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Abstract Screen‐printed electrochemical sensing platforms are ubiquitous within the field of electrochemistry where they provide benefits of being disposable, cost‐effective, reproducible, easily customisable, portable and allow one to transfer the laboratory approach into the field. In this review, we introduce the concept of screen‐printed electrodes, we summarise positive and negative aspects before moving into the current highlights of using traditional screen‐printed carbon electrodes within the field of electroanalysis. We then look to cover metallic and bulk modified varieties, geometric changes (micro, microband and associated arrays), electrode activation and finally the physical length of screen‐printed electrodes, providing insights for future research.

In this overview, we explore the electroanalytical determination of the poisoner's poison: thallium. Thallium was named after the Greek word ''thallos,'' meaning ''green shoot'' or ''twig,'' due to its bright green spectral emission lines. It is toxic, tasteless, odourless and dissolves into water, and has been used by murderers as a challenging poison to detect and there is the need for the analytical determination of thallium. Laboratory based analytical instrumentation provide a routine methodology to measure thallium, but there is scope to develop in-the-field analytical measurements that are comparable to laboratory equipment and in some cases, they can provide even more sensitive analytical approaches. Electrochemistry can support such endeavours, where instrumentation are readily portable where electroanalytical sensors provide highly selective and sensitive outputs but yet are economical to support on-site analysis. In this review, we provide an electroanalytical overview of the current research directed toward the measurement of thallium and offer insights to future research.

Abstract This review aims to provide an overview of sustainable approaches that can be incorporated into well‐known procedures for the development of materials, pre‐ and post‐treatments, modifications, and applications of 3D‐printed objects, especially for fused filament fabrication (FFF). Different examples of conductive and non‐conductive bespoke filaments using renewable biopolymers, bioplasticizers, and recycled materials are presented and discussed. The main final characteristics of the polymeric materials achieved according to the feedstock, preparation, extrusion, and treatments are also covered. In addition to recycling and remanufacturing, this review also explores other alternative approaches that can be adopted to enhance the sustainability of methods, aiming to produce efficient and environmentally friendly 3D printed products. Adjusting printing parameters and miniaturizing systems are also highlighted in this regard. All these recommended strategies are employed to minimize environmental damage, while also enabling the production of high‐quality, economical materials and 3D printed systems. These efforts align with the principles of Green Chemistry, Sustainable Development Goals (SDGs), 3Rs (Reduce, Reuse, Recycle), and Circular Economy concepts.

The overconsumption of conventional plastics has led to several environmental and social-economic issues related to plastic pollution, carbon emissions and resource depletion. Acknowledging these issues, the introduction of alternatives such as bioplastics has been promoted by national, supranational, and international organizations. However, the market for such materials is still niche, where businesses are uncertain about the benefits and costs associated with the use of these innovative materials. Successful (and sustainable) uptake of such alternatives will depend on public acceptance and changes in consumer behavior. Therefore, this study aims to explore how consumers' orientation towards environmental sustainability is related to consumer utilization of alternatives such as bio-based and biodegradable plastics. Consumer knowledge and performance expectations of these materials are also analyzed. This study employed a predominately quantitative research approach, where a self-administered online survey was used to collect the opinions of consumers across society using a snowball sampling technique. Results show continued consumer confusion, unrealistic expectations, and a value-action gap. These elements may have consequences for market uptake and broader implications across the value chain. A key implication is that both policy makers and businesses should address these barriers through enhanced communication of relevant information alongside improved consumer awareness and education.

The sensing of oxalate within urine has been recognised as one of the most important determinations in the investigation of patients with hyperoxaluria. However, current approaches have reported expensive, time consuming, occasionally poor selectivity and are subject to large inaccuracies if great care is not exercised in the handling and measurement of samples. One approach is the use of electroanalytical sensors, which present rapid but highly selective and sensitive outputs, are economical and miniature providing portable sensing platforms to support on-site analysis. In this minireview, recent advances in the electroanalytical sensing of oxalate are presented, overviewing recent electrode configurations and real sample analysis; comparisons to other analytical methods are presented. Finally, the conclusions and future perspective of this field are described in brief.

