Electrochemical detection of H2O2 by means of gold foam-based electrode

In this work, a low-cost electrochemical sensor was developed for the detection of hydrogen peroxide. Hydrogen peroxide is the most used biomarker in monitoring oxidative stress due to its stability and ability to diffuse across the cell membrane. Oxidative stress occurs when the concentration of reactive oxygen species (ROS) in biological fluids increases with respect to the physiological concentration; this condition is a risk factor for many diseases. Among ROS, hydrogen peroxide is the more stable and thus it can be used as a biomarker. Since oxidative stress is not associated with specific symptoms, it is important to monitor the concentration of hydrogen peroxide to prevent the onset of serious diseases or to slow down their progression. In this field, research aims to develop electrochemical sensors for hydrogen peroxide quantification as an alternative to time-consuming and expensive traditional techniques. The proposed sensor was obtained using the common substrate of the printed circuit board (PCB) fabrication. A design consisting of three electrodes of copper was optimized to obtain a complete cell. The working electrode was modified by electrodeposition to obtain a gold foam. Before gold foam deposition, the copper surface was covered with a thin planar film of gold using sputtering. The foam was electrodeposited by potenziostatic deposition at - 2 V using a water solution containing gold precursor and sulfuric acid. The detection of hydrogen peroxide was carried out with a conventional three-electrode system using a homemade cell obtained by 3D printing. Electrochemical tests were carried out in phosphate buffer as blank and by chronoamperometry at – 0.1 V. To build the calibration line, different concentrations of hydrogen peroxide, ranging from 25 to 1000 μM, were tested. The obtained results showed that the current density was proportional to the concentration of hydrogen peroxide, so the sensor can quantify this analyte. Further study will be addressed to characterize the device in terms of selectivity, stability and reproducibility

Nanostructured electrochemical devices for sensing, energy conversion and storage

Nanostructured materials are attracting growing interest for improving performance of devices and systems of large technological interest. In this work, the principal results about the use of nanostructured materials in the field of electrochemical energy storage, electrochemical water splitting, and electrochemical sensing are presented. Nanostructures were fabricated with two different techniques. One of these was the electrodeposition of the desired material inside the channels of a porous support acting as template. The other one was based on displacement reaction induced by galvanic contact between metals with different electrochemical nobility. In the present work, a commercial polycarbonate membrane was used as template. In the field of the electrochemical energy storage, the attention was focused on lead-acid battery, and it has been found that nanostructured morphology enhances the active mass utilization up to about 80%, with consequent increase of specific energy and cycling rates to unattainable values for the commercial battery. Nanostructured Ni-IrO2 composite electrodes showed valuable catalytic activity for water oxidation. By comparison with other Ni-based electrocatalyst, this electrode appears as the most promising anode for electrochemical water splitting in alkaline cells. Also in the field of sensing, the nanostructured materials fabricated by displacement reaction showed performance of high interest. Some new results about the use of copper nanowires for H2O22 sensing will be showed, evidencing better performance in comparison with copper thin film. In this work, we will show that nanostructured electrodes are very promising candidate to form different electrochemical setups that operate more efficiently comparing to device with flat electrode materials

Formoterol Exerts Anti-Cancer Effects Modulating Oxidative Stress and Epithelial-Mesenchymal Transition Processes in Cigarette Smoke Extract Exposed Lung Adenocarcinoma Cells

Lung cancer frequently affects patients with Chronic Obstructive Pulmonary Disease (COPD). Cigarette smoke (CS) fosters cancer progression by increasing oxidative stress and by modulating epithelial-mesenchymal transition (EMT) processes in cancer cells. Formoterol (FO), a long-acting β2-agonist widely used for the treatment of COPD, exerts antioxidant activities. This study explored in a lung adenocarcinoma cell line (A549) whether FO counteracted the effects of cigarette smoke extract (CSE) relative to oxidative stress, inflammation, EMT processes, and cell migration and proliferation. A549 was stimulated with CSE and FO, ROS were evaluated by flow-cytometry and by nanostructured electrochemical sensor, EMT markers were evaluated by flow-cytometry and Real-Time PCR, IL-8 was evaluated by ELISA, cell migration was assessed by scratch and phalloidin test, and cell proliferation was assessed by clonogenic assay. CSE significantly increased the production of ROS, IL-8 release, cell migration and proliferation, and SNAIL1 expression but significantly decreased E-cadherin expression. FO reverted all these phenomena in CSE-stimulated A549 cells. The present study provides intriguing evidence that FO may exert anti-cancer effects by reverting oxidative stress, inflammation, and EMT markers induced by CS. These findings must be validated in future clinical studies to support FO as a valuable add-on treatment for lung cancer management

