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Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a readily available copolymer that comes as an aqueous dispersion with good processability. A flexible voltammetric sensor for the widely used food stabilizer tert.-butylhydroquinone (TBHQ) was constructed by using a film of PEDOT:PSS. The electron transfer efficiency of the electrode was enhanced by doping with dimethyl sulfoxide (DMSO), and mass transport at the electrode-electrolyte interface was increased by adding the cationic surfactant cetyltrimethylammonium bromide (CTAB) which acts as a sorbent for TBHQ. SEM, AFM, XPS, UV − vis and electrochemical analysis were conducted to characterize the properties of the electrode. After optimization of the experimental conditions, the electrode operated at a working potential of 0.17 V (vs. SCE) has a linear response in the 0.5–200 μM TBHQ concentration range and a lower detection limit of 0.15 μM (at S/N = 3). It was applied for the determination of TBHQ in spiked real samples, and recoveries ranged between 96.85 and 103.41%. [ABSTRACT FROM AUTHOR]

Abstract In this work, electrode based on poly(3,4-ethylenedioxythiophene) (PEDOT) was employed for the fabrication of an efficient sensor for 4-chloro-3-methylphenol (PCMC) detection. To improve the dispersity and increase the specific surface area of PEDOT, core-shell structured UiO-66-NH 2 @PEDOT was designed by in-situ oxidation method using Zr-based metal-organic framework (UiO-66-NH 2) as template. In addition, to achieve a further increased active surface area and electron transfer rate of the modified materials, graphene aerogel (GA) was utilized as substrate material for the assembly of UiO-66-NH 2 @PEDOT. Then, the obtained UiO-66-NH 2 @ PEDOT/GA modified electrode was employed as an electrochemical sensor for PCMC detection. Experiment parameters, such as pH value of acetate buffer solution and accumulation time, were optimized in detail. Under the optimized experiment condition, the UiO-66-NH 2 @PEDOT/GA electrode showed a good linear range of 0.6–18 μM, as well as a low detection limit of 0.2 μM (S/N = 3). The UiO-66-NH 2 @PEDOT/GA electrode was applied toward the detection of PCMC in tap water with good recovery. All these features suggest that the prepared PEDOT-based composite could serve as a promising sensing platform for monitoring water pollutants. Graphical abstract 3D UiO-66-NH 2 @PEDOT/GA modified electrode as an electrochemical sensor was employed for 4-chloro-3-methylphenol detection. Unlabelled Image Highlights • A novel 3D UiO-66-NH 2 @PEDOT/GA composite was obtained through facial approach. • UiO-66-NH 2 @PEDOT/GA electrode was applied for the electrochemical detection of PCMC. • Low detection limit and wide linear range for PCMC were obtained. • The method can detect PCMC in tap water with good recovery. [ABSTRACT FROM AUTHOR]

Abstract A highly-sensitive electrochemical sensor based on single walled carbon nanotubes (SWCNTs) nanocomposite electro-catalyst supported molecularly imprinted poly(3,4-ethylenedioxythiophene) (PEDOT) film modified with two-dimensional layered tungsten sulfide (WS 2 ) nanosheet for the detection of vitamin B 2 (VB 2 ) was successfully developed. Molecularly imprinted WS 2 -PEDOT film was prepared by the electrochemical co -polymerization of functional monomer 3,4-ethylenedioxythiophene in the presence of template molecule VB 2 and WS 2 nanosheet. SWCNTs nanocomposite modified electrode was obtained by drop-coating SWCNTs dispersion containing graphene oxide (GO) onto GCE surface. WS 2 was used for improving the denseness and smoothness in the morphology and structure of PEDOT. GO was employed for enhancing the electro-catalytic capacity of SWCNTs and the interaction with template molecule via functional groups. The imprinted sensor was characterized, and its performance and parameters were investigated and optimized using linear sweep voltammetry. Under optimized conditions, the prepared imprinted sensor displayed a good linear response to VB 2 in wide concentration ranges from 0.002 to 0.9 μM with a low detection limit of 0.7 nM, and successfully applied to electrochemically detect VB 2 in drug samples with good reproducibility, repeatability and storage stability. The new design for the facile fabrication of mimic electrode will open up a new horizon in the development of highly-sensitive biomimic/imprinted sensors. Graphical abstract Unlabelled Image Highlights • A novel electrochemical sensor based on graphene oxide-SWCNTs supported WS 2 -MIPs film was developed. • WS 2 -MIPs film was prepared by the electropolymerization of EDOT in the presence of VB 2 and WS 2 nanosheets. • The developed sensor was successfully used for VB 2 detection in real samples with good performance. [ABSTRACT FROM AUTHOR]