The global pandemic of the COVID-19 disease has emphasized the need to develop clinical tests which are simple, fast and inexpensive. In this aspect, electrochemical biosensors are alternatives capable to attend such requirements and providing reliable results, highly required in clinical analysis. Associating the quality of electrochemical biosensors with additive manufacturing technology (3D printing) ensures the production of sensors on a large scale, at a reduced cost, and in an automated way. In this regard, the present work proposes the development of an additive-manufactured electrochemical immunosensor, based on the covalent immobilization of antibodies on electrodes obtained from lab-made conductive filaments, composed of carbon black and polylactic acid, for the detection of the spike S1 protein of the SARS-CoV-2 virus. Due to the readily available carboxylic groups on the surface of the additive-manufactured sensor, it was possible to produce an immunosensor without the need for modification steps with metallic particles. Therefore, the proposed immunosensor showed satisfactory results, with a linear range varying from 0.01 to 4.5 nmol L−1 and a detection limit of 2.7 pmol L−1, with a sensitivity of 7.606 µA nmol−1 L. The 3D-printed immunosensor was fully designed for in loco application and all results were obtained from portable equipment, making it a highly viable alternative to be applied as a point-of-care device.

Our journal, C—Journal of Carbon Research (https://www.mdpi.com/journal/carbon), is an international, scientific, peer-reviewed, open access journal on carbon research, published quarterly online by MDPI [...]

Escherichia coli is listed as a priority 1 pathogen on the World Health Organization (WHO) priority pathogen list. For this list of pathogens, new antibiotics are urgently needed to control the emergence and spread of multidrug-resistant strains. This study assessed eighteen metal ions, graphene, and graphene oxide for their antimicrobial efficacy against E. coli in both planktonic and biofilm growth states and the potential synergy between metal ions and graphene-based compounds. Molybdenum and tin ions exhibited the greatest antimicrobial activity against the planktonic states of the isolates with minimal inhibitory concentrations (MIC) ranging between 13 mg/L and 15.6 mg/L. Graphene oxide had no antimicrobial effect against any of the isolates, while graphene showed a moderate effect against E. coli (MIC, 62.5 mg/L). Combinations of metal ions and graphene-based compounds including tin–graphene, tin–graphene oxide, gold–graphene, platinum–graphene, and platinum–graphene oxide exhibited a synergistic antimicrobial effect (FIC ≤ 0.5), inhibiting the planktonic and biofilm formation of the isolates regardless of their antibiotic-resistant profiles. The bactericidal effect of the metal ions and the synergistic effects when combined with graphene/graphene oxide against medically relevant pathogens demonstrated that the antimicrobial efficacy was increased. Hence, such agents may potentially be used in the production of novel antimicrobial/antiseptic agents.

The use of pesticides is one of the primary means of protecting crops. However, this class of compounds can be highly toxic to the environment and humans. In this aspect, developing analytical devices for monitoring pesticides such as carbendazim in food sources is of paramount importance. Thus, the present work presents the application of a paper-based microfluidic device coupled to an additive manufactured platform and electrochemical sensors (produced from lab-made conductive filaments based on carbon black) for the sustainable detection of carbendazim in honey samples. The microfluidic system presented satisfactory results for the analysis of carbendazim, in the linear range from 0.5 to 40.0 µmol L − 1 with a LOD of 0.09 µmol L − 1. The recovery test performed in honey samples showed values ranging between 92.4 and 108.8%. According to the results, the proposed microfluidic device demonstrated a good potential for detecting carbendazim in real samples, with the advantages of employing sustainable and renewable materials.

Abstract Glucose biosensors play an extremely important role in health care systems worldwide. Therefore, the field continues to attract significant attention leading to the development of innovative technologies. Due to their characteristics, Molecularly Imprinted Polymers (MIPs) represent a promising alternative to commercial enzymatic sensors. In this work, a low‐cost, flexible MIP‐based platform for glucose sensing by integrating MIP particles directly into screen‐printed electrodes (SPEs) is realized. The sensor design allows the detection of glucose via two different transducer principles, the so‐called “heat‐transfer method” (HTM) and electrochemical impedance spectroscopy (EIS). The sensitivity and selectivity of the sensor are demonstrated by comparing the responses obtained toward three different saccharides. Furthermore, the application potential of the MIP‐SPE sensor is demonstrated by analyzing the response in urine samples, showing a linear range of 14.38–330 µm with HTM and 1.37–330 µm with EIS. To bring the sensor closer to a real life application, a handheld dipstick sensor is developed, allowing the single‐shot detection of glucose in urine using EIS. This study illustrates that the simplicity of the dipstick readout coupled with the straightforward manufacturing process opens up the possibility for mass production, making this platform a very attractive alternative to commercial glucose sensors.

Additive manufacturing, or three-dimensional (3D) printing, offers a unique solution for fabricating complex geometries with high tolerances. Currently, many commercial additive manufacturing machines focus on the printing of polymers with limited functionalities. However, conductive polymers (CPs) can be processed to enable the additive manufacturing of conductive, low-density, and low-cost parts for a myriad of applications. This review summarizes the relevant achievements in the additive manufacturing of conductive polymers (CPs) and conductive polymer nanocomposites, with a discussion of the advantages and limitations of processing and printing these materials compared with alternative traditional manufacturing methods and their properties. Finally, the prospective applications of these additive manufacturing printed conductive materials are explored.

