Electrochemical sensor based on imprinted sol–gel and nanomaterial for determination of caffeine

The development of a novel sensitive molecularly imprinted electrochemical sensor is described for the detection of caffeine. The sensor was prepared onto a glassy carbon electrode modified with multiwall carbon nanotubes (MWCNTs)/vinyltrimethoxysilane (VTMS) recovered by a molecularly imprinted siloxane (MIS) film prepared by sol–gel process. MWCNTs/VTMS was produced by a simple grafting of VTMS on MWCNTs surface by in situ free radical polymerization. The siloxane layer was obtained from the acid-catalyzed hydrolysis/condensation of a solution constituted by tetraethoxysilane (TEOS), methytrimethoxysilane (MTMS), 3-(aminopropyl)trimethoxysilane (APTMS) and caffeine, as a template molecule. The morphology and performance of the imprinted siloxane film was characterized by scanning electron microscopy (SEM) and differential pulse voltammetry (DPV). The MIS/MWCNTs-VTMS/GCE sensor was tested in a solution of the caffeine and other similar molecules. After optimization of the experimental conditions, the sensor showed a linear response range from 0.75 to 40 μmol L−1, with a detection limit (LOD) of 0.22 μmol L−1. The imprinted sensor was successfully tested to detect caffeine in real samples.