Biosensor Based on ds-DNA-Decorated Fe2O3/SnO2-Chitosan Modified Multiwalled Carbon Nanotubes for Biodetection of Doxorubicin

In this paper, the Fe
₂
O
₃
/SnO
₂
nanocomposite has been prepared by a solid-phase method in an alkaline medium. The Fe
₂
O
₃
/SnO
₂
composite was characterized by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. A sensitive electrochemical biosensor is also presented for the determination of doxorubicin (DOX) based on a ds-DNA-decorated multiwalled carbon nanotubes-Fe
₂
O
₃
/SnO
₂
-chitosan (ds-DNA-MWNTs-Fe
₂
O
₃
/SnO
₂
CHIT) modified pencil electrode. DOX has shown an oxidation peak at 0.34 V on the surface of the bare pencil graphite electrode (PGE) in pH 7.0. The presence of DNA results in a decrease in the current; moreover, a positive shift in the DOX oxidation peak indicates an intercalative interaction. Finally, a PGE modified with ds-DNA-MWNTs-Fe
₂
O
₃
/SnO
₂
CHIT was tested in order to determine the DOX content in the solution. The dynamic range was from 20.0 to 5552.0 nmol L
^-1
with a detection limit of 0.004 nmol L
^-1
. This sensing platform showed other advantages such as simplicity, good stability, and high sensitivity.