolytes for stable lithium metal batteries.
Green hydrogen production and CO2 fixation have been identified as the fundamental techniques for sustainable economy. The open challenge is to develop high performance catalysts for hydrogen evolution reaction (HER) and CO2 electroreduction (CO2ER) to valuable chemicals. Under such context, this work reported computational efforts to design promising electrocatalyst for HER and CO2ER based on the swarm-intelligence algorithm. Among the family of transition-metal phosphides (TMPs), Pt2P3 monolayer has been identified as excellent bifunctional catalysts due to high stability, excellent conductivity and superior catalytic performance. Different from typical d-block catalysts, p-band center presented by P atoms within Pt2P3 monolayer plays the essential role for its reactivity towards HER and CO2ER, underlining the key value of p-electrons in advanced catalyst design and thus providing a promising strategy to further develop novel catalysts made of p-block elements for various energy applications.
Surfactants with polyoxometalates (POMs) as polar head groups have shown fascinating self-assembly behaviors and various functional applications. However, self-assembly them into reverse micelles is still challenging owing to the large molecular size and intermolecular strong electrostatic repulsions of POM heads. In this work, a zwitterionic POM-based surfactant was synthesized by covalently grafting two cationic long alkyl tails onto the lacunary site of [PW11O39]7−. With decreased electrostatic repulsions and increased hydrophobic effect, the POM-based reverse micelles with an average diameter of 5 nm were obtained. Interestingly, when these reverse micelles were applied for catalyzing the oxidation of styrene, an unprecedented β-hydroxyl peroxide compound of 2-hydroxyl-2-phenylethan-1-tert-butylperoxide was produced in high selectivity of 95.2%. In comparison, the cetyltrimethylammonium electrostatically encapsulated POMs mainly generated the epoxides or 1, 2-diols. A free radical mechanism was proposed for the oxidation reaction catalyzed by the zwitterionic POM surfactants.
Amphiphilic molecules adsorbed at the interface could control the orientation of liquid crystals (LCs) while LCs in turn could influence the distributions of amphiphilic molecules. The studies on the interactions between liquid crystals and amphiphilic molecules at the interface are important for the development of molecular sensors. In this paper, we demonstrate that the development of smectic LC ordering from isotropic at the LC/water interface could induce local high-density distributions of amphiphilic phospholipids. Mixtures of liquid crystals and phospholipids in chloroform are first emulsified in water. By fluorescently labeling the phospholipids adsorbed at the interface, their distributions are visualized under fluorescent confocal microscope. Interestingly, local high-density distributions of phospholipids showing a high fluorescent intensity are observed on the surface of LC droplets. Investigations on the correlation between phospholipid density, surface tension and smectic LC ordering suggest that when domains of smectic LC layers nucleate and grow from isotropic at the LC/water interface as chloroform slowly evaporates at room temperature, phospholipids transition from liquid-expanded to liquid-condensed phases in response to the smectic ordering, which induces a higher surface tension at the interface. The results will provide an important insight into the interactions between liquid crystals and amphiphilic molecules at the interface.
Hierarchical porous carbon (HPC) from bituminous coal was designed and synthesized through pyrolysis foaming and KOH activation. The obtained HPC (NCF-KOH) were characterized by a high specific surface area (SBET) of 3472.41 m2/g, appropriate mesopores with Vmes/Vtotal of 57%, and a proper amount of surface oxygen content (10.03%). This NCF-KOH exhibited a high specific capacitance of 487 F/g at 1.0 A/g and a rate capability of 400 F/g at 50 A/g based on the three-electrode configuration. As an electrode for a symmetric capacitor, a specific capacitance of 299 F/g at 0.5 A/g was exhibited, and the specific capacitance retained 96% of the initial capacity at 5 A/g after 10,000 cycles. Furthermore, under the power density of 249.6 W/kg in 6 mol/L KOH, a high energy density of 10.34 Wh/kg was obtained. The excellent charge storage capability benefited from its interconnected hierarchical pore structure with high accessible surface area and the suitable amount of oxygen-containing functional groups. Thus, an effective strategy to synthesize HPC for high-performance supercapacitors serves as a promising way of converting coal into advanced carbon materials.
Developing efficient and inexpensive OER electrocatalysts is a challenge for overall water splitting. Herein, the heterostructured FeCo LDH@NiCoP/NF nanowire arrays with high performance were rationally designed and prepared using an interface engineering strategy. Benefitting from the special heterostructure between FeCo LDH and NiCoP, the as-synthesized FeCo LDH@NiCoP/NF electrocatalyst exhibits outstanding OER performance with an exceptionally low overpotential of 206 mV to achieve 20 mA/cm2 current density in an alkaline electrolyte. Importantly, a cell constructed using the FeCo LDH@NiCoP/NF electrocatalyst as cathode and anode just needs a voltage of 1.48 V at 10 mA/cm2, and shows excellent stability over 80 h. Experimental and theoretical results verified that the introduction of NiCoP efficiently regulates the electronic structure of FeCo LDH, which tremendously boosts the conductivity and intrinsic catalytic activity of FeCo LDH@NiCoP/NF electrocatalyst. The present work provides guidance for the preparation of other efficient and cheap electrocatalytic materials.
Two novel seco-polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperbenzones A (1) and B (2), were isolated from the roots of Hypericum beanii, together with one known biosynthetic congener 3. Compound 1 incorporates a 6/5/5 ring system with an unprecedented spiro[bicyclo[3.3.0]octane-3,1ʹ-cyclohexane]-2,2ʹ-dione motif. The structures of 1 and 2 were determined by a combination of high resolution electrospray ionization mass spectroscopy (HRESIMS), nuclear magnetic resonance (NMR) spectroscopic analyses, gage-independent atomic orbital (GIAO) NMR chemical shift calculation with DP4+ analyses, electronic circular dichroism (ECD) calculation, and X-ray diffraction analysis. A 1,2-seco retro-Claisen rearrangement from a bicyclo[3.3.1]nonane PPAP precursor and following chemodivergent radical cascade cyclizations are proposed as the key steps in the biosynthetic pathway to yield compounds 1 and 2. Biological investigations indicated that compounds 1 and 3 could decrease intracellular lipid accumulation in a palmitic acid-induced nonalcoholic steatohepatitis (NASH) cell model.