g-C3N4-heme bound to amyloid β peptides: In-situ generation of the secondary co-reactant for dual-enhanced electrochemiluminescence assay of amyloid β detection.

Heme binds to amyloid β -peptide (A β) in the brain of Alzheimer΄s disease (AD) patients, thus forming heme-A β complexes and leading the characteristic pathological features of AD. The heme-A β complexes reduce O 2 by 2e− to obtain co-reactant H 2 O 2. In this work, two-dimensional graphite-like carbon nitride (g-C 3 N 4) was hybridized with heme via π-π interaction to construct an electrochemiluminescence (ECL) biosensor for detection of A β peptides. The capture aptamer was firstly immobilized on the gold electrode, and then incubated with target A β peptides and g-C 3 N 4 -heme. The g-C 3 N 4 -heme-A β composite was subsequently anchored on the electrode and showed a signal-on, label-free ECL emission based on dual co-reactants enhancement attributed to in-situ generated H 2 O 2 and original K 2 S 2 O 8 in PBS buffer. Under the optimum experimental conditions, the ECL biosensor has a sensitive response to A β peptides with a linear range of 10 fM-0.1 μM and a detection limit of 3.25 fM. Considering prominent specificity, reproducibility, and stability, the proposed biosensor was used to assess recovery of A β peptides in human serum and the result was satisfactory. We believe that the established method would offer a useful analytical means for quantifying A β peptides in a biological matrix. [ABSTRACT FROM AUTHOR]