Electrochemical sensor for evaluating oxidative stress in airway epithelial cells

Cigarette smoke exposure induces oxidative stress within the airways. Increased oxidative burden contributes to the pathogenesis of chronic lung disorders and is associated with aging and chronic inflammation. Airway epithelial cells highly contribute to Reactive Oxygen Species (ROS) generation within injured and inflamed lung tissues. Among ROS, hydrogen peroxide (H2O2) can be monitored in the extracellular space. Herein, we present an amperometric/voltammetric sensor based on gold nanoparticles and graphene oxide able to detect H2O2 with good sensitivity and selectivity. Using this sensor, H2O2 release was measured in conditioned medium from primary bronchial epithelial cells (PBEC), bronchial epithelial cell line, 16HBE, and adenocarcinoma alveolar basal epithelial cell line, A549, exposed to cigarette smoke extracts (CSE). 16HBE were also treated with resveratrol, an anti-oxidant compound. The results were compared with those obtained by flow cytometry using the same cells stained with Carboxy-H2DCFDA and MitoSOX Red, which detect intracellular ROS and mitochondrial superoxide, respectively. The exposure to CSE resulted in a significant increase of the cathodic current due to the reduction of H2O2 indicating an increased release. Addition of resveratrol decreased CSE-induced release of H2O2 in 16HBE. All the results paralleled those obtained by flow cytometry. The proposed sensor is highly sensitive and selective, fast and cost effective and can potentially be applied for real time and easy monitoring of oxidative stress

Nanostructured Ni-Fe-P Alloy for Alkaline Electrolyzer

In recent years, the interest towards green hydrogen has drastically increased due to the global decarbonization process. Electrochemical water splitting is considered an attractive solution to convert and store the surplus energy from renewable energy sources. However, hydrogen production by water electrolysis is not economically sustainable. To reduce the cost of produced hydrogen, it is necessary to switch from noble-metal catalyst (Pt, Pd…) to cheap alternatives with a lower per unit energy cost but at the same time able to guarantee a high electrocatalytic activity for both oxygen and hydrogen evolution reactions. Among transition metals, nickel was selected as active material for its low cost and high chemical stability in alkaline media. Currently, the most investigated transition metal catalyst includes alloy of nickel with sulfide, phosphide, and nitride. In this work, a ternary alloy of Nickel-Iron-Phosphorus with nanowires morphology was investigated and compared to the binary alloy of Nickel-Iron. Ni-Fe-P NWs electrodes were obtained by potential-controlled pulse electrochemical deposition using polycarbonate membrane as template. Electrodes morphology and structure were studied by scanning electrode microscopy (SEM), energy diffraction spectroscopy (EDS) and X-ray diffraction (XRD). Electrodes were tested both as cathodes as anodes by Quasi Steady State Polarization (QSSP) and Galvanostatic Test. All the tests were performed in 30% w/w KOH aqueous solution at room temperature. Preliminary results showed better performance of the ternary alloy compared to the binary one

Ni-Fe-S alloy nanostructured electrodes for alkaline electrolyser

In recent years, renewable energy sources are becoming more and more relevant owing to the progressive decarbonization of energy processes to reduce CO2 emissions [1,2]. In this view, worldwide public authorities are encouraging the use of renewable energies by promoting laws and guidelines [3,4]. One of the main drawbacks of renewable sources is their unpredictability, consequently, interest in green hydrogen has drastically increased. One way to produce green hydrogen is by water electrolysis using only electricity from renewable sources. It is a viable strategy to take advantage of the surplus electricity from them. The most relevant part of the cost of electrochemical hydrogen comes from the electricity cost and catalysts. For this reason, research is focused on improving the performance of the electrolyzer, using more efficient and less expensive materials, such as transition metal alloys like Nickel-based alloy [5]. One way to improve the performance of electrolyzers is based on the development of nanostructured electrodes distinguishing for low cost and high electrocatalytic activity. The proposed technique for fabricating the electrodes is known as template electrosynthesis. The template used is a commercial porous polycarbonate membrane (PMC - Whatman, Cyclopore, 20 μm thick), which due to its morphology allows the formation of nanowire-shaped nanostructures, highly interconnected with each other, which have the advantage of possessing a high surface area (about two orders of magnitude higher than planar electrode with the same geometric area). To make the membrane conductive, a gold film of thickness around 20-30 nm is deposited on one of the template surfaces by a sputtering process. After sputtering, a compact nickel layer of thickness around 20 μm is electrodeposited on the gold side. This, in addition to ensuring adequate mechanical strength to the electrode, acts as a current collector. After the electrodeposition of the nickel collector, the next step is the electrodeposition of the NWs formed inside the template pores. In previous works, we have fabricated Ni nanowires by template electrosynthesis, featuring by very high surface area. Starting from the best-performing nickel-iron alloy previously studied [6], this work focuses on the fabrication of nickel-iron-sulfur electrodes. In an aqueous solution containing nickel and iron, a third element is added in different concentrations in order to obtain electrodes with different compositions. The chemical and morphological features of these nanostructured electrodes are carried out through scanning electrode microscopy (SEM) and energy diffraction spectroscopy (EDS) analyses, and those results will be presented and discussed. Subsequently, electrochemical and electrocatalytic tests (Cyclic Voltammetry (CV), Quasi Steady State Polarization (QSSP) and Galvanostatic Step) are carried to establish the best alloy composition and they are carried out for both hydrogen and oxygen evolution reactions. Then, a long-term test conducted at a constant current density in an aqueous solution of potassium hydroxide (30% w/w) will also be reported

