Enzymetically Regulating the Self‐Healing of Protein Hydrogels with High Healing Efficiency

Enzyme‐mediated self‐healing of dynamic covalent bond‐driven protein hydrogels was realized by the synergy of two enzymes, glucose oxidase (GOX) and catalase (CAT). The reversible covalent attachment of glutaraldehyde to lysine residues of GOX, CAT, and bovine serum albumin (BSA) led to the formation and functionalization of the self‐healing protein hydrogel system. The enzyme‐mediated protein hydrogels exhibit excellent self‐healing properties with 100 % recovery. The self‐healing process was reversible and effective with an external glucose stimulus at room temperature.     

De Novo Design of an Endohedral Heteronuclear Dimetallofullerene (UGd)@C60 with Exceptional Structural and Electronic Properties

Ever since the first synthesis of La@C₈₂ and U@C₂₈, there has been a growing interest in the study of endohedral metallofullerenes (EMFs) because of their great potential in various applications. Here we design a novel heteronuclear EMF (U‐Gd)@C₆₀, by using density functional theory (DFT), which shows an encapsulation energy of about ?5.53 eV, comparable to that of U₂@C_60, La₂@C₈₀, and Lu₂@C₇₆. (U‐Gd)@C₆₀ is found to have a surprising twofold, single‐electron U?Gd bond that results from the strong nanoconfinement of the fullerene, dominated by uranium′s 5f and 6d and gadolinium′s 5d atomic orbitals. The ground state shows an 11‐et high spin state, and the net spins distributed on the U‐pole carbons are relatively scattered, while they are highly concentrated on the Gd‐pole carbons. The exceptional electronic characteristics of this novel EMF, containing both uranium and gadolinium atoms encapsulated, might prove useful for future applications in nuclear energy and biomedicine.     

Ultra‐performance liquid chromatography coupled with electrospray ionization/quadrupole time‐of‐flight mass spectrometry for the rapid analysis of constituents in the traditional Chinese medical formula Danggui San

In this work, ultra‐performance LC with ESI quadrupole TOF‐MS (UPLC–ESI‐Q‐TOF‐MS) and automated MetaboLynx analysis was used to rapidly separate and identify the chemical constituents of Danggui San, a traditional Chinese medical formula. The analysis was performed on a Waters UPLC BEH C₁₈ column using a gradient elution system. A hyphenated ESI and Q‐TOF analyzer was used for the determination of the accurate mass of the protonated or deprotonated molecule and fragment ions in both positive and negative modes. Based on retention times, accurate mass, and the mass spectrometric fragmentation characteristics, a total of 47 compounds distributed over the chemical groups of phthalides, flavonoids, monoterpene glycosides, sesquiterpenoids, phenolics, and alkaloids, were simultaneously separated within 18 min and identified or tentatively elucidated in Danggui San for the first time. UPLC–ESI‐Q‐TOF‐MS analysis revealed the complexity of the chemical composition of this formula. The method developed is rapid, accurate, reliable, and highly sensitive to characterize the chemical constituents of Danggui San.     

石墨烯层数测量方法的研究进展

石墨烯具有高导电性、高韧度、高强度、超大比表面积等特点,在电子、航天工业、新能源、新材料等领域有广泛应用。对石墨烯层数测量方法的研究有助于深入理解石墨烯性能与微观结构之间的关系。本文着重阐述了包括光学显微镜、拉曼光谱、原子力显微镜和透射电镜等测量石墨烯层数的方法,同时比较了各种测量方法的优点及局限性,并指出石墨烯层数的测量方法还有待进一步完善。     

Low‐Background,Highly Sensitive DNA Biosensor by Using an Electrically Neutral Cobalt(II) Complex as the Redox Hybridization Indicator

An electrically neutral cobalt complex, [Co(GA)₂(phen)] (GA=glycollic acid, phen=1,10‐phenathroline), was synthesized and its interactions with double‐stranded DNA (dsDNA) were studied by using electrochemical methods on a glassy carbon electrode (GCE). We found that [Co(GA)₂(phen)] could intercalate into the DNA duplex through the planar phen ligand with a high binding constant of 6.2(±0.2)×10⁵ M ^?1. Surface studies showed that the cobalt complex could electrochemically accumulate within the modified dsDNA layer, rather than within the single‐stranded DNA (ssDNA) layer. Based on this feature, the complex was applied as a redox‐active hybridization indicator to detect 18‐base oligonucleotides from the CaMV35S promoter gene. This biosensor presented a very low background signal during hybridization detection and could realize the detection over a wide kinetic range from 1.0×10^?14 M to 1.0×10^?8 M , with a low detection limit of 2.0 fM towards the target sequences. The hybridization selectivity experiments further revealed that the complementary sequence, the one‐base‐mismatched sequence, and the non‐complementary sequence could be well‐distinguished by the cobalt‐complex‐based biosensor.     

