BACKGROUND:Catheter line infection is a common complication within clinical environments, and there is a pressing need for technological options to aid in reducing the possibility of sepsis. The early identification of contamination could be pivotal in reducing cases and improving outcomes. METHOD:A sensing rationale based on a riboflavin-modified electrode system integrated within a modified 3D-printed catheter needle-free connector is proposed, which can monitor changes in pH brought about by bacterial contamination. RESULTS:Riboflavin, vitamin B2, is a biocompatible chemical that possesses a redox-active flavin core that is pH dependent. The oxidation peak potential of the adsorbed riboflavin responds linearly to changes in pH with a near-Nernstian behavior of 63 mV/pH unit and is capable of accurately monitoring the pH of an authentic IV infusate. CONCLUSIONS:The proof of principle is demonstrated with an electrode-printed hub design offering a valuable foundation from which to explore bacterial interactions within the catheter lumen with the potential of providing an early warning of contamination.

The electropolymerization of anthranilic acid (2-aminobenzoic acid) has been shown to lead to the production of a redox polymer functionalized with carboxylate groups capable of complexing metal ions. The polymer was exploited as a means of capturing ferric ion from solution with the iron decorated polymer chains used as seeding points for the formation of Prussian blue (PB). Nanoclusters of PB were dispersed throughout the three-dimensional polymer matrix with deposition achieved through direct electrochemical means or via a dip process. The latter exploited the chemical combination of Fe(III) + Ferrocyanide to yield PB allowing its dispersal of the PB throughout the polymer film. The polymer film and its subsequent modification have been characterized by electron microscopy, X-ray analysis, Raman spectroscopy and electrochemical analysis. The stability toward peroxide has also been explored.

Polyaniline has been utilized in various applications, yet its widespread adoption has often been impeded by challenges. Composite systems have been proposed as a means of mitigating some of these limitations, and anthranilic acid (2-aminobenzoic acid) has emerged as a possible moderator for use in co-polymer systems. It offers improved solubility and retention of electroactivity in neutral and alkaline media, and, significantly, it can also bestow chemical functionality through its carboxylic acid substituent, which can greatly ease post-polymer modification. The benefits of using anthranilic acid (as a homopolymer or copolymer) have been demonstrated in applications including corrosion protection, memory devices, photovoltaics, and biosensors. Moreover, this polymer has been used as a versatile framework for the sequestration of metal ions for water treatment, and, critically, these same mechanisms serve as a facile route for the production of catalytic metallic nanoparticles. However, the widespread adoption of polyanthranilic acid has been limited, and the aim of the present narrative review is to revisit the early promise of anthranilic acid and assess its potential future use within modern smart materials. A critical evaluation of its properties is presented, and its versatility as both a monomer and a polymer across a spectrum of applications is highlighted.

Countering the supply of counterfeit and designer drug pills laced with fentanyl or its analogues has long been a challenge with the potency of the drug and the ease with which it can be obtained impacting greatly on families and the wider society. The introduction of legislative measures to restrict access to the machinery that allows the production of the pills has yielded considerable gains with numerous seizures of pill presses reported. However, the increasing availability of bench top milling machines and advances in 3D printing could render this a short term victory where the technology may be set to outpace the capabilities of conventional law enforcement. While pill presses were once born from high specification industrial machining, low cost mills and 3D printing systems are already at the stage of producing small format presses within the domestic home. Here, a spotlight is trained on fentanyl (and its analogues) from the perspective of pill manufacture and their supply. An overview of pill press mechanics and the approaches presently taken to counter distribution is provided and the potential influence that both milling systems and 3D printing technologies could have in the future is critically evaluated.

The synthesis of a range of new linear substituted heptamethine dyes has been designed and described. The photophysical properties of all the dyes were investigated, with many exhibiting improved fluorescent quantum yields when compared with indocyanine green. Finally, growth inhibition studies were performed in the fission yeast Saccharomyces pombe , which suggests potential antifungals activity in the μM range.

