Modified electrodes with metal or metal oxides nanoparticles are particularly appealing to improve sensor performances and fabricate miniaturized devices, as required also in glucose detection. A Pt electrode modified by drop casting of a novel nanostructured film based on silver nanoparticles (Ag-NPs) capped in a commercial nontoxic polyvinyl alcohol (PVA) matrix is proposed here as a valid alternative to classical glucose (bio)sensors. The extensive electrochemical and spectroscopic characterization by X-ray Photoelectron Spectroscopy (XPS) of this advanced nanomaterial is presented to study its response to glucose and to investigate the chemical nature of deposited Ag.

The present work describes the preparation and the characterization of a composite nanomaterial obtained by the electrochemical deposition of copper nanoparticles (CuNPs) on an electrosynthesized film of poly-3-methylthiophene (P3MT). Copper electrodeposition was achieved by applying a potential pulse program both on Pt and on screen-printed electrodes (SPEs). The microscopic characterization of the composite film by scanning electron microscopy (SEM) suggested that the applied pulse width is correlated to the amount of the deposited particles but it does not influence CuNPs size. The nanocomposite was analyzed also by X-ray Photoelectron Spectroscopy (XPS) confirming the influence of the pulse width on the amount of electrodeposited copper and evidencing the presence of Cu(I) and Cu(II) species in each sample. For a comparison, CuNPs were prepared from solutions of both CuCl2 and Cu(ClO4)2. XPS analysis evidenced the stabilizing effect of Cl− ions on CuNPs promoting their entrapment in P3MT film also when the composite film is exposed to carrier solution in a flow system, contrarily to what observed in the presence of ClO4− ions. Performed electrochemical tests showed that CuNPs/P3MT exhibited a remarkable electrocatalytic activity for glucose oxidation. The composite film deposited on SPEs was successfully used for glucose electrochemical detection in a flow system. The effect of the applied potential and of the flow rate of carrier stream was evaluated: under the selected optimal condition the composite film exhibited a satisfactory response in terms of detection limit, linear range and repeatability. The sensitivity of CuNPs/P3MT to other compounds (ascorbic acid, uric acid, sorbitol, fructose, dopamine) was verified evidencing that the proposed system could be effectively used as an electrochemical detector coupled to a chromatographic system for the simultaneous detection of biomolecules.

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−1cm−2. The developed sensor showed satisfactory reproducibility and anti-interference properties and was successfully applied to BPA determination in mineral water samples.

The electrochemical synthesis of a metal complex based molecularly imprinted polymer (MIP) has been applied to the development of an electrochemical sensor for a chlorophenoxy carboxylic acid (4-(2,4- dichlorophenoxy)butyric acid (2,4-DB)) commonly used as pesticide. MIP has been electrosynthesized on a platinum electrode by using a Co-porphyrin (Co(III)tetrakis(o-aminophenyl) porphyrin) as functional monomer. The entrapment of the template in polymeric matrix after polymerization was verified by FTIR experiments. Washing protocol has been investigated by studying the effect of different solvents as well as of the exposure time to washing mixture by XPS analysis. Under selected conditions almost the total amount of the withdrawn template was removed. An interaction mechanism between MIP and template was hypothesized on the basis of XPS data. The imprinting effect was verified by comparing electrochemical responses of MIP and not-imprinted polymer (NIP) tested by cyclic voltammetry between −0.1 and −1.7V (vs Ag/Ag+ 0.1M in ACN) and at a constant potential (−1.8V vs Ag/Ag+ 0.1M in ACN). In both cases MIP revealed an enhanced electrocatalytic activity towards 2,4-DB reduction. Amperometric MIP response revealed to be particularly satisfactory in terms of linear range (200M–2mM), sensitivity (5.89AmM−1), reproducibility (RSD 17%) and time-stability. Moreover, MIP-based electrodes evidenced a good selectivity against both pesticides and structurally related compounds with a total removal of interference coming from chlorophenols.

