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Herein, we present a novel electrode platform for H2O2 detection based on the immobilization of recombinant Tobacco Peroxidase (r-TOP) onto graphite electrodes (G) modified with p-phenylenediamine (p-PD) diazonium cation grafted multi-walled carbon nanotubes (MWCNTs). The employment of both p-phenylenediamine moieties and covalent cross-linking by using glutaraldehyde allowed us to enhance the sensitivity, stability, and selectivity toward H2O2 detection, as well as preventing enzyme inactivation due to the electro-Fenton reaction. This reaction continuously produces hydroxyl radicals, whose high and unselective reactivity is likely to reduce drastically the operating life of the biosensor. The protection against the electro-Fenton reaction is mainly ascribed to a beneficial enzyme immobilization leading to a correct orientation achieved through cross-linking the enzyme in combination with interaction between the uncoupled -NH2 groups (mainly uncharged at pH 7, considering a pKa of 4.6) available on the electrode surface and the enzyme. In particular, the electrode based on the r-TOP/p-PD/MWCNTs/G platform showed a lower limit of detection of 1.8 μM H2O2, an extended linear range between 6 and 900 μM H2O2, as well as a significant increase in sensitivity (63.1±0.1 μA mM−1 cm−2) compared with previous work based on TOP. Finally, the r-TOP/p-PD/MWCNTs/G electrode was tested in several H2O2 spiked food samples as a screening analytical method for the detection of H2O2. (Less)

We report a new sensitive label-free electrochemical immunosensor to detect Vitamin D

This work presents the realization of a label-free electrochemical immunosensor for the quick, cheap, and straightforward determination of atrazine. This biodevice is based on developing a technological platform where a gold screen printed electrode (Au-SPE) surface was modified by the electrodeposition of a highly porous gold layer. As an internal probe redox, a Prussian Blue thin layer (PB) was then electrosynthetized onto the modified Au-SPE. Atrazine antibody (Ab-ATZ) was immobilized using G protein-functionalized magnetic nanoparticles (MNPs@protG) to ensure the correct orientation of the antibody to enhance the immunoaffinity. Under optimum experimental conditions, the electrochemical characterization of the developed immunosensor displays a linearity range towards atrazine within 0.05-1.5 ng/mL, a LOD of 0.011 ng/mL good reproducibility and stability. The immunosensor was tested in the analysis of spiked drinking water samples with a mean recovery ranging from 95.7 to 108.4%. The overall good analytical performances of this immunodevice suggest its application for the screening and monitoring of atrazine in real matrices.

The development of an electrochemical cell based on poly(vinyl alcohol) (PVA) hydrogel as polymer electrolyte for electrochemical impedance spectroscopy analysis (EIS) is discussed. PVA hydrogel is prepared with different cycles of freeze/thawing (F/T) employing distillated and mineral water as solutions. The PVA-disks obtained are compared for their conductivities in order to employ it in an appropriate cell for diagnostic purposes, reducing the invasiveness of the analysis on the sample. The test of the self-consistent disk of PVA is carried out on a modern sample of copper and on an archaeological bronze coin, obtaining an alternative of the classical electrochemical cell for EIS measurements on ancient metals.

Electrochemical immunosensors are affinity-based biosensors characterized by several useful features such as specificity, miniaturizability, low cost and simplicity, making them very interesting for many applications in several scientific fields. One of the significant issues in the design of electrochemical immunosensors is to increase the system’s sensitivity. Different strategies have been developed, one of the most common is the use of nanostructured materials as electrode materials, nanocarriers, electroactive or electrocatalytic nanotracers because of their abilities in signal amplification and biocompatibility. In this review, we will consider some of the most used nanostructures employed in the development of electrochemical immunosensors (e.g., metallic nanoparticles, graphene, carbon nanotubes) and many other still uncommon nanomaterials. Furthermore, their diagnostic applications in the last decade will be discussed, referring to two relevant issues of present-day: the detection of tumor markers and viruses.

