Search

The metal–organic framework (MOF-74) series has the most open metal sites. The metal ions have different bonding strengths with the ligand in MOF-74 and the bond of the ligand can be successively broken to obtain highly active heteroparticles by controlling the temperature, which is difficult to achieve using traditional methods. Magnetic NiCo/Fe3O4-MOF-74, which is fabricated using trimetallic NiCoFe-MOF-74 as a precursor, is simple and rational in comparison with the traditional magnetic core and tunable MOF shell hybrid composites that are formed using a step-by-step assembly strategy. After thermal treatment under a specific atmosphere, NiCo/Fe3O4-MOF-74 shows higher stability, strong magnetism and more active metal sites compared to the original MOF. NiCo/Fe3O4-MOF-74 shows excellent enrichment capability for the removal of tetracycline, with a high removal efficiency that reached 94.1% within 5 min, which is much higher than that of NiCoFe-MOF-74. The main interaction between the adsorbent and analyte is most likely attributed to the open metal sites that can form a stable metal–ligand with the antibiotic molecules. Furthermore, the material can be reused five times without considerable loss. The prepared material has potential applications for removing antibiotics with high efficiency at low cost. Therefore, the experiments described in this study provide a route to a broad class of MOF-based materials for detecting organic contaminants. [ABSTRACT FROM AUTHOR]

Herein, a simple strategy for constructing activity-controllable nanozymes is proposed based on the glutathione (GSH)-gated surface chemistry of citrate-capped Pt nanoparticles (PtNPs). PtNPs have been shown to have oxidase-like activity that can effectively catalyze the oxidation of 3,3′,5,5′-tertamethylbenzidine (TMB) by O2, resulting in a typical color reaction from colorless to blue. We found that GSH can inhibit the oxidase-like activity of PtNPs as a molecule-gated surface chemistry element, resulting in a dramatic decrease of the oxidation of TMB. The addition of copper ions (Cu2+) could oxidize GSH into glutathione disulfide (GSSG), resulting in the distinct suppression of GSH-modulated PtNP surface chemistry and oxidase-like activity inhibition, which further results in a significant acceleration of TMB oxidation and the obvious recovery of intense blue color. Furthermore, the color-based detection signal associated with the redox of TMB indicator here was found to show good fluorescence and a photothermal effect and exhibit sensitive and selective response toward the proposed molecule-gated surface chemistry and Cu2+ target. On the basis of this phenomenon, we successfully constructed a three-in-one sensor for Cu2+ with a triple signal readout, colorimetric, photothermal (temperature), and fluorescence, depending on the proposed in situ modulation method for PtNP catalysis. The applicability of the three-in-one sensor was also demonstrated by measuring Cu2+ in human serum with a standard addition method, and the results are of satisfactory accuracy as confirmed by ICP-MS measurements. [ABSTRACT FROM AUTHOR]

Surface recombination at the photoanode/electrolyte junction seriously impedes photoelectrochemical (PEC) performance. Through coating of photoanodes with oxygen evolution catalysts, the photocurrent can be enhanced; however, current systems for water splitting still suffer from high recombination. We describe herein a novel charge transfer system designed with BiVO4 as a prototype. In this system, porphyrins act as an interfacial‐charge‐transfer mediator, like a volleyball setter, to efficiently suppress surface recombination through higher hole‐transfer kinetics rather than as a traditional photosensitizer. Furthermore, we found that the introduction of a "setter" can ensure a long lifetime of charge carriers at the photoanode/electrolyte interface. This simple interface charge‐modulation system exhibits increased photocurrent density from 0.68 to 4.75 mA cm−2 and provides a promising design strategy for efficient photogenerated charge separation to improve PEC performance. [ABSTRACT FROM AUTHOR]

Surface recombination at the photoanode/electrolyte junction seriously impedes photoelectrochemical (PEC) performance. Through coating of photoanodes with oxygen evolution catalysts, the photocurrent can be enhanced; however, current systems for water splitting still suffer from high recombination. We describe herein a novel charge transfer system designed with BiVO4 as a prototype. In this system, porphyrins act as an interfacial‐charge‐transfer mediator, like a volleyball setter, to efficiently suppress surface recombination through higher hole‐transfer kinetics rather than as a traditional photosensitizer. Furthermore, we found that the introduction of a "setter" can ensure a long lifetime of charge carriers at the photoanode/electrolyte interface. This simple interface charge‐modulation system exhibits increased photocurrent density from 0.68 to 4.75 mA cm−2 and provides a promising design strategy for efficient photogenerated charge separation to improve PEC performance. [ABSTRACT FROM AUTHOR]

We herein presented a mesoporous cellular foam solid‐phase microextraction coating that showed highly sensitive recognition for weakly polarity polychlorinated biphenyls in water samples. The mesoporous cellular foam coater fiber was for the first time prepared by a simple sol‐gel method. The main experimental parameters including extraction temperature, extraction time, desorption time, stirring rate, and ionic strength were investigated by high‐efficiency orthogonal array design, a L16 (44) matrix was applied for the identification of optimized extraction parameters, and the optimized method was successfully applied to the analysis of environmental water sample. The novel mesoporous cellular foam coated fibers exhibited sensitive limits of detection (0.07–0.28 µg/L), wide linearity (5–3000 µg/L), and good reproducibility (3.5–8.3% for single fiber, and 4.9–8.7% for fiber‐to‐fiber) for polychlorinated biphenyls. The home‐made coating was successfully used in the analysis of polychlorinated biphenyls in real environmental water samples. These results indicate that the synthesized mesoporous cellular foams are promising materials for adsorption and separation applications in sample pretreatment. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new multichannel healing strategy is proposed for fast healing structural damage. • The TiO 2 -CDs-FeOOH smart platform shows remarkable catalytic activity and stability for degradation of organic contaminant. • Multiple electron transfer behavior leads to fast conversion of Fe(III)/Fe(II). • Multichannel healing procedure and MET kinetic information are unveiled by SECM. Abstract Catalyst deactivation derived from slow conversion of Fe(III)/Fe(II) is the critical problem restricting catalytic efficiency of advanced oxidation. Herein, a novel multichannel healing strategy is proposed for fast healing structural damage by designing rationally smart platform (TiO 2 -CDs-FeOOH hollow sandwich hybrid). This ingenious system shows remarkable catalytic activity (0.77 min−1) and stability towards the removal of organic contaminants. Systematic studies confirm that the excellent catalytic activity is attributed to multiple electron transfer (MET) behavior at interface between photocatalytic substrate and FeOOH, leading to highly efficient interfacial charge separation and then fast recovery of Fe(II) on FeOOH surface during H 2 O 2 activation process. Notably, multichannel healing procedure and MET kinetic information are unveiled by UV–vis/scanning electrochemical microscopy (SECM) through an in situ probe scanning technique. A higher ET rate constant k eff (0.92 × 10-2 cm s-1) was revealed over TiO 2 -CDs-FeOOH, two times that of TiO 2 -FeOOH, further confirming that multi-channel electron transfer could achieve fast Fe(III)/Fe(II) conversion. This work offers a new insight to design highly efficient catalysts for the practical applications of sustainable environmental remediation and energy conversion. [ABSTRACT FROM AUTHOR]

Porphyrins, as significant electrochemical luminaries, have garnered extensive attention due to their distinctive structure and superior photoelectric properties in recent years. However, the potential aggregation resulting from water insolubility in aqueous phases, as well as its inherent instability and weaker Q-band, continue to pose challenges for the electrochemiluminescence (ECL) applications of porphyrins. This review provides a comprehensive summary of different strategies aimed at achieving high efficiency of porphyrin in ECL and signal amplification. Finally, a critical perspective and future prospects regarding the developmental trends of porphyrins are presented. • Porphyrin-based luminophores were summarized. • Auxiliary strategies for signal amplification were discussed. • A critical perspective and future prospects regarding the developmental trends of porphyrins was presented. [ABSTRACT FROM AUTHOR]