A sensitive Pb(II) sensor was fabricated based on Co 3 O 4 /reduced graphene oxide/chitosan (Co 3 O 4 /rGO/chitosan) nanocomposite modified glassy carbon electrode (GCE). The Co 3 O 4 /rGO material was synthesized through in situ growth of Co 3 O 4 nanoparticles (NPs) on GO and subsequent hydrazine reduction process. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that Co 3 O 4 NPs with a diameter of around 100 nm are attached on rGO sheets. The structures and compositions of Co 3 O 4 /rGO were further characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Many experimental parameters, such as pH value, deposition time and deposition potential were optimized. Under optimal conditions, the calibration plot for Pb(II), with data acquired at − 0.556 V ( vs . SCE) is linear in the concentration range from 1.0 to 200.0 nM. Combining the good conductivity and high surface area of rGO, strong Pb(II) adsorption ability of Co 3 O 4 NPs, and excellent Pb(II) complex-forming ability of chitosan, the nanocompsite provides a sensitive Pb(II) senor with a detection limit of 0.35 nM. Moreover, the positively charged chitosan can interact with the negatively charged rGO to increase the stability of Co 3 O 4 /rGO nanocomposite. The hybrid nanocomposite Pb(II) senor provides new opportunity for vegetable analysis. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) dotted S-doped carbon (AuNPs/S-C) nanoflakes were synthesized via a facial and simple approach. Typical synthesis route involves the formation of gold nanoparticles/poly(3,4-ethylenedioxythiophene) (AuNPs/PEDOT) and a subsequent calcination process. Many techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) were used to characterize their morphology, structures and compositions. Results indicated that AuNPs with an average size of 5 nm were uniformly dotted on/into the S-C nanoflakes. The AuNPs/S-C/nafion was utilized as a new electrode material for simultaneously electrochemical determination of Cu (II) and Hg (II) using differential pulse anodic stripping voltammetry (DPASV) technique. Benefiting from the efficient metal-complexing ability and electrocatalytic activity of S-C and the good conductivity of AuNPs, the modified electrode exhibited enhanced electrochemical performance compared with bare glassy carbon electrode. Under optimal conditions, the peak currents displayed linear response to the concentrations of Cu (II) and Hg (II) ranges from 0.64 to 63.55 μg/L and 4.01 to 300.89 μg/L, with detection limits of 0.19 μg/L and 1.40 μg/L (S/N = 3), respectively. The modified electrode was also applied for the determination of Cu (II) and Hg (II) in lake water samples with good results. [ABSTRACT FROM AUTHOR]

In this review, PEDOT--PSS is mainly a commercially available PEDOT--PSS, which is a water-dispersible form of the intrinsically conducting PEDOT doped with the water-soluble PSS, including its derivatives, copolymers, analogs (PEDOT:PSSs), even their composites via the chemical or physical modification toward the structure of PEDOT and/or PSS. First, we will focus on discussing the scientific importance of PEDOT--PSS in conjunction with its extraordinary properties and broad multidisciplinary applications in organic/polymeric electronics and optoelectronics from the viewpoint of the historical development and the promising application of representative ECPs. Subsequently, versatile film-forming techniques for the preparation of PEDOT--PSS film electrode were described in details, including common coating approaches and printing techniques, and many emerging preparative methods were mentioned. Then challenges (e.g., conductivity, stability in Water, adhesion to substrate electrode) of PEDOT--PSS film electrode for devices under the high humidity/watery circumstances, especially electrochemical devices are discussed. Fourth, we take PEDOT--PSS film electrode for a relatively new application in sensors as an example, mainly summarized advances in the development of various sensors based on PEDOT--PSSs and their composites in combination with its preparative methods and extraordinary properties. Finally, we give the outlook of PEDOT--PSS for possible applications with the emphasis on PEDOT--PSS film electrode for electrochemical devices, including sensors. [ABSTRACT FROM AUTHOR]

Herein, an electrochemical sensor was developed for detecting heavy metal ions by using a carboimidazole grafted reduced graphene oxide (reduced graphene oxide-NH-carboimidazole, abbreviated as RGO-NH-Ci) modified electrode. The morphology of RGO-NH-Ci material was characterized by scanning electron microscopy (SEM). The electrochemical behaviors of the RGO-NH-Ci modified electrode toward heavy metal ions, including Hg 2 + and Pb 2 + , were investigated with differential pulse anodic stripping voltammetry (DPASV). Compared with pure reduced graphene oxide (RGO), RGO-NH-Ci modified electrode showed improved analytical performance in detecting the two metal ions owing to the strong complexing capacity of Ci and the presence of the amino groups. The detection limits were estimated to be 0.2 nM and 3.0 nM for Hg 2 + and Pb 2 + , respectively, under the optimized conditions. The developed method was also employed to detect the Hg 2 + and Pb 2 + in real water samples, and satisfactory results were obtained. [ABSTRACT FROM AUTHOR]

