Graphene-Paper-Based Electrodes on Plastic and Textile Supports as New Platforms for Amperometric Biosensing

The possibility of exfoliating graphite into graphene sheets allows the researchers to produce a material, termed “graphene paper” (G-paper), conductive as graphite but more flexible and processable. G-paper is already used for electronic applications, like conductors, antennas, and heaters, outperforming metal conductors thanks to its high flexibility, lightness, chemical stability, and compatibility with polymeric substrates. Here, the effectiveness in the use of G-paper for the realization of electrodes on flexible plastic substrates and textiles, and their applicability as amperometric sensors are demonstrated. The performance of these devices is compared with commercial platforms made of carbon-based inks, finding that they outperform commercial devices in sensing nicotinamide adenine dinucleotide (NADH), a key molecule for enzymatic biosensing; the electrodes can achieve state-of-the-art sensitivity (107.2 μA mm−1 cm−2) and limit of detection (0.6 × 10−6 m) with no need of additional functionalization. Thanks to this property, the stable deposition of a suitable enzyme, namely lactate dehydrogenase, on the electrode surface is used as a proof of concept of the applicability of this new platform for the realization of a biosensor. The possibility of having a single material suitable for antennas, electronics, and now sensing opens new opportunities for smart fabrics in wearable electronic applications

Behaviour of Ti electrode in the amperometric determination of high concentrations of strong oxidising species

The study of the capabilities of an unusual electrode material, namely, Ti, is presented: the amperometric determination of species showing responses that, on different materials, cannot be often profitably exploited, is proposed. H2O2 and HClO are successfully analysed, even at high concentrations. In similar conditions, which are quite common in industrial environments, these strong oxidising species are determined by time-consuming, off- or at-line, and multistep procedures. A complex real matrix, such as an industrial detergent, containing high H2O2 concentrations, has been taken as a meaningful study case to check the effectiveness of the electrode system and procedure proposed. Keywords: Amperometric sensor, Titanium electrode, Hydrogen peroxide, Hypochlorite ions, Strong oxidant

Exploring the Spatial Features of Electronic Transitions in Molecular and Biomolecular Systems by Swift Electrons

We devise a new kind of experiment that extends the technology of electron energy loss spectroscopy to probe (supra-)molecular systems: by using an electron beam in a configuration that avoids molecular damage and a very recently introduced electron optics setup for the analysis of the outcoming electrons, one can obtain information on the spatial features of the investigated excitations. Physical insight into the proposed experiment is provided by means of a simple but rigorous model to obtain the transition rate and selection rule. Numerical simulations of DNA G-quadruplexes and other biomolecular systems, based on time dependent density functional theory calculations, point out that the conceived new technique can probe the multipolar components and even the chirality of molecular transitions, superseding the usual optical spectroscopies for those cases that are problematic, such as dipole-forbidden transitions, at a very high spatial resolution

Preliminary evaluation of the use of a disposable electrochemical sensor for selective identification of Δ9-tetrahydrocannabinol and cannabidiol by multivariate analysis

The widespread diffusion of products deriving from Cannabis sativa L. led to the necessity of rapid and reliable methods for the identification of samples containing Δ9-tetrahydrocannabinol (THC), the psychoactive component of the plant, which imparts mental distortions and hallucinations. Although some efficient electrochemical sensors have been already proposed for such a purpose, they do not consider that the plant may also contain huge amounts of cannabidiol (CBD), which possesses an electroactive moiety quite similar to that of THC. The definition of both THC and CBD concentration is at the basis of discrimination between recreational-type and fibretype cannabis samples; detection of these species is not only important in vegetable samples but also in relevant commercial products and in biological fluids. We proposed here a screen-printed electrode coated with a layer of carbon black for the rapid identification of samples containing THC irrespectively of the simultaneous presence of CBD. The most performing carbon black typology used for such a purpose was chosen among various commercial products tested on the basis of preliminary tests performed on 1,3-dihydroxybenzene, constituting the redox active moiety of cannabinoids. The voltammetric responses collected in various solutions containing different amount of THC and CBD were initially elaborated by Principal Component Analysis, assessing the possibility of identifying samples with similar concentrations of THC irrespectively of the CBD concentration values, and vice-versa. Afterwards a preliminary Partial Last Square regression was performed to evaluate the possibility of a quantitative analysis of both THC and CBD. This approach suggests the possibility of using the sensor proposed to screen samples containing THC even in the presence of high amounts of CBD

Development of an electrochemical sensor based on carbon black for the detection of cannabidiol in vegetable extracts

A glassy carbon electrode chemically modified with a carbon black coating is proposed here for the rapid and portable determination of cannabidiol (CBD) in a commercial Cannabis seed oil and in fibre-type Cannabis sativa L. leaves. The mechanism of CBD oxidation was studied in relation to simpler phenyl derivatives bearing the same electroactive group, namely resorcinol and 2-methylresorcinol. These molecules also allowed us to determine the best conditions for the electrochemical detection of CBD, as to the pH value and to the best solvent mixture to use. Carbon black was chosen among nanostructured carbon-based materials owing to its outstanding features as an electrode modifier for analyte detection. The performance of the modified electrode was determined by flow injection analyses of standard solutions of CBD, obtaining a linear correlation between the oxidation current and the analyte concentration; the sensor response is characterised by suitable repeatability and reproducibility. The analysis of commercial products by the standard addition method allowed us to ascertain the accuracy of the sensor for the detection of CBD in real samples

