A novel composite of few-layer Nb2CTx and molecularly imprinted polymer with alkenyl ferrocene as cross-linker for ratiometric electrochemical detection of sulfamethoxazole

A novel composite of few-layer Nb2CTx (FL-Nb2CTx) and molecularly imprinted polymer (MIP-SiO2@Nb2CTx) with alkenyl ferrocene as a cross-linker was employed for ratiometric electrochemical detection of sulfamethoxazole (SMX). FL-Nb2CTx was obtained by delaminating multi-layer Nb2CTx (ML-Nb2CTx) with tetramethylammonium hydroxide. SiO2@Nb2CTx was synthesized with FL-Nb2CTx and tetraethoxysilane. 3methacryloxypropyltrimethoxysilane (MPS) was then functionalized onto SiO2@Nb2CTx to prepare MPSSiO2@Nb2CTx with alkenyl group. MIP-SiO2@Nb2CTx was prepared using free radical polymerization with MPSSiO2@Nb2CTx as the supporter, alkenyl ferrocene and N, N'-methylene diacrylamide (MBA) as the cross-linkers, and SMX as the template molecule. MIP-SiO2@Nb2CTx had good conductivity and large effective surface area. MIP-SiO2@Nb2CTx was applied for ratiometric electrochemical detection of SMX. The response and internal reference signals resulted from the oxidation of SMX and ferrocene (Fc), respectively. The ratio of I SMX/IFc for MIP-SiO2@Nb2CTx sensor was 5.13, 2.94, and 1.50 times higher than those of non-imprinted polymer (NIP), MIP, and MIP-SiO2@Nb2CTx sensors, respectively. The MIP-SiO2@Nb2CTx ratiometric sensor exhibited good linearity for 0.25-20 mu M SMX with detection limit of 0.15 mu M. The relative standard deviations of nonratiometric and ratiometric sensors were 8.3 % and 4.0 %. The MIP-SiO2@Nb2CTx sensor was effectively used to detect SMX in a waste water sample.