The electrosynthesis of a novel polyquinone film onto laser induced graphene (LIG) substrates is presented as a sensitive and scalable route to the production of thiol sensors. The one pot electroreduction of 5-nitro-1,4-naphthoquinone and subsequent electro-oxidation of the resulting amine was found to yield polymeric films consisting of repeating 1,4-naphthoquinone units. The resulting film exhibited electrochemically reversible behaviour (Eo = -0.1V at pH 7 (vs 3M NaCl Ag/AgCl) and found to exhibit a pH sensitivity of 61 mV / pH unit. The quinone groups within the film were found to react with cysteine (as a model thiol biomarker) through conventional 1,4-Michael addition resulting in the covalent modification of the film and the generation of new discrete redox entities. The voltammetric signature of the latter enabled interference free measurement of cysteine concentration at -0.42V with a detection limit of 5.2 mM. This contrasts the response to cysteine at unmodified LIG substrates where a detection potential of +0.55V was required and suffered inevitable interference from other species common to biofluids (i.e. tyrosine). The electrode mechanisms have been elucidated and the nature of the reaction with cysteine investigated using electrochemical and surface characterization techniques. The sensing performance of the polyquinone film towards cysteine is place in context with alternative electrode modifications. Figure 1

In this study, eighteen heptamethine dyes were synthesised and their antifungal activities were evaluated against three clinically relevant yeast species.. The eighteen dyes were placed within classes based on their core subunit i.e. 2,3,3-trimethylindolenine (5a-f), 1,1,2-trimethyl-1H-benzo[e]indole (6a-f), or 2-methylbenzothiazole (7a-f). The results presented herein imply that the three families of cyanine dyes, in particular compounds 5a-f, show high potential as selective scaffolds to treat C. albicans infections. This opens up the opportunity for further optimisation and investigation of this class compounds for potential antifungal treatment.

A series of naphthoquinone-aminophenol derivatives have been synthesized on the basis that their conjugation with a suitable drug candidate could provide a means through which the latter could be released upon the imposition of an appropriate oxidation potential. The approach is based on a three component assembly in which the naphthoquinone redox centre serves as a reporter unit allowing electrochemical interrogation without release of the drug. The central aminophenol serves as the tether to which the drug is linked via an ether bond. Upon oxidation of the aminophenol - ether component, transition of the latter to quinone imine results in the release of the drug. The electrochemical properties of the model system are investigated and the impact of the release process on the functional groups intrinsic to the drug component is critically considered.

Conductive microneedle patches consisting of carbon nanoparticles embedded in a polystyrene matrix have been prepared using micro-moulding techniques. The interfacial properties of the structures before and after electrochemical etching have been characterised using X-ray photoelectron spectroscopy and contact angle. Anodisation of the needles leads to a significant increase in oxygen functionality and is shown to dramatically improve the electroanalytical capabilities of the microneedle array. The detection of uric acid in horse blood was used as a model system through which to assess the performance of the system. The composite approach is shown to lead to viable carbon-based sensors and can offer a rapid prototype option for the development of tailored microneedle systems.

A carbon-loaded polyethylene film was modified through a combination of laser ablation and electrochemical anodisation to yield a mechanically flexible yet electroanalytically sensitive mesh. A custom flavin derivative bearing a pendant phenol substituent was electropolymerised onto the substrate, and its electrochemical properties were investigated. The reversible flavin electrochemistry was retained (Ep = −0.374 V vs. Ag/AgCl, pH 7), and the peak position was found to shift by 60 mV/pH over a range covering pH 2.55 to pH 8.12. The stability of the resulting composite has been evaluated, and the analytical applicability towards the voltammetric measurement of pH in human urine was critically assessed.

The series of rigid meso-aminophenyl-substituted heptamethine dyes presented herein exhibit surprising fluorescence properties, demonstrating larger Stokes shifts when compared with both structurally similar rigid meso-chlorophenyl and linear heptamethine dyes. Based on their photophysical properties, these are of considerable importance to the development of contrast agents, within biology and medicine.

The use of coliforms and Escherichia coli as indicator species for assessing the quality of water is well established and a large variety of methods based on β-galactosidase (B-GAL) activity, inherent to the microbes within this classification, have arisen to enable their detection and enumeration. Chlorophenol red (CPR) is widely used as a chromogenic label, but its capacity for translation to electroanalytical devices has yet to be fully explored. The CPR moiety is capable of undergoing oxidation at carbon substrates (+0.7 V) giving rise to a variety of phenolic intermediates. Electrochemical, XPS and enzymatic techniques were employed to characterise the underpinning chemistry and the intermediate identified as a 1,2-quinone derivative in which the chlorine substituent is retained. The latter was found to accumulate at the electrode and, in contrast to the parent CPR, was found to be detected at a significantly less positive potential (+0.3 V). Bacterial hydrolysis of a CPR labelled substrate was demonstrated with the 1,2-quinone oxidation product found to accumulate at the electrode and detected using square wave voltammetry. Proof of concept for the efficacy of the alternative electrode pathway was established through the detection of E.coli after an incubation time of 2.5 h with no interference from the labelled substrates.