Fig. 4

Optimization of the (a) amount of AuNPs, (b) FeMOF (µg/mL), (c) pH, (d) buffer concentration in the fabrication of the probe. ([RIS] 10 µg/mL, pH 5.0, [Fe(CN)6]−4/[Fe(CN)6]−3, 5 mM, KCl 0.1 M, potential range − 1.0–1.0 V, scan rate 100 mV/s)