Sleep deprivation boosts O2·− levels in the brains of mice as visualized by a Golgi apparatus–targeted ratiometric fluorescence nanosensor

Sleep deprivation (SD) is highly prevalent in the modern technological world. Emerging evidence shows that sleep deprivation is associated with oxidative stress. At the organelle level, the Golgi apparatus actively participates in the stress response. In this study, to determine whether SD and Golgi apparatus stress are correlated, we rationally designed and fabricated a novel Golgi apparatus–targeted ratiometric nanoprobe called Golgi dots for O2·− detection. This probe exhibits high sensitivity and selectivity in cells and brain slices of sleep-deprived mice. Golgi dots can be readily synthesized by coprecipitation of Golgi-F127, an amphiphilic polymer F127 modified with a Golgi apparatus targeting moiety, caffeic acid (CA), the responsive unit for O2·−, and red emissive carbon nanodots (CDs), which act as the reference signal. The fluorescence emission spectrum of the developed nanoprobe showed an intense peak at 674 nm, accompanied by a shoulder peak at 485 nm. As O2·− was gradually added, the fluorescence at 485 nm continuously increased; in contrast, the emission intensity at 674 nm assigned to the CDs remained constant, resulting in the ratiometric sensing of O2·−. The present ratiometric nanoprobe showed high selectivity for O2·− monitoring due to the specific recognition of O2·− by CA. Moreover, the Golgi dots exhibited good linearity with respect to the O2·− concentration within 5 to 40 μM, and the limit of detection (LOD) was 0.13 μM. Additionally, the Golgi dots showed low cytotoxicity and an ability to target the Golgi apparatus. Inspired by these excellent properties, we then applied the Golgi dots to successfully monitor exogenous and endogenous O2·− levels within the Golgi apparatus. Importantly, with the help of Golgi dots, we determined that SD substantially elevated O2·− levels in the brain.