Fig. 6. DPV curves at various concentrations of 4-NP in 0.1 M PBS (pH 5) with a scan rate of 50 mV s⁻¹ for GT-AgNPs (a), MP-AgNPs (b), and GP-AgNPs (c); the corresponding calibration plots of peak current intensity vs. various concentrations of 4-NP (d–f) with error bars.