Resolving the aggregation of osmium (Os) nanozyme is important for improving its catalytic activity. Herein, Os nanoparticles-Bovine serum albumin-MnO2 composite nanosheets (OsNPs-BSA-MnO2) were synthesized by loading Os NPs on BSA-MnO2 nanosheets. The Os NPs well dispersed on the surface of the nanosheets. The composite exhibited specific peroxidase-like activity with negligible oxidase-like activity. The catalytic mechanism was proved due to the generation of ·OH. Steady-state kinetics revealed stronger affinity for both H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB) substrate. Interestingly, OsNPs-BSA-MnO2 composite nanosheets exhibited a much lower activation energy than other osmium-based nanozymes, indicating superior catalytic performance. Moreover, ascorbic acid could effectively inhibit the catalytic activity of composite nanosheet. Thus, a colorimetric method for ascorbic acid detection was established with the limit of detection (LOD) of 1.69 μM and excellent selectivity. For practical application, ascorbic acid in Water-soluble C100 and fetal bovine serum was detected with satisfactory recoveries.

In this study, lysine protected silver nanoclusters (Lys-AgNCs) were prepared and the mimetic property was systematically investigated. The nanoclusters displayed oxidase-like and peroxidase-like activity for the catalytic oxidation of 3, 3', 5, 5'-tetramethylbenzidine (TMB). Interestingly, the nanozyme property could be tuned by adjusting the pH or temperature. In the low pH (3.6-4.2), oxidase-like activity is predominant. In the high pH(4.2-5.4), peroxidase- like activity is the main activity. In the lower temperature (20-40 °C), oxidase-like activity is predominant. Importantly, the Lys-AgNCs showed stronger affinity for TMB. The activation energy of Lys-AgNCs was lower than bare Ag nanoclusters, indicating a faster reaction rate. In addition, a detection method for Hg2+ was designed based on the aggregation enhanced peroxidase-like activity of lysine-Ag nanocluster with limit of detection (LOD) of 0.004 μM. The sensing assay exhibited excellent selectivity owing to the specific interaction between lysine and Hg2+ and can be used in tap water with an acceptable recovery rate. Considering the cost-effective of this method, it is proposed to be used in practical application.

Detection of trypsin is crucial for human health. In this work, bovine serum albumin-protected osmium-silver nanoclusters were prepared. The silver content in the nanoclusters could be regulated by controlling the reagent concentration. Ultraviolet-visible absorption spectra of 3,3',5,5'-tetramethylbenzidine and its oxidized form were used to investigate the catalytic activity of the nanoclusters. All nanoclusters displayed peroxidase-like activity. Especially, the bovine serum albumin-protected osmium-silver nanoclusters with 20

Belite sulfoaluminate cement is attracting increasing attention and being considered as a potential alternative to ordinary Portland cement owing to lower preparation temperature and carbon dioxide (CO2) emission. However, it still has disadvantages of poor workability and low early strength. This study investigated the effects of compound polycarboxylate superplasticiser (PCE) and early strength agent, calcium nitrite (Ca(NO2)2), on flowability and early strength of belite calcium sulfoaluminate (BCSA) cement. Variation patterns of setting time, fluidity, strength and polycarboxylate superplasticiser (PCE) adsorption of the paste were measured; the hydration products and microscopic morphology were also analysed by the heat of hydration, X-ray diffraction and scanning electron microscopy. Results showed that calcium nitrite effectively enhanced adsorption of PCE onto the surface of BCSA cement particles, leading to notable improvement in the fluidity of the paste (reaching up to 275 mm). In the initial hydration stage, 0.7% PCE compounded with 1.2% calcium nitrite inhibited the formation of ettringite (AFt), resulting in prolonged setting time. However, it deepened the degree of hydration of BCSA for 3 days and refined the hydration product, AFt crystals. Consequently, the compressive strength was increased to 95.75 MPa and 107.13 MPa for BCSA cement at 3 days and 28 days, respectively.