An Integrated Approach for Structural Health Monitoring and Damage Detection of Bridges: An Experimental Assessment

The issue of monitoring the structural condition of bridges is becoming a top priority worldwide. As is well known, any infrastructure undergoes a progressive deterioration of its structural conditions due to aging by normal service loads and environmental conditions. At the same time, it may suffer serious damages or collapse due to natural phenomena such as earthquakes or strong winds. For this reason, it is essential to rely on efficient and widespread monitoring techniques applied throughout the entire road network. This paper aims to introduce an integrated procedure for structural and material monitoring. With regard to structural monitoring, an innovative approach for monitoring based on Vehicle by Bridge Interaction (VBI) will be proposed. Furthermore, with regard to material monitoring, to evaluate concrete degradation, a non-invasive method based on the continuous monitoring of the pH, as well as chloride and sulfate ions concentration in the concrete, is presented

Electrochemical sensor for phosphate ions based on laser scriber reduced graphene oxide

This preliminary work shows a new and innovative way to produce laser scribed reduced graphene oxide (LSGO) electrodes using different porous substrates (ranging from paper to plastic and fabric). The obtained electrodes were also tested as electrochemical sensors towards the detection of phosphate ions in water. To obtain the electrodes, a water suspension of GO was filtered on top of substrate (such as Whatman® filter paper) and a complete sensor was obtained from its reduction using a CO2 laser. The electrode is composed of working and counter electrodes made of LSGO and a reference electrode of a Ag/AgCl obtained by using a commercial AgCl conductive paste. Phosphate ions were detected by exploiting the reaction between molybdate and phosphate ions in acidic media (known in literature as molybdenum blue method). This chemical reaction produces the Keggin-type complex (PMo12O40)3-, that can be reduced under applied potential. The obtained results show that phosphate ions can be detected in a wide linear range, from 0.001 mM to 1mM, in presence of 1mM molybdate with a very satisfying selectivity. We also tried to pre-treatment the paper substrate with acidic molybdate ions in order to obtain a ready-made sensor directly usable for the detection of phosphate ions in situ avoiding any kind of real sample manipulation For this aim, the paper substrate was soaked with sulphuric acid and molybdate solution and dried in order to desorb these chemicals directly into the water sample to be analyzed. Preliminary results, shows that the process of absorption and desorption can be carried out by optimizing the volume and concentration of the absorbed solution and thus can be used to obtain a portable, easy to use and fast phosphate sensor for in situ and real time monitoring of water quality

Galvanic deposition of Chitosan-AgNPs as antibacterial coating

Thanks to mechanical properties similar human bones, metallic materials represent the best choice for fabrication of orthopedic implants. Although metals could be widely used in the field of biomedical implants, corrosion phenomena could occur, causing metal ions releasing around periprosthetic tissues leading, in the worst cases, to the development of infections. In these cases, patients need prolonged antibiotic therapies that may cause bacterial resistance. Preventing bacterial colonization of biomedical surfaces is the key to limiting the spread of infections. Antibacterial coatings have become a very active field of research, strongly stimulated by the increasing urgency of identifying alternatives to the traditional administration of antibiotics. Nowadays, the research was focused on coating science to deal with these issues. In particular, the development of the antibacterial composite coatings could be a viable way to provide not only a corrosion resistance but also an antibacterial action and biocompatibility. Chitosan is a great biomaterial used in medicine. It is a natural bioactive polymer and is the second most abundant in nature polysaccharide after cellulose. Chitosan comes from the deacetylation of chitin, a homopolymer of beta-(1-4)-N-acetyl-D-glucosamine, derived from exoskeleton of crustaceans. It is high biocompatible and it is also used in drug delivery. In addition, chitosan has chelating properties due to the amino groups of polysaccharide that are responsible of selective chelation with metal ions. In particular, the attention has been paid to silver nanoparticles for their high stability, low toxicity, biocompatibility and antibacterial properties. These ones are incorporated in polymeric matrix (e.g. chitosan) and they are capable to interact physically with cell walls of bacteria. In this study Chitosan-Silver nanoparticles composite coating on AISI 304L was investigated. These coatings were realized by an alternative method of deposition respect to traditional ones based on galvanic coupling. This process doesn’t request any external power supply and is very easy to carried out. The difference of the electrochemical redox potential between the substrate (cathode) and a sacrificial anode is the pivotal role of the process. Deposition rate is controlled by the ratio of cathodic and anodic area. In practice, electrons generated by anode corrosion flow towards to more noble metal thanks to a short-circuit. As soon electrons arrive to the cathode, the base electrogeneration reactions of nitrate ions and water molecules occur. Production of hydroxyl ions causes an increasing of pH at substrate/solution interface. Hence, deprotonation of amine group leads precipitation of chitosan (pKa=6.4) onto surface. At the same time, silver nanoparticles are incorporated in polymeric matrix of chitosan. Physical-chemical characterizations of the coatings were carried out in order to investigate morphology and chemical composition. In addition, corrosion tests (potentiodynamic polarization and electrochemical impedance spectroscopy) were executed in a simulated body fluid to scrutinize the corrosion resistance. Furthermore, the release of silver nanoparticles from coating in SBF were studied

