A sensitive gold nanoparticle-based aptasensor for colorimetric detection of A beta(1)-40 oligomers

摘要

In this work, a gold nanoparticle-based label-free homogeneous phase colorimetric bioassay was developed for the detection of A beta(1-40) oligomers (A beta O), important biomarkers for diagnosis and monitoring progression of Alzheimer's disease (AD). The prepared A beta O-aptamer decorated AuNPs tended to aggregate in a solution with high concentrations of salt, and displayed a purple color with a maximum absorption peak at 650 nm, a characteristic absorption of aggregated AuNPs. In the presence of A beta O, the specific binding of the target with the aptamer generated folded aptamer structures, which can stabilize AuNPs towards the salt-induced aggregation more effectively than AuNPs stabilized by the aptamer alone, and thus achieved a hypsochromic shift in the absorption spectra. On the basis of this sensitive spectral transformation, the proposed aptasensor was successfully applied for the detection of A beta O with a dynamic range of 1-600 nM and a low detection limit of 0.56 nM. The reliability and practicality of this aptasensor was demonstrated by analysis of A beta O in artificial cerebrospinal fluid (aCSF). We anticipate that the proposed facile colorimetric assay for A beta O will provide applicable information for early diagnosis of AD.