The present work describes the development of a simple and cost-effective electrochemical sensor for sulfadimethoxine (SDM) based on molecularly imprinted overoxidized polypyrrole (PPy). An all electrochemical approach is used for sensor fabrication and application consisting in molecularly imprinted polymer (MIP) galvanostatic deposition on a gold electrode and its overoxidation under different experimental conditions and in SDM amperometric detection. Several parameters influencing the imprinting effect are critically discussed and evaluated. A key role of the electrolyte used in electropolymerization (tetrabuthylammonium perchlorate and lithium perchlorate) has emerged demonstrating its effect on sensing performances of imprinted PPy and, related to this, on its morphology, as highlighted by atomic force microscopy (AFM). The effect of different overoxidation conditions in removing template is evaluated by analyzing MIP films before and after the treatment by X-ray photoelectron spectroscopy (XPS) also evidencing the correlation between MIP chemical structure and its rebinding ability. MIP-template interaction is verified also by Fourier Transform Infrared (FT-IR) spectroscopy. Under the selected optimal conditions, MIP sensor shows a linear range from 0.15 to 3.7 mM SDM, a limit of detection of 70 μM, a highly reproducible response (RSD 4.2%) and a good selectivity in the presence of structurally related molecules. SDM was determined in milk samples spiked at two concentration levels: 0.2 mM and 0.4 mM obtaining a satisfactory recovery of (97±3)% and (96±8)%, respectively.

A novel imprinting scheme, combining for the first time electropolymerization with metal-ion coordination, has been proposed. A MIP for a pesticide (4-(2,4-dichlorophenoxy)butyric acid (2,4-DB)) has been prepared from a Co-porphyrin (Co(III)tetrakis(o-aminophenyl) porphyrin (CoTAPP)) as functional monomer. Such an approach aims to combine advantages of electropolymerization with ones related to the use of metal complexes in imprinting procedures. After verification of template entrapment and subsequent removal by XPS spectroscopy, the imprinting effect was verified by comparing electrochemical responses of MIP and not-imprinted polymer (NIP) tested by Cyclic Voltammetry (CV). MIP revealed an enhanced electrocatalytic activity towards 2,4-DB reduction as well as a good selectivity against both pesticides and structurally related compounds.

The development of an electrosynthesized imprinted polypyrrole (PPY) film onto a platinum sheet as sorbent phase for a fluoroquinolone antibiotic (levofloxacin) is described. Experimental conditions for the electropolymerization of PPY in the presence of the template were optimized. The molecularly imprinted polymer (MIP) film was characterized by X-Ray Photoelectron Spectroscopy (XPS) to verify the template entrapment in the polymeric matrix. After being subject to washing procedures, MIP was analyzed by XPS and a very satisfactory template removal was estimated being equal to 83%. The effectiveness of washing protocol was assessed also by UV–vis and High Performance Liquid Chromatography (HPLC) analysis of corresponding washing solutions. Rebinding experiments were performed by exposing the imprinted PPY film to levofloxacin solutions, subsequently analyzed by HPLC. The effect of solvent and time of exposure was investigated. The imprinting effect was verified by comparing recognition abilities of both MIP and not imprinted polymer (a polymer prepared in the same conditions but in the absence of the template).

In this work a new original amperometric sensor forH2O2 detection based on a Pt electrode modified with Te-microtubes was developed. Te-microtubes, synthesized by the simple thermal evaporation of Te powder, have a tubular structure with a hexagonal cross-section and are open ended. Modified electrode was prepared by direct drop casting of the mixture of Te-microtubes dispersed in ethanol on Pt surface. The spectroscopic characterization of synthesized Te-microtubes and Pt/Te-microtubes modified electrodes was performed by scanning electron microscopy (SEM), energy-dispersive X-rays microanalysis (EDX), X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS). Moreover a complete electrochemical characterization of the new composite material Pt/Te-microtubes was performed by cyclic voltammetry (CV) and cronoamperometry (CA) in phosphate buffer solution (PBS) at pH 7. Electrochemical experiments showed that the presence of Te-microtubes on modified electrode was responsible for an increment of both cathodic and anodic currents in presence of H2O2 with respect to bare Pt. Specifically, data collected from amperometric experiments at −150mV vs. SCE in batch and −200mV vs. SCE in flow injection analysis (FIA) experiments show a remarkable increment of the cathodic current. The electrochemical performances of tested sensors make them suitable for the quantitative determination of H2O2 substrate both in batch and in FIA.

