High Performance Detection of Alzheimer's Disease Biomarkers Based on Localized Surface Plasmon Resonance

In this study, we fabricated sensors to detect Alzheimer's disease (AD) biomarkers – amyloid beta (1-42) (Aβ_1-42) based on localized surface plasmon resonance (LSPR). The sensors were consisted of ligand-exchanged gold nanoparticles (Au NPs) deposited on polyethylene terephthalate substrate using Langmuir-Blodgett (LB) technique. Monoclonal antibodies (anti-Aβ_1-42) were then immobilized as a conjugate form with biotin onto the LB films of ligand-exchanged Au NPs by the aid of streptavidin. The attachment of the biomarkers to the antibodies immobilized on the LB films was detected by measuring absorbance change of plasmonic response peak. The sensor structure was optimized by comparing the results for the Au NPs LB films with different size and film thickness. The optimized sensor was used to detect biomarker at different concentrations in the buffer solution and a diluted cerebrospinal fluid (CSF) solution. As results, the sensor was able to detect even a trace amount of Aβ_1-42 as small as 1 pg/ml from the CSF. This prototype sensor has a great potential because it shows several advantages of facile and inexpensive fabrication, and early detection of the AD.