Latest ArticlesLithium-sulfur (Li-S) batteries with high theoretical capacity and energy density need to solve problems such as the high decomposition energy barrier of Li2S and large volume change of sulfur in the charging process caused by the shuttle effect before practical application. Herein, a green synthesis method is used to prepare polyacrylic acid (PAA) superabsorbent material, and then the pyrolyzed PAA (P/PAA) material is obtained as the positive electrode of Li-S battery. Density functional calculation reveals that the oxygen self-doping pyrolyzed polyacrylic acid (P/PAA) delivered stronger binding energy toward Li2S species in carbonyl C=O than that of graphite powder (GP) which are −1.58 eV and −1.02 eV, respectively. Coupled with the distribution of relaxation time analysis and the in-situ electrochemical impedance approach, it is further demonstrated that the designed P/PAA as sulfur host plays a physical/chemical adsorption dual function in maintaining the stability and rate performance of batteries. With an initial discharge capacity of 1258 mAh/g at 0.1 C and a minimal capacity decline of 0.05% per cycle even after 800 cycles at 0.5 C, the produced cathode demonstrated outstanding electrochemical performance. The average Coulombic efficiency is nearly 100%. The P/PAA electrodes may typically retain 96% of their capacity while declining on average only 0.033% per cycle after 130 cycles at 3 C. This effort provides a new method for the future development of heteroatomic self-doping superabsorbent with promising adsorption properties for polysulfides as cathode materials of Li-S batteries.
In recent years, rechargeable zinc-ion batteries (ZIBs) are considered to be a promising alternative to lithium-ion batteries owing to their high safety and theoretical capacity with low cost. Nevertheless, the in-depth development of rechargeable zinc-ion batteries is restricted by a sequence of issues, such as the dissolution and structure collapse of cathode materials, the formation of by-products, severe anode corrosion, passivation, and the growth of zinc dendrites. The covalent organic frameworks (COFs) can solve the above problems to a certain extent owing to their ideal characteristics, such as rigid structure, insolubility, high porosity, and abundant active sites. COFs, as advanced materials for ZIBs, have attracted researchers' attention. In this review, we systematically summarized the synthesis methods of COFs and discussed the application of several advanced characterization technologies in COFs, which would provide a reference for the in-depth research of COFs. In addition, we elucidated the use of COFs as cathode materials and anode protective layers in rechargeable ZIBs. Finally, we discussed the challenges and solutions in the development of COF materials, which would provide constructive insights into the future direction of COFs.
The preparation of hydrogel adsorbents with admirable performance for efficient selective remove Pb(Ⅱ) in complex wastewater still remains a great challenge. Herein, a novel bifunctional modified polymer hydrogel PAM-PAMPS was prepared by crosslinking acrylamide (AM) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS). Compared with PEG, PAA and PAMPS, PAM-PAMPS exhibited both the maximum adsorption capacity of Pb(Ⅱ) (541.90 mg/g) and satisfactory selectivity for Pb(Ⅱ) in multiple heavy metal ions coexistence solutions. Various characterizations indicated that SO3H and NH2 as active sites on PAM-PAMPS occur the synergistic effects of ion-exchange and coordination with Pb(Ⅱ) during the adsorption process, respectively. The adsorption energy Ead(PAM-PAMPS) obtained from density functional theory (DFT) calculations was lower than the other three hydrogels, manifesting that PAM-PAMPS formed the most stable complex with Pb(Ⅱ), which further demonstrated that Pb(Ⅱ) preferred to combine with PAM-PAMPS to selective capture of Pb(Ⅱ). The practice utilization of PAM-PAMPS was assessed by wastewater of electroplate containing Pb(Ⅱ). Meanwhile, the removal ratio of PAM-PAMPS was maintained at about 89% after 4 adsorption-desorption cycles. This study establishes a new and effective idea for the design and fabrication of bifunctionalized modified polymer hydrogels.
Strand displacement reaction enables the construction of enzyme-free DNA reaction networks, thus has been widely applied to DNA circuit and nanotechnology. It has the characteristics of high efficiency, universality and regulatability. However, the existing regulation tools cannot enable effective control of the reaction sequence, which undoubtedly limits the construction of complex nucleic acid circuits. Herein, we developed a regulation tool, toehold lock, and achieved strict control of reaction sequence without loss of the main reaction signal output. Furthermore, we applied the tool to scenarios such as seesaw circuits, AND/OR logic gates, and entropy-driven circuits, and respectively demonstrated its significant superiority compared to the original method. We believe that the proposed toehold lock has greatly optimized the efficiency of DNA strand displacement-based networks, and we anticipate that the tool will be widely used in multiple fields.
With the increasing emergence of bacterial infections, especially multidrug-resistant (MDR) bacteria, poses an urgent threat. This study demonstrated a novel multifunctional nanotheranostics platform developed by the strategic integration of both in-situ bio-assembly imaging and target bacteria inactivation. Through the introduction of copper ions into bacteria, the Cu2+ could spontaneously bio-self-assembled into a multifunctional copper nanoclusters (NCs) which efficiently enhanced epigallocatechin gallate (EGCG) uptake into bacteria. While visualizing the bacteria, the developed theranostic nanoplatform exhibited highly efficient disinfection activities with negligible side effects as reflected by higher cell viability and insignificant hemolytic effects. Furthermore, the exosomal formulation of EGCG integrated with Cu2+ showed an increased intracellular antibacterial activity, which could eliminate most of the methicillin-resistant Staphylococcus aureus (MRSA) phagocytosed by macrophages, guide macrophages toward M2-like phenotype polarization and alleviate inflammation, without exhibiting obvious cytotoxicity on host RAW264.7. The regimen could be viewed as an effective strategy for the sterilization of intractable bacterial infections.