In this study, polythiophene copolymers have been used as modifier for electrode surfaces in order to allow the immobilization of active pyrroloquinoline quinone dependent glucose dehydrogenase (PQQ-GDH) and to simultaneously improve the direct electrical connection of the enzyme with the electrode. Polymer films are electrosynthesized in aqueous solution without the need of surfactants onto carbon nanotubes modified gold electrodes from mixtures of 3-thiopheneacetic acid (ThCH2CO2H) and 3-methoxythiophene (ThOCH3) using a potentiostatic pulse method. Polythiophene deposition significantly improves the bioelectrocatalysis of PQQ-GDH: the process starts at − 200 mV vs. Ag/AgCl and allows well-defined glucose detection at 0 V vs. Ag/AgCl with high current density. Several parameters of the electro-polymerization method have been evaluated to maximize the anodic current output after enzyme coupling. The polymer deposited by this new procedure has been morphologically and chemically characterized by different methods (SEM, EDX, FT-IR, UV–Vis, XPS and Raman spectroscopy). The bioelectrocatalytic response towards increasing glucose concentrations exhibits a dynamic range extending from 1 μM to 2 mM. The low applied potential allows to avoid interferences from easily oxidizable substances such as uric acid and ascorbic acid. Short and long-term stability has been evaluated. Finally, the PQQ-GDH electrode has been coupled to a bilirubin oxidase (BOD)- and carbon nanotube-based cathode in order to test its performance as anode of a biofuel cell. The promising results suggest a further investigation of this kind of polymers and, in particular, the study of the interaction with other enzymes in order to employ them in building up biosensors and biofuel cells.

This paper presents a new direct electron transfer based-miniaturized glucose/oxygen enzymatic fuel cell (EFC) whose operating ability has been tested in real saliva samples. The bioanode and biocathode are a graphene working electrode and a graphite counter electrode localized on the same screen printed electrode (SPE) modified with poly(vinyl alcohol) N-methyl-4(4′-formylstyryl)pyridinium methosulfate acetal (PVA-SbQ)/cellobiose dehydrogenase from Corynascus Thermophilus (CtCDH) C291Y/AuNPs and with Trametes Hirsuta laccase (ThLac)/AuNPs, respectively. In order to optimize the bioanode, several CDH immobilization procedures were adopted, such as drop-casting, use of Nafion membrane or PVA-SbQ photopolymer. The photopolymer showed the best performance in terms of stability and reliability. As biocathode a partially optimized laccase electrode was employed with the variant that the used nanomaterials allowed to reduce the overpotential of O2/H2O redox reaction catalyzed by Trametes Hirsuta Laccase (ThLac), drop-casted onto the gold nanoparticles (AuNPs) modified SPE. The performances of bioanode and biocathode were tested separately, initially immobilizing the two enzymes onto separated graphene SPEs. An efficient direct electron transfer was achieved for both elements, obtaining an apparent heterogeneous electron transfer rate constant (ks) of 0.99 ± 0.05 s−1 for CtCDH C291Y and 5.60 ± 0.05 s−1 for ThLac. Both electrodes were then assembled in a two compartment EFC obtaining a maximal power output of 5.16 ± 0.15 μW cm−2 at a cell voltage of 0.58 V and an open circuit voltage (OCV) of 0.74 V. Successively, the bioanode and biocathode were assembled in a non-compartmentalized EFC and a remarkable 50% decrease of the maximum power output at the value of 2.15 ± 0.12 μW cm−2 at cell voltage of 0.48 V and an OCV of 0.62 V at pH 6.5 was registered. In order to reduce the cell dimensions in view of its possible integration in biomedical devices, the bioanode and biocaythode were realized by immobilization of both enzymes onto the same SPE. The so miniaturized EFC delivered a maximal power output of 1.57 ± 0.07 μW cm2 and 1.10 ± 0.12 μW cm−2 with an OCV of 0.58 V and 0.41 V in a 100 μM glucose solution and in human saliva, respectively.