A simple and novel amperometric biosensor for glucose detection is proposed. It is based on the immobilization of glucose oxidase (GOx) in a poly(vinyl alcohol) (PVA) matrix directly drop casted on a platinum electrode surface (Pt/GOx-PVA). Glucose was determined in the absence of a mediator used to transfer electrons between the electrode and the enzyme. The correlation between peak current (ip) and scan rate has been verified and the effect of pH solution has been checked. Glucose detection has been performed amperometrically at 400 mV by using pulsed amperometric detection (PAD). Under the selected optimal conditions, the biosensor showed low detection limit (10 mM), wide dynamic range (0.1–37 mM) and high sensitivity. The biosensor amperometric response revealed it to be specific to glucose without significant interference from other sugars and electroactive species coexisting with glucose in biological fluids. Response stability was another interesting feature of the developed system as it was almost completely recovered when the biosensor was left in opportune storage conditions (i.e., a response decrease of only 13% after 35 days in air at room temperature). Finally, X-Ray Photoelectron Spectroscopy (XPS) characterization revealed a homogeneous film deposited on the Pt substrate whose structure is also preserved under operative conditions.

This review highlights the importance of coupling molecular imprinting technology with methodology based on electrochemical techniques for the development of advanced sensing devices. In recent years, growing interest in molecularly imprinted polymers (MIPs) in the preparation of recognition elements has led researchers to design novel formats for improvement of MIP sensors. Among possible approaches proposed in the literature on this topic, we will focus on the electrosynthesis of MIPs and on less common hybrid technology (e.g. based on electrochemistry and classical MIPs, or nanotechnology). Starting from the early work reported in this field, an overview of the most innovative and successful examples will be reviewed.

Surface doping of nano/mesostructured materials with metal nanoparticles to promote and optimize chemi-transistor sensing performance represents the most advanced research trend in the field of solid-state chemical sensing. In spite of the promising results emerging from metal-doping of a number of nanostructured semiconductors, its applicability to silicon-based chemi-transistor sensors has been hindered so far by the difficulties in integrating the composite metal-silicon nanostructures using the complementary metal-oxide-semiconductor (CMOS) technology. Here we propose a facile and effective top-down method for the high-yield fabrication of chemi-transistor sensors making use of composite porous silicon/gold nanostructures (cSiAuNs) acting as sensing gate. In particular, we investigate the integration of cSiAuNs synthesized by metal-assisted etching (MAE), using gold nanoparticles (NPs) as catalyst, in solid-state junction-field-effect transistors (JFETs), aimed at the detection of NO2 down to 100 parts per billion (ppb). The chemi-transistor sensors, namely cSiAuJFETs, are CMOS compatible, operate at room temperature, and are reliable, sensitive, and fully recoverable for the detection of NO2 at concentrations between 100 and 500 ppb, up to 48 h of continuous operation.

The present work describes a novel technology for microstructuring polypyrrole based on the photoelectropolymerization of PPy films on micromachined ntype silicon (n-Si) substrates. The proposed approach conjugates the flexibility of micromachining techniques in fabricating three-dimensional (3D) microstructures with conducting polymers technology leading to the development of novel PPy films whose features at the microscale can be tailored to the specific applications. Photoelectropolymerization process has been previously studied on flat n-Si substrates and, under selected experimental conditions, on micromachined n-Si containing regular array of ordered macropores with pitch of 8 μm, size (s) of 5 μm and depth (d) of 10 μm. Scanning Electron Microscopy (SEM) analysis of both flat and microstructured PPy films evidenced an isotropic polymers deposition uniformly covering the silicon substrates and perfectly replicating micromachined silicon features. The electrochemical response of photogenerated PPy films to selected probe has been observed and the role of micrometer-scale morphology in enhancing film recognition properties has been verified.

A novel flow cell capable of improving piezoelectric response in system combining Electrochemical Quartz Crystal Microbalance (EQCM) and Flow Injection Analysis is presented. The original design of flow cell modified in shape and position of ports compared to other models for QCM is proposed. Electrochemical and viscoelastic experiments showed focusing of the sample in the central zone between ports and a remarkable enhancement of mass sensitivity compared to Sauerbrey value. Enhancement of mass sensitivity may allow piezoelectric device to be applied to the same concentration range of electrochemical ones and may be used as a tool to develop electrochemical sensors.