Enhancement of Electrochemical Properties Using Iron Oxide-Gold Nanocomposite for Tuberculosis Detection Based on rGO-APTES Modified Screen-Printed Electrode

A new electrochemical immunosensor based on iron oxide-gold nanocomposite (Fe
₃
O
₄
-Au NC) as signal enhancement was developed for sensitive detection of
M. tuberculosis
, the causative agent of tuberculosis (TB). Reduced graphene oxide-(3-aminopropyl)-triethoxysilane (rGO-APTES) modified screen-printed electrode (SPE) was employed as a matrix to immobilize the capture antibodies (Ab). The detection signal was amplified due to the large amounts of Ab captured on the large surface area of modified SPE. The Fe
₃
O
₄
-Au NC were functionalized as label to conjugate with primary antibodies (Ab
₁
). Due to the homogeneity and narrow size distribution of Fe
₃
O
₄
-Au NC, several Ab
₁
were bound on each nanocomposite. The introduction of Fe
₃
O
₄
-Au-Ab
₁
onto the electrode surface through sandwich immunoreactions enhances the performance of the sensor. The proposed immunosensor offered a sensitive detection of TB in the range of 0–
$9.0~\mu \text{g}$
/mL, with a detection limit of 1.32 ng/mL. A disposable and sensitive SPE-based electrochemical immunoassay would serve as a promising platform to detect various mycobacterium pathogens for future diagnostic studies.