Metal organic framework (MOF)-derived nanostructures display remarkable characteristics and have broad application potential. Os@ZIF-8 nanocomposites were prepared by a depositional method. The Os nanoparticles distributed on the surface of ZIF-8. The nanocomposites displayed enhanced peroxidase-like activity with smaller Km for both 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 compared to Os NPs due to the confinement effect and large surface area that ZIF-8 provided. From the average reaction rate constants obtained from three different temperatures, the activation energy values were determined. The kinetic data indicated that the Os@ZIF-8 NCs are catalytically more active than Os NPs. In addition, quantitative measurement of Hg2+ was performed based on the formation of Os-Hg alloy. Os@ZIF-8 NCs had a wide detection range between 0 μM and 71.43 μM for Hg2+ with a limit of detection (LOD) of 2.29 μM. Using a MOF with a large surface area to load Os nanoparticles to achieve enhanced nanozyme activity is the novelty of this work.

In this study, Os/Ag nanoparticles (Os/Ag NPs) with smaller Km and almost five times Vmax compared to Os NPs were prepared. This not only reduced the cost of nanozyme, but also improved the catalytic ability. Addition of L-Cysteine or glutathione (GSH) resulted in inhibitory effect on the peroxidase-like activity of Os/Ag nanozyme. Therefore, the L-Cysteine and GSH could be detected by absorption spectra method with limit of detection (LOD) of 0.22 mu M and 0.2 mu M, respectively. Moreover, a colorimetric sensing system for L-Cysteine and GSH based on portable paper strip and smartphone was fabricated with LOD of 1.72 mu M and 1.4 mu M, respectively. Furthermore, this method can be used in fetal bovine serum with recovery rates ranging from 89.42% to 109.0%. The sensing system exhibited good selectivity. This proposed colorimetric sensing assay holds great potential application in the detection of biothiols when no sophisticated equipment are available.Graphical abstractScheme illustration for the colorimetric detection of L-Cysteine and GSH by use of smartphone

The development of efficient blue thermally activated delayed fluorescence (TADF) emitters with an aggregation-induced emission (AIE) nature, for the construction of organic light-emitting diodes (OLEDs), is still insufficient. This can be attributed to the challenges encountered in molecular design, including the inherent trade-off between radiative decay and reverse intersystem crossing (RISC), as well as small singlet-triplet energy splitting (Delta E ST) and the requirement for high photoluminescence quantum yields (phi PL). Herein, we present the design of three highly efficient blue TADF molecules with AIE characteristics by combining pi-extended donors with different acceptors to modulate the differences in the electron-donating and electron-withdrawing abilities. This approach not only ensures high emission efficiency by suppressing close pi-pi stacking, weakening nonradiative relaxation, and enhancing radiative transition but also maintains the equilibrium ratio between the triplet and singlet excitons by facilitating the process of RISC. These emitters exhibit AIE and TADF properties, featuring quick radiative rates and low nonradiative rates. The phi PL of these emitters reached an impressive 88%. Based on their excellent comprehensive performance, nondoped PICzPMO and PICzPMO OLEDs achieved excellent electroluminescence performance, exhibiting maximum external quantum efficiency (EQEmax) of up to 19.5%, while the doped device achieved a higher EQEmax of 20.8%. This work demonstrated that by fusing pi-extended large rigid donors with different acceptors, it is possible to regulate the difference in electron-donating and electron-withdrawing abilities, resulting in a small Delta E ST, high phi PL, and fast RISC process, which is a highly feasible strategy for designing efficient TADF molecules.

Belite sulfoaluminate cement is attracting increasingly attention and considered as a prospective alternative to Ordinary Portland cement (OPC) owing to the lower preparation temperature and CO2 emission. However, it still has disadvantages of poor workability and low early strength. Accordingly, this study investigated the effect of compound polycarboxylate superplasticizer (PCE) and early strength agent, calcium nitrite (Ca(NO2)2), on the flowability and early strength of BCSA cement. The variation patterns of setting time, fluidity, strength and PCE adsorption of the paste were measured. Furthermore, the hydration products and microscopic morphology were analyzed by the heat of hydration, X-ray diffraction analyzer and scanning electron microscope. The results showed that Ca(NO2)2 effectively enhanced the adsorption of PCE onto the surface of BCSA cement particles, leading to a notable improvement in the fluidity of the paste (reaching up to 275 mm). In the initial hydration stage, 0.7% PCE compounded with 1.2% Ca(NO2)2 inhibited the formation of ettringite (AFt), resulting in prolonged setting time. However, it deepened the hydration degree of BCSA for 3d and refined the hydration product, AFt crystals. Consequently, the compressive strength has been increased to 95.75 MPa and 107.13 MPa for BCSA cement at 3d and 28d, respectively.

