A General Approach Based on Sampled-Current Voltammetry for Minimizing Electrode Fouling in Electroanalytical Detection

Mitigating membrane biofouling in biofuel cell system – A review

A biofuel cell (BFC) system can transform chemical energy to electrical energy through electrochemical reactions and biochemical pathways. However, BFC faced several obstacles delaying it from commercialization, such as biofouling. Theoretically, the biofouling phenomenon occurs when microorganisms, algae, fungi, plants, or small animals accumulate on wet surfaces. In most BFC, biofouling occurs by the accumulation of microorganisms forming a biofilm. Amassed biofilm on the anode is desired for power production, however, not on the membrane separator. This phenomenon causes severities toward BFCs when it increases the electrode’s ohmic and charge transfer resistance and impedes the proton transfer, leading to a rapid decline in the system’s power performance. Apart from BFC, other activities impacted by biofouling range from the uranium industry to drug sensors in the medical field. These fields are continuously finding ways to mitigate the biofouling impact in their industries while putting forward the importance of the environment. Thus, this study aims to identify the severity of biofouling occurring on the separator materials for implementation toward the performance of the BFC system. While highlighting successful measures taken by other industries, the effectiveness of methods performed to reduce or mitigate the biofouling effect in BFC was also discussed in this study.

Mass-Spectrometric Imaging of Electrode Surfaces-a View on Electrochemical Side Reactions

Electrochemical side reactions, often referred to as "electrode fouling", are known to be a major challenge in electro-organic synthesis and the functionality of modern batteries. Often, polymerization of one or more components is observed. When reaching their limit of solubility, those polymers tend to adsorb on the surface of the electrode, resulting in a passivation of the respective electrode area, which may impact electrochemical performance. Here, matrix-assisted laser-desorption/ionization mass spectrometry (MALDI-MS) is presented as valuable imaging technique to visualize polymer deposition on electrode surfaces. Oligomer size distribution and its dependency on the contact time were imaged on a boron-doped diamond (BDD) anode of an electrochemical flow-through cell. The approach allows to detect weak spots, where electrode fouling may take place and provides insight into the identity of side-product pathways.

Coupling of Anodic Stripping Voltammetry with Sampled-Current Voltammetry on an Electrode Array: Application to Lead Detection

Electrochemical detection systems are very promising for pollution monitoring owing to their easy miniaturization and low cost. For this purpose, we have recently developed a new concept of device based on Electrodes Array for Sampled-Current Voltammetry (EASCV), which is compatible with miniaturization and portability. In this work, to improve the sensitivity of the analytical method, we added a preconcentration step before EASCV analysis, combining sampled-current voltammetry with anodic stripping voltammetry. Lead was chosen as analyte for this probe of concept owing to its high toxicity. The conditions for electrodeposition of lead on gold were optimized by means of under potential deposition. Current intensities 300 times higher than with linear sweep anodic stripping voltammetry were obtained, showing the interest in the method. The value of the sampling time directly affected the sensitivity of the sensor given by the slope of the linear calibration curve. The sensor exhibited a limit of detection of 1.16 mg L⁻¹, similar to those obtained with linear sweep anodic stripping voltammetry.

Impedimetric aptasensor for the label-free and selective detection of Interleukin-6 for colorectal cancer screening

Despite the fact that cancer research has experienced important advances and remarkable improvement in the curing processes during the last decades, this disease still occupies a leading position among the causes of death worldwide. It has been demonstrated that there is an interconnection between the overexpression of interleukin-6 cytokine and the tumor growth, metastasis, and therapeutic resistance in several types of malignancies. Herein, a highly sensitive and selective aptasensor for quantitative detection of interleukin-6 was developed by using a glassy carbon electrode modified with p-aminobenzoic acid, p-aminothiophenol and gold nanoparticles. A thio-terminated aptamer specific for interleukin-6 was immobilized on the surface of the modified electrode via the formation of gold-sulfur bonds. This DNA oligonucleotide was then used as a detection probe to capture the target protein at the biosensor surface allowing label-free detection by electrochemical impedance spectroscopy. The developed aptasensor showed a good linear response from 5 pgmL^-1 to 100 ngmL^-1 with a detection limit of 1.6 pgmL^-1, within the range of physiological concentration of the protein. The biosensor exhibited high selectivity and has been successfully used to detect interleukin-6 in blood samples collected from patients suffering of colorectal cancer, with excellent recoveries after the addition of known amount of the target protein.