Additive manufacturing (3D-printing) is a rapidly emerging technology grouped under the heading of Industry 4.0 and revolutionises the way products are created. One emerging area is textiles (apparel) where additive manufacturing allows the rapid fabrication of products that are not easily produced using traditional manufacturing approaches. In this review, we provide an overview of recent developments in textile additive manufacturing highlighting this exciting and rapidly growing research area and offer insights into the future perspectives of this promising and innovative technology.

Chromium exerts serious damage to human beings and to aquatic life and is one of the most common environmental contaminant and possess toxicity when present above threshold limits. In comparison with the traditional quantification methods such as atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectrometry, UV-Vis or high-performance liquid chromatography, electrochemical methods towards monitoring chromium ions have the advantages of being portable, rapid, cost effective, simple, sensitive and selective enough to meet regulatory limits. This review presents the recent progress in the field of electroanalysis using different electrode platforms such as solid or screen-printed electrode (SPE) and various functional materials towards chromium determination. The fabrication strategy and the analytical performance of carbon nanomaterials (such as carbon nanotubes and graphene), metal and metal oxide nanomaterials enabled sensors for electrochemical determination of chromium (III) and chromium (VI) ions are summarized systematically. In addition, method validation and the application of these sensors in real samples for the analysis of chromium ions is discussed and future developments in this domain are provided.

Manganese is an essential nutrient of the human body but also toxic at elevated levels with symptoms of neurotoxicity reported, therefore its analytical determination is required. Manganese (II) is ingested primarily through food and drinking water so its routine monitoring in such samples is essential. While laboratory based analytical instrumentation can be routinely used to measure manganese (II), there is a need to develop methods for manganese (II) determination that can be performed in-the-field utilizing simple and inexpensive instrumentation yet providing comparable sensitive analytical measurements. Electrochemistry can provide a solution with instrumentation readily portable and hand-held coupled with electrochemical sensing platforms that are sensitive and provide on-site rapid analytical measurements. Consequently, in this overview we explore the electroanalytical determination of manganese (II) reported throughout the literature and offer insights into future research opportunities within this important field.

Serum creatinine concentration is an important clinical measure of kidney function. However, standard methods of detection, such as the Jaffe method or enzymatic assays, suffer several disadvantages, including non-specificity and procedural complexity, or high cost, respectively. In this work, we propose the use of nano-molecularly imprinted polymers (nMIPs) in conjunction with the novel Heat Transfer Method (HTM) as a promising alternative sensing platform to these existing methods for measuring serum creatinine concentration. More specifically, it is shown that creatinine-imprinted nMIPs can be produced using a solid-phase templating method, and that simple drop-casting onto a cheap, disposable substrate can be used in conjunction with HTM to detect creatinine with a limit-of-detection of (7.0 ± 0.5) μM in buffer solutions. Furthermore, the nMIPs are shown to selectively bind creatinine in comparison to several similar molecules, and the sensing platform is demonstrated to be able to detect changes in creatinine concentration in complex blood plasma samples.

With the increase in antimicrobial resistance, there is an urgent need to find new antimicrobials. Four particulate antimicrobial compounds, graphite (G), graphene oxide (GO), silver–graphene oxide (Ag-GO) and zinc oxide–graphene oxide (ZnO-GO) were tested against Enterococcus faecium, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. The antimicrobial effects on the cellular ultrastructure were determined using Fourier transform infrared spectroscopy (FTIR), and selected FTIR spectral metrics correlated with cell damage and death arising from exposure to the GO hybrids. Ag-GO caused the most severe damage to the cellular ultrastructure, whilst GO caused intermediate damage. Graphite exposure caused unexpectedly high levels of damage to E. coli, whereas ZnO-GO exposure led to relatively low levels of damage. The Gram-negative bacteria demonstrated a stronger correlation between FTIR metrics, indicated by the perturbation index and the minimal bactericidal concentration (MBC). The blue shift of the combined ester carbonyl and amide I band was stronger for the Gram-negative varieties. FTIR metrics tended to provide a better assessment of cell damage based on correlation with cellular imaging and indicated that damage to the lipopolysaccharide, peptidoglycan and phospholipid bilayers had occurred. Further investigations into the cell damage caused by the GO-based materials will allow the development of this type of carbon-based multimode antimicrobials.