Here, a unique triple-layered core-shell structure (Au@N-CQDs@Pt) with an Au metal core, nitrogen-doped carbon quantum dots interlayer, and metal Pt outside shell was obtained by chemical reduction of HAuCl 4 and H 2 PtCl 6 in the presence of N-CQDs. The remarkable advantage of the method reported here is no any stabilizer or surfactant agent involved. The results of transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS) reveal that the as-prepared nanocomposites exhibit the nanostructured dendritic Pt and the quantity of Pt shell can be easily changed through controlling the synthesis time. Specifically, Au@N-CQDs@Pt displays excellent catalytic activity toward methanol oxidation reaction in alkaline condition than Au-Pt without N-CQDs, which indicate the useful application of CQDs in designing new catalysts to be used in direct methanol fuel cells. Schematic of the Au@N-CQDs@Pt preparation process and it application for methanol electrooxidation. Image 1 • Pt nanoparticles were supported on Au@N-CQDs to form core-shell structure. • Au@N-CQDs@Pt shows superior catalytic activities for methanol oxidation reaction. • Enhanced catalytic activities roots in the multibenefits from the adding of N-CQDs. [ABSTRACT FROM AUTHOR]

This paper proposes an adjustable-speed permanent magnet eddy-current coupling with a non-rotary mechanical flux adjuster (MFA) to regulate the speeds of large pump and fan for energy saving. The slip speed of the proposed coupling can be adjusted by shifting MFA along the axial direction. The structural feature and operation principle of the coupling are illustrated and addressed. A magnetic equivalent circuit model is established for analyzing the electromagnetic characteristics of the coupling efficiently. The air-gap magnetic fields, eddy-current densities, and torque–slip characteristics are investigated under different shifting distances of MFA, which reveals the fairly good torque regulation effects. The torque regulation range reaches to about 90% of the maximum torque, which indicates that the coupling can achieve a large speed regulation range by using the relatively simple approach. [ABSTRACT FROM AUTHOR]

• Three-dimensional magnetic nanocomposite was used as the sorbent of MSPE. • The nanocomposite exhibited a good enrichment capability. • The fluoroquinolone antibiotics were absorbed within 2 min. • The method was applied to analysis of real samples with high sensitivity. Recently, water pollution caused by antibiotics is rapidly increasing. Thus, developing efficient, fast and sensitive detection methods for environmental antibiotics monitoring are still remaining elusive. Herein, a method for antibiotics analysis including lecofloxacin, pazcofloxacin and gatifloxacin in water by high performance liquid chromatography (HPLC) using molybdenum disulfide-graphene oxide-supported magnetic nanoparticles (Fe 3 O 4 /GO/MoS 2) as the adsorbent of magnetic solid-phase extraction was developed. The as-prepared magnetic Fe 3 O 4 /GO/MoS 2 nanocomposite exhibited good enrichment capability toward fluoroquinolone antibiotics and the analytes were absorbed within a short time ca. 2 min. The main drive forces of Fe 3 O 4 /GO/MoS 2 nanocomposite and antibiotics were most likely attributed to hydrogen bonding and electrostatic attraction. A sensitive and effective MSPE-HPLC method was developed with low detection limits (LODs) ranging from 0.25 to 0.50 ng mL−1. The recoveries obtained from the analysis of water sample were between 85.6% and 106.1% with relative standard deviations (RSDs, n = 5) lower than 9.5%. The developed method has a good potential for the analysis of organic contaminants in water with low cost and high sensitivity. Therefore, this finding is a promising strategy for designing high efficiency and fast antibiotics detection system. [ABSTRACT FROM AUTHOR]

Highly efficient detection in the aqueous phase for water‐insoluble organic molecule probes is challenging. The bright aggregated‐state electrochemiluminescence (ECL) of 1,1‐disubstituted 2,3,4,5‐tetraphenylsiloles by a co‐reactant approach was discovered, and a heterogeneous aggregation‐induced emission ECL (HAIE‐ECL) was constructed at the electrode surface, showing very high ECL efficiency (37.8 %) and selective recognition for industrially important DNBP plasticizer with a low detection limit of 0.15 nm in the water phase. A mechanistic study indicates that ECL is mainly generated due to the high electron affinity of siloles and restriction of the intramolecular motions caused by their propeller‐like noncoplanar structures. This system realizes the sensing of organic‐based ECL in the water phase by solving the crucial problems of water insolubility and aggregation‐caused quenching (ACQ), and demonstrates potential for further application because of its design and high efficiency. A heterogeneous aggregation‐induced emission electrochemiluminescence (HAIE‐ECL) system with high ECL efficiency has been developed according to the AIE strategy. This system can detect a widely used plasticizer, DNBP, in the aqueous phase, and solve water insolubility and aggregation‐caused quenching (ACQ) in small organic molecule probe systems. [ABSTRACT FROM AUTHOR]

Highly efficient detection in the aqueous phase for water‐insoluble organic molecule probes is challenging. The bright aggregated‐state electrochemiluminescence (ECL) of 1,1‐disubstituted 2,3,4,5‐tetraphenylsiloles by a co‐reactant approach was discovered, and a heterogeneous aggregation‐induced emission ECL (HAIE‐ECL) was constructed at the electrode surface, showing very high ECL efficiency (37.8 %) and selective recognition for industrially important DNBP plasticizer with a low detection limit of 0.15 nm in the water phase. A mechanistic study indicates that ECL is mainly generated due to the high electron affinity of siloles and restriction of the intramolecular motions caused by their propeller‐like noncoplanar structures. This system realizes the sensing of organic‐based ECL in the water phase by solving the crucial problems of water insolubility and aggregation‐caused quenching (ACQ), and demonstrates potential for further application because of its design and high efficiency. [ABSTRACT FROM AUTHOR]

Enzyme-mimicking (nanozyme)-based biosensors are attractive owing to their unique catalytic efficiency, multifunctionality, and tunable activity, but examples of oxidase-like nanozymes are quite rare. Herein, we demonstrated that histidine-capped gold nanoclusters (His@AuNCs) possessed intrinsic oxidase-like activity, which could directly oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to blue colored ox-TMB without H2O2. The assembly of reduced graphene oxide (RGO) with His@AuNCs could further improve its oxidase-like activity and the His@AuNCs/RGO nanocomposites had a lower Michaelis constant (Km) and higher catalytic constant (Kcat) for TMB oxidation. Furthermore, compared to other nanomaterials, the as-prepared His@AuNCs/RGO also exhibited enhanced electrocatalytic activity toward TMB. Interestingly, nitrite inhibited the catalytic (chromogenic) and electrocatalytic processes of His@AuNCs/RGO in the oxidation of TMB. The oxidase-like and electrocatalytic activity of His@AuNCs/RGO was evaluated with nitrite and TMB as substrates, and the results indicated that TMB and nitrite might share the same catalytic active sites. On the basis of these findings, a colorimetric and electrochemical sensor was developed with the His@AuNCs/RGO composite as an oxidase mimic for determination of nitrite with linear ranges of 10–500 μM and 2.5–5700 μM, respectively. The developed method was successfully applied to the detection of nitrites in real samples. The present work suggests that the oxidase-like nanozyme is not only suitable for colorimetric assay but also for development of electrochemical sensors in bioanalysis. Graphical abstract The colorimetric and electrochemical detection of nitrite using His@AuNCs/RGO. [ABSTRACT FROM AUTHOR]

