title: Visual and fluorescent assays for selective detection of beta-amyloid oligomers based on the inner filter effect of gold nanoparticles on the fluorescence of CdTe quantum dots.
abstract: Beta-amyloid (Aβ) peptides are the major constituents of senile plaques in the brains of Alzheimer's disease (AD) patients. Aβ monomers (AβMs) can coalesce to form small, soluble oligomers (AβOs), followed by reorganization and assembly into long, thread-like fibrils (AβFs). Recently, soluble AβOs have been regarded as reliable molecular biomarkers for the diagnosis of AD because of their high toxicity for neuronal synapse and high concentration levels in the brains of AD patients. In this work, we reported a label-free, sensitive and selective method for visual and fluorescent detection of AβOs based on the inner filter effect (IFE) of gold nanoparticles (AuNPs) on the fluorescence of CdTe quantum dots (QDs). Specifically, the fluorescence of CdTe QDs was quenched significantly by AuNPs through the IFE. PrP(95-110), an AβOs-specific binding peptide from cellular prion protein, triggered the aggregation and color change of AuNPs suspension; thus, the IFE of AuNPs on the fluorescence of CdTe QDs was weakened and the fluorescence intensity was recovered. However, in the presence of AβOs, the specific interaction of AβOs and PrP(95-110) prevented the absorption of PrP(95-110) onto the surface of AuNPs. As a result, the aggregation of AuNPs was inhibited and the fluorescence intensity of CdTe QDs was quenched again. This label-free method is specific for detection of AβOs but not for AβMs and AβFs. The detection limits were found to be 0.5nM for the visual assay and 0.2nM for the fluorescent detection. We believe that this work would be valuable for many investigations related to AD diagnosis and drug discovery.
authors.affiliation: Key Laboratory of New Optoelectronic Functional Materials (Henan Province), College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, People's Republic of China.
authors.forename: Ning
authors.initials: N
authors.lastname: Xia
authors.affiliation: Key Laboratory of New Optoelectronic Functional Materials (Henan Province), College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, People's Republic of China.
authors.forename: Binbin
authors.initials: B
authors.lastname: Zhou
authors.affiliation: Key Laboratory of New Optoelectronic Functional Materials (Henan Province), College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, People's Republic of China.
authors.forename: Nanbing
authors.initials: N
authors.lastname: Huang
authors.affiliation: Key Laboratory of New Optoelectronic Functional Materials (Henan Province), College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, People's Republic of China.
authors.forename: Mengsha
authors.initials: M
authors.lastname: Jiang
authors.affiliation: Key Laboratory of New Optoelectronic Functional Materials (Henan Province), College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, People's Republic of China.
authors.forename: Jiebing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of New Optoelectronic Functional Materials (Henan Province), College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, People's Republic of China. Electronic address: liulin@aynu.edu.cn.
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
mesh_terms: D000544:Alzheimer Disease / Q000175:diagnosis; D016229:Amyloid beta-Peptides / Q000032:analysis*; D015374:Biosensing Techniques / Q000379:methods; D019187:Cadmium Compounds / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D010446:Peptide Fragments / Q000032:analysis*; D045663:Quantum Dots / Q000737:chemistry; D012995:Solubility; D013050:Spectrometry, Fluorescence / Q000379:methods; D013691:Tellurium / Q000737:chemistry*
chemical_list: D016229:Amyloid beta-Peptides; D019187:Cadmium Compounds; D005456:Fluorescent Dyes; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D006046:Gold; D013691:Tellurium; C028337:cadmium telluride
keywords: Beta-amyloid; Fluorescent biosensor; Gold nanoparticles; Inner filter effect; Quantum dots; Visual assay