Michael-addition reaction triggering sensitive and facile detection of glutathione employing LSPR-photonic crystals.

Glutathione (GSH) plays a crucial role in various cellular functions, and its abnormal levels often indicate numerous diseases. Therefore, it's essential to develop a simple, rapid, and sensitive method to monitor GSH levels in serum for real-time tracking disease. In this work, a Michael-Addition reaction triggering GSH detection method was constructed based on a Localized Surface Plasmon Resonance enhanced opal Photonic Crystal (LSPR-PC). LSPR-PC was prepared through vertical deposition self-assembly method using the Gold nanoparticles (AuNPs) modified SiO2 microspheres, and the oxidized dopamine (o-DA), as the recognition element, was fixed on the LSPR-PC through Au-N bond, forming a LSPR-o-DA PC. The sulfhydryl group in GSH could undergo a Michael addition reaction with the oxidized dopamine on the PC surface, resulting in a reduction of the reflection peak intensity. The detection limit for GSH was 1.3 ng/mL. Real serum samples were detected using LSPR-o-DA PC, and a commercial GSH kit was chosen as a comparison. The detection results obtained through LSPR-o-DA PC method was consistent with that obtained through GSH kit, indicating that LSPR-o-DA PC method having a good accuracy. Notably, the entire assay process is completed within 20 min. The as-proposed LSPR-o-DA PC method is simple-operation, label-free, rapid and cost-effective, making it a promising tool for clinical diagnostics.