Abstract Immoderate intake of nitrite (NO 2 −) is deleterious human health and may result in causing dangerous diseases. In this study, nitrite detection system was successfully fabricated based on a unique diazo-coupling reaction of p‑Aminobenzoic acid (PABA) and phloroglucinol (1, 3, 5‑trihydroxybenzene). Upon the presence of NO 2 − in an acid medium, p‑Aminobenzoic acid could not only form diazonium ion easily but also couple with p‑Aminobenzoic acid, and results forming yellow water-soluble azo dye that shows maximum absorption at 434 nm. Under the further accurate determination condition, such as acid concentration, amount of reagents and time required, the naked-eye detection of NO 2 − showed excellent selectivity in compared with some anions. Especially, diazotization and coupling reaction proposed here is very fast and control of pH and temperature are unnecessary. Moreover, the color is stable for several days and Beer's law is obeyed over a wide range. Reliable detection can be made in the range of 0.05 to 1 p.p.m. of nitrite ion. Detection limit was calculated to be 0.024 p.p.m. (0.52 μ M) by UV–visible spectroscopy and 0.05 p.p.m. (1.09 μ M) by naked-eye. By using an electrochemical method, IR, SEM, and 1HNMR, the sensing mechanism can be easily verified. More importantly the proposed method was successfully applied for the determination of nitrite in a real water sample. Highlights • Simple rapid nitrite detection based on diazo-coupling reaction in acidic medium is proposed. • Color change observed by naked eye within low concentration of nitrite. • System is selective for nitrite among several common ions. • System is applicable for nitrite analysis in real samples. [ABSTRACT FROM AUTHOR]

Abstract A novel non-enzymatic superoxide anion radical (O 2 •−) sensor was prepared by silver nanoparticles (AgNPs) decorated organic frameworks (MOFs) compound-derived metal oxide coated carbon material. Transmission electron microscopy (TEM) was employed to characterize morphologies and structures of the as-prepared samples AgNPs/Co 3 O 4 @C. Electrochemical studies indicated that the AgNPs/Co 3 O 4 @C/GCE exhibited excellent detection ability to O 2 •−. It offered a linear range of 8 orders of magnitude and a super low detection limits of 0.0564 pM. The sensor was successfully adapted to detection of O 2 •− released from living cells. Furthermore, the capacities of scavenging O 2 •− of food antioxidants were also studied by electrochemical method at cellular milieu. Accordingly, this work provided tremendous potential for reduction incidence of oxidative stress by intaking food antioxidants. Graphical abstract A sensitive non-enzymatic sensor for superoxide anion (O 2 •-) detection is constructed based on silver nanoparticles (AgNPs) and metal organic frameworks (MOFs) compound-derived metal oxide coated carbon material. The sensor could be applied to determination of O 2 •- released from living cells and estimation of O 2 •− scavenging activity of some food antioxidants. fx1 Highlights • A novel nanocomposite AgNPs/Co 3 O 4 @C was prepared. • Fabricated a novel non-enzymatic sensing platform based on the nanocomposites. • The sensor exhibits excellent performance with a super low detection limit of 0.0564 pM. • The sensor was used for detecting the superoxide anion released from living cells. • The capacities of scavenging O 2 •− of food antioxidants were also studied at cellular milieu. [ABSTRACT FROM AUTHOR]

Abstract This paper developed a sensitive method for detecting hydroquinone by combining the unique optical properties of quantum dots and the specificity of enzymatic reactions. The interesting results shown that the fluorescence of graphite phase carbon nitride quantum dot (g-CNQDs) was quenched directly by benzoquinone or indirectly by hydroquinone (H 2 Q), and the possible quenching mechanism was proposed. Quinone might generate by catalyzing the oxidation of H 2 Q with horseradish peroxidase (HRP) in the presence of hydrogen peroxide. The intermediate quinone could effectively quench the fluorescence of g-CNQDs quantum dots. Therefore, a novel fluorescence probe based on g-CNQDs Quantum Dots was successfully used to detect H 2 Q by strongly quenching the fluorescence of g-CNQDs Quantum Dots which mediated by horseradish peroxidase enzymes. The detection limit was as low as 0.04 μM (S/N = 3), and the linear range was 0.5–11.6 μM. This kind of quantum dot-enzyme system has the advantages of simple operation, no modification of quantum dots, low cost, high sensitivity and short detection time. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract A novel Estrone (E1) molecularly imprinted polymers (MIPs-E1)-coated solid-phase microextraction (SPME) fiber was prepared by in-situ polymerization on inner and outer surface of the capillary, namely MIPs-E1-coated in-out-tube SPME (MIPs-E1-IOT-SPME), which combines the advantages of enhanced extraction efficiencies of IOT-SPME and specific adsorption abilities of MIPs, and shows nearly double enrichment capacity compared to in-tube SPME (IT-SPME). The extraction conditions were optimized and a method for determination six endocrine disrupting compounds (EDCs) by MIPs-E1-IOT-SPME coupled with HPLC is developed. The MIPs-E1 coating was characterized by fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), N 2 adsorption-desorption and Thermal gravimetric analysis (TGA). Under the optimum condition, the MIPs-IOT-SPME-HPLC method shows low limits of detection (LODs) (0.21–0.80 μg L−1) and limits of quantification detection (LOQs) (0.69–2.6 μg L−1), wide linear ranges from 10.0 to 1000 μg L−1 for each compound with exception of E2 and E3 from 20.0 to 1000 μg L−1, and acceptable reproducibility of one fiber for five parallel determinations is 2.4–6.6% (RSD) and fiber-to-fiber is 4.5–8.1% (RSD). The satisfactory recoveries are in the range of 88.5–105.1% with good RSDs less than 7.9% at the five spiked levels of 20.0, 50.0, 80.0, 200.0 and 500.0 μg L−1. Moreover, when compared with commercial fibers, the MIPs-E1-IOT-SPME fiber displays excellent adsorption capacity and specific selectivity. Graphical abstract fx1 Highlights • An Estrone (E1) molecularly imprinted polymers-coated solid-phase microextraction fiber was prepared. • The novel SPME fiber was constructed by in-situ polymerization on inner and outer surface of the capillary. • The homemade SPME fiber shows double enrichment capacity and excellent specific selectivity compared to commercial fibers. [ABSTRACT FROM AUTHOR]

Abstract In this study, the characteristic of the designed porphyrin sensitizer was studied by density functional theory (DFT) and time-dependent density functional theory (TDDFT). D-π-A sequence of seven donor-acceptor dyes A-F in the organic dye-sensitized solar cell (DSSCs) was analyzed. Firstly, the structure and frequency of porphyrin dyestuffs with different substituents were optimized by DFT method, and the structure and properties of the ground state of porphyrin dyes were studied by comparing the energy differences of different orbitals. Then, the TDDFT method was used to study the porphyrin molecules with different π bridge. The structure and properties of the excited state are discussed in terms of the energy and charge separation state of the molecular orbital of the porphyrin sensitizer. According to the absorption spectrum, the characteristic of the light absorption for the sensitizer molecule is investigated. The results shown that the key characteristic parameters closely related to the open circuit photovoltage (V OC) and the short circuit current density (J SC) of the porphyrin sensitizers helped to clarify different π bridges. The change of V OC and J SC affected the energy level change of the porphyrin sensitizers with different π bridge. Finally, a suitable π bridge was selected as a porphyrin sensitizer candidate with higher conversion efficiency. Highlights • D-π-A type porphyrin sensitizers were designed. • The properties of dye sensitizers were evaluated by V OC , J SC and other parameters. • The results were helpful for designing new dye sensitizers with high IPCE. [ABSTRACT FROM AUTHOR]

A zeolitic imidazolate framework-8 (ZIF-8) incorporating a graphene oxide sponge (GOS) nanocomposite (ZIF-8–GOS) was synthesized successfully by a simple one-pot preparation method. Compared with the raw materials (ZIF-8 and GOS), the ZIF-8–GOS nanocomposite has a very large surface area (1660 m2 g−1), and super-high pore size (14.95 nm) and pore volume (6.21 cm3 g−1). Based on this, a method using ZIF-8–GOS for solid phase extraction (SPE)-high performance liquid chromatography (HPLC) was established for the analysis of five sex hormones in milk and milk products. The main experimental parameters that can affect the solid extraction process were optimized in detail. From a comparison of ZIF-8, GOS and commercial C18 SPE cartridges, the ZIF-8–GOS adsorbents showed the best compromise between selectivity and efficiency for target analytes. The analytical performance showed low limits of detection (0.52–2.11 µg L−1) and limits of quantification (1.75–6.97 µg L−1), as well as good linear ranges (10.0–3000 µg L−1 for most sex hormones except nandrolone, where the range was 5.0–3000 µg L−1) with remarkable linear correlation coefficients (r ＞ 0.9998). Excellent repeatability was also achieved through intra-day (RSD ＜ 0.39%) and inter-day (RSD ＜ 3.86%) experiments. When the proposed analytical approach was applied to milk and milk products, the results revealed satisfactory recoveries and sensitivities at trace level, with detection of some of the target compounds, which demonstrates the good application potential of the ZIF-8–GOS adsorbent in the trace analysis of organic contaminants. [ABSTRACT FROM AUTHOR]

