A Simple and Renewable Nanoporous Gold‐based Electrochemical Sensor for Bisphenol A Detection

A sensitive and simple electrochemical sensor based on nanoporous gold (NPG) was developed for the detection of bisphenol A (BPA). NPG was prepared by the dealloying method. The NPG modified glassy carbon electrode (GCE) displayed excellent catalytic activity towards the electrooxidation of BPA. The mechanism of the electrooxidation of BPA on NPG/GCE sensor was inferred. The sensor showed a linear range from 0.1 μM to 50 μM with a detection limit of 12.1 nM BPA. Specially, a simple but effective approach was attempted to renew the used sensor. The application of the sensor for real sample analysis was demonstrated.     

Designing and fabrication of a novel gold nanocomposite structure: application in electrochemical sensing of bisphenol A

In this article, a highly sensitive electrochemical sensor is introduced for direct electro-oxidation of bisphenol A (BPA). The novel nanocomposite was prepared based on multi-walled carbon nanotube/thiol functionalised magnetic nanoparticles (Fe₃O₄-SH) as an immobilisation platform and gold nanoparticles (AuNPs) as an amplifying electrochemical signal. The chemisorbed AuNPs exhibited excellent electrochemical activity for the detection of BPA. Some analysing techniques such as Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and energy-dispersive x-ray diffraction exposed the formation of nanocomposite. Under optimum conditions (pH 9), the sensor showed a linear range between 0.002–240 μM, with high sensitivity (0.25 μA μM^?1) along with low detection limit (6.73 × 10^?10 M). Moreover, nanocomposites could efficiently decrease the effect of interfering agents and remarkably enhance the utility of sensor at detection of BPA in some real samples.     

Electrochemical sensing of bisphenol A on single-walled carbon nanotube paper electrodes

The electrochemical detection of BPA often requires modification of electrodes to overcome BPA′s slower kinetics and higher oxidation potential. This work reports a modification-free, paper electrode based on vacuum-filtered SWCNT thin film. The prepared electrode does not need to be polished or transferred into the conducting substrates. The linear sweep voltammetric detection showed a linear response from 0.5–10 μM and 25–100 μM with the experimental LOD of 1.0 μM (S/N=3). The interference study and good recovery percentage (93–105 %) in real water samples demonstrated the method‘s selectivity. The sensor can be promising for developing a simple, low-cost, portable, and paper-based BPA monitoring system.     

A Novel Electrochemical Sensor Based on FeNi3/CuS/ BiOCl Modified Carbon Paste Electrode for Determination of Bisphenol A

In this study, we used voltammetric method in order to examine the electrochemical behavior of BPA. Hence, we constructed a new electrochemical sensor to detect BPA on the basis of the modified carbon paste electrode using FeNi₃/CuS/BiOCl as a novel nanocomposite. Results showed that when using optimized conditions, the new BPA sensor has a wide linear range between 0.1 μM and 300 μM, lower limit of detection of 0.05 μM, and good reproducibility and stability. Based on the findings, it could be concluded that our sensor can be substantially utilized for detecting BPA in the food samples with reasonable outputs.     

末端可裁切碳纳米管薄膜电极的制备及其双酚A电化学检测应用

通过真空抽滤方法得到均匀致密的高导电多壁碳纳米管(MWCNTs)薄膜,利用聚二甲基硅氧烷(PDMS)对其进行封闭处理,制备出末端可裁切的PDMS基柔性碳纳米管薄膜电极,其裁切端面为电化学传感界面。在十六烷基三甲基溴化铵(CTAB)的增敏作用下,所制备的电化学传感器对双酚A(BPA)具有灵敏的电化学响应,其峰电流与BPA浓度在0.05~0.5μmol/L和0.5~12μmol/L范围内呈良好的线性关系,检测限为50nmol/L。通过电极末端的重复裁切可避免电极污染,并实现电极表面的快速更新和重复使用。对同一支电极进行13次连续裁切,用于10μmol/L BPA的检测,其相对标准偏差为3.4%。将该传感器应用于热敏纸样品中BPA的检测,加标回收率在95%~105%之间。     