A novel method is presented for drastically improving the local surface plasma resonance (LSPR) effect of noble metal nanoparticles (NPs) and nanoclusters (NCs). This is realized by magnetizing particles comprising a ferri-magnetic core and a noble metal nanoshell. In this study, we prepared Fe3O4 @SiO2 @Ag composite particles. Ag NPs and NCs had the size of 10-15 nm and 2-3 nm, respectively. The photoluminescence (PL) intensities of ZnO and YAG:Ce substrates coated with the magnetic composite particles increased by 160 % and 50 %, respectively, after magnetization under a magnetic field of 18 mT compared to the unmagnetized state. The activity of Ni-foam-based-Fe3O4 @SiO2 @Ag working electrode for water electrolysis was also significantly improved after magnetization. The increasing rate of current density after magnetization was 226 mA & BULL;cm  2/0.1 V, which is higher than 158 mA & BULL;cm  2/0.1 V before the magnetization. The mechanism for drastic performance enhance-ment of PL and water electrolysis postulates that after magnetization, the remanence of the ferrimagnetic Fe3O4 core provides a local magnetic field to strengthen the local electric field in the confined area of Ag NPs/NCs. It was confirmed by the higher intensity of peaks in Raman spectroscopy and contributed to the enhancement of LSPR effect. This efficient and practical approach to magnetization-induced LSPR improvement has potential application prospects in LSPR-related fields.

Ternesite (4CaO center dot 2SiO(2)center dot CaSO4)-Ye'elimite (3CaO center dot 3Al(2)O(3)center dot CaSO4) (simplified as TY) cement clinker was successfully prepared from steel slag at 1200 degrees C in this study. XRD, TG/DSC and SEM were used to analyze the mineral composition and hydration products of the TY clinker. The sintering process and hydration mechanism of the TY clinker were investigated. Results show that a large amount of ternesite and ye'elimite have been formed at 1200 degrees C, while ternesite has not been decomposed. Clinker minerals include ternesite, ye'elimite, gypsum and a small amount of iron phase. Iron phase from steel slag can promote the formation of liquid phase with the presence of gypsum at 1200 degrees C and thus lead to the coexistence of ternesite and ye'elimite. The compressive strength of TY cement cured at 28 d is 59.5 MPa, which is higher than that of P. II 42.5 cement. This research provides a sustainable and energy-effective way for the reutilization of steel slag, an otherwise valueless waste.

基于Hg 2+ 对明胶-金纳米粒子（G-AuNPs）类过氧化物酶活性的增强作用，构筑了一种新型的Hg 2+ 传感器。所制备G-AuNPs 具有类氧化物酶活性和类过氧化物酶活性，表现为能够催化O 2 或H 2 O 2 氧化3，3，5，5’-四甲基联苯胺（TMB）生成氧化TMB（oxTMB）的反应，在652 nm处出现紫外可见吸收特征峰。对影响类过氧化物酶活性的实验参数进行优化，获得最佳反应条件。通过稳态动力学研究获得米氏常数K m 分别为 0.70 mmol/L(H 2 O 2 为底物)和0.78 mmol/L（TMB为底物）。Hg 2+ 能够增强G-AuNPs的类过氧化物酶活性，使吸收信号升高，且升高幅度与Hg 2+ 浓度呈线性关系，在0～15 μmol/L和15～35 μmol/L范围内的线性方程分别为y=1.314+0.0135x和y=0.704+0.055x，检出限为1.65 μmol/L。该传感体系对Hg 2+ 具有良好的选择性，其它常见金属离子不干扰对Hg 2+ 的检测。所设计传感器具有无需修饰、检测时间短、选择性好的优点，有望用于现场污染水中Hg 2+ 的检测。

Twisted rigid structures combined with short conjugation length building blocks provide an effective molecular design strategy for deep blue (CIE y < 0.1) aggregation-induced emission and thermally activated delayed fluorescence emitters.