Abstract In this work, we proposed a naked-eye colorimetric strategy for simultaneous detection of cysteine and lysine based on 3,3′,5,5′-tetramethylbenzidine (TMB) system in a neutral condition (pH 7.0). Based of the fact that Ag+ could oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to oxidized TMB (oxTMB) and induce a blue color solution corresponding to an absorption peak centered at 652 nm, thus the adding of cysteine or lysine to formation of different product results in the blue color fading to colorless quickly or change to scarlet, respectively. With this strategy, the limit of detection in experimental measurement for cysteine and lysine is 2.46 μM and 3.87 μM, respectively. And the selectivity can also be guaranteed among the other amino acid. The cost is quite low since the use of TMB and Ag+. More importantly, the colorimetric detection operation is very simple without any further modification process and the reaction under physiological conditions is more meaningful for detection of amino acid. Graphical abstract Image 1 Highlights • A sensitive nanomaterials-free colorimetric sensor was explored by using a facile strategy. • TMB colorimetric system for simultaneously detecting cysteine and lysine can be achieved in a mild aqueous solution. • TMB colorimetric system was successfully converted into INHIBIT/NOR logic gate and paper-based analytical devices. [ABSTRACT FROM AUTHOR]

Abstract A newly fluorescence probe for detection of Serotonin based on a Mn-doped ZnS quantum dots@silica nanoparticle@molecularly imprinted polymers (QDs@SiO 2 @MIPs) was successfully created. QDs@SiO 2 @MIPs were characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, UV spectroscopy, X-ray powder diffraction, and fluorescence spectroscopy. A complex was produced between the amino group of QDs@SiO 2 @MIPs and the hydroxyl group of 5-HT when 5-HT rebinding, the energy of the QDs would be transferred to the complex, which led to its fluorescence quenching. The composite material has a high selectivity with an imprinting factor of 5.96. The linear regression equation is F 0 /F = 0.0036Cq-0.0512 , with a correlation coefficient of 0.9928 in a liner range from 50 to 500 ng/mL. The limit of detection(LOD) was 0.69 ng/mL. The probe exhibited simple preparation process, high sensitivity, good selectivity, low detection limit, short analysis time and could be applied to detect 5-HT in human serum successfully. Graphical abstract A fluorescence probe for detection of Serotonin based on a Mn-doped ZnS quantum dots@silica nanoparticle@molecularly imprinted polymers (QDs@SiO 2 @MIPs) was designed. fx1 Highlights • A fluorescent probe for detecting 5-HT based on a Mn:ZnS QD@SiO 2 @MIPs was created. • The selectivity of this probe was validated via the molecular imprinting technique. • The probe could be applied to detect 5-HT in human serum successfully. [ABSTRACT FROM AUTHOR]

An approach for fabrication of graphene sponge (GS)-based solid-phase extraction (SPE) followed by high-performance liquid chromatography (HPLC) with ultraviolet detection (HPLC-UV) is proposed, which was applied to determine the six benzotriazole UV filters in water and cosmetic samples. Several extraction conditions including type of elution solvent, the volume of elution solvent, and salt effect were optimized. Under the optimum conditions, the GS-SPE-HPLC-UV method shows a low limit of detection (LOD, S/N = 3) of 0.02-0.08 μg L−1 for standard solution, limits of quantification (LOQ, S/N = 10) of 0.07-0.26 μg L−1 for standard solution, wide linear ranges from 20.0 to 1000 μg L−1 for all compounds for standard solution, correlation coefficients (r) of more than 0.999, except for 2-(2′-hydroxy-5′-methylphenyl)benzotriazole (UV-P), and acceptable reproducibility (relative standard deviations, RSDs < 6.5% for intra-day, RSDs < 8.1% for inter-day). The satisfactory recoveries were obtained in the range 89-105% with RSDs lower than 9.8% at the three spiked levels of 20, 50, and 100 μg L−1. Every home-made GS-SPE cartridge can be reused for more than 60 cycles. The method is facile, low-cost, rapid, sensitive, and suitable for the determination of UV filters in water and cosmetics samples.ᅟ [ABSTRACT FROM AUTHOR]

In the present work, the classical synthesis method of 5,10,15,20-(4-sulphonatophenyl) porphyrin (TPPS 4 ) was improved. The synthesis process became more environmentally friendly, and the yield was increased by 10%. We constructed a sensitive fluorescent sensor for detection hydrogen peroxide (H 2 O 2 ) and glucose (C 6 H 12 O 6 ) by using the hyperfluorescence of TPPS 4 . The TPPS 4 -Fe 3+ complex system of the sensor could generate electron transfer process (ET) in the process of hydrogen peroxide (H 2 O 2 ) and glucose oxidation, which quenched the TPPS 4 fluorescence. The system had a linear range of 0–42 μM for hydrogen peroxide, and the minimum detectable limit (LOD) was 1.24 nM (S/N = 3). Compared with other detection methods, the proposed method had the advantages of higher sensitivity, lower detection limit and more simple operation. [ABSTRACT FROM AUTHOR]

Three-dimensional NiCo 2 O 4 is a kind of superior sensing material owing to its high electron transfer capability, large available surface area and numbers of active sites. In this work, NiCo 2 O 4 of the three-dimensional chestnut-like structure were easily achieved through a one step hydrothermal process. Afterwards, the morphology and structure were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Based on the three-dimensional porous chestnut-like NiCo 2 O 4 , an electrochemical sensor for hydrazine (N 2 H 4 ) detection is fabricated. This electrochemical platform can realize good selectivity, excellent stability, high sensitivity (∼2154.4 μA mM -1  cm -2 ), and low detection limit (0.3 μM), as well as a wide linear range from 1 μM to 1096 μM. The synergistic effect of nickel-cobalt in such mixed transition metal oxides which Co in Co 3 O 4 is partially replaced by Ni are beneficial for enhancing sensing properties. This study proves that three-dimensional porous chestnut-like NiCo 2 O 4 is electrochemically active for catalytic performance which is particular and promising material for good application in the practical detection of N 2 H 4 . [ABSTRACT FROM AUTHOR]

The porphyrin aggregate is recognized as an attractive candidate for developing artificial light-harvesting systems. Using 5, 10, 15, 20-tetrakis-(4-carboxyphenyl) porphyrin (TCPP), the porphyrin aggregates with different morphologies (sphere, rod and flake) are controllably prepared by the surfactant-assisted self-assembly reaction, and then synthesize the ternary bionic-system (e.g. porphyrin composites). These composites are characterized by scanning-electron microscopy (SEM), atomic force microscope (AFM) and spectroscopic technology. The combinatorial technique consisted of ultraviolet–visible spectroscopy and scanning electrochemical microscopy (UV–vis/SECM) is used to record SECM approach curves of porphyrin photocatalysis under visible light illumination at the specific zones, where morphology-dependent porphyrin composite is recognized to be distributed evenly on ITO surface. Heterogeneous photoelectron transfer rates ( k eff ) are given by simulating SECM approach curves. It is suggested that rod-like porphyrin aggregate composite has highest photocatalytic efficiency with the kinetics rate to be 8.624 × 10 −2  cm s −1 , the largest k eff of which is obtained at the excitation wavelength of 469 nm. These findings are also proved by photocatalytic decomposition test of pollutants (methyl orange). It is indicated that one-dimensional nanostructure is advantageous for separation of electrons and holes and directional transmission of photoelectron. [ABSTRACT FROM AUTHOR]