In this study, the ability of an unmodified ESI Z-spray source to carry out ambient ion soft landing (AISL) and microdroplet reactions (MR) was tested. To this aim, heme proteins were ionized and landed onto the working area of multi-walled carbon nanotubes electrodes. The voltammetric and spectroscopic analyses of the modified electrodes evidenced a strong interaction of unfolded structures of the heme proteins with the carbon nanotubes surface. Moreover, the possibility to use the ESI Z-spray source to study microdroplet reactions was attempted by exploring the accelerated acid-catalyzed decomposition of carbohydrates. The study demonstrated that a commercial ESI Z-spray source can provide successful modifications of surfaces by AISL, and represents a suitable platform for the study of accelerated microdroplet reactions.

The establishment of a polythiophene-supported electron transfer of PQQ-dependent glucose dehydrogenase (PQQ-GDH) at multiwalled carbon nanotubes is reported. For this purpose, thiol-functionalized MWCNTs are deposited on a gold electrode, which is further modified by on-top electropolymerization of different thiophene monomers. The enzyme is covalently bound to such an electrode by activating the carboxy groups of the polymer. The presence of the polythiophene copolymers allows for electrochemical wiring of PQQ-GDH that can subsequently transfer the electrons from the glucose oxidation to the electrode. Bioelectrocatalysis starts just at −0.2 V vs. Ag/AgCl and the anodic current reaches high values already at 0 V vs. Ag/AgCl. In order to improve the catalytic response, different parameters in the electropolymerization process are evaluated and buffer effects are investigated. The modified electrode surface is characterized by SEM-EDX, FTIR, UV–vis and XPS. The bioelectrocatalytic response towards increasing glucose concentrations is measured at 0 V vs. Ag/AgCl, showing a dynamic range extending from 1 μM to 500 μM.

This work reports the first employment of a gel polymer-based electrochemical cell to perform electrochemical impedance analysis of archaeological remains. The patinas of three Roman coins are studied through of electrochemical techniques (especially Electrochemical Impedance Spectroscopy, EIS) along with Electron Scanning Microscopy (SEM-EDS) and X-ray diffraction (XRD), in order to validate the results obtained with jellified electrolyte. SEM-EDS and XRD analyses reveal the composition of the patinas suggesting that the original alloys were made of Cu and Cu–Sn–Pb. Furthermore, EIS results make one able to assess some characteristics of coins, as for instance, the presence of a noble patina . This outcome is corroborated by the SEM-EDS and XRD analysis, suggesting that the method based on the jellified electrolyte on archaeological samples can be employed. Moreover, supporting studies are carried out using Voltammetry of Microparticles (VMP), which is able to detect the presence of some specific corrosion products (cuprite). So far, EIS is not a common technique in the Cultural Heritage field despite it can provide useful information about the conditions of conservation, i.e., corrosion processes. Here we can show the advantages of developing a gel-based system for EIS measurement which allows carrying out a punctual and quick analysis on the ancient bronze roman coins.

In this work, we present a new electrochemical biosensor array for the evaluation of pH changes and total polyphenols content based on a conductive polymer used to immobilize anthraquinone-2-carboxylic acid (ANTQ), on the first electrode, and Trametes versicolor laccase on the second one. In particular, the anthraquinone based electrode was sensitive to pH changes detected through potentiometric measurements, while the laccase-based electrode was used to detect the total polyphenols content by using amperometry. After a preliminary characterization of both electrodes, the so prepared array was used to monitor the variation of pH and polyphenols content in different samples of purple passion fruit (Passiflora edulis Sims) stored post harvesting at different temperatures such as room temperature, 4 oC and -20 oC.