Stable and Sensitive Amperometric Determination of Endocrine Disruptor Bisphenol A at Residual Metal Impurities Within SWCNT

A simple and attentive method was attempted for the determination of endocrine disruptor molecule, Bisphenol A (BPA) using residual metal impurity act as a reactant present in as received SWCNT. The electrochemical behavior of BPA oxidation and its reaction mechanism was investigated by cyclic voltammetry using “as received SWCNT modified on glassy carbon electrode” (SWCNT/GCE) and the obtained results were compared with bare GCE. The SWCNT/GCE showed high electrocatalytic activity, sensitivity, stability and more importantly not much surface fouling compared with bare GCE. This is because of the formation of electroactive quinone and catechol as byproducts on SWCNT/GCE during electro‐oxidation of BPA. More interestingly, the electrochemically acid treated SWCNT/GCE not showed any characteristic oxidation and reduction peaks during electro‐oxidation of BPA which indicates that the presence of a residual metal impurity in SWCNT plays a vital role in electro‐oxidation of BPA. The amperometric detection of BPA oxidation on SWCNT/GCE showed excellent stability and good linear response from the wide range of concentration of 10–100 μM. The limit of detection and sensitivity of BPA electro‐oxidation on SWCNT/GCE is to be 7.3 μM (S/N=3) and 0.6494 μA/μM cm² respectively. Finally, the fabricated sensor using SWCNT/GCE was successfully applied for the detection of BPA in plastic water bottles with excellent recovery range from 98–102 %.     

Development of an Electrochemical Sensor Based on Covalent Molecular Imprinting for Selective Determination of Bisphenol‐A

In this study, an electrochemical sensor was developed and used for selective determination of bisfenol‐A (BPA) by integrating sol‐gel technique and multi‐walled carbon nanotubes (MWCNTs) modified paste electrode. BPA bounded by covalently to isocyanatopropyl‐triethoxy silane (ICPTS) was synthesized as a new precursor (BPA‐ICPTS) and then BPA‐imprinted polymer (BPA‐IP) sol‐gel was prepared by using tetramethoxysilane (TMOS) and BPA‐ICPTS. Non‐imprinted polymer (NIP) sol‐gel was obtained by using TMOS and (3‐Aminopropyl) triethoxysilane. Both BPA‐IP and NIP sol‐gels were characterized by nitrogen adsorption‐desorption analysis, FTIR, SEM, particle size analyzer and optical microscope. Carbon paste sensor electrode was fabricated by mixing the newly synthesized BPA‐IP with MWCNTs, graphite powder and paraffin oil. The electrochemical characterization of the sensor electrode was achieved with cyclic and differential pulse voltammetric techniques. The response of the developed sensor under the most proper conditions was linear in BPA concentration range from 4.0×10⁻⁹ to 1.0×10⁻⁷ mol L⁻¹ and 5.0×10⁻⁷ to 5.0×10⁻⁵ mol L⁻¹ and the detection limit was 4.4×10⁻⁹ mol L⁻¹. The results unclosed that the proposed sensor displayed high sensitivity and selectivity, superior electrochemical performance and rapid response to BPA.     

An Electrochemical Sensor Based on Nitrogen‐doped Carbon Nanofiber for Bisphenol A Determination

In this paper, bisphenol A was determined by electrochemical method at a nitrogen‐doped carbon nanofiber modified carbon paste electrode (NCNF/CPE) with high sensitivity and good selectivity. NCNF was obtained by a simple electrospinning followed by carbonization procedure, in which polyacrylonitrile (PAN) as precursor and nitrogen doping was realized by re‐utilizing the tail gas that produced in the thermal pretreatment process. Good reproducibility and high stability were obtained for BPA detection at NCNF modified CPE. Current response plotted with BPA concentration was linear in the range of 0.1–60 μM with LOD of 0.05 μM. The proposed electrochemical sensor was employed for BPA determination with satisfactory recoveries for real water samples, indicating the practical applicability of NCNF/CPE.     

