A one‐pot method for synthesis of reduced graphene oxide‐supported Cu–Cu2O and catalytic application in tandem reaction of halides and sodium azide with terminal alkynes

Reduced graphene oxide (RGO)‐supported Cu–Cu₂O nanocomposite material (Cu‐Cu₂O@RGO) was prepared through a one‐pot reflux synthesis method. The morphology, crystal structure and composition of the prepared Cu‐Cu₂O@RGO were characterized using transmission electron microscopy, X‐ray diffraction, and X‐ray photoelectron, infrared and Raman spectroscopies. Cu‐Cu₂O@RGO as a heterogeneous catalyst was applied to tandem reactions of halides and sodium azide with terminal alkynes to synthesize effectively 1,4‐disubstituted 1,2,3‐triazoles. Moreover, the catalyst showed excellent recyclability performance with very little leaching of the metal. Compared with homogeneous catalysts, Cu‐Cu₂O@RGO as a green and efficient catalyst was recoverable, easy to separate and highly stable in the tandem method for the synthesis of 1,2,3‐triazole compounds.     

Highly efficient oxidation of 2-imidazoline-5-carboxylic derivatives to imidazole-5-carboxylic derivatives by dioxygen

A highly efficient and environmental-benign oxidation by dioxygen (or air) as the sole oxidant was first applied for the conversion of 2-imidazoline-5-carboxylic derivatives to imidazole-5-carboxylic derivatives in very good and excellent yields. The substituent effect on 2-imidazoline ring was investigated. This protocol was also suitable for the synthesis of 2-imidazoles in relatively large scale.     

Surface modification of PDMS by surface-initiated atom transfer radical polymerization of water-soluble dendronized PEG methacrylate

The current paper reports the synthesis of a highly hydrophilic, antifouling dendronized poly(3,4,5-tris(2-(2-(2-hydroxylethoxy)ethoxy)ethoxy)benzyl methacrylate) (PolyPEG) brush using surface initiated atom transfer radical polymerization (SI-ATRP) on PDMS substrates. The PDMS substrates were first oxidized in H₂SO₄/H₂O₂ solution to transform the Si-CH₃ groups on their surfaces into Si-OH groups. Subsequently, a surface initiator for ATRP was immobilized onto the PDMS surface, and PolyPEG was finally grafted onto the PDMS surface via copper-mediated ATRP. Various characterization techniques, including contact angle measurements, attenuated total reflection infrared spectroscopy, and X-ray photoelectron spectroscopy, were used to ascertain the successful grafting of the PolyPEG brush onto the PDMS surface. Furthermore, the wettability and stability of the PDMS-PolyPEG surface were examined by contact angle measurements. Anti-adhesion properties were investigated via protein adsorption, as well as bacterial and cell adhesion studies. The results suggest that the PDMS-PolyPEG surface exhibited durable wettability and stability, as well as significantly anti-adhesion properties, compared with native PDMS surfaces. Additionally, our results present possible uses for the PDMS-PolyPEG surface as adhesion barriers and anti-fouling or functional surfaces in biomedical applications.     

离子色谱脉冲安培法测定蜂蜜中的葡萄糖、果糖、蔗糖

利用离子色谱脉冲安培检测器对蜂蜜中葡萄糖、果糖、蔗糖的测定方法进行了研究。采用CARBOPAC^TM PAl分离柱和脉冲安培检测器,对淋洗分离条件进行了实验,选择50mmol/L NaOH作淋洗液,可使蜂蜜中的葡萄糖、果糖、蔗糖很好地分离。检出限分别为：葡萄糖2μg/kg,果糖2μg/kg,蔗糖5μg/kg。加标回收率为90％－108％。该方法只需简单的前处理、无基体干扰,分离效果好,测定准确率高,适用于蜂蜜中葡萄糖、果糖、蔗糖的测定。     

DNA‐Based Adaptive Plasmonic Logic Gates

Self‐assembled plasmonic logic gates that read DNA molecules as input and return plasmonic chiroptical signals as outputs are reported. Such logic gates are achieved on a DNA‐based platform that logically regulate the conformation of a chiral plasmonic nanostructure, upon specific input DNA strands and internal computing units. With systematical designs, a complete set of Boolean logical gates are realized. Intriguingly, the logic gates could be endowed with adaptiveness, so they can autonomously alter their logics when the environment changes. As a demonstration, a logic gate that performs AND function at body temperature while OR function at cold storage temperature is constructed. In addition, the plasmonic chiroptical output has three distinctive states, which makes a three‐state molecular logic gate readily achievable on this platform. Such DNA‐based plasmonic logic gates are envisioned to execute more complex tasks giving these unique characteristics.     

