Smartphone-Assisted Electrochemiluminescence Imaging Platform Based on Protamine-Enhanced Gold Nanoclusters for Ultrasensitive and Visualized Detection of Zearalenone

Abstract Zearalenone (ZEN) contamination in grains poses a serious threat to human and animal health, yet existing imaging-based platforms for rapid visualized detection remain limited by insufficient sensitivity, limited luminescence efficiency, and poor signal stability, hindering further practical applications. Herein, a portable smartphone-assisted electrochemiluminescence (ECL) imaging platform was developed for ultrasensitive and visualized detection of ZEN based on protamine-enhanced 6-aza-2-thiothymine-stabilized gold nanoclusters (Prot/ATT-Au NCs) synthesized by a protein-assisted assembly strategy. The resulting Prot/ATT-Au NCs achieved a 108-fold enhancement in ECL intensity relative to bare ATT-Au NCs and demonstrated an ECL efficiency approximately 5.01-fold higher than that of the benchmark Ru(bpy)32+ system, enabling naked-eye-visible green ECL emission. This enhancement was attributed to Prot-induced hydrogen-bonding and electrostatic confinement that suppressed nonradiative decay and facilitated radiative transitions. Integrated with catalytic hairpin assembly amplification, the developed ECL imaging system allowed ZEN to be visually quantified over a wide linear range of 1 pg/mL to 10 μg/mL with a detection limit of 0.38 pg/mL, along with excellent specificity, stability, reproducibility, and real-sample recoveries. Furthermore, it was applied for the determination of ZEN in naturally contaminated corn samples. This work provides a facile strategy for engineering high-performance ECL emitters and offers a robust route toward portable food safety monitoring.