The demand for new devices that enable the detection of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) at a relatively low cost and that are fast and feasible to be used as point-of-care is required overtime on a large scale. In this sense, the use of sustainable materials, for example, the bio-based poly (ethylene terephthalate) (Bio-PET) can be an alternative to current standard diagnostics. In this work, we present a flexible disposable printed electrode based on a platinum thin film on Bio-PET as a substrate for the development of a sensor and immunosensor for the monitoring of COVID-19 biomarkers, by the detection of L-cysteine and the SARS-CoV-2 spike protein, respectively. The electrode was applied in conjunction with 3D printing technology to generate a portable and easy-to-analyze device with a low sample volume. For the L-cysteine determination, chronoamperometry was used, which achieved two linear dynamic ranges (LDR) of 3.98−39.0 μmol L−1 and 39.0−145 μmol L−1, and a limit of detection (LOD) of 0.70 μmol L−1. The detection of the SARS-CoV-2 spike protein was achieved by both square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) by a label-free immunosensor, using potassium ferro-ferricyanide solution as the electrochemical probe. An LDR of 0.70−7.0 and 1.0−30 pmol L−1, with an LOD of 0.70 and 1.0 pmol L−1 were obtained by SWV and EIS, respectively. As a proof of concept, the immunosensor was successfully applied for the detection of the SARS-CoV-2 spike protein in enriched synthetic saliva samples, which demonstrates the potential of using the proposed sensor as an alternative platform for the diagnosis of COVID-19 in the future.

Zero-emission hydrogen and oxygen production are critical for the UK to reach net-zero greenhouse gasses by 2050. Electrochemical techniques such as water splitting (electrolysis) coupled with renewables energy can provide a unique approach to achieving zero emissions. Many studies exploring electrocatalysts need to “electrically wire” to their material to measure their performance, which usually involves immobilization upon a solid electrode. We demonstrate that significant differences in the calculated onset potential for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can be observed when using screen-printed electrodes (SPEs) of differing connection lengths which are immobilized with a range of electrocatalysts. This can lead to false improvements in the reported performance of different electrocatalysts and poor comparisons between the literature. Through the use of electrochemical impedance spectroscopy, uncompensated ohmic resistance can be overcome providing more accurate Tafel analysis.

In this overview we explore the electroanalytical determination of the molecule of murder: atropine. Atropine, occurs naturally in various plants of the nightshade family, including the deadly nightshade (Atropa belladonna). On the one hand, atropine, a tropane alkaloid, has medical uses, named on the World Health Organisations list of essential medicines, used for example in resuscitations and as an antidote to certain poison gases and insecticides, but on the other hand, it is fatal in a high enough dose. Atropine derives it names from atropos, one of the three Fates, where in Greek mythology, one of the Fates determining the individuals moment of death. There is clearly a need to analytically determine atropine within clinical and other misdemeanours situations. In this overview, we review the current research directed to the electroanalytical sensing of atropine.

Cadaverine is a biomolecule of major healthcare importance in periodontal disease; however, current detection methods remain inefficient. The development of an enzyme biosensor for the detection of cadaverine may provide a cheap, rapid, point-of-care alternative to traditional measurement techniques. This work developed a screen-printed biosensor (SPE) with a diamine oxidase (DAO) and multi-walled carbon nanotube (MWCNT) functionalised electrode which enabled the detection of cadaverine via cyclic voltammetry and differential pulse voltammetry. The MWCNTs were functionalised with DAO using carbodiimide crosslinking with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS), followed by direct covalent conjugation of the enzyme to amide bonds. Cyclic voltammetry results demonstrated a pair of distinct redox peaks for cadaverine with the C-MWCNT/DAO/EDC-NHS/GA SPE and no redox peaks using unmodified SPEs. Differential pulse voltammetry (DPV) was used to isolate the cadaverine oxidation peak and a linear concentration dependence was identified in the range of 3–150 µg/mL. The limit of detection of cadaverine using the C-MWCNT/DAO/EDC-NHS/GA SPE was 0.8 μg/mL, and the biosensor was also found to be effective when tested in artificial saliva which was used as a proof-of-concept model to increase the Technology Readiness Level (TRL) of this device. Thus, the development of a MWCNT based enzymatic biosensor for the voltammetric detection of cadaverine which was also active in the presence of artificial saliva was presented in this study.

Changing the connection length of an additively manufactured electrode (AME) has a significant impact on the electrochemical and electroanalytical response of the system. In the literature, many electrochemical platforms have been produced using additive manufacturing with great variations in how the AME itself is described. It is seen that when measuring the near-ideal outer-sphere redox probe hexaamineruthenium (III) chloride (RuHex), decreasing the AME connection length enhances the heterogeneous electrochemical transfer (HET) rate constant (k0) for the system. At slow scan rates, there is a clear change in the peak-to-peak separation (ΔEp) observed in the RuHex voltammograms, with the ΔEp shifting from 118 ± 5 mV to 291 ± 27 mV for the 10 and 100 mm electrodes, respectively. For the electroanalytical determination of dopamine, no significant difference is noticed at low concentrations between 10- and 100-mm connection length AMEs. However, at concentrations of 1 mM dopamine, the peak oxidation is shifted to significantly higher potentials as the AME connection length is increased, with a shift of 150 mV measured. It is recommended that in future work, all AME dimensions, not just the working electrode head size, is reported along with the resistance measured through electrochemical impedance spectroscopy to allow for appropriate comparisons with other reports in the literature. To produce the best additively manufactured electrochemical systems in the future, researchers should endeavor to use the shortest AME connection lengths that are viable for their designs.

