Chiral Mo Se2nanoparticles For Ultrasensitive Monitoring Of Reactive Oxygen Species In Vivo

Reactive oxygen species（ROS）are a family of small molecules with redox activity that play an important role in a variety of physiological processes and can contribute to a range of diseases such as cancer,neurodegenerative diseases,bacterial infections,acute kidney injury,and acute hepatitis.The quantification of ROS is crucial for the early diagnosis and personalized treatment of these diseases,however,according to most research findings,it remains difficult to quantify the biological levels of ROS in an accurate and timely manner.Although various quantification methods have been applied for ROS monitoring,including colorimetric,fluorescence,electrochemical,etc.,rapid feedback and highly sensitive ROS detection methods in complex biological systems are still lacking.Therefore,there is a need to develop assays with high sensitivity,good biocompatibility,and other characteristics to detect ROS in complex biological systems.In this work,a novel probe is developed,based on chiral molybdenum diselenide（MoSe₂）nanoparticles（NPs）modified by the fluorescent molecule,Cyanine 3（Cy3）,as a dual-mode nanoprobe based on CD and fluorescent signals.Besides the low toxicity of the molybdenum selenide nanoparticles,molybdenum and selenium are highly susceptible to altering redox states,making them ideal for ROS detection in vivo.The high selectivity and sensitivity to ROS in complex biological environments are attributed to the Mo⁴⁺and Se^2-oxidation reactions on the NPs.The probe takes advantage of the ability of chiral molybdenum selenide to react with ROS to alter the chiral and fluorescent signals of the monitoring system.These signals can indicate dynamic changes in ROS levels in solution and cells,and even in tumors.Chiral MoSe₂NPs show intensive circular dichroism（CD）signals at 390 and 550 nm,whereas the fluorescence of Cy3 at 560 nm is quenched by MoSe₂NPs due to the fluorescence resonance energy transfer（FRET）effect.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（LOD）of CD and fluorescent signals detection values in living cells are 0.0093 nmol/10⁶cells and 0.024nmol/10⁶cells,respectively.Furthermore,chiral MoSe₂nanoprobes can monitor ROS levels in vivo by fluorescence.Collectively,these results reveal that chiral MoSe₂nanoprobes exhibit a remarkable ability to quantify ROS levels in living organisms,and could therefore provide a new tool for exploring chiral nanomaterials as a potential biosensor to investigate biological events.