Electrochemical detection of pathogenic bacteria - recent strategies, advances and challenges

Bacterial infections represent one of the leading causes of mortality worldwide, nevertheless the design and development of rapid, cost‐efficient and reliable detection methods for pathogens remains challenging. In recent years, electrochemical sensing methods have gained increasing attention for the detection of pathogenic bacteria, due to their increasingly competitive sensitivity. However, combining sensitivity with cost efficiency, high selectivity and a facile working procedure in a portable device is difficult. The presented review provides a summary of biosensing strategies for bacteria, published since 2015, by covering significant achievements towards custom‐designed portable point‐of‐care devices. Herein, the direct chemical recognition of bacteria via enzyme activity or secretion products, as well as their detection at various electrode surfaces and materials, such as nanomaterials, indium tin oxide or paper‐based immunosensors, is discussed. Furthermore, newly established hyphenated sensing principles, incorporated into lab‐on‐a‐chip and microfluidic devices, are presented and remaining technical challenges and limitations are considered

Electrochemical detection of pathogenic bacteria - recent strategies, advances and challenges

Bacterial infections represent one of the leading causes of mortality worldwide, nevertheless the design and development of rapid, cost‐efficient and reliable detection methods for pathogens remains challenging. In recent years, electrochemical sensing methods have gained increasing attention for the detection of pathogenic bacteria, due to their increasingly competitive sensitivity. However, combining sensitivity with cost efficiency, high selectivity and a facile working procedure in a portable device is difficult. The presented review provides a summary of biosensing strategies for bacteria, published since 2015, by covering significant achievements towards custom‐designed portable point‐of‐care devices. Herein, the direct chemical recognition of bacteria via enzyme activity or secretion products, as well as their detection at various electrode surfaces and materials, such as nanomaterials, indium tin oxide or paper‐based immunosensors, is discussed. Furthermore, newly established hyphenated sensing principles, incorporated into lab‐on‐a‐chip and microfluidic devices, are presented and remaining technical challenges and limitations are considered

A nano-carbon electrode optimized for adsorptive stripping voltammetry: Application to detection of the stimulant selegiline in authentic saliva

A multilayer Carbon Black (CB) modified Glassy Carbon Electrode (GCE) is proposed, developed and optimized for Adsorptive Stripping Voltammetry (AdSV). The thick (up to 1000 monolayers) multilayer CB modification offers a significant enhancement in sensitivity for AdSV but not diffusive voltammetry. The detection of the stimulant selegiline, which is a prohibited drug for athletes in sports competitions, is used as model for application of the proposed electrochemical method in saliva samples. The analytical performance of the CB-GCE for detection of seligeline in authentic saliva samples revealed a limit of detection of 0.12 μmol L−1 which is sufficiently low to allow a possible application of this fast method in the doping control of this drug

Polyselenides on the route to electrodeposited selenium

The electrochemical oxidation of aqueous solutions of hydrogen selenide (HSe − ) and of hydrogen polyselenide ions (HSe x− ) on glassy carbon electrodes at pH = 9.2 is reported. In both cases, the oxidation leads to deposits of selenium. The role of polyselenides as intermediates in the process is demonstrated. At 25 °C amorphous selenium is formed whereas at 70 °C crystalline selenium is deposited. The possible use of selenium films for technological purposes is discussed

Semi-circular potential sweep voltammetry: experimental verification and determination of the formal potential of a reversible redox couple

The use and merits of a semi-circular potential waveform in place of the conventional triangular waveform has been reported [J. Electroanal. Chem. 2018, 818, 140–148] on the basis of computational simulations. We report the experimental application of this new method to the study of the electrochemically reversible [Ru(NH3)6]3+/2+ redox couple at a macroelectrode. The method is used to determine the formal potential of this redox couple. Agreement between theory and experiment is good

Determination of standard electrochemical rate constants from semi-circular sweep voltammetry: a combined theoretical and experimental study

