Newly Developed Electrochemiluminescence Based on Bipolar Electrochemistry for Multiplex Biosensing Applications: A Consolidated Review

Recently, there has been an upsurge in the extent to which electrochemiluminescence (ECL) working in synergy with bipolar electrochemistry (BPE) is being applied in simple biosensing devices, especially in a clinical setup. The key objective of this particular write-up is to present a consolidated review of ECL-BPE, providing a three-dimensional perspective incorporating its strengths, weaknesses, limitations, and potential applications as a biosensing technique. The review encapsulates critical insights into the latest and novel developments in the field of ECL-BPE, including innovative electrode designs and newly developed, novel luminophores and co-reactants employed in ECL-BPE systems, along with challenges, such as optimization of the interelectrode distance, electrode miniaturization and electrode surface modification for enhancing sensitivity and selectivity. Moreover, this consolidated review will provide an overview of the latest, novel applications and advances made in this field with a bias toward multiplex biosensing based on the past five years of research. The studies reviewed herein, indicate that the technology is rapidly advancing at an outstanding purse and has an immense potential to revolutionize the general field of biosensing. This perspective aims to stimulate innovative ideas and inspire researchers alike to incorporate some elements of ECL-BPE into their studies, thereby steering this field into previously unexplored domains that may lead to unexpected, interesting discoveries. For instance, the application of ECL-BPE in other challenging and complex sample matrices such as hair for bioanalytical purposes is currently an unexplored area. Of great significance, a substantial fraction of the content in this review article is based on content from research articles published between the years 2018 and 2023.

Sensitivity enhancement of cloth-based closed bipolar electrochemiluminescence glucose sensor via electrode decoration with chitosan/multi-walled carbon nanotubes/graphene quantum dots-gold nanoparticles

In this work, a novel facile closed bipolar electrochemiluminescence (C-BP-ECL) sensor has been developed for highly sensitive detection of glucose based on the integration of chitosan (CS), poly(diallyldimethylammonium chloride)-functioned multi-walled carbon nanotubes (PDDA-MWCNTs) and graphene quantum dots-gold nanoparticles (GQDs-AuNPs) on the wax/carbon ink-screen-printed cloth-based device. When CS, PDDA-MWCNTs and GQDs-AuNPs are successively decorated onto the cathode of closed bipolar electrode (C-BPE), the C-BPE anode can emit much stronger C-BP-ECL signals. Moreover, the cathodic decoration of the C-BPE can generate a stronger ECL signal in comparison with its anodic decoration. Under optimized conditions, glucose can be detected in the range of 0.1-5000 μM, and the limit of detection is estimated to be 64 nM, which is about three orders of magnitude lower than that in case of the bare C-BPE cathode (31 μM). It has been shown that the proposed sensor has high detection sensitivity, wide dynamic range, and as well acceptable reproducibility, selectivity and stability. Finally, the applicability and validity of the C-BP-ECL sensor are demonstrated for the detection of glucose in human serum samples. We believe that this novel highly-sensitive sensor will have potential applications in various areas such as clinical diagnosis, food analysis and environmental monitoring.

A miniaturized solid salt reverse electrodialysis battery: a durable and fully ionic power source

A novel pump-free miniaturized reverse electrodialysis (RED) system was designed to provide lasting power transduced from salinity gradients, named solid salt RED (ssRED), and this quasi-battery uses a solid salt instead of electrolyte solution for streamlined usage. It is portable, flexible, comparable in size to a universal serial bus flash drive, and easily activated with a small amount of water. It maintains a constant ionic concentration gradient through precipitation reactions between a pair of different salts. This precipitation-assisted solid salt RED (PssRED) is an unprecedented ionic power source as it can generate steady electricity in the absence of a driving pump. The PssRED was successfully coupled with bipolar electrode (BPE) microchip sensors which require stable ionic electricity and a polyelectrolyte ionic diode to realize a fully ionic circuit. It is envisioned that the range of application could be expanded to supply electromotive force to various devices through an ionic charge flow.

Bipolar Electrodes with 100% Current Efficiency for Sensors

A bipolar electrode (BPE) is an electron conductor that is embedded in the electrolyte solution without the direct connection with the external power source (driving electrode). When the sufficient voltage was provided, the two poles of BPE promote different oxidation and reduction reactions. During the past few years, BPEs with wireless feature and easy integration showed great promise in the various fields including asymmetric modification/synthesis, motion control, targets enrichment/separation, and chemical sensing/biosensing combined with the quantitative relationship between two poles of BPE. In this perspective paper, we first describe the concept and history of the BPE for analytical chemistry and then review the recent developments in the application of BPEs for sensing with ultrahigh current efficiency (η_c = i_BPE/i_channel) including the open and closed bipolar system. Finally, we offer the guide for possible challenge faced and solution in the future.