Development of a high sensitivity fluorescence immunoassay for Amyloid Beta 42 by a silicon microarray platform

M. Cretich, P. Gagni, L. Sola, M. Chiari
Consiglio Nazionale delle Ricerche, IT

Keywords: silicon, microarrays, Alzheimer’s disease, polymer coating


Alzheimer’s disease (AD) affects millions of people around the world with rising incidence as population age. Here we present the use of a label/label free silicon/silicon oxide (Si/SiO2) based microarray platform to develop a highly sensitive immunoassay for Aβ42, a biomarker to diagnose AD in non-demented subjects. By varying the thickness of SiO2, it is possible to enhance the emission of any fluorophore of choice by constructive interference with significant improvements in detection sensitivity and to employ the Interferometric Reflectance Imaging Sensor (IRIS), a platform amenable to high-throughput screening for label free multiplexed detection. Silicon technology and tuned modulation of the oxide layer facilitate dual detection of label-based and label-free detection schemes on a single chip. Silicon chips have been coated by copoly(DMA-NAS-MAPS), a ter-copolymer that is the result of an optimized composition of DMA, 3-(trimethoxysilyl)propyl methacrylate (MAPS) and NAS. An optimal antibody pair has been selected based on specificity of recognition and optimal binding yeald on the coated silicon surface studied by the IRIS interferometric platform. Finally, incubation conditions were optimized and the unprecedented limit of detection for Aβ42 of 73 pg/mL in artificial CSF was achieved.