Chances and challenges of long-distance electron transfer for cellular redox reactions

Quinones stimulate reactive oxygen species production from zero-valent iron over centimeter distances

Zero-valent iron (ZVI) has demonstrated high potential for in-situ remediation of contaminated groundwater and soils. Upon exposure to oxygen, ZVI generates reactive oxygen species (ROS). In parallel with the electron transfer mediated-reductive path, ROS plays a critical role in the oxidative degradation of organic pollutants during ZVI remediation of groundwater and soil. Yet, the efficiency is often constrained by the confined ROS production localized to the surface or immediate vicinity of ZVI particles. Here, we demonstrate that quinones significantly enhance ROS production from ZVI over centimeter-scale distances. H₂O₂ and •OH were detected over 1 cm from ZVI particles after 24 h of incubation, with production increasing alongside quinone concentration and incubation time, reaching 318.3 ± 50.0 µM and 1263.2 ± 143.5 nM at 2 mm, respectively. The broad applicability of quinone in promoting remote ROS generation was demonstrated for various ZVI materials. This remote ROS production is driven by sequential electron transfer from ZVI to quinone, long-distance electron transfer via quinone, and subsequent electron transfer from reduced quinone to oxygen. The resulting increase in ROS production amount and extended range improved ZVI remediation efficiency by 5- to 15-fold for organic pollutant degradation. These findings provide a promising strategy for enhancing ROS-mediated ZVI remediation in heterogeneous environments.

From ferroptosis to cuproptosis, and calcicoptosis, to find more novel metals-mediated distinct form of regulated cell death

Regulated cell death (RCD), also known as programmed cell death (PCD), plays a critical role in various biological processes, such as tissue injury/repair, development, and homeostasis. Dysregulation of RCD pathways can lead to the development of many human diseases, such as cancer, neurodegenerative disorders, and cardiovascular diseases. Maintaining proper metal ion homeostasis is critical for human health. However, imbalances in metal levels within cells can result in cytotoxicity and cell death, leading to a variety of diseases and health problems. In recent years, new types of metal overload-induced cell death have been identified, including ferroptosis, cuproptosis, and calcicoptosis. This has prompted us to examine the three defined metal-dependent cell death types, and discuss other metals-induced ferroptosis, cuproptosis, and disrupted Ca2+ homeostasis, as well as the roles of Zn2+ in metals' homeostasis and related RCD. We have reviewed the connection between metals-induced RCD and various diseases, as well as the underlying mechanisms. We believe that further research in this area will lead to the discovery of novel types of metal-dependent RCD, a better understanding of the underlying mechanisms, and the development of new therapeutic strategies for human diseases.