A highly sensitive resonance light scattering probe for Alzheimer׳s amyloid-β peptide based on Fe3O4@Au composites

The fabrication of Fe3O4@Au composites as a novel resonance light scattering (RLS) probe for the sensitive detection of Alzheimer׳s amyloid-β peptide (Aβ) was demonstrated. Amino groups coated magnetic Fe3O4 nanoparticles were covered with gold shell by the classical Frens method. The resultant colloids were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS) and UV-visible spectra. The results indicated that the composite particles with core/shell structure and an average diameter of ~320 nm were stable and biocompatible. The RLS intensity of Fe3O4@Au composites was significantly enhanced by interacting with Aβ. Under optimal conditions, good linear relationship between the ratio of RLS intensity I/I0 at 463.0 nm and the logarithmic value of Aβ concentration in the range of 5.0×10-15-5.56×10−9 M was found. The limit of detection (LOD) was 1.2×10−15 M. The proposed method is simple, sensitive and cost-effective and complementary to other existing methods for protein analysis.