Fabrication of selective electrochemical sensor for the detection of folic acid in spinach, wheat and tablets using functionalized graphene-oxide based molecular imprinted polymer

Abstract

A novel cost-effective sensor material was developed from modified graphene oxide based molecular imprinted polymer (GO-MIP) for the detection of folic acid (FA). This GO-MIP was obtained through several processes including functionalization, polymerization and template molecule introduction/removal during the synthesizing process. Firstly, graphene oxide (GO) was prepared by modified Hummers method which undergoes hydroxyl functionalization to form GO–OH. It further undergoes surface modification with allyl bromide in presence of sodium hydroxide (NaOH) and dimethyl sulfoxide (DMSO) to form vinylated GO–OH (GO–O–CH=CH2). The GO–O–CH=CH2 subjected to further molecular imprinting process with methacrylic acid (MAA) as the monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linker, azobisisobutyronitrile (AIBN) as the initiator and FA as the template molecule. The different preparatory stages of materials were characterized by FTIR, XRD and SEM techniques to understand the formation. The obtained GO–MIP was used as an active material for FA sensing. The pH studies were carried out using cyclic voltameteric measurement and maximum current is obtained at pH 4.0. The proposed GO-MIP based electrode showed excellent electrocatalytic activity toward FA detection at optimized conditions. The limit of detection obtained in the present study is 1.0 nM. The results obtained from the real time usability of electrodes in wheat flour, tablet and spinach are well with commercially available FA monitors. The results endorse the promising application of GO-MIP toward superior FA sensing with long-term stability.