Ultrasensitive SERS Nanoprobe Sandwich Immunoassay for Quantitative Detection of Alzheimer’s Disease Plasma Biomarkers

Abstract

It is required to develop a sensitive and accurate sensing platform that can quantify amounts of amyloid-beta peptides (Aβ40 and Aβ42) in blood for non-invasive and cost-effective diagnosis of Alzheimer’s disease (AD). Herein, a SERS nanoprobes-based sandwich immunoassay has been developed for the non-invasive, sensitive, and multiplexed detection of Aβ40 and Aβ42 from clinical plasma samples for AD diagnosis. The AgNGS SERS nanoprobes were synthesized through a rapid single-step reaction, and they exhibited their unique and strong SERS signals with a huge signal enhancement of 10 7 and long-term stability. The AgNGS SERS nanoprobes conjugated with an antibody specific to Aβ40 or Aβ42 can detect the corresponding Aβ biomarkers from human plasma samples based on their strong SERS signals. The SERS nanoprobes-based sandwich immunoassay was able to detect Aβ40 and Aβ42 at concentrations as low as 0.25 and 0.33 pg/mL, respectively, in a simple and rapid manner from plasma samples.