Dual-signal electrochemiluminescence biosensor based on bipolar emitter C₃N₄/N-CDs for trenbolone detection

Trenbolone (TB), a banned anabolic steroid, poses serious environmental and health risks, necessitating highly sensitive and selective detection methods. Electrochemiluminescence (ECL) sensing has emerged as a promising approach owing to its low background noise, broad detection range, and ultralow detection limits. However, traditional luminophores such as graphitic C₃N₄ are limited by poor structural stability and low ECL efficiency, while carbon dots (CDs) often exhibit low quantum yield and high excitation requirements. To address these limitations, a sandwich-type ECL sensor was developed for TB detection, using PDDA-modified nanoflower-like C₃N₄/N-CDs as the signal emitter and an iron-centered metal-organic framework as the substrate. In the presence of the co-reactant H₂O₂, the C₃N₄/N-CDs composite exhibited efficient “dual-potential” ECL under cathodic and anodic potentials. Simultaneously, MIL-53(Fe) catalyzed the decomposition of H₂O₂, generating additional free radicals that further enhanced the anodic and cathodic ECL signals. This quantitative ratio strategy enabled the accurate quantification of TB. Under optimized conditions, this ECL biosensor exhibited excellent performance, with a linear detection range from 0.1 pg/mL to 50 ng/mL and an ultra-low detection limit of 35.3 fg/mL (anodic) and 37.6 fg/mL (cathodic). This approach effectively reduced system errors and background signals, significantly improving detection reliability. The developed system demonstrates strong potential for detecting and analyzing other environmental pollutants.