Cu nanoparticle/graphene oxide/single walled carbon nanotube (CuNP/GO/SWCNT) composites were prepared by a facile electrodeposition method and used for constructing nonenzymatic glucose sensor. Scanning electron microscopy (SEM) and Raman spectroscopy were employed to characterize the morphology and structures of the samples. The electrocatalytic performance of CuNP/GO/SWCNT composites towards glucose oxidation was studied by cyclic voltammetry (CV) and current–time measurements. Electrochemical results indicated that CuNP/GO/SWCNT electrode exhibited a higher electrocatalytic activity towards the oxidation of glucose than CuNP, CuNP/GO and CuNP/SWCNT electrodes. This was because the GO/SWCNT composite as substrate material not only possessed excellent conductivity, but also provided large surface area for the high loading of the CuNPs. Meanwhile, the good dispersibility, independent and multi-layer structure of CuNP, could enhance the charge-transport properties, and afford more active sites for the catalytic oxidation of glucose. Under the optimized conditions, the sensor showed a high sensitivity of up to 930.07 μA mM − 1 cm − 2 , with a wide linear range of 1 μM to 4.538 mM and a low detection limit of 0.34 μM (S/N = 3). It also exhibited excellent stability, reproducibility, selectivity, and reliable measurement in real human blood samples. All of these excellent properties made the CuNP/GO/SWCNT composite material promising for the development of effective nonenzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

Electrochemically reduced graphene oxide (ERGO) based voltammetric sensors have drawn considerable attentions due to their simple preparation process and outstanding electrochemical properties. While quite a lot of work suffers from problems in terms of sensitivity and cycling stability. Here, we demonstrate that the reduction extent of ERGO displays a crucial role in enhancing sensitivity and preventing electrode fouling. To illustrate this, partially reduced and relatively complete reduced ERGO films were prepared via the electrochemical method. The reduction extent was controlled by performing cyclic voltammetry with varieties of reduction cycle numbers. Results indicated that partially reduced ERGO film with 5 reduction cycle numbers (ERGO 5 ) showed the highest sensitivity towards electrochemical oxidation of isoniazid (INZ) among all the ERGO films with different reduction extents, and acquired better electrode stability as compared with ERGO 15 . Under the optimal conditions, the peak currents on ERGO 5 modified electrode increased linearly with the concentrations of INZ in the range of 0.09–100 μM. The detection limit of INZ reached 15 nM (S/N = 3). The present work has a guidance meaning in developing ERGO based sensors for detecting other electroactive analytes. [ABSTRACT FROM AUTHOR]

Maleic hydrazide (MH) was successfully detected using a novel electrochemical sensor based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)-carboxymethyl cellulose-single-walled carbon nanotubes modified glassy carbon electrode (PEDOT:PSS-CMC-SWCNT/GCE). A commercially available aqueous PEDOT:PSS dispersion with good processability and conductivity was used as electrode modified substrate material, while a water-soluble and adhesive CMC was selected as both binder and dopant to improve the long-term electrode stability in water of the PEDOT:PSS composite film and obtain synergistically enhanced electrocatalytic ability for analytes. A commercially available SWCNT dispersion with good processability, enhanced electrocatalytic ability and large rough surface area was selected as enhancer to improve the sensing performance of PEDOT:PSS composite electrode. The properties of the prepared composite film and its electrode were characterized and employed for the electrochemical detection of MH. The electrochemical behaviors of MH, optimum experimental parameters, and the performance of sensing electrode were investigated. The fabricated PEDOT:PSS-CMC-SWCNT/GCE accelerated electron transfer, enhanced synergistically electrocatalytic ability toward MH oxidation and displayed excellent sensing performance such as wide linear range (0.8–51 μM) and a low limit of detection (0.1 μM) and good sensing stability. [ABSTRACT FROM AUTHOR]

A novel poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) composite film with superior stability in water, adhesion and flexibility, which is very critical for maintaining the long-term stability in water of the PEDOT:PSS film electrode, was easily prepared by introducing a water-soluble, anionic, non-toxic and biocompatible biopolymer (sodium carboxymethyl cellulose, Na-CMC) into a commercially available aqueous dispersion of the conducting polymer (PEDOT:PSS dispersion). The high conducting PEDOT:PSS-CMC film exhibited good flexibility and long-term stability in water after being soaked in water for 35 days. The high performance film electrode with excellent adhesion, long-term electrode stability in water (retaining almost 99.4% of its original activity for 105 days), and electrochemical properties was prepared facilely by drop-coating, and displayed good synergistically enhanced electrocatalytic ability towards the anodic oxidation of harmful substances and nutritional ingredients in edible agro-products, which were employed for its application in electrochemical sensors. The simultaneous or individual detection of maleic hydrazide, salicylic acid, nitrite, sunset yellow, and tryptophan was successfully realized using PEDOT:PSS-CMC/GCE, and exhibited superior sensing stability. All satisfactory results indicated that the introduction of CMC into PEDOT:PSS could improve the flexibility, adhesion, long-term electrode stability in water and electrocatalytic ability, which would provide a promising platform for the application in electrochemical fields of the high performance film electrode, especially the application in electrochemical sensors. [ABSTRACT FROM AUTHOR]