In this paper, sulfonated nitrogen sulfur co-doped graphene (S-NS-GR) nanocomposite, i.e., nitrogen sulfur co-doped graphene functionalized with SO 3 H group as a novel catalyst support material was prepared. Pt Pd nanoparticles (Pt Pd NPs) were deposited on the surface of S-NS-GR by a facile electrochemical approach. The morphology and structure of Pd-PtNPs/S-NS-GR were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and electrochemical impedance spectroscopy (EIS), respectively. In addition, the electrocatalytic performance of catalyst for methanol oxidation reaction (MOR) was systematically studied by cyclic voltammetry and chronoamperometry in alkaline media. Compared with Pt Pd NPs supported on nitrogen sulfur co-doped graphene (Pt-PdNPs/NS-GR), the excellent performance of Pd-PtNPs/S-NS-GR is mainly ascribed to the embedding of abundant functional groups ( SO 3 H) into the NS-GR layers, which not only facilitate the homogeneous distribution of metal NPs, but also strengthen the interaction between metals and support material, thus improve the stability of catalyst in MOR. [ABSTRACT FROM AUTHOR]

Here, we report a nanocomposite composed of silver nanoparticles and multi-walled carbon nanotubes (AgNPs/MWNTs) utilized as an efficient electrode material for sensitive detection superoxide anion (O 2 •− ). The procedure to synthesize AgNPs/MWNTs nanocomposites was green and facile. In the presence of functionalized multi-wall carbon nanotubes (MWNTs), silver nanoparticles (AgNPs) were in situ generated by chemical reduction of silver nitrate with glucose as a reducing and stabilizing agent to give the desired AgNPs/MWNTs nanocomposites. The nanocomposites can be easily used for the construction of an electrochemical sensor on glassy carbon electrode (GCE). The characterization of sensor and experimental parameters affecting its activity were investigated employing scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), and cyclic voltammetry (CV). The resulted sensor exhibited favorable electrochemical performance for O 2 •− sensing with a low detection limit of 0.1192 nM and wide linear range of 6 orders of magnitude, which guarantees the capacity of sensitive and credible detection of O 2 •− released from living cells. Notably, a simulation experiment indicated the capacity to resist oxidative stress is limited in biological milieu. Thus this work has great potential for further applications in biological researches. [ABSTRACT FROM AUTHOR]

The development of highly selective homogeneous electron transfer reagents is highly desirable for synthetic chemistry. An isolable spirosilole tetra-anion described in this paper has been proved to be a promising soluble electron transfer reagent. The reduction of octaphenyl-1,1′-spirobisilole (1) with lithium resulted in the formation of the isolable spirosilole tetra-anion in good yield. The tetra-anion (2) has been characterized by nuclear magnetic resonance (NMR) and cleanly underwent electron transfer reactions with dioxygen, carbonyl groups, and transition metal halides to yield reduction products with the regeneration of 1. [ABSTRACT FROM AUTHOR]

A novel silyl-substituted bis(1, 1′-silolide) dianion has been isolated and characterized by single-crystal X-ray analysis for the first time. The 1H, 29Si, and 13C NMR spectra show significant delocalization of the negative charges to the silole ring. X-ray crystallography revealed equalized C−C distances and DFT calculation also indicates for significant aromaticity. Reaction with trimethylchlorosilane gave the expected bis(1, 2, 5-tris(trimethylsilyl)-3, 4-diphenyl-silacyclopentadienyl). [ABSTRACT FROM AUTHOR]

[Display omitted] • Proposes a cost-effective and efficient photochemical modification system, which introducing a BiVO 4 seed layer to improve photoelectrochemical (PEC) performance without any cocatalysts or sacrificial agents. And the photocurrent density of BiVO 4 seed layer with a thickness of 312 nm was improved by 40% to 0.99 mA cm−2 at 1.23 V RHE. • The BiVO 4 seed layer effectively inhibits the recombination of electron-hole pairs and improves the charge transfer efficiency , leading to a "slow" decrease in the current density of the composite photoanode from 32% to 9.8%. • Using the feedback model of the scanning photoelectrochemical microscopy (SPECM) to in-situ quantitatively study the hole transfer kinetics of BiVO 4 with different seed layer thicknesses, revealed that photoelectrode with a seed layer thickness of 312 nm have the highest kinetic rate constant (0.62 × 10−2 cm s−1), which is roughly 5 times of the pristine photoelectrode (0.11 × 10−2 cm s−1). Although the catalytic effect can be enhanced by using sacrificial agents, it still faces numerous difficulties in large-scale production applications. Investigating the improvement of photocatalytic efficiency without sacrificial agents is therefore crucial. This study proposes a cost-effective and efficient photochemical modification system that utilizes a seed layer of BiVO 4 to improve photoelectrochemical (PEC) performance, the result shows that the photocurrent density of BiVO 4 with a seed layer thickness of 312 nm was improved by 40% to 0.99 mA cm−2 at 1.23 V RHE without any sacrificial agent. Meanwhile, Electrochemical impedance spectroscopy (EIS) and intensity modulated photocurrent spectroscopy (IMPS) demonstrated that the introduction of the seed layer effectively prevents the recombination of electron-hole pairs and improves the charge transfer efficiency, leading to a "slow" decrease in the current density of the composite photoanode (from 32% to 9.8%) in combination with the linear sweep voltammetry (LSV) results. We exhibit the scanning photoelectrochemical microscopy (SPECM) method to in-situ quantitatively study the hole transfer kinetics with different seed layer thicknesses using the feedback model and find those photoelectrodes with a thickness of 312 nm has the highest kinetic rate constant of 0.62 × 10−2 cm s−1 which is approximately 5 times higher than that of the pristine photoelectrode (0.11 × 10−2 cm s−1). [ABSTRACT FROM AUTHOR]

Advanced oxidation processes (AOPs) are regarded as promising strategies for generating powerful oxygen-containing radicals that can degrade nearly all organic compounds. However, developing catalysts with highly active sites for carrying out AOPs is still a significant challenge. Herein, we design and synthesize of ultra-small cobalt nanoclusters with N, O-dual coordination (O-Co-N) on porous carbonized peat moss (CPM-Co-2) for the efficient catalytic purification of water through peroxymonosulfate (PMS)-based AOPs. Density functional theory calculations revealed that introducing O causes the d -band center of the O-Co-N configuration to shift away from the Fermi level, which significantly decreased the desorption energy of sulfate radicals (SO 4 •−) and accelerated the rate-limiting step to promote the reaction. The CPM-Co-2 showed excellent catalytic activity and stability in the remediation of organic pollutants and bacteria. The immensely increased catalytic activity achieved through regulating the metal coordination environment provided useful insights for the future design and synthesis of catalyst. [Display omitted] • Tuning the electronic structure of ultra-small nanoclusters using N, O-dual coordination. • Large scale, low cost, and repeatability of catalyst greatly enhance the practical application of AOPs. • The O-Co-N active site reduces the desorption capacity of SO 4 •− and increases the generation rate of reactive oxygen species. • Excellent catalytic activity and stability in the remediation of organic pollutants and bacteria. [ABSTRACT FROM AUTHOR]

