Molecularly imprinted polypyrrole nanonecklaces for detection of herbicide through molecular recognition-amplifying current response

Molecularly imprinted polypyrrole (PPy) nanonecklaces were facilely synthesized through a two-step oxidative polymerization route for the amperometric detection of non-electrochemically active herbicide. It has been demonstrated that dissolved oxygen can preoxidize pyrrole to form PPy oligomer bundles, which further self-assemble into necklace-like micelles in the presence of cetyltrimethylammonium bromide. Subsequently, these microstructures were immediately gelled through quick polymerization of residual pyrrole monomers, leading to the formation of PPy nanonecklaces. Meanwhile, herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was synchronously imprinted into the formed PPy and highly dense imprinted sites were generated in PPy nanonecklaces because the necklace-like structure with microgaps/pores provides the facile and complete removal of templates. The imprinted nanonecklaces exhibit the high capacity and fast kinetics to uptake 2,4-D molecules, and produce a imprinting factor of ∼4.2. Importantly, the recognition and binding to 2,4-D significantly amplify the current response by a factor of 8 times in amperometric measurements, providing a sensitive detection of 2,4-D. The molecular imprinting strategy opens a novel avenue to the direct detection of non-electrochemically active species in a more convenient, simpler and cheaper way than the traditional competition-displacing approaches.

Molecular imprinting in polypyrrole (PPy) nanonecklaces have been achieved through the initial preoxidization of pyrrole by dissolved oxygen and subsequent quick polymerization by ammonium persulfate (APS), and the selective binding of imprinted sites to target species leads to the amplification of current response by a factor of 8 times toward the detection of trace herbicide.Figure optionsDownload as PowerPoint slideHighlights
► Molecular imprinting in polypyrrole nanonecklaces can be facilely achieved through the initial preoxidization of pyrrole and subsequent quick polymerization.
► The resultant imprinted nanonecklaces exhibit the high capacity and fast kinetics to uptake herbicide 2,4-dichlorophenoxyacetic acid (2,4-D).
► Importantly, the recognition and binding to 2,4-D significantly amplify the current response by a factor of 8 times in amperometric measurements, providing a sensitive detection of non-electrochemically active 2,4-D.