Semi-circular potential sweep voltammetry has recently been proposed as a sensitive method to estimate electrochemical rate constants [J. Electroanal. Chem., 835 (2019) 60–66]. Herein, this approach is experimentally verified using microdisc electrode voltammetry. The reduction of hexaamineruthenium (III) chloride and the oxidation of ferrocenemethanol, both in aqueous solution, at carbon electrodes were studied. The rate constants obtained from semi-circular voltammetry for both investigated redox systems are in agreement with independent values obtained from the conventional Nicholson method at macroelectrodes. The method compares favourably in terms of simplicity and speed as it requires recording only a single voltammogram. This approach provides a novel, fast complementary method for the evaluation of the standard electrochemical rate constant

Non-triangular potential sweep cyclic voltammetry of reversible electron transfer: Experiment meets theory

Conventionally, cyclic voltammetry is performed using triangular waveforms; however, complications can arise from the discontinuity of the capacitive current at the potential vertex in the triangular wave. Recent literature (J. Electroanal. Chem. 2017, 801, 381–387) showed theoretically the opportunities offered by non-triangular waveforms. Herein, we test this theory for the reversible aqueous system [Ru(NH 3 ) 6 ] 3+/2+ using cosine-based waves at a glassy carbon macroelectrode. The match between the theoretical and experimental results is excellent and offers an alternative and novel method to determine the formal potential E f o of the Ru 3+ /Ru 2+ system. The scan rate dependency of the voltammograms is investigated; and for the cosine wave voltammetry the peak currents are 24% higher than that obtained from the typical triangular waves, coinciding with the simulation results

Non-triangular potential sweep cyclic voltammetry of reversible electron transfer: Experiment meets theory

Conventionally, cyclic voltammetry is performed using triangular waveforms; however, complications can arise from the discontinuity of the capacitive current at the potential vertex in the triangular wave. Recent literature (J. Electroanal. Chem. 2017, 801, 381–387) showed theoretically the opportunities offered by non-triangular waveforms. Herein, we test this theory for the reversible aqueous system [Ru(NH 3 ) 6 ] 3+/2+ using cosine-based waves at a glassy carbon macroelectrode. The match between the theoretical and experimental results is excellent and offers an alternative and novel method to determine the formal potential E f o of the Ru 3+ /Ru 2+ system. The scan rate dependency of the voltammograms is investigated; and for the cosine wave voltammetry the peak currents are 24% higher than that obtained from the typical triangular waves, coinciding with the simulation results

Electrochemical behavior of single CuO nanoparticles: Implications for the assessment of their environmental fate

The electrochemical behavior of copper oxide nanoparticles is investigated at both the single particle and at the ensemble level in neutral aqueous solutions through the electrode‐particle collision method and cyclic voltammetry, respectively. The influence of Cl− and NO3− anions on the electrochemical processes occurring at the nanoparticles is further evaluated. The electroactivity of CuO nanoparticles is found to differ between the two types of experiments. At the single‐particle scale, the reduction of the CuO nanoparticles proceeds to a higher extent in the presence of chloride ion than of nitrate ion containing solutions. However, at the multiparticle scale the CuO reduction proceeds to the same extent regardless of the type of anions present in solution. The implications for assessing realistically the environmental fate and therefore the toxicity of metal‐based nanoparticles in general, and copper‐based nanoparticles in particular, are discussed

Electrochemical oxidation of the phospha‐ and arsaethynolate anions, PCO– and AsCO–

The anions PCO– and AsCO– are shown to be electroactive and are studied in aqueous and non‐aqueous solutions. Cyclic voltammetry is used to extract fundamental physicochemical parameters such as oxidation peak potentials, and transfer and diffusion coefficients of the anions to better understand the nature of the oxidation process. Variation of the potential scan rate reveals that electro‐oxidation of PCO– with the release of CO is controlled by diffusion and is a one‐electron irreversible process yielding phosphorus‐containing deposits. In contrast, the oxidation of AsCO– is a near electrochemically reversible process, forming pure arsenic deposits, with a chemically irreversible follow‐up reaction. For both anions, the electrode surface is substantially “blocked” by the reaction products. The formed deposits were characterized by scanning electron microscopy and energy dispersive X‐ray spectroscopy