Fungal alkylresorcinols are a class of polyketides, which are commonly synthesized by the hybridization of highly reducing polyketide synthase (hrPKS) with non-reducing polyketide synthase (nrPKS). In this study, we identified and demonstrated a new assembly model for synthesizing alkylresorcinol (scirpilin A, 1), which was accomplished by collaboration of a hrPKS (FscA) and a type Ⅲ PKS (FscB). Furthermore, three post-tailoring enzymes (FscC, FscD, and FscE) act iteratively on 1 skeleton, including successive 14e− oxidation of inert carbons, di-halogenation, and di-methylation, to form highly oxidized and multi-substituted alkylresorcinols. Our work presents an unusual synthesis manner of alkylresorcinols, sheds light on the collaborative mechanism between hrPKS and type Ⅲ PKS and provides three valuable enzymatic catalysts for the tailoring of alkylresorcinol family natural products in future.
Two-dimensional (2D) mesoporous pseudocapacitive polymer/graphene heterostructures combine the advanced merits of 2D materials and mesoporous materials, possessing unique nanosheet structure, large specific surface area (SSA), abundant oxygen/nitrogen-containing groups, desirable electrical conductivity and admirable electrochemical redox activity, and hold great potential for constructing high-performance planar micro-supercapacitors (MSCs). Herein, we demonstrate the interfacial assembly of 2D mesoporous polydopamine/graphene (mPDG) heterostructures with well-defined mesopore structure (12 nm) and adjustable thickness (7.5–14.1 nm) for planar high-energy pseudocapacitive MSCs. Attributed to medium thickness, exposed mesopore of 12 nm and large SSA of 108 m2/g, the mPDG with 10.8 nm thickness reveals prominent mass capacitance of 419 F/g and impressive cycling stability with ~96% capacitance retention after 5000 cycles. Furthermore, the symmetric mPDG-based MSCs with "water-in-salt" gel electrolyte present wide voltage window of 1.6 V, superior volumetric energy density of 11.5 mWh/cm3, outstanding flexibility and self-integration ability. Therefore, this work offers a new platform of controllably synthesizing 2D mesoporous heterostructures for high-performance MSCs.
Due to their superior fluorescence, phosphorescence, and catalytic capabilities, carbon dots (CDs), an emerging class of fluorescent carbon nanomaterials, have a wide range of potential applications. The properties of CDs have recently been controlled extensively by heteroatom doping. Boron atoms have been effectively doped into the structure of CDs due to their similar size to carbon atoms and excellent electron-absorbing ability to further improve the performance of CDs. In this review, we summarize the research progress of boron-doped CDs in recent years from the aspects of doping strategies, effects of boron doping on different performances of CDs and applications. Starting from the two aspects of single boron doping and boron and other atom co-doping, from different precursor materials to different synthesis methods, the doping strategies of boron-doped CDs are reviewed in detail. Then, the effects of boron doping on the fluorescence, phosphorescence and catalytic performance of CDs and applications of boron-doped CDs in optical sensors, information encryption and anti-counterfeiting are discussed. Finally, we further provide a prospect towards the future development of boron-doped CDs.
Photothermal therapy (PTT) and photodynamic therapy (PDT) have received tremendous attention owing to their great potential for tumor treatment. However, two main issues hamper the antitumor performance of PDT: overexpression of glutathione (GSH) in tumors, which consumes PDT-induced reactive oxygen species (ROS), and hypoxia within the tumor microenvironment. The drawbacks of PTT include uneven temperature distribution and the upregulation of the heat-shock proteins in tumors, both of which result in ineffective treatment. To address these issues, a MnO2 doped nano-delivery system (HTIM-PMs) was synthesized by one-step self-assembly of disulfide bond bridged copolymers for indocyanine green (ICG) and MnO2 loading. The surface of polymeric micelles was layered with hyaluronan (HA) and transactivator (TAT) peptides to improve active targeting and increase cell penetration. After internalization, HTIM-PMs showed responsiveness to the tumor microenvironment (acid pH, high glutathione, high H2O2). Breaking the disulfide bond reduced the intratumoral GSH level and simultaneously released the MnO2 and ICG. The released MnO2 further reduced the GSH level and promoted O2 generation, thus enhancing the PDT effect. The PTT-mediated hyperthermia accelerated blood flow, which is beneficial for O2 distribution, and promotes ROS diffusion. These PTT-mediated adjuvant effects further overcame the limitations of PDT and the robust PDT effect in turn compensated for the deficiency of PTT. This promising platform exhibited a significant improvement in the PTT-PDT cancer treatment strategy compared to previously reported nanostructures.
Herein, we unveil the intelligent detection of multiple catechol isomers in complex environments utilizing both laser-induced graphene (LIG) and artificial neural network (ANN). The large scale-up manufacturing of LIG-based sensors (LIGS) with three-electrode configuration on polyimide (PI) is achieved by direct laser-writing and screen-printing technologies. Our LIGS shows excellent electrochemical performance toward catechol isomers, i.e., hydroquinone (1, 4-dihydroxybenzene, HQ), catechol (1, 2-dihydroxybenzene, CT), and resorcinol (1, 3-dihydroxybenzene, RC), with a low limit of detection (LOD) (CC, 0.079 µmol/L; HQ, 0.093 µmol/L; RC, 1.18 µmol/L). Moreover, the ANN model is developed for machine-intelligent to predict concentrations of catechol isomers under an interfering environment via a single LIGS. Using six unique parameters extracted from the differential pulse voltammetry (DPV) response, the machine learning-based regression provides a coefficient of correlation with 0.998 and is able to correctly predict the total and individual concentrations in complex river samples. Hence, this work provides a guide for the preparation and application of LIGS via facile and cost-efficient mass production and the development of an intelligent sensing platform based on the ANN model.
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