Lignin nanoparticles (LNPs) acted as a renewable and efficient platform for the immobilization of horseradish peroxidase (HRP) and glucose oxidase (GOX) by a layer by layer procedure. The use of concanavalin A as a molecular spacer ensured the correct orientation and distance between the two enzymes as confirmed by Forster resonance energy transfer measurement. Layers with different chemo–physical properties tuned in a different way the activity and kinetic parameters of the enzymatic cascade, with cationic lignin performing as the best polyelectrolyte in the retention of the optimal Con A aggregation state. Electrochemical properties, temperature and pH stability, and reusability of the novel systems have been studied, as well as their capacity to perform as colorimetric biosensors in the detection of glucose using ABTS and dopamine as chromogenic substrates. A boosting effect of LNPs was observed during cyclovoltammetry analysis. The limit of detection (LOD) was found to be better than, or comparable to, that previously reported for other HRP–GOX immobilized systems, the best results being again obtained in the presence of a cationic lignin polyelectrolyte. Thus renewable lignin platforms worked as smart and functional devices for the preparation of green biosensors in the detection of glucose.

One of the main problems in the development of immunosensors is to overcome the complexity of binding antibodies to the sensor surface. Most immobilizing methods lead to a random orientation of antibodies with a lower binding site density and immunoaffinity. In order to control the orientation of antibody immobilization, several resorc[4]arene derivatives were designed and synthesized. After the spectroscopic characterization of resorc[4]arene self-assembled monolayers (SAMs) onto gold films, the surface coverage and the orientation of insulin antibody (Ab-Ins) were assessed by a surface plasmon resonance (SPR) technique and compared with a random immobilization method. Experimental results combined with theoretical studies confirmed the dipole-dipole interaction as an important factor in antibody orientation and demonstrated the importance of the upper rim functionalization of resorcarenes. Accordingly, resorcarene 5 showed a major binding force towards Ab-Ins thanks to the H-bond interactions with the amine protein groups. Based on these findings, the resorcarene-based immunosensor is a powerful system with improved sensitivity providing new insight into sensor development.

Efficient direct electron transfer (DET) between cellobiose dehydrogenase from Corynascus thermophilus (CtCDH) and a novel gold electrode platform, obtained by covalent linking of green AuNPs and AgNPs modified with a dithiol self-assembled monolayer, consisting of biphenyl-4,4'-dithiol (BPDT), was presented. The green AuNPs and AgNPs were synthesized using quercetin as reducing agent at room temperature. TEM experiments showed that the AuNPs and AgNPs were circular in shape with an average diameter of 5 and 8nm, respectively. Cyclic voltammetry of CtCDH immobilized onto the AuNPs/BPDT/AuE and the AgNPs/BPDT/AuE electrode platforms were carried out and compared with naked AuE, BPDT/AuE, AuNPs/AuE, and AgNPs/AuE. A pair of well-defined redox waves in neutral pH solution due to efficient DET of CtCDH was present with both MNPs/BPDT/AuE platforms. No DET communication was found with platforms without MNPs linked to BPDT. The apparent heterogeneous electron transfer rate constants (kS) of CtCDH were calculated to be 21.5±0.8s-1 and 10.3±0.7s-1, for the AuNPs/BPDT/AuE and the AgNPs/BPDT/AuE platforms, respectively. The modified electrodes were successively used to develop an eco-friendly biosensor for lactose detection. The CtCDH/AuNPs/BPDT/AuE based biosensor showed the best analytical performances with an excellent stability, a detection limit of 3µM, a linear range between 5 and 400µM and a sensitivity of 27.5±2.5µAcm-2mM-1. Such performances were favorably compared with other lactose biosensors reported in literature. The biosensor was successively tested to quantify lactose content in real milk and cream samples. No significant interference present in the sample matrices was observed.

In this paper we report on a facile, cost effective and environmental friendly green synthesis method of gold and silver nanoparticles (NPs) by using quercetin as reducing agent. The obtained NPs were characterized by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), dynamic light scattering (DLS) and UV-Vis spectroscopy and parameters such as pH, ionic strength and temperature, effectively affecting shape and size of NPs, have been carefully studied and optimized. The obtained results showed that the synthesized NPs were circular in shape with an average diameter of 5 and 8 nm for the AuNPs and the AgNPs, respectively. The “green” NPs, showing increased electroactive areas (AEA) and electronic transfer rate constants (k0), were successively used to fabricate a novel third generation lactose biosensor based on cellobiose dehydrogenase from Trametes villosa (TvCDH). The TvCDH/AuNPs based lactose biosensor revealed the best results showing very efficient DET and a detection limit for lactose of 3.5 mM, a large linear range from 10 to 300 mM, a high sensitivity (5.4 μA mM−1 cm−2) and long-term stability.

