Metal oxide nanoparticle based electrochemical sensor for total antioxidant capacity (TAC) detection in wine samples

A single-use electrochemical screen-printed electrode is reported based on biomimetic properties of nanoceria particles (CeNPs). The developed tool showed an easy approach compared to the classical spectrophotometric methods reported in literature in terms of ease of use, cost, portability, and unnecessary secondary reagents. The sensor allowed the detection of the total antioxidant capacity (TAC) in wine samples. The sensor has been optimized and characterized electrochemically and then tested with antioxidant compounds occurred in wine samples. The electrochemical CeNPs modified sensor has been used for detection of TAC in white and red commercial wines and the data compared to the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS)-based spectrophotometric method. Finally, the obtained results have demonstrated that the proposed sensor was suitable for the simple and quick evaluation of TAC in beverage samples

Catalase-based modified graphite electrode for hydrogen peroxide detection in different beverages

A catalase-based (NAF/MWCNTs) nanocomposite film modified glassy carbon electrode for hydrogen peroxide (H2O2) detection was developed. The developed biosensor was characterized in terms of its bioelectrochemical properties. Cyclic voltammetry (CV) technique was employed to study the redox features of the enzyme in the absence and in the presence of nanomaterials dispersed in Nafion polymeric solution. The electron transfer coefficient, , and the electron transfer rate constant, , were found to be 0.42 and 1.71 s−1, at pH 7.0, respectively. Subsequently, the same modification steps were applied to mesoporous graphite screenprinted electrodes. Also, these electrodes were characterized in terms of their main electrochemical and kinetic parameters. The biosensor performances improved considerably after modification with nanomaterials. Moreover, the association of Nafion with carbon nanotubes retained the biological activity of the redox protein. The enzyme electrode response was linear in the range 2.5– 1150 mol L−1, with LOD of 0.83 mol L−1. From the experimental data, we can assess the possibility of using the modified biosensor as a useful tool for H2O2 determination in packaged beverages

L'elettrolisi: un'occasione per riflettere sulla Chimica, ma anche sulla storia, l'economia, l'ambiente

Pensiamo che partire da esempi tratti dal mondo che ci circonda, in cui le procedure della Chimica, sia teoriche che sperimentali, appaiano in tutto il loro intreccio con le attività umane, possa costituire un metodo efficace per fornire a vari livelli un’immagine della disciplina corretta. Ciò può aiutare ad approcciarsi ad essa senza paure e senza trionfalismi. Nell’articolo in particolare si tratteranno alcuni significativi processi di elettrolisi, evidenziando il loro sviluppo storico e le loro implicazioni dal punto di vista produttivo e del rapporto con uomo e ambiente.We believe that an effective way to provide, at various levels, a correct image of Chemistry could be based on examples from the world around us, in which the procedures of the discipline, both theoretical and experimental, appear in all their interweaving with human activities. This may help to approach it without fear and without triumphalism. In the article in particular we discuss some significant electrolysis processes, highlighting their his- torical development and their implications from the point of view of production and the rela- tionship with man and environment

Inhibition-based first-generation electrochemical biosensors: theoretical aspects and application to 2,4-dichlorophenoxy acetic acid detection

In this work, several theoretical aspects involved in the first-generation inhibition-based electrochemical biosensor measurements have been discussed. In particular, we have developed a theoretical-methodological approach for the characterization of the kinetic interaction between alkaline phosphatase (AlP) and 2,4- dichlorophenoxy acetic acid (2,4-D) as representative inhibitor studied by means of cyclic voltammetry and amperometry. Based on these findings, a biosensor for the fast, simple, and inexpensive determination of 2,4-D has been developed. The enzyme has been immobilized on screen-printed electrodes (SPEs). To optimize the biosensor performances, several carbon-based SPEs, namely graphite (G), graphene (GP), and multiwalled carbon nanotubes (MWCNTs), have been evaluated. AlP was immobilized on the electrode surface by means of polyvinyl alcohol with styryl-pyridinium groups (PVA-SbQ) as cross-linking agent. In the presence of ascorbate 2-phosphate (A2P) as substrate, the herbicide has been determined, thanks to its inhibition activity towards the enzyme catalyzing the oxidation of A2P to ascorbic acid (AA). Under optimum experimental conditions, the best performance in terms of catalytic efficiency has been demonstrated by MWCNTs SPE-based biosensor. The inhibition biosensor shows a linearity range towards 2,4-D within 2.1–110 ppb, a LOD of 1 ppb, and acceptable repeatability and stability. This analysis method was applied to fortified lake water samples with recoveries above 90 %. The low cost of this device and its good analytical performances suggest its application for the screening and monitoring of 2,4-D in real matrices