Hierarchical nanocomposites of poly(3,4-ethylenedioxythiophene) nanorods array on graphene oxide nanosheets (PEDOT/GO) were synthesized via a liquid–liquid interfacial polymerization method. The synthesized composites were characterized by using Fourier transform infrared (FTIR) and Raman spectroscopic studies, and their morphology was analyzed by transmission electron microscopy (TEM). Characterization and surface morphology results indicated that PEDOT with a nanorods-like structure successfully anchored on the surface of GO sheets, which could enhance the electro-active sites of the nanocomposites. Then the obtained PEDOT/GO nanocomposites were utilized to modify glassy carbon electrode and designed for the trace level sensing of rutin. Electrochemical results revealed that the PEDOT/GO nanocomposites modified electrode exhibited larger oxidation peak currents of rutin than pure PEDOT and GO owing to the synergistic effect of GO and PEDOT nanorods. Under optimized conditions, the anodic peak current was linear to the concentration of rutin in the range from 0.004 to 60 μM with the detection limit of 0.00125 μM. To further validate its possible application, the proposed method was successfully used for the determination of rutin in pharmaceutical formulations with satisfactory results. [ABSTRACT FROM AUTHOR]

Abstract: The water-stability and adhesion are one of major problems of PEDOT:PSS film electrode nowadays due to easy swelling, disintegration, cracking-off, and falling of PEDOT:PSS film itself in water. The synergetic or complementary effects between organic and inorganic components can improve properties or performances of composite materials which have recently gained extensive interest in many fields. Two highly water-stable poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) composite materials based on an environmentally friendly polymer and the most studied and promising novel carbon nanomaterials available today are successfully prepared by the incorporation of the poly(vinyl alcohol) (PVA) and multiwalled carbon nanotubes (MWCNTs) or carboxylic group functionalized graphene (GR-COOH) into a commercially available aqueous dispersion of PEDOT:PSS. The two as-prepared highly water-stable PEDOT:PSS–PVA–novel carbon nanomaterials composite film electrodes with excellent adhesion properties are employed for the electrochemical determination of ternary mixture containing epinephrine, uric acid and tryptophan or niclosamide using linear sweep voltammetrys. PVA, a binding agent with adhesive properties, high tensile strength and good flexibility, can enhance the adhesion and binding force between PEDOT:PSS film and electrode interface, and improve swelling and degradation of PEDOT:PSS film in water. MWCNTs and GR-COOH with excellent electrical, optical, thermal and mechanical properties can enhance the electrocatalytic performance and sensing stability of PEDOT:PSS film electrodes. Especially, GR-COOH improves flexibility of PEDOT:PSS–PVA film. The fabricated film electrodes with superior water-stability and adhesion properties exhibit excellent electrocatalytic activity towards sensing application. Satisfactory results indicate that the prepared PEDOT:PSS organic/inorganic composites materials can provide a promising platform for the potential application of electrochemical modified electrode. [Copyright &y& Elsevier]

Abstract: A commercially available aqueous poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid (PEDOT:PSS) as the immobilization matrix of biologically active species for the development of sensing and biosensing devices has not been widely reported due to its swelling and disintegration in aqueous solution. In this paper, a lowly swelling and disintegrating PEDOT:PSS composite films as the electrochemical biosensing platform was successfully developed by the incorporation of the biocompatible binding agent and common ionic liquid. Nafion was selected as a binding agent, mainly because Nafion could provide the biocompatible environment for biologically active species, improve the adhesion and binding force between films and electrode interface, and prevent peeling off of both enzyme molecules and films. 1-Butyl-3-methylimidazolium tetrafluoroborate, one of common ionic liquids, was used for the secondary dopant and enhancer to improve the water-resistance and electrochemical properties of PEDOT:PSS films. Ascorbate oxidase was used as a mode for the development and application of the electrochemical biosensor. The prepared PEDOT:PSS composite modified electrode exhibited the pronounced water-stability. Moreover, the fabricated biosensor displayed an excellent bioelectrocatalytic activity to the oxidation of vitamin C, fast current response, high sensitivity, wide linear range, low detection limit, high bioaffinity and specificity, and satisfactory results in practical application, indicating that the fabricated biosensor has good electrochemical biosensing performance. Meanwhile, the excellent water-stability, repeatability, reproducibility, storage stability, and electrochemical biosensing performance also make PEDOT:PSS composite modified matrix an interesting candidate for the sensing and biosensing application in the near future. [Copyright &y& Elsevier]

In this work, carbon nanohorn (CNH)–decorated multi-walled carbon nanotube (MWCNT) (CNH@MWCNT) composite was prepared and used to modify glass carbon electrode (GCE) as sensitive electrochemical sensor for niclosamide (NA) determination. Herein, the decoration of CNHs induces higher dispersibility for MWCNTs, and endows the composite with better conductivity, larger surface area, and higher catalytic activity, which leads to significantly enhanced electrochemical behavior toward NA oxidation. The parameters such as mass ratios of CNHs and MWCHTs, the amount of composite materials, the accumulation time, and the solution pH are systematically optimized. Under optimized conditions, the developed electrochemical sensor exhibits a low detection limit of 2.0 nM with a wide linear range of 7.0 nM–10.0 µM and high anti-interference ability. In addition, the sensor displays good stability, repeatability, and reproducibility. The feasibility of the assay was verified by testing NA in brown rice and rice field water samples. [ABSTRACT FROM AUTHOR]