This short article overviews the use of screen-printed electrodes (SPEs) in the field of electroanalysis and compares their application against traditional laboratory based analytical techniques. Electroanalysis coupled with SPEs can offer low-cost, precise, sensitive, rapid, quantitative information and laboratory equivalent results. The combined use of SPEs and electroanalysis reduces the need of sample transportation and preparation to a centralised laboratory allowing experimentalists to perform the measurements where they are needed the most. We first introduce the basic concepts and principles of analytical techniques to the reader, with particular attention to electroanalysis, and then discuss the application of SPEs to common analytical targets such as food, environmental, forensics, cancer biomarkers and pathogenic monitoring and sensing.

In this overview, we explore the electroanalytical determination of theophylline. Theophylline finds use as a bronchodilator for treating diseases such as asthma and chronic obstructive pulmonary disease (COPD). There is a need to measure the concentration of theophylline in pharmaceuticals for QA/QC purposes as well as in plasma samples to ensure the doses of theophylline are at the correct therapeutic levels. If the concentration levels of theophylline deviate from the therapeutic levels (10–20 µg/mL for asthma), then patients can experience adverse effects. As such, there is a desire to progress from traditional laboratory based techniques to portable rapid testing. In this overview, we review the endeavours directed to the development of theophylline electroanalytical sensors, noting current and future trends.

Molecular recognition has been described as the “ultimate” form of sensing and plays a fundamental role in biological processes. There is a move towards biomimetic recognition elements to overcome inherent problems of natural receptors such as limited stability, high-cost, and variation in response. In recent years, several alternatives have emerged which have found their first commercial applications. In this review, we focus on molecularly imprinted polymers (MIPs) since they present an attractive alternative due to recent breakthroughs in polymer science and nanotechnology. For example, innovative solid-phase synthesis methods can produce MIPs with sometimes greater affinities than natural receptors. Although industry and environmental agencies require sensors for continuous monitoring, the regulatory barrier for employing MIP-based sensors is still low for environmental applications. Despite this, there are currently no sensors in this area, which is likely due to low profitability and the need for new legislation to promote the development of MIP-based sensors for pollutant and heavy metal monitoring. The increased demand for point-of-use devices and home testing kits is driving an exponential growth in biosensor production, leading to an expected market value of over GPB 25 billion by 2023. A key requirement of point-of-use devices is portability, since the test must be conducted at “the time and place” to pinpoint sources of contamination in food and/or water samples. Therefore, this review will focus on MIP-based sensors for monitoring pollutants and heavy metals by critically evaluating relevant literature sources from 1993 to 2022.

Electrochemical biosensors for the detection of vital biomarkers is a well-established technology that utilises a transducer and recognition element in tandem to determine the presence of an analyte. There is growing interest in using Molecularly Imprinted Polymers (MIPs) as recognition elements in a wide range of sensing devices due to their economic viability and scalability. The inherent properties of polymer platforms, alongside the vast array of monomeric options, synthetic routes and incorporation strategies allow for the production of a multitude of sensitive and selective recognition elements that have significant advantages over classically utilised biological entities. MIPs exhibit superior chemical and thermal stability offering a wider variety of immobilization/incorporation strategies, virtually unlimited ambient shelf-life and a longer product lifetime, whilst the vast array of monomers available offer flexibility to their synthesis. Even though some sensor platforms have been reported for the detection of vital biomarkers, the use of MIPs has a number of challenges and drawbacks that need to be overcome in order to produce sensing platforms with the required sensitivity and specificity for clinical use. In this review, we will provide an overview of the reasoning behind using MIPs as recognition elements in electrochemical biosensors for vital biomarkers, discuss the problems synergizing MIPs and electrochemical read-out strategies and offer insights into the future perspectives of this promising and innovative technology.

