A sandwich electrochemiluminescence (ECL) biosensing system for soybean agglutinin (SBA) detection was developed with AuPt@C-60 nanoflowers (AuPt@C-60 NFs) as a novel co-reactant accelerator to enhance the performance of N-(aminobutyl)-N-(ethylisoluminol) (ABEI). In this strategy, nanoflower-liked AuPt@C-60 complex served as a matrix for loading a large sum of ABEI and galactosamine (Gal) by Au-N and Pt-N bonds to achieve the nanocomposite Gal-ABEI-AuPt@C-60 NFs. Dissolved oxygen was used as a co-reaction reagent, while AuPt@C-60 complex acted as a co-reactant accelerator for dissolved oxygen to enhanced the ECL emission of ABEI. Gal, as an identifying element, was highly loaded by electrodeposited gold nanoparticles (Dp Au) on the electrode to recognize SBA, and further combine with Gal-ABEI-AuPt@C-60 NFs to form a sandwich model. As a result, the proposed SBA biosensor exhibited a wide linear range from 1.0 ng . mL(-1) to 5.0 mu g . mL(-1) and a low detection limit of 0.33 ng . mL(-1). In addition, the biosensor displayed an excellent selectivity and an acceptable stability and reproducibility. The combination of AuPt@C-60 NFs and ABEI provided a new ECL sensing platform without exogenous co-reactant. (C) 2019 The Electrochemical Society.