Herein we report on a new hybrid enzymatic fuel cell (EFC) based on mediated/direct electron transfer, which is assembled by considering two different configurations: i) two normal screen printed electrodes (SPEs) in one electrochemical cell and ii) two double-sided SPEs each one comprising both bioanode and biocathode, connected in series. After a deep electrodes characterization, they are assembled according to the first configuration obtaining a maximal power output of 25.8 ± 0.7 μW cm−2 at a cell voltage of 0.57 V and an open circuit voltage (OCV) of 0.78 V. Moreover, the EFC performance are substantially improved by using the second configuration (EFCs connected in series) obtaining a maximal power output of 59.6 ± 1.9 μW cm−2 at a cell voltage of 1.16 V and an open circuit voltage (OCV) of 1.58 V. Finally, the last EFC configuration is tested in human saliva and serum showing good performance in terms of OCV and maximal power output as proof-of-concept to power implantable bioelectronics (e.g., pacemaker) or develop self-powered glucose biosensors.

Traditional cleaning methods with organic solvents often are not suitable for removal of aged resin so researchers have to find new formulations. In this work, a case study is reported in which new microemulsions were applied on the surface of a painting covered by some aged resin layers used during a previous restoration. Based on the quality of the intervention and the analysis of a sample of the varnish carried out with both MALDI-TOF and ATR-IR spectrometers, it was conjectured that this undesired material could be an acrylic polymer. So it was chosen to use xylene, ethyl acetate and propylene carbonate (XYL and EAPC) microemulsions (O/W oil in water). The first is able to solubilise only acrylic polymers, the second may solve both acrylic and vinyl resins. The first has had the greatest effect allowing complete varnish removal and original artwork restoration.

Nafion, an ion exchange polymer that is very resistant to chemical attack, even by strong oxidant at high temperatures, has found great increasing use as a film material; however, its use as immobilizing agent in third-generation biosensors is hindered due to the low rate of charge transfer in the pure Nafion film. In this work we showed that the use of functionalized multi-walled carbon nanotubes Nafion/MWCNTs composite film for modification of the carbon-based electrode surfaces would increase the charge transfer rate greatly; the composite has proven to efficiently immobilize two different heme proteins (catalase and cytochrome c) and to enhance the electrochemical performances of several carbon electrode materials (glassy carbon, mesoporous graphite, graphite and graphene) either used as classical electrodes or screen printed ones. The electrochemical signal of both redox proteins becomes more reversible and the electron transfer kinetic constant increases. At the same time the biological activity is maintained indicating that the immobilization procedure allows the proteins to retain a native-like structure.

