Mn-doped dual-emission CdZnSe/Mn:ZnS quantum dots for self-calibrated ratiometric sensing of Alzheimer's disease biomarker.

Abstract

BACKGROUND: Accurate detection of Alzheimer's disease (AD) biomarkers is critical for early identification, precise diagnosis, and timely therapeutic intervention. Nevertheless, conventional detection techniques rely on single-signal readout, which is susceptible to environmental interference and yields unreliable results in complex biological matrices. Therefore, developing reliable, sensitive and selective sensing platforms for AD biomarkers are highly desirable. RESULTS: Herein, a self-calibrated ratiometric fluorescence aptasensor based on Mn-doped dual-emission CdZnSe/Mn:ZnS quantum dots (QDs) is constructed for detecting AD biomarker amyloid-β oligomers (AβO). Possessing two characteristic fluorescence peaks at 425 nm and 628 nm, CdZnSe/Mn:ZnS QDs act as dual self-calibrating references. CdZnSe/Mn:ZnS QDs and Ag NPs are modified at two termini of hairpin H1 (CdZnSe/Mn:ZnS QDs-H1-Ag NPs), quenching the 425 nm fluorescence (FL425 off and FL628 on). Upon AβO recognition, aptamer-functionalized magnetic beads convert AβO into released DNA strands (S). These S strands react with CdZnSe/Mn:ZnS QDs-H1-Ag NPs and black hole quencher 3-labeled H2 (H2-BHQ3) to trigger catalytic hairpin assembly (CHA) for signal amplification, quenching Mn-doped FL628 while restoring core FL425 and yielding an AβO-dependent FL425/FL628 ratiometric response. The aptasensor achieves a 5.2 fM detection limit and effectively distinguishes AD patients from healthy subjects, with results well consistent with standard diagnostic methods. SIGNIFICANCE: This study demonstrates the great potential of intrinsic dual-emission Mn-doped QDs for self-calibrated ratiometric biosensing. By integrating magnetic beads-mediated signal transduction and CHA amplification, the aptasensor achieves high sensitivity and robust anti-interference performance toward AβO in clinical samples, providing a reliable analytical tool for early auxiliary diagnosis of AD.

Abstract as supplied by the indexing source. © the authors / publisher.