Biocompatible WSe₂@BSA Dots with Merged Catalyst and Coreactant for Efficient Electrochemiluminescence

Electrochemiluminescence (ECL) is a powerful tool for clinical diagnosis due to its exceptional sensitivity. However, the standard tripropylamine (TPrA) coreactant for Ru(bpy)₃Cl₂, the most widely studied and used ECL system, is highly toxic. Despite extensive research on alternative coreactants, they often fall short in poor efficiency. From a reaction kinetics perspective, accelerating electrooxidation rate of Ru(bpy)₃Cl₂ is an essential way to compensate the efficiency limitation of coreactants, but is rarely reported. Here, a hybrid electrocatalyst@coreactant dots for the ECL of Ru(bpy)₃Cl₂ is reported. The as-prepared WSe₂@bovine serum albumin (WSe₂@BSA) dots is biocompatible, and demonstrate dual functions, i.e., the BSA shell works as a coreactant, meanwhile, the WSe₂ core effectively catalyzes Ru(bpy)₃Cl₂ oxidation. As a result, WSe₂@BSA dots exhibit an exceptionally high efficiency comparable to TPrA for the ECL of Ru(bpy)₃Cl₂. In addition, the procedure for synthesizing WSe₂@BSA dots is facile (room temperature, atmospheric conditions), rapid (5 min), and scalable (for millions of bioassays). A biosensor utilizing WSe₂@BSA dots shows promise for highly sensitive detecting glypican-3 in clinical liver cancer serum samples, especially for alpha-fetoprotein-negative patients. This work opens a new avenue for developing a highly efficient ECL system for biosensing and clinical diagnosis.