A low-cost, scalable and reproducible approach for the mass production of screen-printed electrode (SPE) platforms that have varying percentage mass incorporations of 2D hexagonal boron nitride (2D-hBN) (2D-hBN/SPEs) is demonstrated herein. These novel 2D-hBN/SPEs are explored as a potential metal-free electrocatalysts towards oxygen reduction reactions (ORRs) within acidic media where their performance is evaluated. A 5% mass incorporation of 2D-hBN into the SPEs resulted in the most beneficial ORR catalysis, reducing the ORR onset potential by ca. 200 mV in comparison to bare/unmodified SPEs. Furthermore, an increase in the achievable current of 83% is also exhibited upon the utilisation of a 2D-hBN/SPE in comparison to its unmodified equivalent. The screen-printed fabrication approach replaces the less-reproducible and time-consuming drop-casting technique of 2D-hBN and provides an alternative approach for the large-scale manufacture of novel electrode platforms that can be utilised in a variety of applications.

Bio-based and biodegradable materials have the potential to replace traditional petroleum-based plastics across a range of products and contribute to a more circular economy. However, the uptake of these materials will not succeed unless consumers, manufacturers, and regulators are convinced of their efficacy. Investigating performance and safety concerns put forward by academic and non-academic communities, this paper assesses whether these concerns are being adequately addressed by current policy and regulation. In addition, measures to overcome significant concerns are developed through a series of stakeholder engagement events, informed by the Prospex-CQI-and STIR methodology. Discussions across the stakeholder engagement events have highlighted several concerns that create barriers to market up-take of bio-based and biodegradable plastic products, including the continued confusion regarding terminology and resultant communication, difficulties in navigating the plethora of documents related to safety, the appropriateness of safety documents when applied to new products, and the overall suitability and sustainability of such materials as an alternative to traditional plastics. To overcome these concerns, a series of recommendations for research, policy, and practice are made with respect to the following key areas of concern: regulation and legislative instruments, material quality and performance, market penetration and availability, waste management infrastructure, sourcing and supply chain, communication and information provision, and material health and safety.

Robust, reliable, and affordable analytical techniques are essential for screening and monitoring food and water safety from contaminants, pathogens, and allergens that might be harmful upon consumption. Recent advances in decentralised, miniaturised, and rapid tests for health and environmental monitoring can provide an alternative solution to the classic laboratory-based analytical techniques currently utilised. Electrochemical biosensors offer a promising option as portable sensing platforms to expedite the transition from laboratory benchtop to on-site analysis. A plethora of electroanalytical sensor platforms have been produced for the detection of small molecules, proteins, and microorganisms vital to ensuring food and drink safety. These utilise various recognition systems, from direct electrochemical redox processes to biological recognition elements such as antibodies, enzymes, and aptamers; however, further exploration needs to be carried out, with many systems requiring validation against standard benchtop laboratory-based techniques to offer increased confidence in the sensing platforms. This short review demonstrates that electroanalytical biosensors already offer a sensitive, fast, and low-cost sensor platform for food and drink safety monitoring. With continued research into the development of these sensors, increased confidence in the safety of food and drink products for manufacturers, policy makers, and end users will result.

Abstract The effects of metal ion solutions (silver, copper, platinum, gold and palladium) were determined individually and in combination against Enterococcus faecium, Acinetobacter baumannii and Klebsiella pneumoniae. Platinum, gold and palladium showed the greatest antimicrobial efficacy in zone of inhibition (ZoI) assays. When tested in combinations using ZoI assays, gold/platinum, gold/palladium and platinum/palladium were indicative of synergy. Microbial inhibitory concentration demonstrated platinum and gold against Enterococcus faecium, platinum against Klebsiella pneumoniae and platinum and silver against Acinetobacter baumannii were optimal. Minimal bactericidal concentrations determined the greatest bactericidal activity was again platinum gold and palladium against all three bacteria. Fractional Inhibitory Concentration (FIC) studies demonstrated that the silver/platinum combination against Enterococcus faecium, and silver/copper combination against Acinetobacter baumannii demonstrated antimicrobial synergy. Following crystal violet biofilm assays for single metal ion solutions, antimicrobial efficacies were demonstrated for all the metals against all the bacteria Synergistic assays against biofilms demonstrated gold/palladium, gold/platinumand platinum/palladium resulted in the greatest antimicrobial efficacy. Overall, platinum, palladium and gold metal ion solutions in individual use or combination demonstrated the greatest antimicrobial efficacies against planktonic or biofilm bacteria. This work demonstrates the potential for using a range of metal ions, as biocidal formulations against both planktonic or biofilm bacteria.

The C—Journal of Carbon Research (ISSN 2311-5629) is quite pleased to announce the publication of its 300th article [...]

