Fig. 3

A ECL behavior of pure luminol (a), ZIF-67@luminol (b), luminol@AuPt/ZIF-67 (c). B ECL behavior of luminol@AuPt/ZIF-67/GCE without (a) and with (b) GSH, MnO₂@CNTs/luminol@AuPt/ZIF-67/GCE without (c) and with (d) GSH in 5 mL PBS (0.1 M, pH 8.0) containing 10 mM H₂O₂. C ECL curve and D EIS of bare GCE (a), after luminol@AuPt/ZIF-67 modification (b), after Ab₁ modification (c), after BSA blocking (d), after 10 ng mL⁻¹ RBP4 incubation (e), after Ab₂-MnO₂@CNTs immobilization (f), and after adding 20 mM GSH (g), respectively measured in 5 mL PBS (0.1 M, pH 8.0) containing 10 mM H₂O₂ and in 5 mM Fe(CN)₆^3−/4− containing 0.1 M KCl at 150 mV s⁻¹. The inset was the equivalent circuit for EIS