Aplicação de uma plataforma nanoestruturada e filmes de polímeros impressos a base de sol-gel para determinação do 4-nitrofenol

The present work describes the development of a highly sensitive voltammetric sensor for 4-NP using 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. It is possible to observe (Fig.1) when the glass-carbon surface is modified with MWCNT / VTMS in the presence of Imprinted polymer, a reduction current characteristic of the nitro group present in the 4-NP molecule is observed. However, there is no response of the target analyte either when using the unmodified or modified electrode with carbon nanotubes. The infrared absorption spectra of the MIS and NIS in KBr pellets and between 500 and 4000 cm−1 were obtained. There was no significant difference between the spectra of the imprinted and non-imprinted materials (data not shown). Scanning Electron Microscopy was applied to visualize particles (Fig. 3) of different size and morphologic of MIP structure. It shows that SEM analysis can be used for distinguishing between imprinted and non-imprinted polymers, and the difference between MIS with or without templatemolecules. After optimizing the operational conditions, the sensor provided a linear response range for 4-NP from 1 up to 100 µmol/L with sensitivity, limit of detection (LOD), and limits of quantification (LOQ) of 12 µAL/µmol, 0,24 µmol/L, and 0,8 µmol/L respectively. The excellent performance of the imprinted siloxane/MWCNTs electrode towards 4-NP can be assigned to the presence of functionalized MWCNTs, with electrochemical activities, associated with a porous siloxane imprinted film with binding sites.