Voltammetric sensor using a symmetrical derivative of anthrone3 (1,7-diamino-3,9-dibutyl benzo[1,2,3-de:4,5,6-d’e’]diquinoline-2,8(3H,9H)-dione) (SPE-A) has been developed as a probe for Hg(II) ions. Performance of the probe as screen-printed electrode modified with the receptor (SPE-A) has been compared with anthrone3 in solution phase, using 1:1 water-acetonitrile solvent system. Anthrone3 displayed an electrochemically quasi-reversible nature in voltammograms with both the systems and is presented as a novel disposable voltammetric sensor for mercury ions. Upon interaction with cations, both the electrode systems showed sensitivity towards Hg2+ ions with a lower detection limit of 0.61 µM. The magnitude of the voltammetric current with the SPE-A exhibited three times the current obtained with a bare glassy carbon electrode (GC). Kinetic performance of the SPE-A electrode is better than the GC electrode. The morphological studies indicate reusability of the electrodes.

Lactate is widely measured in critically ill patients as a robust indicator of patient deterioration and response to treatment. Plasma concentrations represent a balance between lactate production and clearance. Analysis has typically been performed with the aim of detecting tissue hypoxia. However, there is a diverse range of processes unrelated to increased anaerobic metabolism that result in the accumulation of lactate, complicating clinical interpretation. Further, lactate levels can change rapidly over short spaces of time, and even subtle changes can reflect a profound change in the patient’s condition. Hence, there is a significant need for frequent lactate monitoring in critical care. Lactate monitoring is commonplace in sports performance monitoring, given the elevation of lactate during anaerobic exercise. The desire to continuously monitor lactate in athletes has led to the development of various technological approaches for non-invasive, continuous lactate measurements. This review aims firstly to reflect on the potential benefits of non-invasive continuous monitoring technology within the critical care setting. Secondly, we review the current devices used to measure lactate non-invasively outside of this setting and consider the challenges that must be overcome to allow for the translation of this technology into intensive care medicine. This review will be of interest to those developing continuous monitoring sensors, opening up a new field of research.

Electron transfer plays a vital role in drug metabolism and underlying toxicity mechanisms. Currently, pharmaceutical research relies on pharmacokinetics (PK) and absorption, distribution, metabolism, elimination and toxicity (ADMET) measurements to understand and predict drug reactions in the body. Metabolic stability (and toxicity) prediction in the early phases of the drug discovery and development process is key in identifying a suitable lead compound for optimisation. Voltammetric methods have the potential to overcome the significant barrier of new drug failure rates, by giving insight into phase I metabolism events which can have a direct bearing on the stability and toxicity of the parent drug being dosed. Herein, we report for the first time a data-mining investigation into the voltammetric behaviour of reported drug molecules and their correlation with metabolic stability (indirectly measured via t½), as a potential predictor of drug stability/toxicity in vivo. We observed an inverse relationship between oxidation potential and drug stability. Furthermore, we selected and prepared short- (2 h) drug molecules to prospectively survey the relationship between oxidation potential and stability.

We demonstrate a facile methodology for the mass production of graphene oxide (GO) bulk-modified screen-printed electrodes (GO-SPEs) that are economical, highly reproducible and provide analytically useful outputs. Through fabricating GO-SPEs with varying percentage mass incorporations (2.5%, 5%, 7.5% and 10%) of GO, an electrocatalytic effect towards the chosen electroanalytical probes is observed, which increases with greater GO incorporated compared to bare/graphite SPEs. The optimum mass ratio of 10% GO to 90% carbon ink produces an electroanalytical signal towards dopamine (DA) and uric acid (UA) which is ca. ×10 greater in magnitude than that achievable at a bare/unmodified graphite SPE. Furthermore, 10% GO-SPEs exhibit a competitively low limit of detection (3σ) towards DA at ca. 81 nM, which is superior to that of a bare/unmodified graphite SPE at ca. 780 nM. The improved analytical response is attributed to the large number of oxygenated species inhabiting the edge and defect sites of the GO nanosheets, which are able to exhibit electrocatalytic responses towards inner-sphere electrochemical analytes. Our reported methodology is simple, scalable, and cost effective for the fabrication of GO-SPEs that display highly competitive LODs and are of significant interest for use in commercial and medicinal applications.

Molecularly Imprinted Polymers (MIPs) were synthesised for the selective detection of amoxicillin in aqueous samples. Different functional monomers were tested to determine the optimal composition via batch rebinding experiments. Two different sensor platforms were tested using the same MIP solution; one being bulk synthesized and surface modified Screen Printed Electrodes (SPEs) via drop casting the microparticles onto the electrode surface and the other being UV polymerized directly onto the SPE surface in the form of a thin film. The sensors were used to measure amoxicillin in conjunction with the Heat-Transfer Method (HTM), a low-cost and simple thermal detection method that is based on differences in the thermal resistance at the solid−liquid interface. It was demonstrated that both sensor platforms could detect amoxicillin in the relevant concentration range with Limits of Detection (LOD) of 1.89 ± 1.03 nM and 0.54 ± 0.10 nM for the drop cast and direct polymerisation methods respectively. The sensor platform utilising direct UV polymerisation exhibited an enhanced response for amoxicillin detection, a reduced sensor preparation time and the selectivity of the platform was proven through the addition of nafcillin, a pharmacophore of similar shape and size. The use of MIP-modified SPEs combined with thermal detection provides sensors that can be used for fast and low-cost detection of analytes on-site, which holds great potential for contaminants in environmental aqueous samples. The platform and synthesis methods are generic and by adapting the MIP layer it is possible to expand this sensor platform to a variety of relevant targets.

