Microbial monooxygenase amperometric biosensor for monitoring of Baeyer–Villiger biotransformation

Polyelectrolytes Assembly: A Powerful Tool for Electrochemical Sensing Application

The development of sensing coatings, as important sensor elements that integrate functionality, simplicity, chemical stability, and physical stability, has been shown to play a major role in electrochemical sensing system development trends. Simple and versatile assembling procedures and scalability make polyelectrolytes highly convenient for use in electrochemical sensing applications. Polyelectrolytes are mainly used in electrochemical sensor architectures for entrapping (incorporation, immobilization, etc.) various materials into sensing layers. These materials can often increase sensitivity, selectivity, and electronic communications with the electrode substrate, and they can mediate electron transfer between an analyte and transducer. Analytical performance can be significantly improved by the synergistic effect of materials (sensing material, transducer, and mediator) present in these composites. As most reported methods for the preparation of polyelectrolyte-based sensing layers are layer-by-layer and casting/coating methods, this review focuses on the use of the latter methods in the development of electrochemical sensors within the last decade. In contrast to many reviews related to electrochemical sensors that feature polyelectrolytes, this review is focused on architectures of sensing layers and the role of polyelectrolytes in the development of sensing systems. Additionally, the role of polyelectrolytes in the preparation and modification of various nanoparticles, nanoprobes, reporter probes, nanobeads, etc. that are used in electrochemical sensing systems is also reviewed.

Wiring Bacterial Electron Flow for Sensitive Whole-Cell Amperometric Detection of Riboflavin

A whole-cell bioelectrochemical biosensing system for amperometric detection of riboflavin was developed. A "bioelectrochemical wire" (BW) consisting of riboflavin and cytochrome C between Shewanella oneidensis MR-1 and electrode was characterized. Typically, a strong electrochemical response was observed when riboflavin (VB2) was added to reinforce this BW. Impressively, the electrochemical response of riboflavin with this BW was over 200 times higher than that without bacteria. Uniquely, this electron rewiring process enabled the development of a biosensing system for amperometric detection of riboflavin. Remarkably, this amperometric method showed high sensitivity (LOD = 2.2 nM, S/N = 3), wide linear range (5 nM ∼ 10 μM, 3 orders of magnitude), good selectivity, and high resistance to interferences. Additionally, the developed amperometric method featured good stability and reusability. It was further applied for accurate and reliable determination of riboflavin in real conditions including food, pharmaceutical, and clinical samples without pretreatment. Both the cost-effectiveness and robustness make this whole-cell amperometric system ideal for practical applications. This work demonstrated the power of bioelectrochemical signal amplification with exoelectrogen and also provided a new idea for development of versatile whole-cell amperometric biosensors.