A disposable electrochemical sensor for amyloid-β42 protein based on molecular imprinted polymers with nitrogen doped carbon dots-graphene nanohybrid

Abstract

This work presented a molecularly imprinted polymer (MIP) electrochemical sensor for determination of amyloid-β42 (Aβ42) as an Alzheimer’s disease (AD) biomarker. A nitrogen-doped carbon-dot-graphene (NCD-G) nanohybrid was synthesized through a simple ultrasonic method. Polypyrrole (PPY) was used as an imprinted polymer with an Aβ42 template for the electropolymerization process. The NCD-G and MIP were modified on a screen-printed carbon electrode (SPCE) without binding agent. The morphology and electrochemical properties of MIP/NCD-G modified SPCE were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and square wave voltammetry (SWV). The developed sensor exhibited good linear response in a range from 5 to 70 pg/mL with a limit of detection (LOD) of 1 pg/mL under optimal conditions. This sensor shows excellent performance due to the enhancement of effective surface area, electrical conductivity, and electrocatalytic activity. This MIP sensor takes advantage of molecularly imprinted technique combined with nanohybrid to achieve high selectivity and sensitivity. Moreover, it possessed good reproducibility and miniaturization that could be applied as a platform for portable devices in healthcare in the future. This work provides the combination of a zero-dimensional and two-dimensional materials, nitrogen doped carbon dots-graphene nanohybrid (NCD-G) by self-assembly through a simple ultrasonication method and applied as a molecularly imprinted polymer (MIP) sensor for determination of amyloid-β42 protein. We propose a minimum number of preparation steps which NCD-G could enhance the MIP sensor performance, owing to the synergistic effects with high selectivity and sensitivity. The hybrid formation of the carbon dots with graphene using their π-π interactions in carbon nanostructures. NCD-G nanohybrid and MIP modified on screen printed carbon electrode (SPCE) for the determination of amyloid-β42 have not been previously investigated. Moreover, this disposable strip is a single-use tool that might be essential for on-site devices.