Development of an electrochemical sensor based on carbon black for the detection of cannabidiol in vegetable extracts

A glassy carbon electrode chemically modified with a carbon black coating is proposed here for the rapid and portable determination of cannabidiol (CBD) in a commercial Cannabis seed oil and in fibre-type Cannabis sativa L. leaves. The mechanism of CBD oxidation was studied in relation to simpler phenyl derivatives bearing the same electroactive group, namely resorcinol and 2-methylresorcinol. These molecules also allowed us to determine the best conditions for the electrochemical detection of CBD, as to the pH value and to the best solvent mixture to use. Carbon black was chosen among nanostructured carbon-based materials owing to its outstanding features as an electrode modifier for analyte detection. The performance of the modified electrode was determined by flow injection analyses of standard solutions of CBD, obtaining a linear correlation between the oxidation current and the analyte concentration; the sensor response is characterised by suitable repeatability and reproducibility. The analysis of commercial products by the standard addition method allowed us to ascertain the accuracy of the sensor for the detection of CBD in real samples

On the feasibility of a portable electrochemical measuring system for the on-site measurement of cannabinoids

Given the neuroprotective, anti-inflammatory, and analgesic properties of cannabidiol (CBD), many countries have recently legalized the use of fiber-type Cannabis products, including those known as 'Cannabis light'. Nonetheless, in freely commercialized products, it is not uncommon to find Δ9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, in concentrations exceeding the legal limit. To determine whether a product is commercially viable, the THC/CBD ratio is typically analyzed using chromatographic techniques. However, chromatographic techniques have costs, complexity, and response times that prevent their in-situ use, making control actions much more expensive and ineffective. In this work, we report our preliminary activities aimed at verifying the possibility of performing in-situ analysis of cannabinoids in cannabis-derived products using an ad-hoc designed measuring system based on screen-printed electrodes modified with carbon black. The results obtained from preliminary tests comparing fiber cannabis (legal THC concentration) and recreational cannabis (illegal THC concentration) suggest that the proposed system can allow the effective and efficient in-situ analysis of cannabis-derived products

Preparation and characterization of reusable Sonogel-Carbon electrodes containing carbon black: Application as amperometric sensors for determination of cathecol

A novel strategy for the preparation of reusable carbon electrode containing carbon black (CB) has been developed. CB has been introduced as the conductive and sensitive component, together with graphite, in the composite electrode material of Sonogel-Carbon (SNGC) electrodes, obtaining SNGC-CB electrodes. A complete characterization of the electrodes has been performed using scanning electron microscopy, Raman spectroscopy, cyclic voltammetry and impedance spectroscopy. The overall procedure for the preparation of the electrodes is very fast, cost effective, simple and characterized by high reproducibility, leading to RSD=2.4%. The presence of CB nanostructures in the formulation leads to improved performances in the detection of small phenolic molecules, such as dihydroxybenzeneswith respect to pristine SNGC electrodes. In particular, the device allows the electrochemical determination of catechol with high sensitivity and low limit of detection, even in the presence of one of its isomers, namely hydroquinone. Measurements performed in water samples has led to good apparent recover

Synthesis, spectroscopic and electrochemical characterization of Co(II)-terpyridine based metallopolymer

A new oligothienyl-based metallopolymer including Co(terpyridine)2complex units is synthesised by electrochemical oxidation of the relevant monomer. The chemical structure of the polymer chains and the electronic interaction between the organic portions and the metal centres are investigated by spectroscopic (X-rays photoelectron spectroscopy included), electrochemical, and spectroelectrochemical techniques. Thanks to the low potential of the Co(III)/Co(II) redox couple in the Co(terpyridine)2complex and to the presence of oligothienyl spacer, strong electron interaction between the organic backbone and the metal centres have been demonstrated

A novel class of tetrairon(III) single-molecule magnets with graphene-binding groups

Tripods of general formula R’–O–CH2C(CH2OH)3 are excellent site-specific ligands for the preparation offunctionalized Fe4 single-molecule magnets. Herein, we describe the synthesis and characterization oftwo novel complexes designed to bind graphene surfaces, in which the R group consists of an alkyl spacer–(CH2)n– (n = 6 and 10) and a terminal pyrenyl moiety. The site-specific ligand substitution on [Fe4(OMe)6(dpm)6] (Hdpm = dipivaloylmethane) with the new tripods has been studied with 2H NMR on isotopically-enriched samples, revealing that, once formed, these clusters are stable in solution over longtimescales. It was not possible to isolate the new compounds as crystalline solids, nevertheless they werechemically characterized by elemental analysis and 1H NMR. The presence of the pyrenyl ending groupsprompted us to investigate the effect of metal complexation on fluorescence, and a full pyrene-to-ironcluster excitation energy transfer was observed. The analysis of the magnetic behaviour revealed anS = 5 ground spin state with a negative zero-field splitting parameter D = 0.42 cm1