Comparison between a direct-flow SPR immunosensor for ampicillin and a competitive conventional amperometric device: analytical features and possible applications to real samples

In this research, we developed a direct-flow surface plasmon resonance (SPR) immunosensor for ampicillin to perform direct, simple, and fast measurements of this important antibiotic. In order to better evaluate the performance, it was compared with a conventional amperometric immunosensor, working with a competitive format with the aim of finding out experimental real advantages and disadvantages of two respective methods. Results showed that certain analytical features of the new SPR immunodevice, such as the lower limit of detection (LOD) value and the width of the linear range, are poorer than those of a conventional amperometric immunosensor, which adversely affects the application to samples such as natural waters. On the other hand, the SPR immunosensor was more selective to ampicillin, and measurements were more easily and quickly attained compared to those performed with the conventional competitive immunosensor

Organogels for low-polar organic solvents. Potential applications on cultural heritage materials

Traditional cleaning methods for removing undesired substances from artworks often involve the use of toxic volatile solvents, raising concerns about human health and environmental impact. Over time, various cleaning systems, such as thickeners, rigid, peelable, and nanostructured gels, have been introduced in the conservation sector to minimize solvent use and toxicity. However, these methods are primarily tailored for aqueous solutions or medium-to-high-polar solvents, leaving sustainable organogels for low-polar solvents largely unexplored. This paper explores the application of Low-Molecular-Weight Gelators (LMWGs) in the field of cultural heritage conservation, focusing on their potential to gel low-polar organic solvents. LMWGs, including cholesterol derivatives, fatty acidderived compounds, anthryl, anthraquinone, amino acid, and saccharide-based organogelators, offer biocompatible and cost-effective options by forming supramolecular gels that immobilize solvents and reduce their release into the environment. This study highlights the need to transition from traditional, often toxic, solvents to greener and more sustainable cleaning systems by emphasizing LMWGs’ biodegradability, biocompatibility, and sustainability. While challenges such as optimizing gel properties and ensuring compatibility with artwork surfaces still need to be addressed, LMWGs hold promise as organogelators in conservation practice. Further research into LMWGs should focus on their optimization for conservation applications by adjusting their rheological properties and physico-chemical stability

Evaluation of the cleaning effect of natural-based biocides. Application on different phototropic biofilms colonizing the same granite wall

Natural derivatives, such as essential oils, are presented as an alternative to classical biocides to the treatment of biocolonization. Thus, in this work, the cleaning and biocidal potential of some natural derivatives towards two natural biofilms' growth on the same granite wall, with different microbial composition, was evaluated. For this purpose, three essential oils (EOs) (from Origanum vulgare, Thymus vulgaris and Calamintha nepeta) and their main active principles (APs) (carvacrol, thymol and R-(+)-pulegone, respectively) were embedded in a hydrogel matrix, with different combinations of EOs and APs, in order to evaluate the synergistic action of different actives. For comparative purposes, pure hydrogel and a mechanical method (brushing) were also used. Colorimetric measurements and chlorophyll a fluorescence analyses were performed to evaluate the cleaning action of the treatments on the biofilms. Overall, the EOs and APs present in the hydrogel proved to be reliable treatments to limit natural biocolonization, with O. vulgare being one of the most effective treatments in combination with other compounds, due to the majority presence of carvacrol. Moreover, the effect of the different treatments strictly depended on the biofilm in question, as well as its ability to adhere to the substrate

Nanoparticles modified screen printed electrode for electrochemical determination of COD

