Development of Chemically Signal Amplified Nano-Biosensor Mediated by Poly-L-Lysine

Amyloid β (Aβ) is considered to be one of a potential biomarker to monitor Alzheimer's Disease (AD) not only for diagnostic purposes but for early detection. Here we describe a novel nano-biosensor for Aβ mediated by poly-L-lysine (PLL) which was used for the amplification of detection signal for Aβ. The indirect enzyme-linked immunosorbent assay (ELISA) method was modified using PLL for the amplification of the Aβ detection signal. A commercially available ELISA plate was modified by PLL using chemical agent and the amplified amino groups were activated by a chemical agent for the detection of Aβ. The detection was carried out by the traditional immunochemistry using primary antibody and fluorescence molecules conjugated secondary antibody. In the result, the fluorescence intensity was increased by the increasing treated Aβ amount, and the sensitivity was approximately 2 times higher in the concentration of 2 ng/mL Aβ treatment, and approximately 4 times higher in the concentration of 200 ng/mL Aβ treatment compare with that of indirect ELISA detection method. We suggest our novel signal amplification method for the Aβ early detection.