Metal ions have great significance for agricultural development, food safety, and human health. In turn, there exists an imperative need for the development of novel, sensitive, and reliable sensing techniques for various metal ions. Agricultural sensors for the diagnosis of both agricultural safety and nutritional health can establish quality and safety traceability systems of both agro-products and food to guarantee human health, even life safety. Metal-organic frameworks (MOFs) are utilized widely for the design of diversified sensors due to their distinctive structural characteristics and extraordinary optical and electrical properties. To serve agricultural sensors better, this review is dedicated to providing a brief overview of the synthesis of MOFs, the modification of MOFs, the fabrication of MOF-based film electrodes, the applications of MOF-based agricultural sensors for metal ions, which are centered on electrochemical sensors and optical sensors, and current challenges of MOF-based agricultural sensors. In addition, this review also provides potential future opportunities for the development and practical application of agricultural sensors. [ABSTRACT FROM AUTHOR]

This review (with 155 refs.) summarizes the progress made in the past few years in the field of electrochemical sensors based on graphene-derived materials for the determination of heavy metal ions. Following an introduction of this field and a discussion of the various kinds of modified graphenes including graphene oxide and reduced graphene oxide, the review covers graphene based electrodes modified (or doped) with (a) heteroatoms, (b) metal nanoparticles, (c) metal oxides, (d) small organic molecules, (e) polymers, and (f) ternary nanocomposites. Tables are provided that afford an overview of representative methods and materials for fabricating electrochemical sensors. Furthermore, sensing mechanisms are discussed. A concluding section presents new perspectives, opportunities and current challenges.Schematic illustration of electrochemical sensor for heavy metal ion sensing based on heteroatom-doped graphene, metal-modified graphene, metal-oxide-modified graphene, organically modified graphene, polymer-modified graphene, and ternary graphene based nanocomposites. [ABSTRACT FROM AUTHOR]

In this work, TiO2-MXene/poly (3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) composite was utilized as an electrode material for the sensitive electrochemical detection of baicalein. The in-situ growth of TiO2 nanoparticles on the surface of MXene nanosheets can effectively prevent their aggregation, thus presenting a significantly large specific surface area and abundant active sites. However, the partial oxidation of MXene after calcination could reduce its conductivity. To address this issue, herein, PEDOT:PSS films were introduced to disperse the TiO2-MXene materials. The uniform and dense films of PEDOT:PSS not only improved the conductivity and dispersion of TiO2-MXene but also enhanced its stability and electrocatalytic activity. With the advantages of a composite material, TiO2-MXene/PEDOT:PSS as an electrode material demonstrated excellent electrochemical sensing ability for baicalein determination, with a wide linear response ranging from 0.007 to 10.0 μM and a lower limit of detection of 2.33 nM. Furthermore, the prepared sensor displayed good repeatability, reproducibility, stability and selectivity, and presented satisfactory results for the determination of baicalein in human urine sample analysis. [ABSTRACT FROM AUTHOR]

In this work, a two-dimensional leaf-like framework-L embedded electrochemically reduced graphene oxide (ERGO@ZIF-L) was proposed as an outstanding electrode material for the sensitive electrochemical sensing of benomyl (BM). ZIF-L is surrounded by ERGO, which could effectively ensure the stability and dispersion of ZIF-L. With this unique combination, the prepared ERGO@ZIF-L displayed excellent synergistic characteristics with a large surface area, excellent conductivity, plentiful active sites, and high electrocatalytic properties, thus endowing it with high sensitivity for BM determination. The experimental parameters, such as solution pH, material volume, and accumulation time, were optimized. Under optimal conditions, the BM sensor showed a wide linear range (0.009–10.0 μM) and low-limit detection (3.0 nM). Moreover, the sensor displayed excellent stability, repeatability, and reproducibility, and good anti-interference capability. The method was successfully applied to detect BM in real-world samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] PEDOT/ZrO2NPs nanocomposite film was synthesized by one-step polymerization. [•] ZrO2NPs could improve the electrical and catalytic properties of PEDOT. [•] The modified electrode showed high electrochemical activity for VB2, VB6 and VC. [•] The modified electrodes were applied to simultaneous determination of VB2, VB6 and VC. [•] The method was successfully applied to detect VB2, VB6 and VC in practical sample. [Copyright &y& Elsevier]

