SERS-fluorescence nanoprobe for monitoring and imaging mitochondrial ROS during cell apoptosis

Fumonisin B1 (FB₁) is a mycotoxin that can induce oxidative stress in cells, leading to apoptosis. This study developed an innovative dual-mode nanoprobe that combines fluorescence and SERS detection to dynamically track the expression levels of mitochondrial reactive oxygen species (ROS) during FB₁-induced apoptosis in cells. This probe utilizes gold-silver structured Au@AgNPs as the nanoprobes substrate, with mitochondrial-targeting polypeptide MLS labeled with the fluorescent molecule Rhodamine B modified on its surface, enabling precise targeting of cellular mitochondria. Upon the presence of ROS, the silver layer on the gold core is etched, causing the polypeptide chain attached to the silver surface to detach, which leads to the separation of Rhodamine B from the nanoprobe. This results in a decrease in Raman signals and an increase in fluorescence signals. SERS-fluorescence imaging results show that with prolonged FB₁ exposure, the intracellular fluorescence signals increase while SERS signals decrease. The design of this nanoprobe fully utilizes the advantages of SERS and fluorescence dual detection, providing a novel tool for in-depth investigation of the toxin-induced apoptosis process.