The structure–property relationship between biomineralized calcium phosphate compounds upon a fluorescent quenching–recovery platform and their distinct crystalline structure and surficial functional groups are investigated. A fluorescence-based sensing platform is shown to be viable for the sensing of 8-hydroxy-2-deoxy-guanosine in simulated systems.

N-acyliminium ions are useful reactive synthetic intermediates in a variety of important carbon–carbon bond forming and cyclisation strategies in organic chemistry. The advent of an electrochemical anodic oxidation of unfunctionalised amides, more commonly known as the Shono oxidation, has provided a complementary route to the C–H activation of low reactivity intermediates. In this article, containing over 100 references, we highlight the development of the Shono-type oxidations from the original direct electrolysis methods, to the use of electroauxiliaries before arriving at indirect electrolysis methodologies. We also highlight new technologies and techniques applied to this area of electrosynthesis. We conclude with the use of this electrosynthetic approach to challenging syntheses of natural products and other complex structures for biological evaluation discussing recent technological developments in electroorganic techniques and future directions.

The modification of electrode surfaces is widely implemented in order to try and improve electron transfer kinetics and surface interactions, most recently using graphene related materials. Currently, the use of ‘as is’ graphene oxide (GO) has been largely overlooked, with the vast majority of researchers choosing to reduce GO to graphene or use it as part of a composite electrode. In this paper, ‘as is’ GO is explored and electrochemically characterized using a range of electrochemical redox probes, namely potassium ferrocyanide(II), N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD), dopamine hydrochloride and epinephrine. Furthermore, the electroanalytical efficacy of GO is explored towards the sensing of dopamine hydrochloride and epinephrine via cyclic voltammetry. The electrochemical response of GO is benchmarked against pristine graphene and edge plane-/basal plane pyrolytic graphite (EPPG and BPPG respectively) alternatives, where the GO shows an enhanced electrochemical/electroanalytical response. When using GO as an electrode material, the electrochemical response of the analytes studied herein deviate from that expected and exhibit altered electrochemical responses. The oxygenated species encompassing GO strongly influence and dominate the observed voltammetry, which is crucially coverage dependent. GO electrocatalysis is observed, which is attributed to the presence of beneficial oxygenated species dictating the response in specific cases, demonstrating potential for advantageous electroanalysis to be realized. Note however, that crucial coverage based regions are observed at GO modified electrodes, owing to the synergy of edge plane sites and oxygenated species. We report the true beneficial electrochemistry of GO, which has enormous potential to be beneficially used in various electrochemical applications ‘as is’ rather than be simply used as a precursor to making graphene and is truly a fascinating member of the graphene family.

Cobalt phthalocyanine (CoPC) compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC) onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes L-ascorbic acid, oxygen and hydrazine. It is found that no “electrocatalysis” is observed towards L-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where “electrocatalysis” has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate.

The accurate detection of biological materials has remained at the forefront of scientific research for decades. This includes the detection of molecules, proteins, and bacteria. Biomimetic sensors look to replicate the sensitive and selective mechanisms that are found in biological systems and incorporate these properties into functional sensing platforms. Molecularly imprinted polymers (MIPs) are synthetic receptors that can form high affinity binding sites complementary to the specific analyte of interest. They utilise the shape, size, and functionality to produce sensitive and selective recognition of target analytes. One route of synthesizing MIPs is through electropolymerization, utilising predominantly constant potential methods or cyclic voltammetry. This methodology allows for the formation of a polymer directly onto the surface of a transducer. The thickness, morphology, and topography of the films can be manipulated specifically for each template. Recently, numerous reviews have been published in the production and sensing applications of MIPs; however, there are few reports on the use of electrosynthesized MIPs (eMIPs). The number of publications and citations utilising eMIPs is increasing each year, with a review produced on the topic in 2012. This review will primarily focus on advancements from 2012 in the use of eMIPs in sensing platforms for the detection of biologically relevant materials, including the development of increased polymer layer dimensions for whole bacteria detection and the use of mixed monomer compositions to increase selectivity toward analytes.