Photonic Crystal of Polystyrene Nanomembrane: Signal Amplification and Low Triggered Potential Electrochemiluminescence for Tetracycline Detection

In this work, a low triggered potential electrochemiluminescence strategy based on gold-filled photonic crystals (GPCs) electrodes composed of photonic crystals self-assembled with polystyrene spheres and gold nanoparticles embedded in the gaps of the photonic crystals was proposed. The GPCs electrodes served as the detection platform to bind antigen, and Ru(bpy)32+-COOH as a luminophore was labeled on the antibody (Ab). Then, Ru(bpy)32+-COOH/Ab was connected to the immobilized antigen on the surface of the photonic crystals by the immunoreaction to avoid direct contact with the gold nanoparticles surface. ECL emission can only be initiated by electrochemical oxidation of tripropylamine (TPrA) since Ru(bpy)32+-COOH cannot be oxidized directly on the electrode surface. The TPrA·+ and TPrA· radicals generated by the oxidation of TPrA can spread to the vicinity of Ru(bpy)32+-COOH over a short distance and react with the Ru(bpy)32+-COOH, eventually producing ECL emission. The potential of ECL emission caused by TPrA oxidation was about 300 mV lower than that caused by Ru(bpy)32+-COOH oxidation because the oxidation potential of TPrA (0.95 V vs SCE) was lower than Ru(bpy)32+-COOH (1.25 V vs SCE). Furthermore, the photonic crystals nanomembrane has the capability to enhance electrochemiluminescence. Thereafter, tetracycline antibiotic as a model compound was successfully detected via competitive immunoassay on GPCs electrodes with a detection limit of 0.075 pg/mL (S/N = 3), which has broad application prospects in the field of analysis and detection.