Nanocomposite-modified nanopores: A promising platform for selective detection of copper ions

Abstract

This research introduces an innovative platform designed for the selective detection of copper (II) (Cu²⁺) ions, employing a singular nanopore embedded within a 12 $\mu$ m-thick polyethylene terephthalate (PET) membrane. The track-etched nanopore was subsequently modified with nanomaterials in an allylamine hydrochloride (PAH)-modified asymmetric nanopore through electrostatic interactions. The nanomaterials included copper oxide (CuO), graphene oxide (GO), and their composite (GO/CuO), were synthesized using wet chemistry, and their structures and optical properties were thoroughly investigated using x-ray diffraction and diffuse reflectance spectroscopy. In the distinctive feature of the platform, Cu²⁺ ions gain access to coordination sites across a broad surface covered by the immobilized nanomaterials, facilitating effective binding. The selective response of GO/CuO modified pores towards Cu²⁺ ions was notably observed through ion transportation (I –V) studies, surpassing the response of unmodified nanopores and those modified with CuO alone. This selective behavior was demonstrated in the presence of various monovalent and divalent competing ions. Quantitative assessment of I –V studies was conducted by evaluating the intrinsic rectification ratio of asymmetric nanopores, providing a robust measure of platform's efficacy. Furthermore, we identified the optimal pH for detecting Cu²⁺ ions as 7, enhancing the specificity and accuracy of our method.