A Novel Flexible Electrochemical Ascorbic Acid Sensor Constructed by Ferrocene Methanol doped Multi-walled Carbon Nanotube Yarn

An ascorbic acid (AA) electrochemical sensor was fabricated by ferrocene methanol (Fc−OH) modified multi-walled carbon nanotube yarn (CNTY). The prepared sensor (Fc−OH/CNTY) exhibited outstanding flexibility, highly stretchability, excellent bendability and obviously electrocatalytic activity for oxidation of ascorbic acid. The morphology of Fc−OH/CNTY was evaluated by scanning electron microscope. The electrochemical behaviour of Fc−OH/CNTY sensor was studied by cyclic voltammetry and amperometry measurements. Moreover, the influence of Fc−OH concentration, applied potential and electrolyte solution pH were also investigated to obtain the best sensor performance. The prepared sensor exhibited a wide linear range from 3 μM to 3.0 mM toward AA, and a detection limit of 1.32 μM (S/N=3). It also possessed a good lifetime and a fast response speed (2.83 s). In addition, the Fc−OH/CNTY sensor remained 90 % and 60 % of its initial activity after 100 and 500 times bending, respectively, which indicated a potential application on flexible, implantable and/or wearable electrochemical sensors.     

Sensitive Voltammetric Determination of Bisphenol A Based on a Glassy Carbon Electrode Modified with Copper Oxide‐Zinc Oxide Decorated on Graphene Oxide

A highly sensitive and selective chemical sensor was prepared based on metallic copper‐copper oxides and zinc oxide decorated graphene oxide modified glassy carbon electrode (Cu?Zn/GO/GCE) through an easily electrochemical method for the quantification of bisphenol A (BPA). The composite electrode was characterized via scanning electron microscopy (SEM), X‐Ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of BPA in Britton‐Robinson (BR) buffer solution (pH 7.1) was examined using cyclic voltammetry (CV). Under optimized conditions, the square wave voltammetry (SWV) response of Cu?Zn/GO/GCE towards BPA indicates two linear relationships within concentrations (3.0 nmol L^?1?0.1 μmol L^?1 and 0.35 μmol L^?1?20.0 μmol L^?) and has a low detection limit (0.88 nmol L^?1). The proposed electrochemical sensor based on Cu?Zn/GO/GCE is both time and cost effective, has good reproducibility, high selectivity as well as stability for BPA determination. The developed composite electrode was used to detect BPA in various samples including baby feeding bottle, pacifier, water bottle and food storage container and satisfactory results were obtained with high recoveries.     

Application of nanosized MCM-41 to fabrication of a nanostructured electrochemical sensor for the simultaneous determination of levodopa and carbidopa

A novel carbon paste electrode modified with nanosized mesoporous MCM-41 was prepared, and used as an electrochemical sensor to study the electro oxidation of levodopa (LD), carbidopa (CD) and their mixtures. Using differential pulse voltammetry (DPV), a highly selective and simultaneous determination of LD and CD has been explored at the modified electrode. The electrochemical sensor displayed a good resolving function for the overlapping voltammetric responses of LD and CD into two separate peaks with a potential difference of 370 mV. DPV peak currents of LD increased linearly with concentration over the 0.13 μM to 1250.00 μM range and exhibited a detection limit of 0.072 μM. Also, the proposed electrochemical sensor was used for the determination of LD and CD in some real samples, using the standard addition method.     

Development of Pen-type Portable Electrochemical Sensor Based on Au-W Bimetallic Nanoparticles Decorated Graphene-chitosan Nanocomposite Film for the Detection of Nitrite in Water,Milk and Fruit Juices

The development and fabrication of a simple, portable, and sensitive detection tool to precisely monitor nitrite level is of growing importance in electrochemistry research, given the strong interest in the protection of drinking water quality, treatment of wastewater, food production, and control of remediation processes. This work describes the fabrication of a simple, cost-effective, pen-type electrochemical sensor based on bimetallic gold and tungsten nanoparticles electrochemically decorated on graphene-chitosan modified pencil graphite electrode (PGE) for the trace detection of nitrite in real samples. The prepared nanocomposite was characterized using XRD, SEM, and EDS. The electrochemical behavior of the sensor was evaluated by cyclic voltammetry (CV) and impedance electrochemical spectroscopy (EIS). Results revealed that the proposed sensor displayed excellent electrocatalytic activity towards electro-oxidation of nitrite with an irreversible redox reaction. The AuNPs-WNPs@Gr-Chi/PGE sensor exhibited excellent analytical performance with a wide linear range from 10 to 250 μM towards nitrite. The LOD and LOQ were calculated to be 0.12 μM and 0.44 μM, respectively. The designed electrochemical sensor was successfully applied for the detection of nitrite in water, milk, and natural fruit juice samples.     

