Molecularly imprinted polymer decorated 3D-framework of functionalized multi-walled carbon nanotubes for ultrasensitive electrochemical sensing of Norfloxacin in pharmaceutical formulations and rat plasma

In this work, a 3D-framework of functionalized multi-walled carbon nanotubes (fMWCNTs) decorated with molecularly imprinted polymer (MIP), has been fabricated to achieve fast and ultrasensitive electrochemical molecular sensing. The cavity networks of MIP layer from Norfloxacin (NFX) molecules offers simultaneous identification and quantification of NFX; and thus, ensures its high selectivity. The porous structure of fMWCNT 3D-framwork effectively increases the specific surface area, and the copolymer of fMWCNTs and MIP shows synergistic effect for electrocatalytic reaction of NFX at the modified sensor. Under optimized conditions, the fabricated sensors show wide linear detection ranges of 0.003-0.391 μM and 0.391–3.125 μM, low limit of determination (LOD) of 1.58 nM, and excellent selectivity in discriminating NFX according to its structural analogues and possible interferences. Precise and fast quantification of NFX in pharmaceutical formulations (Yunnan Baiyao and Ouyi Pharmaceutical) and rat plasma samples (N = 4) suggests its simplicity and reliability. The recoveries from pharmaceutical formulations ranged from 97.36 to 109.58% with the precisions (relative standard deviations, RSD, n = 3) of 1.74–3.41%; and the recoveries from rat plasma samples ranged from 83.00 to 115.67% with RSDs (n = 3) of 0.45–10.30%. Considering the advantages of easy fabrication, and selective and sensitive detection, such sensors with different types of MIPs would be widely applied in the fields of pharmaceutical analysis, and environmental and clinical therapeutic drug monitoring.