Luteolin (LUT) is one of the biologically active functional components, which was widely used in pharmacological applications. Thus, development of sensitive analytical methods for LUT determination is highly desired. In this work, Ti 3 C 2 -MXene/ZIF-67/CNTs heterostructure was exploited as a new electrochemical sensing platform for the sensitive determination of LUT. For the design of composite, the in-situ growth of ZIF-67 on CNTs surface ensures the stability of their binding and enhances the synergetic catalysis. Conductive MXene as matrix for the loading of ZIF-67/CNTs can promote the catalytic ability of composite. Electrochemical results show that the MXene/ZIF-67/CNTs modified electrode displays preeminent electrocatalytic activity and enhances electrochemical response to the redox reaction of LUT, ascribing to the synergistic effect of ZIF-67/CNTs and MXene. Upon the optimization of experimental parameters, e.g., pH, enrichment time, the sensor based on MXene/ZIF-67/CNTs composite exhibits excellent performance with wide linear relationship ranging from 0.1–1000 nM and a low limit of detection (LOD) of 0.03 nM (S/N = 3). Besides, MXene/ZIF-67/CNTs electrode performs high selectivity, stability, and acceptable reproducibility. Furthermore, the constructed sensor was successfully utilized to detect LUT in real samples with satisfactory recovery. A novel electrochemical sensor was fabricated based on MXene/ZIF-67/CNTs nanocomposite for the detection of luteolin. Unlabelled Image • Ti 3 C 2 MXene/zeolite imidazolate framework-67/carbon nanotubes nanocomposite (MXene/ZIF-67/CNTs) was synthesized. • MXene/ZIF-67/CNTs showed high specific surface area and good conductivity. • A novel electrochemical sensor for luteolin detection was fabricated based on MXene/ZIF-67/CNTs with high sensitivity. • This sensor was successfully applied for the detection of luteolin in real sample. [ABSTRACT FROM AUTHOR]

The environmental stability, water-processibility and life-span of black phosphorene (BP) severely limit the application of its electronic devices in aqueous system containing oxygen. We reported the controllable preparation of in-situ reduction and deposition of silver nanoparticles on the BP surface and its amino-functionalized multi-walled carbon nanotubes (NH 2 -MWCNT) nanocomposite. With the addition of both NH 2 -MWCNT and Ag+, the BP-based nanocomposite was prepared by ultrasonic-assisted liquid-phase exfoliation and was dispersed in carboxymethyl cellulose sodium (CMC) aqueous solution. The morphology, microstructure, and electrochemical properties of the nanohybrid were characterized. NH 2 -MWCNT-BP-AgNPs showed high environmental stability, good water-processibility, satisfactory life-spans, superior electrocatalytic capacity with enzyme-like kinetic characteristics. The nanohybrid was applied as electrochemical sensors for single/simultaneous analysis of uric acid (UA), xanthine (XT) and hypoxanthine (HX). Excellent voltammetric responses for simultaneous determination in linear ranges of 0.1–800 μM with a limit of detection (LOD) of 0.052 μM for UA, 0.5–680 μM with a LOD of 0.021 μM for XT, and 0.7–320 μM with a LOD of 0.025 μM for HX under optimal conditions. Besides, the developed nanozyme sensor was employed for simultaneous voltammetric analysis of UA, XT and HX in real samples with acceptable recoveries. This work will provide theoretical guidance and experimental support for the preparation and application of two-dimensional materials, nanozymes and sensing devices. • High environmental stable, water-processable few-layer BP nanocomposite was prepared. • The morphology, structure and electrochemical performance of NH 2 -MWCNT-BP-AgNPs were characterized. • The NH 2 -MWCNT-BP-AgNPs displayed oxidase-like characteristic on UA, XT and HX. • The NH 2 -MWCNT-BP-AgNPs nanozyme was applied in single, selectiveand simultaneous detection of UA, XT and HX. [ABSTRACT FROM AUTHOR]

Abstract Two novel chiral 3,4-dihydro-2 H -thieno[3,4- b ][1,4]dioxepine (ProDOT)-based electrochemical sensor, employing a pair of glassy carbon electrodes modified with chiral poly(2-Phenyl-propionic acid 3,4-dihydro-2 H -thieno[3,4- b ][1,4]dioxepin-3-ylmethyl ester) (PProDTM-PP), were utilized for the enantioselective detection of chiral 3,4-dihydroxyphenylalanine (DOPA). The enantioselective recognition between chiral PProDTM-PP modified glassy carbon electrodes and chiral DOPA was studied by using different electrochemical technologies. The redox activity and electrochemical stability of chiral PProDTM-PP was good. (R)-PProDTM-PP and (S)-PProDTM-PP showed higher peak current responses toward D -DOPA and L -DOPA, respectively. Furthermore, the recognition efficiencies of chiral PProDTM-PP are between 1.48 and 1.89, which is higher than chiral PEDOT-based electrochemical sensors (around 1.10). The chiral PProDTM-PP provides an alternative to chiral recognition. [ABSTRACT FROM AUTHOR]