A simple and sensitive portable system for a rapid evaluation of bisphenol A contamination in potable and environmental waters using a mesoporous silica-modified carbon paste electrode

In this work, two ordered mesoporous silicas (HMS and SBA-15) were prepared and incorporated into carbon paste electrodes (CPEs) to obtain mesostructured sensors for a rapid determination of bisphenol A (BPA) in waters by voltammetric techniques. The materials were characterised by nitrogen adsorption-desorption measurements, transmission electron microscopy and scanning electron microscopy. The electrochemical properties of the modified carbon paste electrodes were studied by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Results showed that the sensor modified with HMS (HMS-CPE) exhibited strong adsorption activity toward the oxidation of BPA, with a well-defined voltammetric peak at +0.6 V. Moreover, the HMS-CPE exhibited a wider linearity range, from 0.44 to 3.5 μM BPA, with a detection limit of 61 nM (S/N = 3) and good reproducibility by DPV. The enhanced performance of the HMS-CPE could be attributed to its high surface area, with a 3 D wormhole-like channel structure that favoured an excellent accessibility, high adsorption capacity and faster adsorption rate of BPA. This novel sensor was coupled to a portable system and successfully applied for a rapid determination of BPA in tap, mineral, well and river water samples with good recovery, ranging from 98 ± 12 to 103 ± 7%.     

Functional graphene-gold nano-composite fabricated electrochemical biosensor for direct and rapid detection of bisphenol A

In this research, the graphene with excellent dispersity is prepared successfully by introducing gold nanoparticle to separate the individual sheets. Various techniques are adopted to characterize the prepared graphene and graphene-gold nanoparticle composite materials. This fabricated new composite material is used as the support material to construct a novel tyrosinase based biosensor for detection of bisphenol A (BPA). The electrochemical performances of the proposed new enzyme biosensor were investigated by differential pulse voltammetry (DPV) method. The proposed biosensor exhibited excellent performance for BPA determination with a wide linear range (2.5 × 10⁻³–3.0 μM), a highly reproducible response (RSD of 2.7%), low interferences and long-term stability. And more importantly, the calculated detection limit of the proposed biosensor was as low as 1 nM. Compared with other detection methods, this graphene-gold nanoparticle composite based tyrosinase biosensor is proved to be a promising and reliable tool for rapid detection of BPA for on-site analysis of emergency BPA related pollution affairs.     

Biosensor for bisphenol A leaching from baby bottles using a glassy carbon electrode modified with DNA and single walled carbon nanotubes

We have developed a biosensor for highly sensitive and selective determination of the endocrinic disruptor bisphenol A (BPA). It is based on glassy carbon electrode modified with calf thymus DNA and a composited prepared from single walled carbon nanotubes (SWNT) and Nafion. The interaction between BPA and DNA was studied by voltammetry. The binding constant was determined to be 3.55?×?10³ M^?1, and the binding site has a length of 4.3 base pairs. These electrochemical studies provide further information for a better understanding of the toxicity and carcinogenicity of BPA. Under optimal conditions, the biosensor displays a linear electrochemical response to BPA in the 10 nM to 20 μM concentration range, with a detection limit as low as 5.0 nM (at an S/N of 3). The method was successfully applied to the quantification of BPA in leachates from plastic baby bottles. Recoveries range from 94.0 % to 106.0 % which underpins the excellent performance of this SWNT-based DNA sensor.

