Solid-State Laser-Assisted Synthesis of Cobalt Single-Atom Catalysts for Detecting Superoxide Radical Anions

Cobalt single-atom nanozymes (CoSAN) are demonstrated as excellent nanomaterials for a wide range of electrochemical applications. Traditional solution-based synthesis of CoSAN faces challenges such as multiple steps, extensive washings, and high-temperature annealing. To address these issues, we introduce a single-step solid-state synthesis using laser technology. This approach facilitates atomic dispersion of cobalt while concurrently generating laser-scribed graphene (LSG) nanosheets. The presence of Co atoms on the LSG surface is confirmed by using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and inductively coupled plasma-optical emission spectroscopy (ICP-OES). The resulting CoSAN electrode exhibits excellent electrocatalytic sensing performance to superoxide anions (O₂^•-), providing rapid electron transfer and excellent signal amplification. Elevated levels of O₂^•- serve as indicators of oxidative stress, which is associated with several chronic diseases. The CoSAN sensor achieves high sensitivity and low detection limits for the electrochemical determination of O₂^•- in lab samples, human serum samples, and neuroblastoma cells. The straightforward synthesis method and outstanding electrochemical sensing properties of CoSAN suggest significant potential for biomedical diagnostic applications.