The development of electrochemical methods for enantioselective recognition is a focus of research in pharmaceuticals and biotechnology. In this study, a pair of water-soluble chiral 3,4-ethylenedioxythiophene (EDOT) derivatives, (R)-2'-hydroxymethyl-3,4-ethylenedioxythiophene ((R)-EDTM) and (S)-2'-hydroxymethyl-3,4-ethylenedioxythiophene ((S)-EDTM), were synthesized and electrodeposited on the surface of a glassy carbon electrode (GCE) via current-time (I-t) polymerization in an aqueous LiClO4 electrolyte. These chiral PEDOT polymers were used to fabricate chiral sensors and to investigate the enantioselective recognition of d-/l-3,4-dihydroxyphenylalanine, d-/l-tryptophan, and (R)-/(S)-propranolol enantiomers, respectively. The results indicated that the (R)-PEDTM/GCE sensor showed a higher peak current response toward the levo or (S) forms of the tested enantiomers, while the opposite phenomenon occurred for (S)-PEDTM/GCE. The mechanism of the stereospecific interaction between these enantiomers and the chiral polymers was determined. Therefore, a model of the chiral recognition by the chiral conducting polymer electrodes and an electrochemical method was proposed. The chirality of the enantiomers was confirmed by two parameters: the chirality of the electrode and the peak current response. These findings pave the way for the application of chiral PEDOT as electrode modification material in the electrochemical chiral recognition field. [ABSTRACT FROM AUTHOR]

We present a novel label-free electrochemical immunosensor for detecting carcinoembryonic antigen (CEA) based on three-dimensional (3D) gold nanoparticles/prussian blue-poly(3,4-ethylenedioxythiophene) (AuNPs/PB-PEDOT) nanocomposite, which was firstly synthesized by a simple redox reaction between the PB precursors and EDOT in an aqueous solution, followed by the electrochemical reduction of HAuCl 4 . The 3D nanocomposite not only possessed large surface area and favorable microenvironment, but also exhibited remarkable conductivity, stability and excellent biocompatibility. In addition, PB showed excellent redox properties. Then AuNPs/PB-PEDOT was used as both electron mediators and 3D matrices in the fabrication of immunosensor. FT-IR spectra were employed to confirm the formation of PB, PEDOT and PB-PEDOT. Significantly, the AuNPs/PB-PEDOT exhibited a 3D and hierarchically porous nanostructure, while the PB-PEDOT showed core-shell structure. The AuNPs/PB-PEDOT modified immunosensor showed good linearity with the concentration of CEA ranging from 0.05 to 40 ng mL −1 , and the detection limit was 0.01 ng mL −1 . Moreover, the prepared electrode displayed good selectivity, high stability and good repeatability, and showed great potential for application in real sample analysis. [ABSTRACT FROM AUTHOR]

Poly(9-fluorenecarboxylic acid) (PFCA) thin film was successfully fabricated onto the surface of indium tin oxide glass by one-step electropolymerization of commercially available 9-fluorenecarboxylic acid in boron trifluoride diethyl etherate. Meanwhile, PFCA thin film could specifically recognize Fe 3+ . Fe 3+ was generated by the oxidization of Fe 2+ in the presence of H 2 O 2 that was produced by biochemical reactions and resulted in fluorescence quenching of PFCA thin film. Furthermore, a sensing platform was designed for highly selective fluorescent detection of glucose. The qualitative and quantitative analysis of Fe 3+ , H 2 O 2 and glucose with detection limits of 1 μM, 2.9 μM and 3.4 μM respectively could be implemented by a simple, cost-effective, reusable, practical and multi-functional PFCA thin film. The fabricated PFCA-based chemo/bio sensing film for fluorescent detection of Fe 3+ in rice sample or glucose in serum sample was assessed. Satisfactory results indicate that this work will provide not only a new strategy for fluorescent detection of important substances in agricultural science, but also significant theoretical guidance and important reference value for the practical application and development of multi-functional sensing device. [ABSTRACT FROM AUTHOR]

• A machine learning strategy was applied for electrochemical sensor and supercapacitor. • The carbonized metal–organic framework showed excellent electrochemical response for niclosamide (NA) and good capacitance. • Both adsorption and binding energy were theoretically calculated and the structure of prepared material was optimized. Machine learning (ML) plays an important role in the electrochemical application of electrode materials. In this work, an emerging machine learning strategy for both electrochemical sensor and supercapacitor using carbonized metal–organic framework (C-ZIF-67) is proposed. The morphology and element analysis of C-ZIF-67 are characterized and further demonstrate the presence of C, N, O, Co elements. The ML model based on artificial neural network (ANN) algorithm as a powerful tool to realize intelligent analysis of niclosamide (NA), the derivative technique as an auxiliary means of voltammogram treatment to reduce personal error from data-reading and improve the sensitivity of electrochemical responses at very low concentrations, and the theoretical calculation is employed for both adsorption and binding energy, optimized structure of the prepared sensing material. The developed sensor displays excellent electrochemical response about 196.6-fold improvement compared with the bare GCE for NA, wider linear ranges of intelligent analysis from 1 nM to 9 μM with low limit of detection of 0.3 nM, and satisfactory practicability. ML model with ANN algorithm is also employed for predicting the performance of supercapacitor. The supercapacitor shows good performance with capacitance of 336.67 F/g at the current density of 2 A/g and excellent prediction with acceptable errors. This work will provide a new strategy for the development and electrochemical application of bifunctional electrode materials using the ML technique combined with theoretical calculation. [ABSTRACT FROM AUTHOR]