Solar-driven evaporation is thought to be a fantastic strategy for freshwater generation, but the evaporated vapor inevitably accumulates volatile organic compounds (VOCs) in the initial wastewater, leading to secondary pollution of the condensed water. Here we demonstrate a dual-functional solar evaporator based on the graphite-N (g-N) doped biochar derived from biomass waste for simultaneous desalination and VOCs degradation. The doped g-N can activate potassium peroxomonosulfate (PMS) to produce plenty of singlet oxygen (1O 2) and thus decomposing VOCs, whereas numerous micropores can capture VOCs. Taking wood biomass waste as an example, its derived g-N doped wood carbon (g-N/WC) evaporator delivers a high degradation efficiency of ∼99.91 % toward VOCs (including phenol, Bisphenol A (BPA), 4,4′-Sulfonyldiphenol (BPS), and p-Chlorophenol (4-CP)), and a great evaporation rate of 1.31 kg m−2 h−1 under 1 sun. Life cycle assessment (LCA) results demonstrate that the environmental impacts across all categories and CO 2 emissions of the g-N/WC evaporator are reduced by up to 98 % and 82 %, respectively, compared with other emerging materials. The developed solar evaporator repurposes biomass waste to simultaneously solve water scarcity and waste mismanagement crises with an extremely low carbon footprint, representing a promising approach toward worldwide sustainable wastewater purification and biomass waste management. • All-in-one solar evaporator was designed for desalination and VOCs degradation. • Carbon footprint is reduced about 82 % comparing with other emerging materials. • Degradation efficiency is reached 99.9 % toward VOCs as the waste water evaporated. • Water treatment performance was well maintained for 7 days continuous test. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnFe 2 O 4 calcined at different temperatures effectively activated PI to degrade SMX. • Multiple active species existed in the 500-MFO/PI system, IO 3 • was the predominant. • Degradation pathway of SMX was proposed via HPLC-MC detection and DFT calculation. • Acute and chronic toxicity of the final by-products decreased via ECOSAR prediction. This study synthesized spinel MnFe 2 O 4 at different temperatures, which was applied to activate periodate (PI) for sulfamethoxazole (SMX) degradation. It was found that the 500-MFO (MnFe 2 O 4 calcined at 500 ℃) demonstrated superior activity in PI activation, with notable sustainability but strong substrate selectivity. Furthermore, a comprehensive analysis, including quenching experiment, electron paramagnetic resonance (EPR) technique, X-ray photoelectron spectroscopy (XPS) analysis, metal ions leaching detection, homogeneous PI activation, and methyl phenyl sulfoxide (PMSO) probe test, revealed that homo- and heterogeneous pathways as well as free and non-free radical routes coexisted in the 500-MFO/PI system. Multiple active species, including iodate radical (IO 3 •), hydroxyl radical (•OH), superoxide radical (O 2 •-), singlet oxygen (1O 2), and Mn(IV) were identified, with IO 3 • from heterogeneous activation being the primary species. When PMSO and SMX coexisted, PMSO could react with Mn(IV), promoting the regeneration of Mn reaction sites and the production of IO 3 •, thereby being beneficial for the degradation of SMX. The degradation pathways of SMX were elucidated through high-performance liquid chromatography-mass spectrometry (HPLC-MS) and density functional theory (DFT) calculation. The acute and chronic toxicity of thirteen by-products to aquatic organisms were predicted using the Ecological Structure Activity Relationships (ECOSAR) software, with the corresponding results revealing that although the toxicity of intermediates fluctuated, the final products were environmentally benign. Therefore, this investigation provides a viable method for SMX degradation in wastewater treatment. [ABSTRACT FROM AUTHOR]

The RGO/AuNPs/CS/ZnTCPP nanocomposites were successfully prepared with reduced graphene oxide (RGO) loaded with Au nanoparticles (AuNPs) existed in chitosan (CS) and water-soluble zinc meso-tetra (4-carboxylphenyl) porphyrin (ZnTCPP) by π-π nanoassembly method and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), 1 H NMR spectra and UV–vis absorption spectroscopy. The most important advantage of the RGO/AuNPs/CS/ZnTCPP nanocomposites was environmentally friendly. Indium tin oxide (ITO) electrode surface was modified with the RGO/AuNPs/CS/ZnTCPP nanocomposites exhibited a good photocurrent response at −0.2 V under whitelight of Xenon lamp illumination. The photocurrent response could be greatly increased by adding hydroquinone (HQ) to the solution. Electrons of ZnTCPP were excited from HOMO to LUMO by irradiating light. The photoexcited electrons injected into the RGO, and then transferred to AuNPs further to the ITO. Addition of HQ resulted in the enhanced photocurrent signal by acting as a sacrificial electron donor; Thereby scavenged the photogenerated holes of the excited ZnTCPP and oxidized to benzoquinone (BQ). Based on the above interaction, detection of HQ was developed by a novel photoelectrochemical (PEC) sensor (S/N = 3) with a linear range from 5 to 300 nmol/L (r = 0.997) and detection limit of 0.5 nmol/L. Proposed biosensor is simple, rapid and this was successfully applied for the quantification HQ in the real sample matrices. [ABSTRACT FROM AUTHOR]

RGO-Fe 3 O 4 -Ag 3 PO 4 composite (RFA-Cs) photocatalyst was prepared by a facile and effective electrostatic self-assembly method for photodegradation of Rhodamine B (RhB) under visible light irradiation. The prepared composites were fully characterized by scanning electron microscopy (SEM), X-ray diffraction meter (XRD), UV–vis diffuse reflectance spectroscopy (UV–vis), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL) and electrochemical impedance spectroscopy (EIS). The RFA-Cs exhibit extremely high photocatalytic activity and better re-usability. The photocatalytic conversion of RhB reaches as high as 100% after 2 min of light irradiation. A possible photocatalytic degradation and charge separation mechanism were suggested based on the PL spectra and the active species trapping experiments. [ABSTRACT FROM AUTHOR]

An ultrasensitive and stable “dual-potential” ratiometric electrochemiluminescence (ECL) sensor is reported for specific DNA, the femtomolar detection limit (0.12 fM, S/N = 3) and high selectivity insure its potential applications in cancer biomarkers searching or monitoring. The excellent performance of the sensor comes from simultaneously fabricated layer by layer structure “target DNA + Hemin / Au-Luminol NPs / DNA* / sl DNA / TGA / QDs / MWNTs / GCE” mode which was based on the enhancing effect of luminol by G-quadruplex / hemin and Au nanoparticles and the quenching effect of CdSe/ZnS by G-quadruplex / hemin. (i) DNA-SH could combine with Au-Luminol NPs via S-Au bond to solve the problem of poor solubility and weak ECL intensity of luminol in neutral medium. (ii) Target DNA and Hemin formed the G-quadruplex / hemin peroxidase mimicking DNAzyme could enhance the ECL of luminol and quench the ECL of CdSe/ZnS simultaneously. (iii) DNA* was employed to increase a certain distance between CdSe/ZnS and Au-Luminol for enhancing the CdSe/ZnS QDs initial ECL intensity. The dual-potential ratiometric mode lower the influence of background and side reaction of the ECL sensor which were the most important factors in trace sensing. [ABSTRACT FROM AUTHOR]

Herein, three-dimensional (3D) graphene aerogels (GAs) were synthesized successfully by a simple hydrothermal reduction method and introduced as dispersing materials of matrix solid-phase dispersion (MSPD) for the determination of six chlorophenols (CPs) in soil samples via high performance liquid chromatography (HPLC). Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy (Raman), transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and N2 adsorption–desorption transmission were applied to characterize the synthesized GAs. The GA-SPE-HPLC-UV method shows low limits of detection (0.02–0.10 μg L−1), wide linear ranges (50–1000 μg L−1), and acceptable reproducibility (relative standard deviation, RSD ＜ 6.8% for intra-day, RSD ＜ 8.6% for inter-day). Moreover, the method was further applied for the analysis of six CPs in real samples with good recoveries (86.1–111.1%) and satisfactory precision (RSD ＜ 9.8%). The GAs are more effective in CP adsorption than commercial C18 (octadecylsilane) and SWCNTs (single-walled carbon nanotubes). It is confirmed that the proposed method has high sensitivity, outstanding selectivity, and good reproducibility towards the determination of trace CPs in the soil. [ABSTRACT FROM AUTHOR]

