A novel fluorescent probe for formaldehyde based-on monomer-excimer conversion and its imaging in live cells

A novel fluorescent probe was developed for formaldehyde, which can be synthesized by one-step Buchwald–Hartwig reaction. When hydrazino-group of probe reacted with formaldehyde, hydrophobic reaction product aggregates into nanoparticles and results in the blue fluorescence due to the monomer-excimer effect. With enough sensitivity, high selectivity, good stability in physiological pH range and excellent biocompatibility, this probe can image formaldehyde in living cells.     

A coumarin based highly selective fluorescent chemosensor for sequential recognition of Cu2+ and PPi

In this study, we have successfully synthesized a new coumarin based fluorescent chemosensor 1, in which tren and quinolone are introduced as receptors for sequential recognition of Cu²⁺ and PPi. The structure of chemosensor 1 was characterized by ¹H NMR, ¹³C NMR and ESI-HR-MS. Sensor 1 showed an obvious “on-off” fluorescence quenching response toward Cu²⁺, and the quenching efficiency reached a maximum of 99.6% with the addition of 20 equiv. of Cu²⁺. The 1-Cu²⁺ complex showed an “off-on” fluorescence enhancement response toward PPi over many competitive anions, especially HPO₄^2? and H₂PO₄^?. The detection limit of sensor 1 was 1.9?×?10^?6?M to Cu²⁺ and 5.96?×?10^?8?M to PPi. In addition, sensor 1 showed a 1:1 binding stoichiometry to Cu²⁺ and sensor 1-Cu²⁺ showed a 2: 1 binding stoichiometry to PPi in CH₃CN/HEPES buffer medium (9:1 v/v, pH?=?7.4). The stable pH range of sensor 1 to Cu²⁺ and 1-Cu²⁺ to PPi was from 4 to 8.     

Electrochemical Reduction of Carbon Dioxide to Methanol on Hierarchical Pd/SnO2 Nanosheets with Abundant Pd–O–Sn Interfaces

Electrochemical conversion of CO₂ into fuels using electricity generated from renewable sources helps to create an artificial carbon cycle. However, the low efficiency and poor stability hinder the practical use of most conventional electrocatalysts. In this work, a 2D hierarchical Pd/SnO₂ structure, ultrathin Pd nanosheets partially capped by SnO₂ nanoparticles, is designed to enable multi‐electron transfer for selective electroreduction of CO₂ into CH₃OH. Such a structure design not only enhances the adsorption of CO₂ on SnO₂, but also weakens the binding strength of CO on Pd due to the as‐built Pd–O–Sn interfaces, which is demonstrated to be critical to improve the electrocatalytic selectivity and stability of Pd catalysts. This work provides a new strategy to improve electrochemical performance of metal‐based catalysts by creating metal oxide interfaces for selective electroreduction of CO₂.     

On the mechanism of microporous carbon supercapacitors

Microporous carbon shows the highest supercapacitor performance among other carbon nanomaterials, and thus, is considered as the most promising candidate for the fabrication of high-performance supercapacitors. However, it has puzzled the researchers as micropores do not have enough space for the formation of the so-called double layer. Several models have been proposed to explain the mechanism of energy storage by microporous supercapacitors. The most common one is that the micropores are initially filled by both anions and cations, and charging/discharging is via ion-exchange through these single row-filled micropores. Although this theory has been supported by several computational calculations, it is discussed here that this model is in disagreement with the experimental facts commonly accepted in the literature.     

Electrochemically controlled fiber‐in‐tube solid‐phase microextraction method for the determination of trace amounts of antipsychotic drugs in biological samples

In this study, a novel ‘fiber‐in‐tube’ configuration was applied to electrochemically controlled fiber‐in‐tube solid‐phase microextraction of antipsychotic drugs (perphenazine and chlorpromazine) from biological samples. To prepare an electrochemically controlled fiber‐in‐tube solid‐phase microextraction column, first eight stainless‐steel wires were placed into the stainless‐steel column. Then, a nanostructured Cu‐Cr‐Al ternary layered double hydroxide/polythiophene coating was prepared on the inner surface of the stainless‐steel tube and on the surfaces of the stainless‐steel wires by a facile in situ electrodeposition method. The nanostructured coating exhibited enhanced long lifetime, good mechanical stability, high porosity, and large specific surface area compared with polythiophene and Cu‐Cr‐Al layered double hydroxide coatings. Under the optimal conditions, the limits of detection were in the range of 0.07–0.8 μg/L. This method showed good linearity for perphenazine and chlorpromazine in the ranges of 0.3–300 and 0.2–300 μg/L, respectively, with coefficients of determination more than 0.9982. The inter‐ and intra‐assay precisions (RSD%, n = 3) were in the ranges of 3.0–5.1 and 2.5–4.5% at three concentration levels of 5, 25 and 50 μg/L, respectively. Finally, the method was applied for the analysis of the drugs in human urine and plasma samples.     

