Optimization of CNT growth-upheaved nanofilm for highly sensitive fluorescent detection of Alzheimer's disease

Alzheimer's disease (AD) is a complex neurological disease that results from the excessive accumulation of insoluble protein plaques—such as amyloid-beta, tau protein, and beta-amyloid precursor protein—in the brain. Cerebrospinal fluid (CSF) biomarkers are known to have high accuracy for the early diagnosis of AD. In this study, we developed a large-area fluorescent biosensor using a rough nanofilm upheaved by carbon nanotube (CNT) growth, then investigated its performance in the detection of AD biomarkers in both artificial CSF and monkey CSF. The results showed that the proposed fabrication process enabled optimization of the nanofilm surface roughness in a 2.5 mm × 2.5 mm sensing area for better sensitivity in the identification of biomarkers. CNTs grown for 10 min produced the best surface area, roughness, and hardness in the upheaved nanofilm. Plasma treatment on the nanofilm was confirmed to maximize the adsorption of AD biomarkers. Fluorescence detection over a large area was also possible with high sensitivity (up to 0.1 fM) for the detection of AD biomarkers in both artificial CSF and monkey CSF. Altogether, these results show the great potential of CNT growth-upheaved nanofilm for use in rapid large-area sensing platforms for clinical applications.