A Wearable Copper Ion Detection Sensor Enabled by Graphene Quantum Dot-Modified Vertical Aligned Carbon Nanotube Array for Potential Alzheimer’s Disease Screening

With increasing severity of population aging, the incidence of Alzheimer’s disease (AD) is on the rise, significantly impacting the quality of life and safety of individuals. AD is characterized by multiple interrelated pathological factors, among which the accumulation of copper ions (Cu²⁺) not only accelerates the aggregation of amyloid-β peptides (Aβ), but also generates reactive oxygen species through the Fenton Reaction, leading to oxidative damage in neurons. Currently, monitoring copper ion concentrations suffers from complex processes and insufficient detection limits. In this work, we propose a novel wearable Cu²⁺ detection sensor (WCDS) based on graphene quantum dots (GQDs) integrated with a vertical carbon nanotube array (VACNT). By modification of the three-dimensional VACNT array with large specific surface area GQDs, high-precision detection of Cu²⁺ has been achieved. The WCDS demonstrates an effective linear sensing range from 100 fM to 10 nM, with a detection limit as low as 16.9 fM. The simplicity of the preparation process, along with low detection limit and great stability, positions this WCDS as a promising solution for large-scale and high-precision copper ion detection in the population. This capability provides new possibilities for early screening and monitoring the progression of Alzheimer’s disease.