Fabrication of Ni-alloy nanostructured elecrodes for alkaline electrolizers

In last years, renewable energy sources are becoming more and more important owing to the progressive decarbonization of energy processes to reduce CO2 emissions [1,2]. In this view, governments and authorities all around the world are encouraging the use of renewable energies by promoting laws and initiatives for the most sustainable energy transition [3,4]. One of the main drawbacks of renewable sources is their unpredictability, consequently, interest in hydrogen has drastically increased. One way to produce green hydrogen is by water electrolysis using only electricity from renewable sources. It is a viable strategy to take advantage of the surplus electricity. The most relevant part of the cost of electrochemical hydrogen comes from the electricity cost and catalysts. For this reason, research is focused on improving the performance of the electrolyzer, using more efficient and less expensive materials, such as transition metal alloys like Nickel-based alloy [5]. One of the possible ways to improve the performance of electrolyzers is based on the development and fabrication of nanostructured electrodes with a low cost and high electrocatalytic activity. In previous works, Ni nanowires were fabricated by template electrosynthesis, featuring by very high surface area. Starting from the best-performing nickel-iron alloy previously studied [6], this work focuses on the fabrication of nickel-iron-sulfur electrodes. In an aqueous solution containing nickel and iron, a third element was added in different concentrations in order to obtain electrodes with different compositions. The chemical and morphological features of these nanostructured electrodes were studied through scanning electrode microscopy (SEM) and energy diffraction spectroscopy (EDS) analyses, and those results will be presented and discussed. Electrochemical and electrocatalytic tests (Cyclic Voltammetry (CV), Quasi Steady State Polarization (QSSP) and Galvanostatic Step) were carried out to establish the best alloy composition for both hydrogen and oxygen evolution reactions. Long-term tests performed at a constant current density in an aqueous solution of potassium hydroxide (30% w/w) will be also reported. Acknowledgments This research was funded by CNMS, Centro Nazionale per la Mobilità sostenibile (MUR, PNRR-M4C2, CN00000023), spoke 12 – innovative propulsion. References [1] A.T.D. Perera, R.A. Attalage, K.K.C.K. Perera, V.P.C.Dassanayake, “Designing standalone hybrid energy systems minimizing initialinvestment, life cycle cost and pollutant emission” Energy, 54, 2013, 237-248. [2] K. Bandara, T. Sweet, J. Ekanayake, “Photovoltaic applications for off-grid electrification using novel multi-level inverter technology with energy storage”, Renewable Energy, 37, 2012, 82-88 [3] P. Balcombe, D. Rigby, A. Azapagic, “Motivations and barriers associated with adopting microgeneration energy technologies in the UK”, Renewable and Sustainable Energy Reviews, 22, 2013, 655-666. [4] H. Meyar-Naimi, S. Vaez-Zadeh, “Sustainable development-based energy policy making frameworks, a critical review”, Energy Policy, 43, 2012, 351-361. [5] F. Safizadeh, E. Ghali, G. Houlachi, “Electrocatalysis developments for hydrogen evolution reaction in alkaline solutions – A Review”, International Journal of Hydrogen Energy, 40, 2015, 256–274. [6] B. Buccheri, F. Ganci, B. Patella, G. Aiello, P. Mandin, R. Inguanta, “Ni-Fe alloy nanostructured electrodes for water splitting in alkaline electrolyser”, Electrochimica Acta, Volume 388, 2021, 0013-4686