Zhenxia Zhao

Graphene-wrapped chromium-MOF(MIL-101)/sulfur composite for performance improvement of high-rate rechargeable Li–S batteries

A graphene/chromium-MOF(MIL-101) composite is investigated to serve as a host for sulfur immobilisation in Li–S batteries. The unique structure with a large specific area and a conductive shell ensures a high dispersion of sulfur in the composite and minimizes the loss of polysulfides to the electrolyte.

Construction of soft porous crystal with silole derivative: strategy of framework design, multiple structural transformability and mechanofluorochromism

Novel fluorescent organic soft porous crystals have been designed and prepared based on a multi-substituted silole bearing 1-phenyl-2,2-dicyanoethene moieties (molecule 8). 8 exhibited a series of emission colors, ranging from yellow to dark red with an over 70 nm shift of emission maximum. Molecule 8 also showed the ability to reversibly switch between different solid states, and a typical mechanofluorochromism was observed by cyclic operation of the grinding–heating–cooling processes. In addition, two single crystals (O and R) were successfully obtained in proper conditions, and the crystallographic data indicated that crystal O and R had reasonable hollow structures, inside which different solvent molecules were selectively encapsulated. More importantly, we have presented a proof-of-concept example of the strategy for the designation of organic soft porous crystals with a conjugated fluorophore and demonstrated the successful achievement of softness, porosity and crystallization ability. This design strategy is instructive to design and construct organic soft porous crystals with other conjugated building blocks and develop novel smart and stimuli-responsive photo/electronic materials.

High-Throughput and Rapid Screening of Novel ACE Inhibitory Peptides from Sericin Source and Inhibition Mechanism by Using in Silico and in Vitro Prescriptions

Several novel peptides with high ACE-I inhibitory activity were successfully screened from sericin hydrolysate (SH) by coupling in silico and in vitro approaches for the first time. Most screening processes for ACE-I inhibitory peptides were achieved through high-throughput in silico simulation followed by in vitro verification. QSAR model based predicted results indicated that the ACE-I inhibitory activity of these SH peptides and six chosen peptides exhibited moderate high ACE-I inhibitory activities (log IC50 values: 1.63-2.34). Moreover, two tripeptides among the chosen six peptides were selected for ACE-I inhibition mechanism analysis which based on Lineweaver-Burk plots indicated that they behave as competitive ACE-I inhibitors. The C-terminal residues of short-chain peptides that contain more H-bond acceptor groups could easily form hydrogen bonds with ACE-I and have higher ACE-I inhibitory activity. Overall, sericin protein as a strong ACE-I inhibition source could be deemed a promising agent for antihypertension applications.

Graphitized Porous Carbon for Rapid Screening of Angiotensin-Converting Enzyme Inhibitory Peptide GAMVVH from Silkworm Pupa Protein and Molecular Insight into Inhibition Mechanism

A novel hydrophobic hexapeptide with high angiotensin-converting enzyme (ACE) inhibitory activity was screened from silkworm pupa protein (SPP) hydrolysate via graphitized porous carbon and reverse-phase high-performance liquid chromatography methods. Graphitized porous carbon derived from dopamine, possessing high surface area and high graphitic carbon, was used to rapidly screen and enrich hydrophobic peptides from SPP hydrolysate. The ACE inhibition pattern and mechanism of the purified peptide were also systematically studied by the classic Lineweaver-Burk model and by molecular docking/dynamic simulation. The novel hydrophobic hexapeptide was identified as Gly-Ala-Met-Val-Val-His (GAMVVH, IC50 = 19.39 ± 0.21 μM) with good thermal/antidigestive stabilities. Lineweaver-Burk plots revealed that GAMVVH behaved as a competitive ACE inhibitor. It formed hydrogen bonds with S1 and S2 pockets of ACE and established competitive coordination with Zn(II) of ACE. The synergy of hydrogen bonds with active pockets and Zn(II) coordination efficiently changed the three-dimensional structure of ACE and thus inhibited bioactivity of ACE.