Palladium(II)-catalyzed oxidative Heck coupling of thiazole-4-carboxylates

Oxidative Heck coupling of thiazole-4-carboxylates via palladium(II)-catalyzed C-H bond activation has been achieved in moderate to good yields. No ligand, and no acidic additive were used in the reaction. The results showed that this protocol tolerated a series of substitutions on the thiazole ring. A preliminary attempt of direct arylation with p-xylene via Pd(II)-catalyzed C-H bond activation has also been done.     

Electrogenerated chemiluminescence biosensing for the detection of prostate PC-3 cancer cells incorporating antibody as capture probe and ruthenium complex-labelled wheat germ agglutinin as signal probe

A highly selective and sensitive electrogenerated chemiluminescence (ECL) biosensor for the detection of prostate PC-3 cancer cells was designed using a prostate specific antibody as a capture probe and ruthenium complex-labelled wheat germ agglutinin as a signal probe. The ECL biosensor was fabricated by covalently immobilising the capture probe on a graphene oxide-coated glassy carbon electrode. Target PC-3 cells were selectively captured on the surface of the biosensor, and then, the signal probe was bound with the captured PC-3 cells to form a sandwich. In the presence of tripropylamine, the ECL intensity of the sandwich biosensor was logarithmically directly proportion to the concentration of PC-3 cells over a range from 7.0 × 10² to 3.0 × 10⁴ cells mL⁻¹, with a detection limit of 2.6 × 10² cells mL⁻¹. The ECL biosensor was also applied to detect prostate specific antigen with a detection limit of 0.1 ng mL⁻¹. The high selectivity of the biosensor was demonstrated in comparison with that of a lectin-based biosensor. The strategy developed in this study may be a promising approach and could be extended to the design of ECL biosensors for highly sensitive and selective detection of other cancer-related cells or cancer biomarkers using different probes.     

Preparation and in vitro properties of redox-responsive polymeric nanoparticles for paclitaxel delivery

Rice-like polymeric nanoparticles (NPs) composed of a new redox-responsive polymer, poly(ethylene glycol)-b-poly(lactic acid) (MPEG-SS-PLA), were prepared to carry paclitaxel (PTX) for glutathione (GSH)-regulated drug delivery. The PTX-loaded MPEG-SS-PLA NPs were fabricated using an optimized oil-in-water emulsion/solvent evaporation method. The size and morphology of the prepared NPs were characterized by scanning electron microscopy (SEM). The SEM results demonstrate that the NPs were dispersed as individual particles and were rice-shaped. The PTX loading efficiency, in vitro release, and stability of the NPs were analyzed by high-performance liquid chromatography (HPLC). The HPLC results revealed that the NPs released almost 90% PTX within 96 h when GSH presented at intracellular concentrations, whereas only a very small PTX amount was released at plasma GSH levels. The in vitro cytotoxicities of the NPs against A549, MCF-7, and HeLa carcinoma cells were assessed using a standard methyl thiazolyl tetrazoliun (MTT) assay. The MTT assay results show that the NPs caused concentration- and time-dependent changes in cell viability. To investigate the cellular uptake of the PTX-loaded NPs, visual endocytosis assay was performed using the fluorescent dye coumarin-6 as a model drug. The endocytosis assay results reveal rapid penetration and intracellular accumulation of coumarin-6-loaded NPs, as well as rapid coumarin-6 dispersion from the NPs. Overall, these findings establish that the NPs containing the synthesized redox-responsive polymer MPEG-SS-PLA can be used as potential carrier systems for antitumor drug delivery.     

非晶合金条带的爆炸焊接

 报道了利用爆炸焊接技术对铁基、铁镍基非晶合金条带（厚度约25 μm）进行单层和多层爆炸焊接的结果。金相分析结果表明，条带间相互结合良好；X光衍射结果说明，焊接后的条带仍保持非晶态，即使采用表面已有部分晶化德条带进行焊接，焊接后仍转化为非晶态。这说明在焊接过程中条带表面已发生熔化，且冷却速度也可达10⁶ K/s量级。     

Synthesis of Giant π-Extended Molecular Macrocyclic Rings as Finite Models of Carbon Nanotubes Displaying Enriched Size-Dependent Physical Properties

Bottom-up synthesis of π-extended macrocyclic carbon rings is promising for constructing length- and diameter-specific carbon nanotubes (CNTs). However, it is still a great challenge to realize size-controllable giant carbon macrocycles. Herein, a tunable synthesis of curved nanographene-based giant π-extended macrocyclic rings (CHBC[n]s; n=8, 6, 4), as finite models of armchair CNTs, is reported. Among them, CHBC[8] contains 336 all-carbon atoms and is the largest cyclic conjugated molecular CNT segment ever reported. CHBC[n]s were systematically characterized by various spectroscopic methods and applied in photoelectrochemical cells for the first time. This revealed that the proton chemical shifts, fluorescence, and electronic and photoelectrical properties of CHBC[n]s are highly dependent on the macrocycle diameter. The tunable bottom-up synthesis of giant macrocyclic rings could pave the way towards large π-extended diameter- and chirality-specific CNT segments.