Red-Emissive Carbon Dots Combined with Ferric Ions for Detection of Total Antioxidant Capacity in Food

Abstract

In general, the total antioxidant capacity (TAC) in food is vital for evaluating the quality of antioxidant food and health monitoring. Most studies about the access of the TAC in food are mainly focused on typical colorimetric strategies. Herein, a simple and sensitive strategy for TAC in beverages and fruit has been proposed based on amino/hydroxyl-functionalized carbon dots (N 2 H 4 -CDs) and Fe 3+ . The fluorescence (FL) of N 2 H 4 -CDs at 650 nm can be effectively and selectively quenched via the formation of the nonfluorescence complex (Fe 3+ /N 2 H 4 -CDs). Moreover, the FL of N 2 H 4 -CDs is concentrated in the red region, which can eliminate the interference in complex biological environments. Interestingly, based on the theoretical calculations of density functional theory (DFT), we have confirmed that the surface amino and hydroxyl play an essential role in selective association with Fe 3+ , resulting in effective quenching. Moreover, because Fe 3+ can be reduced by antioxidants to Fe 2+ , the quenched FL of N 2 H 4 -CDs can be restored in the presence of ascorbic acid (AA) and glutathione (GSH). Therefore, the typical antioxidants (AA) and especially certain thiol antioxidants (GSH) can also be analyzed by the proposed strategy. More importantly, we have proved that this strategy is successfully utilized for analyzing the TAC in beverages and fruit.

Selenium Nanoparticles for Antioxidant Activity and Selenium Enrichment in Plants

“…This oxidative damage can result in cell death and mutations and pose a severe threat to human health and well-being. 4,5 Selenium (Se) is an essential nutrient for humans and animals, as well as a beneficial element for plant growth. It serves as the active site of various enzymes, including glutathione peroxidase, which directly or indirectly participates in the removal of free radicals.…”

“…Disruption of this balance, such as an excessive presence of reactive oxygen species (ROS), can adversely affect metabolic processes and contribute to the development of diseases. , For example, the hydroxyl free radical (•OH) is a highly active ROS that, when present in excess, can react with biomolecules through addition and dehydrogenation reactions. This oxidative damage can result in cell death and mutations and pose a severe threat to human health and well-being. , Selenium (Se) is an essential nutrient for humans and animals, as well as a beneficial element for plant growth. It serves as the active site of various enzymes, including glutathione peroxidase, which directly or indirectly participates in the removal of free radicals. − Selenium’s antioxidant capacity is demonstrated in its ability to enhance the activity of superoxide dismutase and glutathione peroxidase, as well as inhibit lipid peroxidation. − Additionally, low concentrations of selenium can promote plant growth, improve plant antioxidant capacity, and enhance the quality of fruits and vegetables. − However, the commonly used selenium source, selenite, is a toxic chemical substance that poses significant safety risks in practical applications …”