A low-temperature-fabrication of Ag nanowires (NWs) was introduced for cost cutting and safety. Nucleating at room temperature (RT) for about 6 h and growing at 50-70 degrees C favored the formation of Ag NWs with the aspect ratio of more than 1000. The preferred growth mechanism of Ag NWs was the stacking of (2 2 0) or (2 (2) over bar 0) planes, which were the twinning planes of high-density twin crystals. Coating the as-prepared Ag NWs on the surface of SnO2 transparent semiconductor film and heat treating the bilayer film at 200-300 degrees C, the adhesion property and conductive performance of SnO2 film were significantly enhanced.

A label-free sensing strategy based on the enzyme-mimicking property of Glutathione-Ag nanoparticles (GSH-AgNPs) was demonstrated for colorimetric detection of vitamin B1 (VB1). Firstly, obvious blue color accompanied with an absorption peak at 652 nm was observed due to the high peroxidase-like activity of GSH-AgNPs towards 3,3',5,5'-tetramethylbenzidine (TMB). Then, in the presence of VB1, the mimetic activity of GSH-AgNPs could be strongly restrained, evidenced as a promiment colorimetric change to colorless, which can be used to achieve the visualization detection VB1. Linear relationship between absorbance response and VB1 concentration from 0 to 0.2 µM were obtained. The detection limit was calculated as low as 40 nM. The inhibition reasons were thoroughly discussed. Considering the advantages of rapid response, easy procedure and high selectivity, the proposed method possesses potential application in environment and biological analysis for VB1 detection.

精氨酸修饰银纳米材料可作为一种新型探针,用于重金属汞离子的灵敏和选择性检测.精氨酸修饰银纳米材料具有过氧化物酶样活性,汞离子能够增强其催化活性,使吸收峰信号增强,从而实现汞离子的定量检测.与其他金属离子相比,该传感器对汞离子显示出良好的选择性.所制备的精氨酸修饰银纳米材料无须任何处理即可直接用于检测体系,大大简化了检测流程.总之,该传感器具有简单、快捷等优点,可作为汞离子检测的有力工具.

Abnormal levels of glutathione (GSH) and glutathione oxidized (GSSG) usually relates to some diseases, thus quantifying the amount of GSH or GSSG is of great significance. A label-free sensing assay based on the enzyme-mimicking property of Cytidine-Au nanoclusters (Cy-AuNCs) was demonstrated for colorimetric detection of GSH, GSSG and glutathione reductase (GR). Firstly, obvious blue color accompanied with an absorption peak at 652 nm was observed due to the high peroxidase-like activity of Cy-AuNCs toward 3,3',5,5'-tetramethylbenzidine (TMB). Then, in the presence of target, the mimetic activity of Cy-AuNCs could be strongly inhibited and used to achieve the visualization detection. The inhibition effect arose from the surface interaction between GSH and Cy-AuNCs. Linear relationships between absorbance response and concentration were obtained between 0 and 0.4 mM for GSH, 0-2.5 mM for GSSG and 0-0.2 U/mL for GR. The limit of detection (LOD) was calculated as low as 0.01 mM, 0.03 mM and 0.003 U/mL for GSH, GSSG and GR, respectively. Furthermore, the proposed method displayed rapid response, easy procedure and high selectivity. (C) 2020 Elsevier B.V. All rights reserved.

