Boronate-Based Fluorescent Probes as a Prominent Tool for H2O2 Sensing and Recognition

: Given the crucial association of hydrogen peroxide with a wide-range of human diseases, this compound has currently earned the reputation of being popular biomolecular target. Although various of analytical methods have attracted our attention, fluorescent probes have been used as prominent tools to determine H2O2 to reflect the physiological and pathological conditions of biological systems, As the sensitive responsive portion of these probes, Boronate ester and boronic acid groups are vital reporter as the sensitive responsive part for H2O2 recognition. In this review, we summarized boronate ester/boronic acid group-based fluorescent probes for H2O2 reported from 2012 to 2020 and generally classify the fluorophores into six categories to exhaustively elaborate the design strategy and comprehensive systematic performance. We hope that this review will inspire the exploration of new fluorescent probes based on boronate ester/boronic acid groups for detection of H2O2 and other relevant analytes.

Distinct mechanisms underlie H2O2 sensing in C. elegans head and tail

Environmental oxidative stress threatens cellular integrity and should therefore be avoided by living organisms. Yet, relatively little is known about environmental oxidative stress perception. Here, using microfluidics, we show that the tail phasmid PHA neurons function as oxidative stress sensing neurons in C. elegans, and act in a complementary manner to I2 pharyngeal neurons: both can detect H2O2, but with different sensitivities; and both are light sensing, but with distinct responses. We uncovered that while different but related receptors, GUR-3 and LITE-1, mediate H2O2 signaling in I2 and PHA neurons, the peroxiredoxin PRDX-2 is essential in both and may promote H2O2-mediated receptor activation. Altogether, our data suggest that oxidative stress sensing relies on the integration of inputs from head and tail neurons which use partially distinct H2O2 signaling pathways. We propose that this might broaden the sensory repertoire of the nematode to respond appropriately to a large range of oxidative stressors.

Gold Nanoframe Array Electrode for Straightforward Detection of Hydrogen Peroxide

The nanostructuring of a sensing membrane is performed through colloidal nanosphere lithography (NSL) techniques with a tiny polystyrene nanobead template 100 nm in size. The solvent ratio adjustment has been proven to be effective in assisting the monolayer deposition of small templating particles with minimal defects. Two distinct structures, namely, a billowy gold nanostructure (BGN) where the nanobead template is left unetched and a gold nanoframe array (GNA) with a regular ring-like structure after template removal, are used for the extended-gate field-effect transistor (EGFET) electrodes. The GNA structure generates an electroactive surface area significantly (~20%) larger than its geometrical area as well as a greater surface roughness than the BGN. When integrated with the portable constant voltage–constant current (CVCC) FET circuitry for pH screening to determine the optimized measurement conditions for H2O2 sensing, the GNA sensing membrane also shows more improved Nernstian sensitivity at ~50 mV/pH than the BGN electrode. The more optimized sensitivity is then proven using the GNA in the detection of H2O2, the most common representative reactive oxygen species (ROS) involved in the environment, food, and neurodegenerative diseases, such as Parkinson´s and Alzheimer´s diseases. The GNA electrode has a sensitivity of 70.42 mV/log µM [H2O2] and a limit of detection (LoD) of 1.183 µM H2O2. The integrated ion sensing system employing unique, highly ordered gold array gate electrodes and a portable CVCC circuit system has shown a stable real-time output voltage signal, representing an alternative to bulky conventional FET devices for potential on-site H2O2 detection.