Ultrafast Screening of a Novel, Moderately Hydrophilic Angiotensin-Converting-Enzyme-Inhibitory Peptide, RYL, from Silkworm Pupa Using an Fe-Doped-Silkworm-Excrement-Derived Biocarbon: Waste Conversion by Waste

A novel, moderately hydrophilic peptide (RYL) with high ACE-inhibitory activity was screened ultrafast via a concept of waste conversion using waste. This novel peptide was screened from silkworm pupa using an Fe-doped porous biocarbon (FL/Z-SE) derived from silkworm excrement. FL/Z-SE possessed magnetic properties and specific selection for peptides due to Fes dual functions. The selected RYL, which has moderate hydrophilicity (LogP = -0.22), exhibited a comparatively high ACE-inhibitory activity (IC50 = 3.31 ± 0.11 μM). The inhibitory kinetics and docking-simulation results show that, as a competitive ACE inhibitor, RYL formed five hydrogen bonds with the ACE residues in the S1 and S2 pockets. In this work, both the screening carbon material and the selected ACE-inhibitory peptide were derived from agricultural waste (silkworm excrement and pupa), which offers a new way of thinking about the development of advanced uses of the silkworm byproducts and wastes.

Highly Advanced Degradation of Thiamethoxam by Synergistic Chemisorption-Catalysis Strategy Using MIL(Fe)/Fe-SPC Composites with Ultrasonic Irradiation

MIL(Fe)/Fe-doped nanospongy porous biocarbon (Fe-SPC) composite was fabricated from MIL-100(Fe) via in situ growth on a unique Fe-doped nanospongy porous biocarbon (Fe-SPC) and was used as Fenton-like catalyst for advanced degradation of thiamethoxam (THIA). Fe was loaded on silkworm excrement and calcined to Fe-SPC with nanospongy and high sp2 C structure. The in situ growth strategy embedded the Fe-SPC into MIL-100(Fe) crystals and formed conductive heterojunctions with an intensified interface by Fe-bridging effect, which was confirmed by negative shift of Fe3+ binding energy in X-ray photoelectron spectroscopy. MIL(Fe)/Fe-SPC composites exhibited high degree of crystallinity and surface area (Brunauer-Emmett-Teller: 1730 m2/g). Liquid chromatography-mass spectrometry and density functional theory simulations demonstrated that THIA was converted to a relatively stable compound (C4H5N2SCl), which could be captured by MIL-100(Fe) with strong chemical bonding energy (Fe-N, -587 kJ/mol), followed by a significant geometric distortion, resulting in a thorough degradation. Efficient charge separation and synergistic chemisorption-catalysis strategy resulted in the high catalytic activity of MIL(Fe)/Fe-SPC. The composite catalyst concurrently exhibited high mineralization ratio with 95.4% total organic carbon removal (at 25 °C and 180 min) and good recycling ability under wider neutral/alkaline conditions. Endorsing to these intriguing properties, MIL(Fe)/Fe-SPC can be deemed an efficient contender for removal of hard-degradable pesticides and other environmental pollutants in practical applications.

An Unprecedented Case: A Low Specific Surface Area Anatase/N-Doped Carbon Nanocomposite Derived from a New Single Source Precursor Affords Fast and Stable Lithium Storage

A nanocomposite of ultrafine anatase nanoparticles (<5 nm) embedded N-doped carbon (TiO2-NPs/NC) with a relatively low specific surface area was successfully synthesized by in situ pyrolysis of a new and cheap single source precursor of (H2en)3[Ti4(O2)4(Hcit)2(cit)2]·12H2O (en = ethylenediamine and H4cit = citric acid) under 550 °C and an inert atmosphere. The precursor in crystalline state was isolated from an aqueous solution containing of titanium butoxide, citric acid, hydrogen peroxide, and ethylenediamine and was characterized. The crystal structure was determined by X-ray single crystal diffraction. To our surprise, the low surface area TiO2-NPs/NC exhibits a high specific capacity, superior rate capability, excellent cycle performance, and good processability as a negative material for rechargeable lithium-ion batteries (LIBs). A large reversible capacity of 360 and 125 mA h g-1 and a high Coulombic efficiency (the average value is ∼99.8%) could be kept even after 1000 cycles under a current density of 0.3 and 6 A g-1, respectively. An analysis of the voltammetric sweep data shows that the pseudocapacitive behavior occurred at the surface of the material and the lithium intercalation processes contribute to the total stored charge, resulting in the high capacity of the TiO2-NPs/NC nanocomposite. The potentiostatic intermittent titration technique used to determine the lithium ion diffusion (DLi+) suggested the TiO2-NPs/NC nanocomposite displays a high DLi+. In addition, the high electric conductivity provided by the NC substrate and the ultrafine anatase particles can mitigate the diffusion path for electrons and ions and tolerate higher strain, and thus effectively decrease pulverization and improve the rate and cycle performance. In particular, the observed superior lithium storage properties, resulting from the low surface area nanocomposite with ultrafine nanoparticles embedded NC substrate, are expected to have fundamental and practical implications for the preparation of high performance electrodes in LIBs or other cells.