Electroanalytical Determination of Paracetamol Using Pd Nanoparticles Deposited on Carboxylated Graphene Oxide Modified Glassy Carbon Electrode

The study presents a novel paracetamol (PA) sensor based on Pd nanoparticles (PdNPs) deposited on carboxylated graphene oxide (GO?COOH) and nafion (Nf) modified glassy carbon electrode (GCE). The morphologies of the as prepared composites were characterized using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FTIR). The experimental results demonstrated that Nf/GO?COOPd displayed excellent electrocatalytic response to the oxidation PA. The linear range was 0.04–800 μM for PA with limit of detection of 0.012 μM and excellent sensitivity of 232.89 μA mM^?1 cm^?2. By considering the excellent performance of Nf/GO?COOPd composite such as wider linear range, lower detection, better selectivity, repeatability, reproducibility, and storage stability, the prepared composite, especially GO?COOH support, with satisfactory electrocatalytic properties was a promising material for the modification of electrode material in electrochemical sensor and biosensor field.     

基于纳米金增敏的双酚A二氧化钛凝胶分子印迹电化学传感器的制备及应用

以纳米金(Au NPs)为增敏材料,双酚A(BPA)为模板分子,结合表面溶胶凝胶法和自组装法,制备了BPA纳米金-Ti O_2凝胶分子印迹电化学传感器。利用扫描电子显微镜和能谱对Au NPs进行了表征,利用红外光谱仪对Ti O_2凝胶、BPA以及BPA印迹Ti O_2凝胶进行表征。在最优条件下,该传感器对BPA在1.0×10~(-8)~1.0×10~(-5)mol/L浓度范围内具有良好的线性关系,线性相关系数为0.995,检测限为0.6×10~(-8)mol/L,并将该分子印迹传感器应用于实际样品中BPA的分析检测,其回收率为97.4%~103%。     

High Performance Non‐enzymatic Glucose Sensor Based on One‐Step Electrodeposited Nickel Sulfide

Nanostructured NiS thin film was prepared by a one‐step electrodeposition method and the structural, morphological characteristics of the as‐prepared films were analyzed by X‐ray diffractometry (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X‐ray analysis (EDAX). The electrocatalytic activity of NiS thin film towards glucose oxidation was investigated by fabricating a non‐enzymatic glucose sensor and the sensor performance was studied by cyclic voltammetry (CV) and amperometry. The fabricated sensor showed excellent sensitivity and low detection limit with values of 7.43 μA μM ^?1 cm^?2 and 0.32 μM , respectively, and a response time of <8 s.     

基于表面分子印迹技术及相转化过程的双酚A电化学传感器

以双酚A (Bisphenol A, BPA)为模板, 氨基化硅胶为载体合成了对BPA有特异选择性的表面分子印迹聚合物(surface molecularly imprinted polymer, sMIP). 然后以聚氯乙烯(PVC)为支撑基质, 通过相转化过程(phase inversion process)制成BPA分子印迹聚合物膜, 将聚合物膜固载到处理过的金电极表面, 制成电流型双酚A电化学传感器. 优化了pH值、温度等实验条件, 结果表明在10～120 μg/mL范围内对双酚A有良好的线性响应(R＝0.9971). 传感器用于实际水样的测定, 结果令人满意.     

Direct electrochemical detection of bisphenol A at PEDOT-modified glassy carbon electrodes

The electrochemical behavior of bisphenol A (BPA) was studied on poly(3,4-ethylenedioxythiophene) (PEDOT)-modified glassy carbon electrodes by cyclic voltammetry. It was observed that BPA oxidation on PEDOT film produced a BPA polymer (pBPA) showing excellent redox activity with anodic and cathodic peaks at 0.15 and 0.01 V, respectively; the former being evaluated for BPA electrochemical sensing. The amount of deposited pBPA has been estimated by electrochemical and spectroscopic analysis by X-ray photoelectron spectroscopy. The effect of scan rate and pH on the oxidation of pBPA film has been studied. The oxidation current was found to vary linearly with BPA concentration in the range 90–410 μM, and a detection limit of 55 μM was evaluated. Results of BPA amperometric detection have also been collected by using a repetitive potential step program to give a linear response to BPA in the concentration range 40–410 μM with a detection limit of 22 μM and a sensitivity of 1.57 μAμM^?1?cm^?2. The developed sensor showed satisfactory reproducibility and anti-interference properties and was successfully applied to BPA determination in mineral water samples.