The Chemical Oxygen Demand (COD) is a parameter widely used to determine organic pollutants in water and is defined as the number of oxygen equivalents necessary to oxidize the organic compounds. The standard method for COD measurement (the dichromate titration) suffers from several inherent drawbacks such as the long time of the process and the consumption of toxic chemicals. Hence, interest is growing towards those methods employing electrochemical oxidation of organic compounds, as they allow to dispense with toxic reagents and above all to perform a continuous determination. In this work a new electrochemical method for COD measurement has been developed based on direct oxidation of organic molecules on suitably modified electrodic surfaces. In particular, we have developed various sensors based on modified working electrode surfaces obtained by electrodepositing copper and/or nickel oxide nanoparticles onto several commercial screen printed electrodes. Glucose was used as the standard compound for COD measurements: C6H12O6 + 6O2 → 6CO2 + 6H2O The metallic nanoparticles catalyze the oxidation of the glucose, as well as of different organic pollutants, and make the detection possible at relatively low potential, also in presence of chloride as interferent. The analytical parameters were optimized and the results obtained highlight how the electrodeposition of different metallic nanoparticles onto several screen printed electrode surfaces can influence the selectivity and sensitivity towards the COD detection in real matrices, via electrochemical method. The results were compared with those obtained by the standard method and showed a good agreement. These findings provide an interesting strategy to obtain a simple, cheap, portable and eventually continuous sensor for COD measurement

La diagnostica per la conoscenza storica e artistica delle opere d'arte. Il ruolo delle analisi sui pigmenti nel restauro degli affreschi di Michelangelo nella Cappella Sistina

Il pensiero inerente la tutela delle opere d’arte ha subito una notevole evo- luzione nel corso della storia ed oggi è diventato indispensabile affiancare la scienza della conservazione alle consuete metodologie di restauro. Le scienze applicate ai Beni Culturali coinvolgono studiosi provenienti da diversi campi di ricerca e la collaborazione diventa una prerogativa imprescindibile per il successo dell’intervento conservativo e, soprattutto, per la conoscenza approfondita dell’opera in tutti i suoi aspetti, dai materiali costitutivi alla tecnica di realizzazione. Nell’articolo illustreremo quanto detto soffermandoci tra l’altro sul restauro degli affre- schi di Michelangelo della Cappella Sistina. Questo è stato definito come il primo restauro moderno, proprio perché le analisi hanno accompagnato ogni intervento tecnico sugli affre- schi, i quali sono tornati allo splendore originario nel rispetto dei principi teorici del restauro. In questo e in altri casi la diagnostica è diventata quindi un importante ausilio per lo stu- dio dei Beni Culturali, anche se la scelta della tecnica analitica deve essere relazionata sempre alla domanda alla quale si cerca la risposta. Le scienze applicate permettono di approfondire la storia dell’opera, la tecnica dell’artista, caratterizzano i materiali, ricostruendone le antiche rotte commerciali; tutte queste informazioni permettono di raggiungere una conoscenza senza pari, indispensabile per la valorizzazione, la tutela e la conservazione dei Beni Culturali.he approach to the protection of artwork has considerably evolved through- out history; placing side by side the conservation science and the usual methods of restoration has today become unavoidable. Science Applied to Cultural Heritage involves scholars from different research fields making their collaboration of paramount importance for the success of the conservation process and, above all, for the in-depth knowledge of the artwork in all its aspects, from the constituent materials to the realization technique. This article will discuss this topic taking into particular account the restoration of Michelangelo’s frescoes in the Sistine Chapel. This was defined as the first modern restoration, because scientific tests have accompanied for the first time any technical intervention on the frescoes, which were returned to their original splendor in respect of the theoretical principles of restoration. In this specific case and in other ones, the diagnostics has therefore become an important aid in Cultural Heritage studies, provided that the choice of the analytical technique is always related to the answer that one is trying to pursue. Applied sciences provide an insight into the history of the artworks, the artists’ techniques, the knowledge of employed materials – that allow one to reconstruct the ancient trade routes; all this information can accomplish an unsurpassed knowledge, which is becoming essential for the development, protection and conservation of Cultural Heritage

Nanostructure-Based Electrochemical Immunosensors as Diagnostic Tools

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 nanostruc- tures 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