Integration of ITO with polyaniline for scalable smart aptasensing interface design: Towards a rainbow assay of Carbamazepine by green Apta-Chip

Carbamazepine (CBZ) is an FDA-approved drug for controlling abnormal nerve impulses in the nervous system and brain. Despite the advantages, its overdose causes suicide cases. Close dosage monitoring of CBZ without complex equipment is essential to guarantee its safety and effectiveness from a medicolegal view. This study introduces a novel technology in fabricating the advanced aptasensing interface as the multi-mode Apta-Chip for the electrochemical and visual detection of the CBZ drug in human biofluids based on the green analytical chemistry (GCA) principles. The cornerstone of this study is the integration of the unique electrochromic behavior of polyaniline (PANI) as the sensing platform that undergoes an electric-induced change in coloration and excellent properties of the aptamer (Apt) sequence as the highly selective bioreceptor to CBZ. The molecular dynamic (MD) simulation investigation confirms the conformation changes of the Apt sequence upon incubating CBZ to trap it. The current decrease and resistance increase of the Apta-Chip surface induced by the CBZ/Apt complex forming provides an electrochemical measurement of CBZ by a linear dynamic range (LDR) value from 1 fM to 900 nM and a limit of detection (LOD) value of 333.33 aM. Additionally, different oxidation degrees of PANI in the presence of varying concentrations of CBZ provide a rainbow color switching of the Apta-Chip surface from dark blue to green and yellow colors, corresponding to low, medium and high concentrations, respectively. The utilizing safe and biocompatible chemicals, the unique platform with scalable and miniature size as well as user-friendliness methodology in the high selective Apta-Chip fabrication not only guarantee its applicability as the clinical point of care (PoC) device but also offer promising directions that pave the way for progress in other visual home kits for the assay of various analytes.