Amperometric immunosensor based on the conducting layer of PAni/Fe3 O4 nanocomposites for the detection of Aβ42

Abstract

Conducting PAni/Fe3
O4
 nanocomposites were synthesized and electrochemically deposited 
on fluorine-tin-oxide (FTO)-coated glass to form a transducing layer owing to their catalytic, 
magnetic, and electrical properties. This synthesized conducting layer was used to immobi
lized anti-β42
 for the detection of Alzheimer’s disease. The electrode modification process was characterized by electrochemical impedance spectroscopy, cyclic voltammetry, and 
field emission scanning electron microscopy. Some factors influencing the performance 
of the amperometric immunosensor were optimized. The experiment outcome indicates 
a conducting layer of the nanocomposites on the FTO-coated glass in the range of −1.5 to 
0.5 V at 0.10 Vs−1 in a 10 ml solution of PAni-Fe3
O4
 nanocomposites. Electrochemical imped
ance changes occurred only after PAni/Fe3
O4
 bound to surface of bare FTO, confirming the 
deposition and indicating that the new modified electrode can be used as a transducing 
matrix for the immobilization of the biomarker. Tests performed with this immunosensor 
showed good linearity with a detection limit of 0.061 µg/ml−1 at 3σ.