Synthesis,Physical Properties,and Anion Recognition of Two Novel Larger Azaacenes: Benzannelated Hexazaheptacene and Benzannelated N,N′‐Dihydrohexazaheptacene

Two novel larger azaacenes with six or ten N atoms in their backbones, benzannelated 9,11,13,22,24,26‐hexazatetrabenzo[a,c,l,n]heptacene ( HATBH , 1 ) and benzannelated 9,26‐dihydro‐9,11,13,22,24,26‐hexaza‐tetrapyrido[3,2‐a: 2′,3′‐c: 3′′,2′′‐l: 2′′′,3′′′‐n]heptacene ( DHATPH, 2 ), have been successfully synthesized in two steps. The theoretical band gaps estimated through DFT calculations for HATBH ( 1 ) and DHATPH ( 2 ) are 1.949 eV and 2.278 eV, which are close to the experimentally obtained optical band gaps (2.14 eV and 2.39 eV). Interestingly, HATBH ( 1 ) can act as efficient anion sensor for F^? and H₂PO₄^?, while DHATPH ( 2 ) selectively responds to F^? among the ten different anions used (F^?, Cl^?, Br^?, I^?, PF₆^?, HSO₄^?, NO₃^?, BF₄^?, AcO^?, and H₂PO₄^?). Our synthetic strategy could offer a promising and easy way to obtain even larger azaacenes.     

Ultrasonic Preparation of Hierarchical Graphene‐Oxide/TiO2 Composite Microspheres for Efficient Photocatalytic Hydrogen Production

Hierarchical graphene oxide (GO)‐TiO₂ composite microspheres with different GO/TiO₂ mass ratios were successfully prepared by mixing GO and TiO₂ microspheres under ultrasonic conditions. Ultrasonication helped the GO and TiO₂ microsphere to uniformly mix on the microscale. The results showed that the GO‐TiO₂ composites that were prepared by ultrasonic mixing exhibited significantly higher hydrogen‐evolution rates than those that were synthesized by simple mechanical grinding, owing to synergetic effects, including enhanced light absorption and scattering, as well as improved interfacial charge transfer because of the excellent contact between the GO sheets and TiO₂ microspheres. In addition, GO‐TiO₂‐3 (3 wt. % GO) showed the highest hydrogen‐generation rate (305.6 μmol h^?), which was about 13 and 3.3‐times higher than those of TiO₂ microsphere and GO‐P25 (with 3 wt. % GO), respectively. Finally, a tentative mechanism for hydrogen production is proposed and supported by photoluminescence and transient photocurrent measurements. This work highlights the potential applications of GO‐TiO₂ composite microspheres in the field of clean‐energy production.     

Malathion detection method using microhotplate-based preconcentrator and ion mobility spectrometer

A simple and rapid method using a microhotplate-based preconcentrator and an ion mobility spectrometer (IMS) is proposed for the detection of malathion in water. The preconcentrator is prepared by micro-electro-mechanical system (MEMS) process. Coated with Polydimethylsiloxane (PDMS), it has the advantages of solvent-less, low energy cost, self-heating and ease to combine with IMS. The operating conditions of the preconcentrator-IMS system, such as extraction time, extraction temperature, agitation speed and desorption temperature, were optimised. Using the preconcentrator, the sampling procedure can be simplified and the detection limit of the system can be decreased. A linear relationship between the IMS response and the concentration of the analyte solution was verified. The malathion detection limit based on 3 times the baseline noise is 0.43?µg?L^?1 and the total analysis time is less than 30?minutes.     

双态发光三苯胺基有机硼配合物的设计、合成与应用

以三(4-溴苯)胺、4-氨基苯硼酸频哪醇酯、4-二乙氨基水杨醛和三氟化硼乙醚溶液为原料,经过Suzuki偶联反应、缩合反应和配位反应,设计、合成了一种新型三枝结构的三苯胺有机硼配合物(TPAB),使用 ¹H和 ¹³C NMR对 TPAB的结构进行了表征,通过紫外可见吸收光谱和荧光发射光谱详细研究了TPAB溶液和固体态的光物理性能以及不同的外部条件对其发光性能的影响。发现 TPAB溶液和固体态都具有较强的荧光发射,在四氢呋喃溶液中的吸收峰位于 417 nm,发射峰位于 548 nm,荧光量子产率为 40.49%,荧光寿命为 1.72 ns;TPAB 固体的荧光发射峰位于 582 nm,荧光量子产率为 11.43%,荧光寿命为 0.72ns,表明TPAB具有优良的双光发光性能。此外,TPAB具有良好的发光稳定性,不受pH、金属离子、氨基酸和压力的影响。基于化合物优异的发光性能,将其应用于荧光细胞成像,在肝癌细胞(HepG2)中表现出良好的单光子和双光子荧光成像效果。     

Highly oxidized graphene with enhanced fluorescence and its direct fluorescence visualization

We prepared hyper-oxidized graphene (HOG) as a form of graphene derivative by additional oxidation of graphene oxide (GO) sheets. HOG, which formed more functional groups and isolated conjugated clusters on the sheets, accordingly showed high solubility in water and alcohols, high transmittance and film transparence, longer fluorescence decay constant time, and enhanced fluorescence in states of solution and solid. By contrast, GO has much weaker fluorescence in solution and its fluorescence is totally quenched in solid. The influences of concentration, metallic ions, and pH on HOG fluorescence in aqueous solution were also investigated in detail. Due to HOG’s strong fluorescence, direct visualization was realized on substrates and in solution. In addition, direct 3D fluorescence visualizations of HOG phase in polymer composites were achieved. These results show the great potential of HOG in a broad range of applications, from biological labeling, probes, and drug carriers to high-performance composites and nanomanipulation.