High-color purity organic emitters with a simultaneous combination of aggregation-induced emission (AIE) and thermally activated delayed fluorescence (TADF) characteristics are in great demand due to their excellent comprehensive performances toward efficient organic light-emitting diodes (OLEDs). In this work, two D-π-A-structure emitters, ICz-DPS and ICz-BP, exhibiting AIE and TADF properties were developed, and both the emitters have narrow singlet (S1)-triplet (T1) splitting (ΔEST) and excellent photoluminescence (PL) quantum yields (ΦPL), derived from the distorted configurations and weak intra/intermolecular interactions, suppressing exciton annihilation and concentration quenching. Their doped OLEDs based on ICz-BP provide an excellent electroluminescence external quantum efficiency (ηext) and current efficiency (ηC) of 17.7% and 44.8 cd A-1, respectively, with an ηext roll-off of 2.9%. Their nondoped OLEDs based on ICz-DPS afford high efficiencies of 11.7% and 30.1 cd A-1, with pure-blue emission with Commission Internationale de l'Éclairage (CIE) coordinates of (0.15, 0.08) and a low roll-off of 6.0%. This work also shows a strategy for designing AIE-TADF molecules by rational use of steric hindrance and weak inter/intramolecular interactions to realize high ΦPL values, fast reverse intersystem crossing process, and reduced nonradiative transition process properties, which may open the way toward highly efficient and small-efficiency roll-off devices.

基于L-半胱氨酸(L-Cysteine)对壳聚糖-金纳米粒子(CS-AuNPs)过氧化物酶样活性的抑制,构建了一种新型、简单和灵敏的半胱氨酸传感器.CS-AuNPs具有过氧化物酶样活性,表现为在H2O2存在下,能够使3,3',5,5'-四甲基联苯胺(TMB)发生氧化生成蓝色产物.半胱氨酸能明显抑制其活性,加入半胱氨酸后,体系颜色变浅,在波长652 nm处吸收值降低.利用过氧化物酶样活性的降低,设计了一种灵敏度高、选择性好的检测半胱氨酸的比色传感器.结合紫外-可见吸收光谱,检测限低至0.4 μmol/L,低于细胞中半胱氨酸的正常水平(30～200μmol/L).讨论了半胱氨酸抑制催化活性的机理.该传感器具有无需修饰、检测步骤少、肉眼观察方便等优点,在分析和生物技术领域具有潜在的应用价值.

聚乙烯亚胺保护的金纳米粒子(PEI-AuNP)可作为一种新型比色探针,用于I-的检测.碘化物能够诱导PEI-AuNP聚集,使溶液从红色逐渐变成黑色,通过颜色变化可以初步判断碘化物浓度.同时,聚集引起的吸光度变化与I-的浓度成正比,可实现定量分析.检测限和线性范围分别为0.8 μmol/L和0 ～ 57μmol/L.与其他干扰离子相比,该传感器对I-显示出良好的选择性.所制备的PEI-AuNP无需任何处理即可直接用于检测体系,简化了检测流程,可用于I-定量检测.

Nanomaterial-based artificial peroxidase has attracted extensive interests due to their distinct advantages over natural counterpart. Cu@Au/Pt and Cu@Ag/Pt nanocomposite with rambutan-like structure were prepared and discovered to function like peroxidase, which was illustrated by catalyzing the oxidation reaction of 3,3',5,5'-tetramethylbenzidine (TMB) accompanied with a blue color change. Steady-state investigation indicates that the catalytic kinetics of Cu@Au/Pt and Cu@Ag/Pt all followed typical Michaelis-Menten behaviors and Cu@Au/Pt showed a strong affinity for H2O2, while Cu@Ag/Pt showed strong affinity for TMB. The color change and absorbance intensity strongly depend on the concentration of H2O2, thus the direct determination of H2O2 and indirect detection of glucose were demonstrated using Cu@Au/Pt with a detection limit of 1.5 μM and 6 μM, respectively. What is more important, the method was applied for detection of glucose in 50% fetal bovine serum with a detection limit of 80 μM, which is much lower than the lowest glucose content in blood for diabetes (7 mM). Moreover, the Cu@Au/Pt nanocomposite were also successfully applied for sensing l-cysteine because of the inhibition effect. Considering the good peroxidase-like activity and novel structure, Cu@Au(Ag)/Pt is expected to have a wide range of applications in bioassays and biocatalysis.