In this work we have developed a new electrochemical DNA-based biosensor for the selective determination of the Hg(2+) ion by the use of different electrodes modified with polythymine, bearing methylene blue, as redox probe, in 3' position. The determination of Hg(2+) can be employed with an excellent degree of selectivity by the use of DNA biosensors through the formation of the complex Thymine-Hg-Thymine (T-Hg-T): in fact, Hg(2+) tends to bind two thymines, generating a T-Hg-T complex with a formation constant higher than that one of the coupling Adenine-Thymine, which can be employed for a selective, fast and cost-effective Hg(2+) detection. The presence of the Hg(2+) in solution leads to the formation of T-Hg-T complex thus causing the "hairpin-like" folding of oligonucleotide, leading to an improved electronic exchange of methylene blue with the electrode surface due to the reduced distance and thus to an increase of the faradic current which is detected by means of square wave voltammetry (SWV). To test the feasibility of this kind of biosensor to be applied to the analysis of Hg(2+) we have developed several biosensors configuration by modifying the electrochemical sensor transducer: (a) Au electrode; (b) Au screen-printed electrode (SPE). The proposed system, allows the determination of Hg(2+) in the range 0.2-100 nM (0.05-20 ppb), with a sensitivity 0.327 µA/nM, LOD 0.1 nM (0.02 ppb), LOQ 0.2 nM (0.05 ppb) and RSD ≤4.3% when Au electrode is used as electrochemical transducer; on the other hand, in the case of Au SPE the linear range is 0.2-50 nM (0.05-10 ppb), with a sensitivity 0.285 µA/nM, while LOD and LOQ are the same as previously and RSD is ≤3.8%. This enabled the detection of mercury in real samples (waters and fishes) with good accuracy (recoveries 92-101% on waters and 92-107% on fishes, respectively) and reproducibility (RSD ≤9.6% for measurements on waters and ≤8.8% on fishes, respectively).

The immobilization procedure is one of the key factors affecting the electron transfer based biosensors performance. It must assure both the enzyme retention activity and an efficient communication between the redox center of the enzyme and the electrode surface. In this regard, hydrogels are attractive materials due to their three-dimensional hydrophilic networks and their high-water concentration, promoting the biomolecule long-term stability and providing a suitable scaffold for trapping. To this aim, we have synthesized a gelling tripeptide Fluorenylmethyloxycarbonyl-triphenylalanine (FmocPhe 3 ) produced starting from Fmoc-phenylalanine and diphenylalanine by the catalytic activity of Lipase in water and characterized its performance as a new immobilization support for biosensors. For this purpose, we have evaluated the main bioelectrochemical properties of Trametes versicolor Laccase (TvL) immobilized within the hydrogel and a hydrogel-nanocomposite structure in the presence of gold nanoparticles (AuNPs). Either the Fmoc and the benzyl rings inside the tripeptide structure contributed to the hydrogel network formation by π-π stacking interactions, which promoted the physical entrapment of Laccase as well as the interaction with the carbon-based electrode surface. Furthermore, the π-electrons flow throughout the tripeptide based hydrogel allowed a good electron transfer between the immobilized enzyme and the electrode. The obtained results showed a significative increase in the hydrogel nanocomposite-based graphite biosensor performance with respect to those obtained with the hydrogel-based graphite biosensor. The experimental results, in terms of analytical performance and costs, assessed the possible use of FmocPhe 3 based hydrogels in the development of electrochemical biosensors.

In this work a detailed description of the development of amine oxidase-based electrochemical biosensors for the selective determination of the biogenic amines is presented. The enzymes required for this operation are Polyamine Oxidase (PAO) and Spermine Oxidase (SMO) which are physically entrapped in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ), a photo-cross-linkable gel, onto screen printed electrode (SPE) surface. The developed biosensors are deeply characterized in the analysis of biogenic amines by using flow injection amperometric (FIA) technique. The enzymatic electrodes are characterized by good sensitivity, long-term stability, and reproducibility. To test the feasibility of the developed biosensors in the analysis of real matrices, they are used for the analysis of blood samples. The results obtained are in good agreement with those obtained with the GC-MS reference method.

In this work a detailed description of the development of amine oxidase-based electrochemical biosensors for the selective determination of the biogenic amines is presented. The enzymes required for this operation are Polyamine Oxidase (PAO) and Spermine Oxidase (SMO) which are physically entrapped in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ), a photo-cross-linkable gel, onto screen printed electrode (SPE) surface. The developed biosensors are deeply characterized in the analysis of biogenic amines by using flow injection amperometric (FIA) technique. The enzymatic electrodes are characterized by good sensitivity, long-term stability, and reproducibility. To test the feasibility of the developed biosensors in the analysis of real matrices, they are used for the analysis of blood samples. The results obtained are in good agreement with those obtained with the GC-MS reference method.