高性能多级花状Co3O4基无酶葡萄糖电化学传感器

以硝酸钴、碳酸钠、尿素为原料,泡沫镍为基体,采用水热和煅烧相结合的二步法制备了一种多级花状Co_3O_4/Ni异质结构的无酶葡萄糖传感器。通过X射线衍射与扫描电镜对Co_3O_4/Ni电极的成分及形貌进行了表征,并采用循环伏安法在1mol/L KOH溶液中测试了Co_3O_4/Ni异质结构葡萄糖传感器电极的电化学性能。结果表明,通过二步法在泡沫镍表面制备的Co_3O_4呈现多级花状纳米纤维结构。将制备的Co_3O_4/Ni异质结构作为电极构建的无酶葡萄糖传感器表现出响应时间快(低于5s)、检测灵敏度高(7.4m A·(mmol/L)~(-1)·cm~(-2))、检出限低(1.17μmol/L,S/N=3)和线性检测范围宽(0~5 mmol/L)的特点。进一步的抗干扰性检测表明所制备的传感器在+0.44V vs.SCE对葡萄糖表现出良好的选择性。本文所制备的多级花状Co_3O_4基电极在无酶葡萄糖传感器的发展中有着很大的应用潜力。     

Design,synthesis and evaluation of a novel fluorescent probe to accurately detect H2S in lysosomes

A novel H₂S-responsive fluorescent probe Rh-Lyso-H₂S has been designed and synthesized. The Rh-Lyso-H₂S shows high sensitivity and selectivity toward H₂S, with a limit of detection of 3.36?×?10^?7?M. The reason is that Rh-Lyso-H₂S changed from a stable non-conjugated closed-ring lactone conformation with weak fluorescence to a conjugated open-ring conformation with strong fluorescence in the presence of H₂S. The Rh-Lyso-H₂S has a good lysosome-targeting capacity and is used to detect lysosomal H₂S in living cells, which is driven via the protonation of its basic morpholine moiety by acidic lysosomes. Rh-Lyso-H₂S is triggered by H₂S via removing the thiophenecarboxylate group, and the corresponding activated mechanism of Rh-Lyso-H₂S toward H₂S is proposed.     

Ovalbumin-stabilized gold nanoclusters with ascorbic acid as reducing agent for detection of serum copper

Ovalbumin-stabilized gold nanoclusters(OVA@AuNCs) were prepared with ascorbic acid as a reducing agent. This strategy could realize the synthesis of water-soluble OVA@AuNCs within 20 min. The asprepared fluorescent probe showed a red fluorescence emission at 630 nm. Moreover, the properties of the OVA@AuNCs were characterized by transmission electron microscope, dynamic light scattering,ultraviolet-visible spectroscopy, fluorescent spectroscopy. Based on the surface electron density decrease-induced fluorescence quenching mechanism, the OVA@AuNCs provided high sensitivity and selectivity for sensing copper ions. A good linear relationship was obtained between the fluorescence intensity of OVA@AuNCs and the concentration of copper ions in the range of 5.0-100.0 μmol/L(R~2=0.999) with a detection limit of 640 nmol/L Furthermore, the rat serum copper contents were determined by using the OVA@AuNCs based assay, indicating great potential of fluorescent probes for application in biological and clinical analysis.     

Synthesis of 1,8-naphthalimide-based fluorescent nano-probes and their application in pH detection

Fluorescent nano-probes with particle sizes of 20 nm, 120 nm and 300 nm for proton were prepared through click reaction. The photophysical properties of the nano-probes were mainly affected by the particle size.     

Small-molecule fluorescent probes for the detection of carbon dioxide

This review summarizes the design principles, recognition mechanisms, properties and functions of various kinds of small-molecule fluorescent probes for the detection of carbon dioxide