Polyethylenimine-carbon nanotubes composite as an electrochemical sensing platform for silver nanoparticles

For the first time, polyethylenimine (PEI) and carbon nanotubes (CNT) composites (PEI-CNTs) were employed for investigation of electrochemical response of silver nanoparticles (AgNPs) in this work. The PEI-CNTs were easily prepared by sonicating the mixture of PEI and CNTs solution and characterized by SEM, Raman and electrochemical impedance spectroscopy (EIS). The PEI-CNTs/GCE enhanced the electrochemical response for three AgNPs with different capping agents, including citrate-AgNPs (Cit-AgNPs), humic acid-AgNPs (HA-AgNPs) and gum acacia-AgNPs (GA-AgNPs), by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronocoulometry (CC). On these findings, a new electrochemical method based on LSV was developed for the detection of AgNPs. Under the optimum conditions, the proposed method showed a good linear range from 5 to 200   ng/L, and the limits of detection (LODs) were 4.77   ng/L for Cit-AgNPs, 2.48   ng/L for HA-AgNPs and 1.01   ng/L for GA-AgNPs, respectively. The potential of using the PEI-CNTs modified GCE for determining AgNPs in water samples has been successfully demonstrated.