Hybrid magnetic nanocomposites based on Cu-MOFs, graphene oxide (GO), and Fe 3 O 4 nanoparticles (NPs) were prepared via chemical bonding approach, which GO were used as platforms to load nanostructured Cu-MOFs and Fe 3 O 4 NPs. The composite features both magnetic separation characteristics and high MOFs porosity, making it an excellent adsorbent for magnetic solid-phase extraction (MSPE). The as-synthesized nanocomposites are characterized by XRD, TGA, SEM, TEM, nitrogen adsorption-desorption analysis and FT-IR spectroscopy. The composites are used in MSPE of six aromatic insecticides from various real samples prior to their quantification by HPLC. Amount of adsorbent, extraction times, extraction temperature, desorption times and oscillation rate are optimized. Under the optimal conditions, the method has a relative standard deviations (RSDs) of 1.9–2.7%, and good linearity (correlation coefficients higher than 0.9931). The low LOD and LOQ for six insecticides are found to be 0.30–1.58 μg L -1 and 1.0–5.2 μg L -1 , respectively. The RSDs of within batch extraction are 1.6–9.5% and 3.9–12% for batch to batch extraction. The experimental results suggest that the nanocomposites have potential application for removal of hazardous pollutants from effluents. [ABSTRACT FROM AUTHOR]

Visual inspection is expected as an ideal technique, which can directly and conveniently detect heavy metal ions by observing the color change. Insensitivity of detecting weakly colored heavy transition metal ions and low adsorptivity of metal ions on nanoparticle surface are two main factors hindering the application of visual detection in heavy metal ions detection. Herein, we demonstrated an operational colorimetric sensor based on the color dependence of nanoparticles aggregation to selective and facile detect weakly colored transition heavy metal Cd 2+ ions that have been considered as the origin of the “Itai-itai” disease. Uniform colloidal 15 nm graphite-like nitride doped carbon quantum dots-capped gold nanoparticle (Au@g-CNQDs) was successfully prepared, wherein the existence of numerous heptazine, carboxyl and hydroxyl groups on the nanoparticle's surface strengthened adsorption of the Cd 2+ ions on the surface of Au@g-CNQDs through the “cooperative effect”. As a consequence, without expensive and intricate exogenous indicators or other special additives, the Cd 2+ ions could sensitively and quickly captured to detect at ultra-low concentration within 30 s by the naked-eye. Under the optimal conditions, the Cd 2+ ions sensor possesses good analytical performances with a wide linear range of 0.01–3.0 μM and a detection limit of 10 nM (S/N = 3). Moreover, the biodistribution and aggregation of Cd 2+ ions were detected effectively in mice organ tissues suggesting its great potential use for real-word applications. [ABSTRACT FROM AUTHOR]

A novel three-dimensional (3D) hybrid consisting of molybdenum disulfide nanosheets (MoS 2 ) uniformly bound at N-doped macro-mesoporous carbon (N-MMC) surface was fabricated by the solvothermal method. The resulting MoS 2 /N-MMC hybrid possesses few-layer MoS 2 nanosheets structure with abundant edges of MoS 2 exposed as active sites for hydrogen evolution reaction (HER), in sharp contrast to large aggregated MoS 2 nanoflowers without N-MMC. The high electric conductivity of N-MMC and an abundance of exposed edges on the MoS 2 nanosheets make the hybrid excellent electrocatalytic performance with a low onset potential of 98 mV, a small Tafel slope of 52 mV/decade, and a current density of 10 mA cm −2 at the overpotential of 150 mV. Moreover, the MoS 2 /N-MMC hybrid exhibits outstanding electrochemical stability and structural integrity owing to the strong bonding between MoS 2 nanosheets and N-MMC. [ABSTRACT FROM AUTHOR]

A novel and highly sensitive photoelectrochemical biosensor for the detection of glucose based on ternary nanocomposites of Au/CuS/TiO2 (Au/CuS/TiO2) has been fabricated. Highly ordered TiO2 nanotube arrays (TiO2 NTs) were prepared by anodization of Ti foils, and CuS nanoparticles (NPs) and Au NPs were deposited on TiO2 NTs by the successive ionic layer adsorption and reaction (SILAR) method. The resultant Au/CuS/TiO2 exhibited excellent photoelectrochemical behavior as a glucose sensor under white light illumination due to the remarkable photocatalytic capabilities of TiO2 and CuS, and the surface plasmonic resonance (SPR) effect of Au NPs. The fabricated Au/CuS/TiO2 non-enzymatic photoelectrochemical sensor showed brilliant catalytic activity, favourable selectivity, good reproducibility and long-term stability for glucose detection under optimized conditions. The linear range was 0.1–3 μM (R = 0.9942) with a detection limit of 0.03 μM (S/N = 3). Moreover, the proposed sensor detected glucose in human serum samples. Thus, Au/CuS/TiO2 appears to be a promising photocatalyst for a non-enzymatic glucose sensor. [ABSTRACT FROM AUTHOR]

How to improve the accuracy of target detection substance in low-content and complex of real sample, which is still a major challenge in the analysis field. There is no doubt that the internal standard method is the best choice in the analysis methods. The internal standard method of ECL strategy can furnish more accurate detection results in the changeable complex environment, and it can dispel the primary vaguest interference in the system through the self-calibration of two emission spectra. Herein, we effectually explored a strong and stable bimodal ECL system based on graphitic carbon nitride quantum dots (g-CNQDs) as single luminophore in the presence of double coreactants potassium persulfate (K2S2O8) and tetrabutylammonium bromide (TBAB) under the optimized conditions. ECL-1 at 2.82 V and ECL-2 at 1.73 V were observed when the potential was scanned between -3 and 3 V at the scan rate of 0.2 V·s-1. The ECL-1 was responding to the analyte, that is, ascorbic acid (AA) and the ECL-2 was not for a certain concentration of AA; hence, the developed bimodal ECL system was used as internal standard method for quantitative AA in human serum due to the different sensitivity of the double-peak ECL signals to the target analytes. The linear relationships were obtained based on the ln I (ECL-1/ECL-2) against the concentration of AA in the concentration range of 3.5 to 330 nM, with a detection limit of 110 pM (S/N = 3). [ABSTRACT FROM AUTHOR]

Rapid determination of cysteine in aqueous solution is important for the diagnosis and treatment of some diseases. We herein present a simple yet facile colorimetric indicator-displacement assay for cysteine in aqueous solution with a sensitive optical readout based on the competitive binding affinity between the 1-(2-pyridylazo)-2-naphthol (PAN) indicator and cysteine target towards the host Zn2+. In the absence of cysteine, Zn2+ can induce an appreciable yellow-to-pink color change for the PAN solution through the formation of a PAN–Zn2+ complex. However, adding cysteine to the above PAN–Zn2+ complex solution resulted in a ligand exchange reaction between PAN and cysteine with about 57 nm blue-shift in the absorbance maximum (from 527 nm to 470 nm), accompanied by a visible color change of the solution from pink to yellow. The obtained indicator-displacement assay provides a good detecting performance for cysteine with a detection limit of 7.32 μM (S/N = 3) using a UV/vis spectrometer as well as with a good linear range from 25 to 1000 μM. In particular, the proposed sensing system could be successfully used for the fabrication of a colorimetric INHIBIT logic gate and converted into the test paper and image capture analytical devices for the onsite visual determination of cysteine in practical applications. [ABSTRACT FROM AUTHOR]

An original electrochemiluminescent (ECL) luminophore porphyrin nanosphere–graphene oxide composite (TCPP NS-GO) was prepared. The TCPP NS-GO could produce greatly enhanced ECL in buffer with potassium peroxydisulfate (K 2 S 2 O 8 ) as the co-reactant. The enhancement ECL mechanism of TCPP NS-GO/K 2 S 2 O 8 system was investigated in detail. Moreover, The TCPP NS-GO composite had an abundant surface functional group to expand its application, which exhibited high sensitivity and selectivity to Fe 3+ . The wide linear relationship between ECL intensity and Fe 3+ concentration from 0.002 to 5.128 μmol L −1 (R 2 = 0.998) was found with the detection limit as low as 1 nmol L −1 . The ECL quenching mechanism of Fe 3+ was proved by UV-vis absorption spectroscopy, Fluorescence emission spectroscopy (FL) and Fourier transform infrared spectroscopy (FT-IR) analysis technology. [ABSTRACT FROM AUTHOR]