Herein, a sensitive voltammetric method for the determination of diethylstilbestrol (DES), illegally used as a growth promoter in animal husbandry, was developed using electrochemically reduced graphene oxide–multiwalled carbon nanotubes (ERGO–MWCNTs) modified electrode. The incorporated multiwalled carbon nanotubes (MWCNTs) served as electrical conducting wires, which could facilitate the electrochemical reduction of graphene oxide (GO). Compared to either electrochemically reduced graphene oxide (ERGO) or MWCNTs, integrating these nanostructures resulted in a strong synergistic effect between the two materials consequently leading to a superior hybrid material with higher activity for the electro-oxidation of DES. The electron transfer coefficient ( α ), the standard rate constant ( k s ), electrochemically effective surface area ( A ) and the saturating absorption capacity ( Г s ) were calculated. Under the optimized conditions, ERGO–MWCNTs modified electrode exhibited better linearity than either ERGO or MWCNTs over ranges from 0.01 to 40 μM with the detection limit of 3 nM ( S / N = 3). Moreover, the proposed method was successfully applied to determine DES in real sample and satisfactory results were obtained. The results showed that the modified electrode exhibits an excellent catalytic activity, good sensitivity and reproducibility. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two hydrophilic PEDOT derivatives were electrosynthesized and characterized. [•] PC4-EDOT-COOH/GCE exhibited good electrochemical recognition towards MBC. [•] The recognition mechanism of MBC was proved by quantitative calculation. [•] The method was used to trace monitor of MBC in paddy water and commercial juice. [ABSTRACT FROM AUTHOR]

By exploiting the electrostatic interaction between positively charged 3,4-ethylenedioxythiophene cation radicals and negatively charged sulfonated graphene (SG) sheets, we prepared a poly(3,4-ethylenedioxythiophene)-sulfonated graphene (SG-PEDOT) composite film by a one-step electrochemical process. The composite was further decorated with gold nanoparticles (AuNPs) and employed as an electrode material for the detection of L-cysteine (Cys). The SG-PEDOT composite film is shown to provide a rough surface for the electrodeposition of AuNPs and to improve substrate accessibility and interaction with Cys. Moreover, the AuNPs-decorated composite exhibits better electrocatalytic performance than that of a SG-PEDOT composite only. Under optimum experimental conditions, the amperometric current of the sensor is linearly related to the concentration of Cys in the 0.1 to 382 µM range, and the detection limit is 0.02 µM (at S/N=3). The modified electrode displays favorable selectivity, good stability and high reproducibility. The method was successfully applied to the detection of Cys in spiked human urine. [ABSTRACT FROM AUTHOR]

Highlights: [•] The necklace-like GO-MWCNTs nanohybrid was facilely synthesized by ultrasonication. [•] The nanocomposites can be effectively used for the detection of Azithromycin. [•] Low detection limit with wide linear range could be obtained. [•] The method was applied to determine Azi in real samples. [ABSTRACT FROM AUTHOR]

• Facile and rapid one-step mass production of flexible 3D porous graphene electrode. • The flexible electrode as nanozyme was applied for simultaneous detection of XT and HX. • ML model with ANN algorithm was built to realize smart analysis and digital output for evaluating the fish freshness. In this report, we have prepared 3D porous graphene flexible nanozyme electrode on polyimide by direct laser-writing technology using a home-made computer-controlled laser scribing machine, which is a cost-efficient and one-step mass-production method. This flexible electrode exhibited outstanding mechanical flexibility, distinctive 3D porous structure, expected cycle stability, high conductivity, which was employed as a novel electrochemical nano-sensing platform for intelligent evaluation of fish freshness via simultaneous detection of both xanthine (XT) and hypoxanthine (HX) and smart analysis and digital output using machine learning (ML) model based on artificial neural network (ANN) algorithm. The as-prepared flexible electrode showed an enzyme-like kinetic (nanozyme) characteristic during the detection of XT (0.3–179.9 μM) and HX (0.3–159.9 μM) with a limit of detection (LOD) of 0.26 μM and 0.18 μM, respectively. The fish freshness was evaluated by voltammetric detection of both XT and HX in fish sample with different storage times, and ML model with ANN algorithm was built to realize smart analysis and digital output for evaluating the fish freshness. This will provide an experimental support for biomimetic flexible nano-sensing platform based on nanozyme flexible electrode via facile and rapid one-step mass production and intelligent nano-sensing platform based on ML model for intelligent operation for smart analysis and intelligent transformation for digital output. [ABSTRACT FROM AUTHOR]