Integration of Riboflavin-Modified Carbon Fiber Mesh Electrode Systems in a 3D-Printed Catheter Hub

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

Integration of Riboflavin-Modified Carbon Fiber Mesh Electrode Systems in a 3D-Printed Catheter Hub

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

Microbial water quality: Voltammetric detection of coliforms based on riboflavin–ferrocyanide redox couples

The ability to screen water for the presence of faecal contamination is a pressing need for rural communities dependent upon local purification systems. While there are a multitude of coliform detection assays based on the activity of β-galactosidase, this report details the adaptation of a voltammetric pH sensing strategy which could offer rapid analysis. The approach exploits the bacterial metabolism of lactose via pyruvate to lactate with the subsequent decrease in pH measured by examining the peak separation of a riboflavin (sensing) – ferrocyanide (reference) couple. Disposable carbon fibre electrodes were used as in situ sensors in Escherichia coli cultures (103–107 cfu/mL) with detection times of 4 h enabling confirmation of coliform activity. The bacterial compatibility of the riboflavin–ferrocyanide system in combination with the simplicity of the detection methodology, stand in marked contrast to many existing coliform assays and could open new avenues through which voltammetric pH sensing could be employed. Keywords: Galactosidase, pH, Riboflavin, Coliform, Water quality, Senso

Electrochemically initiated release: exploring new modalities for controlled drug release

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

Design of a smart sensor mesh for the measurement of pH in ostomy applications

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

Electroanalytical properties of chlorophenol red at disposable carbon electrodes: Implications for Escherichia coli detection

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