Abstract: An effective dual‐emission fluorescent metal‐organic framework (MOF)‐based nanoprobe has been established for ultrasensitive and rapid ratiometric detection of Cu2+. Such a nanoprobe was prepared by encapsulating fluorescein isothiocyanate (FITC), and Eu(III) complex‐functionalized Fe3O4 into the zeolitic imidazolate framework material (ZIF‐8). In this nanoprobe, FITC was used as a reference signal, thus improving the influence of external uncertainties. The Eu‐complex signal could be quenched after adding an amount of Cu2+. The ZIF‐8 could enrich the target analytes, which can amplify the fluorescence signal due to the good adsorption properties of the ZIF‐8. Based on above structural and compositional features, the detection limit of the nanoprobe is 0.1 n m for Cu2+, almost 2×104 times lower than the maximum allowable amount of Cu2+ in drinking water, which constructed a platform for effective detection of Cu2+. Using the nanoprobe to detect Cu2+ in aqueous solution is rapid and the probe still remained stable. Additionally, this sensor for the ratiometric fluorescence imaging of copper ions was also certified in real samples and live cells. [ABSTRACT FROM AUTHOR]

Derived from diarylamine sensitizer diphenyl-(7-pyridin-4-yl-9H-carbazol-2-yl)-amine (N13), a series of novel DA carbazole-based organic dye sensitizers with different -linkers were designed for searching more effective sensitizers in dye-sensitized solar cells (DSSCs) design. Optimized geometries, electronic structure, and other parameters, which can evaluate the performance of DSSCs effectively and intuitively, were theoretically calculated by density functional theory (DFT) and time-dependent DFT methods at the M06/6-31G(d,p) level. The results indicated that the maximum absorption wavelength of designed dye was red-shifted and the molar absorption coefficient () became higher. This phenomenon can be explained by the modification of the -bridge. The simulated Ultraviolet-visible spectroscopy (UV-Vis) absorption spectrum showed that the designed N,N-diphenyl-7-(5-(7-(5-(pyridin-4-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-9H-carbazol-2-amine (N22) dye presents the largest red-shifted absorption band and the designed (E)-N,N-diphenyl-7-(2-(5-(pyridin-4-yl)-[2,2-bithiophene]-5-yl)vinyl)-9H-carbazol-2-amine (N21) dye showed the largest , both of them depicted a high short-circuit photocurrent density (. Meanwhile, the charge separation hampered by long -linkers was also observed. These results are helpful for designing new sensitizers and providing effective guiding to experimental synthesis. [ABSTRACT FROM AUTHOR]

Novel magnetic mesoporous molecularly imprinted polymers (MMIPs) were prepared based on surface precipitation polymerization using Triclosan (TCS) as template and methacrylic acid as functional monomer. The synthesized MMIPs-TCS were applied to the adsorbent of magnetic solid-phase extraction (MSPE) coupled with HPLC for the enrichment and determination of TCS. The MMIPs-TCS were characterized by fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 adsorption-desorption transmission, and vibrating sample magnetometry. Under the optimum condition, the MMIPs-TCS-MSPE-HPLC method shows low limits of detection (LODs) (0.20–0.90 μg L −1 ) and limits of quantification detection (LOQs) (0.66–2.97 μg L −1 ), wide linear ranges from 10.0 to 1000 μg L −1 for each compound with exception of 2,4,6-TCP from 20.0 to 1000 μg L −1 , and acceptable reproducibility (relative standard deviation, RSD <6.6% for intra-day, RSD <8.1% for inter-day). The satisfactory recoveries were in the range of 89.5%–108.4% with good RSDs less than 8.0% at the three spiked levels of 20, 50 and 80 μg L −1 . Moreover, the adsorption experiments show the MMIPs-TCS possess rapid binding affinity, excellent magnetic response, specific selectivity and high adsorption capacity toward TCS with a maximum adsorption capacity of 1955.8 μg g −1 . [ABSTRACT FROM AUTHOR]

In this work, a novel nanohybrid (AuPtNPs/S-NS-GR) of well-defined Au-Pt bimetallic nanoparticles (Au-PtNPs) decorated on sulfonated nitrogen sulfur co-doped graphene (S-NS-GR) was developed. Firstly, nitrogen sulfur co-doped graphene (NS-GR) was synthesized by one-step thermal annealing method. Secondly, phenyl SO 3 H- group was introduced onto the surface of NS-GR via diazotization reaction, which could provide more binding sites for the formation of metal nanoparticles. Finally, Au-Pt bimetallic nanoparticles were anchored on the surface of S-NS-GR by using electrochemical deposition. The prepared material was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and electrochemical impedance spectra (EIS). In addition, the electrocatalytic activity towards dopamine (DA) and uric acid (UA) was systematically studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Under optimum conditions, the linear ranges for the detection of DA and UA were 1.0 × 10 −8 – 4.0 × 10 −4 M and 1.0 × 10 −6 – 1.0 × 10 −3 M with the limits of detection (LOD, S/N = 3) of 0.006 μM and 0.038 μM, respectively. Furthermore, the modified electrode was applied to real sample analysis. [ABSTRACT FROM AUTHOR]

The GO-COOH/AuNPs/ZnAPTPP nanocomposites were constructed using zinc monoamino porphyrin (ZnAPTPP) through π–π conjugation with carboxylated graphene oxide (GO-COOH) loaded with Au nanoparticles (AuNPs). Prepared materials were characterized by 1 H NMR spectra, UV–vis absorption spectroscopy and electrochemical impedance spectroscopy. ITO electrode surface was modified with the prepared nanocomposites showed a good photocurrent response when the bias potential, −0.1 V was applied. Nanocomposites modified ITO electrode exhibited good photo-response to the 4-nitrophenol (4-NP). ZnAPTPP were excited from HOMO to LUMO under light irradiation, the photoexcited electrons injected into the conduction band of GO-COOH, and then transferred to AuNPs further to the ITO. The presence of GO-COOH and AuNPs improved the separation of photogenerated charges due to their synergetic effect and excellent conductivity. Externally added 4-NP scavenges the photogenerated holes i.e. it acts as a sacrificial electron donor thereby it enhances the photocurrent of the system. Based on this interaction, a novel method for photoelectrochemical detection of 4-NP was developed with a linear range from 0.1 to 15 nmol/L (r = 0.996) and detection limit of 0.04 nmol/L (S/N = 3). Proposed method is simple and sensitive and this was successfully applied for the quantification 4-NP in river water sample matrices. [ABSTRACT FROM AUTHOR]

As efficient electron transfer mediator, various nanomaterials with smart performance have been explored in non-enzymatic sensor fabrication. We herein present an electron transfer mediator actuated electrochemical non-enzymatic sensor to assay nitrite, enabled by electrochemical reduced graphene oxide (ERGO) and 1-(2-pyridylazo)-2-naphthol (PAN). The composites of PAN-ERGO coating on electrode surface were successfully fabricated through a facile and green cyclic voltammetry technique. With the aid of ERGO nanosheets on the electrode surface, the electron transfer mediator of PAN nanostructures was easily immobilized and hybridized with ERGO, resulting in a remarkably synergistic effect between ERGO sensing substrate and the electrodeposited PAN coating for target electron transfer. The results demonstrated that the electrocatalytic current increased linearly with the nitrite concentration in the range of 7.49–1752.6 μM and 1752.6–3500 μM, with a good detection limit of 0.67 μM and 1.44 μM (signal-to-noise ratio, S/N = 3), respectively. The present work provide some new insights for the smart design of high efficiency electrocatalytic materials that based on the composites of electrochemical reduced graphene oxide and other substances. [ABSTRACT FROM AUTHOR]