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

•Highly sensitive biosensor for detection of amyloid beta (1-42) (Aβ1-42) was fabricated.•Visible light was utilized as light source in the detection system.•The sensor was able to detect trace amount of Aβ1-42 as small as 1 pg/ml.•Aβ1-42 was successfully detected in a diluted cerebrospinal fluid In this study, we fabricated sensors to detect Alzheimer’s disease (AD) biomarkers – amyloid beta (1-42) (Aβ1-42) 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-Aβ1-42) 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 Aβ1-42 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.