Affinity-based biosensors (ABBs) have started to be considered in sport medicine and doping control analysis because they are cheap, easy to use and sufficiently selective analytical devices, characterized by a reversible interaction with the analyte under investigation allowing the use of the same sensor for multiple analyses. In this review we describe the main categories of substances reported in the World Anti-Doping Agency Prohibited List and how ABBs may contribute to their detection. Although several ABBs proposed in the last few years display limit of detections that are in principle matching the World Anti-Doping Agency requirements, their application in the framework of ‘traditional’ antidoping tests seems quite unlikely, mainly because of the still insufficient selectivity especially in the case of ‘pseudo-endogenous’ compounds, and on the lack of complete information regarding potential matrix effects in real samples and following their routine use. At the same time, ABBs could contribute to fill a significant information gap concerning complementary evidence that can be obtained from their use ‘on the spot’, as well as to preselect a risk population of individuals to be targeted for a full antidoping test; while in sport medicine they could contribute to obtaining analytical information of physiological relevance from the measurement of specific parameters or markers before, during and after physical exercise.

Electrochemical biosensors provide an attractive means of analyzing the content of a biological sample due to the direct conversion of a biological event to an electronic signal. The signal transduction and the general performance of electrochemical biosensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. We show herein a novel electrochemical biosensing platform based on the coupling of two different nanostructured materials (gold nanoparticles and fullerenols) displaying interesting electrochemical features. The use of these nanomaterials improved the electrochemical performance of the proposed biosensor.An application of the nanostructured enzyme-based biosensor has been developed for evaluating the detection of polyphenols either in buffer solution or in real wine samples.

In this work, we developed an impedimetric label-free immunosensor for the detection of 2,4-Dichlorophenoxy Acetic Acid (2,4-D) herbicide either in standard solution and spiked real samples. For this purpose, we prepared by electropolymerization a conductive polymer poly-(aniline-co-3-aminobenzoic acid) (PANABA) then we immobilized anti-2,4-D antibody onto a nanocomposite AuNPs-PANABA-MWCNTs employing the carboxylic moieties as anchor sites. The nanocomposite was synthesized by electrochemical polymerization of aniline and 3-aminobenzoic acid, in the presence of a dispersion of gold nanoparticles, onto a multi-walled carbon nanotubes-based screen printed electrode. Aniline-based copolymer, modified with the nanomaterials, allowed to enhance the electrode conductivity thus obtaining a more sensitive antigen detection. The impedimetric measurements were carried out by electrochemical impedance spectroscopy (EIS) in faradic condition by using Fe(CN)63-/4- as redox probe. The developed impedimetric immunosensor displayed a wide linearity range towards 2,4-D (1-100ppb), good repeatability (RSD 6%), stability and a LOD (0.3ppb) lower than herbicide emission limits.

Electrochemical biosensors provide an attractive means of analyzing the content of a biological sample due to the direct conversion of a biological event to an electronic signal. The signal transduction and the general performance of electrochemical biosensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. We show herein a novel electrochemical biosensing platform based on the coupling of two different nanostructured materials (gold nanoparticles and fullerenols) displaying interesting electrochemical features. The use of these nanomaterials improved the electrochemical performance of the proposed biosensor.An application of the nanostructured enzyme-based biosensor has been developed for evaluating the detection of polyphenols either in buffer solution or in real wine samples.

