Chiral MoSe₂ Nanoparticles for Ultrasensitive Monitoring of Reactive Oxygen Species In Vivo

Abstract Reactive oxygen species (ROS) are involved in neurodegenerative diseases, cancer, and acute hepatitis, and quantification of ROS is critical for the early diagnosis of these diseases. In this work, a novel probe is developed, based on chiral molybdenum diselenide (MoSe₂) nanoparticles (NPs) modified by the fluorescent molecule, cyanine 3 (Cy3). Chiral MoSe₂ NPs show intensive circular dichroism (CD) signals at 390 and 550 nm, whereas the fluorescence of Cy3 at 560 nm is quenched by MoSe₂ NPs. In the presence of ROS, the probe reacts with the ROS and then oxidates rapidly, resulting in decreased CD signals and the recovery of the fluorescence. Using this strategy, the limit of detection values of CD and fluorescent signals in living cells are 0.0093 nmol/10⁶ cells and 0.024 nmol/10⁶ cells, respectively. The high selectivity and sensitivity to ROS in complex biological environments is attributed to the Mo⁴⁺ and Se²⁻ oxidation reactions on the surface of the NPs. Furthermore, chiral MoSe₂ NPs are able to monitor the levels of ROS in vivo by the fluorescence. Collectively, this strategy offers a new approach for ROS detection and has the potential to inspire others to explore chiral nanomaterials as biosensors to investigate biological events.