Electroanalytical overview: The pungency of chile and chilli products determinedviathe sensing of capsaicinoids

When you bite into a chile pepper or eat food containing chile (chilli), one might feel heat, or other associated feelings, some good such as the release of endorphins, and some bad. The heat, or pungency, and related feelings from eating chile peppers are the result of their chemical composition,i.e.the concentrations of capsaicinoids. The major components are capsaicin and dihydrocapsaicin, which occur in chiles in the ratio of 6 : 4. Other capsaicinoids occur in smaller concentrations and are known as the “minor” capsaicinoids. Wilbur L. Scoville in 1912 created an organoleptic test, now known as the Scoville scale, which asked a panel of tasters to state when an increasingly dilute solution of the chile pepper in alcohol no longer burned the mouth. Following the Scoville scale, a plethora of analytical techniques later followed. In this overview, we explore the endeavours directed to the development of electrochemical-based sensors for the determination of capsaicin and related compounds, starting from their use in hyphenated laboratory set-ups to their modern use as stand-alone electroanalytical sensors. The latter have the advantage of providing a rapid and sensitive methodology that has the potential to be translated in the field; future trends and issues to be overcome are consequently suggested

Electroanalytical overview: The detection of the molecule of murder atropine

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

Electroanalytical Overview: The Sensing of Mesalamine (5-Aminosalicylic Acid)

Mesalamine, known as 5-aminosalicylic acid, is a medication used primarily in the treatment of inflammatory bowel disease, including ulcerative colitis and Crohn’s disease. 5-Aminosalicylic acid can be measured using various benchtop laboratory techniques which involve liquid chromatography-mass spectroscopy, but these are sophisticated and large, meaning that they cannot be used on-site because transportation of the samples, chemicals, and physical and biological reactions can potentially occur, which can affect the sample’s composition and potentially result in inaccurate results. An alternative approach is the use of electrochemical based sensing platforms which has the advantages of portability, cost-efficiency, facile miniaturization, and rapid analysis while nonetheless providing sensitivity and selectivity. We provide an overview of the use of the electroanalytical techniques for the sensing of 5-aminosalicylic acid and compare them to other laboratory-based measurements. The applications, challenges faced, and future opportunities for electroanalytical based sensing platforms are presented in this review

Additive manufacturing for electrochemical labs: An overview and tutorial note on the production of cells, electrodes and accessories

Additive Manufacturing (AM) is an ever-growing part of modern scientific research due to its ability to create complex features, low wastage, ever-decreasing cost of entry and rapid prototyping capabilities. Up to this point, the use of AM in electrochemical research has focused around two of the main components of the experimental setup: the working electrode, and the electrochemical cell. In this paper we highlight how researchers have utilised AM in the literature and offer our own insights into how this technology can be exploited to benefit all areas of electrochemical research. For the development of electrodes, much of the literature utilises commercially available conductive PLA filaments in conjunction with FFF printing, with only a few groups expanding into the development of their own bespoke conductive materials. AM offers huge advantages in the production of electrochemical cells, allowing users to produce bespoke designs to fit their experimental needs, rapidly producing these at low cost and easily modifying the design to improve performance. However, the use of AM in electrochemical laboratories should not stop there. We present basic designs of electrodes, cells and even accessories that can benefit all electrochemical researchers (new and experienced) in their quest for reproducible and reliable results. These designs are offered free of charge, are available to download from the Supporting Information and can be easily modified to meet any users’ specific needs. As such, we feel AM should be a staple of every laboratory and hope this work inspires people to think about all the ways that AM can benefit their research environments

Electroanalytical point-of-care detection of gold standard and emerging cardiac biomarkers for stratification and monitoring in intensive care medicine - a review

Determination of specific cardiac biomarkers (CBs) during the diagnosis and management of adverse cardiovascular events such as acute myocardial infarction (AMI) has become commonplace in emergency department (ED), cardiology and many other ward settings. Cardiac troponins (cTnT and cTnI) and natriuretic peptides (BNP and NT-pro-BNP) are the preferred biomarkers in clinical practice for the diagnostic workup of AMI, acute coronary syndrome (ACS) and other types of myocardial ischaemia and heart failure (HF), while the roles and possible clinical applications of several other potential biomarkers continue to be evaluated and are the subject of several comprehensive reviews. The requirement for rapid, repeated testing of a small number of CBs in ED and cardiology patients has led to the development of point-of-care (PoC) technology to circumvent the need for remote and lengthy testing procedures in the hospital pathology laboratories. Electroanalytical sensing platforms have the potential to meet these requirements. This review aims firstly to reflect on the potential benefits of rapid CB testing in critically ill patients, a very distinct cohort of patients with deranged baseline levels of CBs. We summarise their source and clinical relevance and are the first to report the required analytical ranges for such technology to be of value in this patient cohort. Secondly, we review the current electrochemical approaches, including its sub-variants such as photoelectrochemical and electrochemiluminescence, for the determination of important CBs highlighting the various strategies used, namely the use of micro- and nanomaterials, to maximise the sensitivities and selectivities of such approaches. Finally, we consider the challenges that must be overcome to allow for the commercialisation of this technology and transition into intensive care medicine. Graphical abstract: [Figure not available: see fulltext.

Nano-molecularly imprinted polymers for serum creatinine sensing using the heat transfer method

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

The effect of water ingress on additively manufactured electrodes

Additive Manufacturing (AM), otherwise known as 3D printing, is becoming increasingly popular in the field of electrochemistry since it allows affordable, on-demand production of bespoke devices. Provided a suitably conductive polymer composite material is used, this can include working electrodes. However, while a number of publications have shown such Additively Manufactured Electrodes (AMEs) to be effective, there remain several fundamental areas which must be understood to continue the development of AM for electrochemistry. One such area is the effect of solvent ingress on AME performance, with water probably representing the most important solvent for study considering the amount of electrochemical sensing directed towards biological and environmental systems. Therefore, in this work we study the effect of up to 28 days of water immersion on the physical properties and electrochemical performance of AMEs made from a commonly used conductive material, Protopasta. It is shown that water immersion leads to water uptake of around 1–1.5% by mass for our specific electrode design, which in turn causes a decrease in measured peak current, but an increase in the heterogeneous electron transfer rate constant, k0. These observations are rationalised in terms of Ohmic drop and conductive filler surface chemistry, respectively. Overall, it can be concluded that water ingress is likely to be a concern for any application where AMEs are expected to have extended contact with water, although we note that more work is required to fully understand the extent of the issue

Electroanalytical overview: The detection of chromium

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