In this work, we have developed for the first time a method to make novel gold and platinum hybrid bimetallic nanostructures differing in shape and size. Au-Pt nanostructures were prepared by electrodeposition in two simple steps. The first step consists of the electrodeposition of nanocoral Au onto a gold substrate using hydrogen as a dynamic template in an ammonium chloride solution. After that, the Pt nanostructures were deposited onto the nanocoral Au organized in pores. Using Pt (II) and Pt (IV), we realized nanocoral Au decorated with Pt nanospheres and nanocoral Au decorated with Pt nanoflowers, respectively. The bimetallic nanostructures showed better capability to electrochemically oxidize hydrogen peroxide compared with nanocoral Au. Moreover, Au-Pt nanostructures were able to lower the potential of detection and a higher performance was obtained at a low applied potential. Then, glucose oxidase was immobilized onto the bimetallic Au-Pt nanostructure using cross-linking with glutaraldehyde. The biosensor was characterized by chronoamperometry at +0.15 V vs. Ag pseudo-reference electrode (PRE) and showed good analytical performances with a linear range from 0.01 to 2.00 mM and a sensitivity of 33.66 µA/mM cm2. The good value of Kmapp (2.28 mM) demonstrates that the hybrid nanostructure is a favorable environment for the enzyme. Moreover, the low working potential can minimize the interference from ascorbic acid and uric acid as well as reducing power consumption to effect sensing. The simple procedure to realize this nanostructure and to immobilize enzymes, as well as the analytical performances of the resulting devices, encourage the use of this technology for the development of biosensors for clinical analysis.

In mammalian secretions, such as milk, lactoferrin is an important iron-binding glycoprotein, present in large quantities; it is also contained in powdered milks for babies sold in drugstores. Our team tested the feasibility of constructing a new immunosensor for lactoferrin analysis based on surface plasmon resonance (SPR) using two different devices and operating in batch or flow mode. The new method proposed is not competitive but “direct” and has the advantage of halving the measurement time which was deemed to be too long as is often the case in previous research when competitive immunological methods were used. Lastly, detailed comparison was made of the analytical features of new devices with those of classical or screen-printed immunosensor methods and the advantages and disadvantages of the new SPR method investigated. Lastly several applications and comparisons were carried out on cow and goat milk and on different types of dried milk for babies.

In this work, we have developed for the first time a method to make novel gold and platinum hybrid bimetallic nanostructures differing in shape and size. Au-Pt nanostructures were prepared by electrodeposition in two simple steps. The first step consists of the electrodeposition of nanocoral Au onto a gold substrate using hydrogen as a dynamic template in an ammonium chloride solution. After that, the Pt nanostructures were deposited onto the nanocoral Au organized in pores. Using Pt (II) and Pt (IV), we realized nanocoral Au decorated with Pt nanospheres and nanocoral Au decorated with Pt nanoflowers, respectively. The bimetallic nanostructures showed better capability to electrochemically oxidize hydrogen peroxide compared with nanocoral Au. Moreover, Au-Pt nanostructures were able to lower the potential of detection and a higher performance was obtained at a low applied potential. Then, glucose oxidase was immobilized onto the bimetallic Au-Pt nanostructure using cross-linking with glutaraldehyde. The biosensor was characterized by chronoamperometry at +0.15V vs. Ag pseudo-reference electrode (PRE) and showed good analytical performances with a linear range from 0.01 to 2.00mM and a sensitivity of 33.66µA/mMcm

The reversible assembly of β-cyclodextrin-functionalized gold NPs (β-CD Au NPs) is studied on mixed self-assembled monolayer (SAM), formed by coadsorption of redox-active ferrocenylalkylthiols and n-alkanethiols on gold surfaces. The surface coverage and spatial distribution of the β-CD Au NPs monolayer on the gold substrate are tuned by the self-assembled monolayer composition. The binding and release of β-CD Au NPs to and from the SAMs modified surface are followed by surface plasmon resonance (SPR) spectroscopy. The redox state of the tethered ferrocene in binary SAMs controls the formation of the supramolecular interaction between ferrocene moieties and β-CD-capped Au NPs. As a result, the potential-induced uptake and release of β-CD Au NPs to and from the surface is accomplished. The competitive binding of β-CD Au NPs with guest molecules in solution shifted the equilibrium of the complexation-decomplexation process involving the supramolecular interaction with the Fc-functionalized surface. The dual controlled assembly of β-CD Au NPs on the surface enabled to use two stimuli as inputs for logic gate activation; the coupling between the localized surface plasmon, associated with the Au NP, and the surface plasmon wave, associated with the thin metal surface, is implemented as readout signal for "AND" logic gate operations.