Electrochemical enhancement using iron oxide-gold nanocomposite for detection of tuberculosis based on rGO-APTES modified screen printed electrode
A new electrochemical immunosensor based on Fe3O4-Au nanocomposite (NC) as signal enhancement was proposed for the detection of Mycobacterium Tuberculosis ESAT-6-like protein EsxB. In this study, Fe3O4-Au NC was synthesis via coprecipitation method and size of NC was viewed under high resolution...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/90513/1/FS%202019%2079%20-%20IR.pdf |
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| Summary: | A new electrochemical immunosensor based on Fe3O4-Au nanocomposite (NC) as
signal enhancement was proposed for the detection of Mycobacterium Tuberculosis
ESAT-6-like protein EsxB. In this study, Fe3O4-Au NC was synthesis via coprecipitation
method and size of NC was viewed under high resolution transmission
electron microscopy (HRTEM) with average diameter of 1.629-1.915 nm. Meanwhile,
X-ray diffraction (XRD) analysis confirmed that Fe3O4-Au NC exhibited all possible
peaks of Fe3O4 and new peaks at 38.37° (111) and 44.63° (200) are belongs to crystal
plane of metallic gold. Additionally, UV-Vis absorption study shows peak at 545 nm
was appeared indicating that Au shell was successfully coated on Fe3O4 NC.
Characterization by FTIR demonstrated that the peak at 1670 cm-1 assigned to C=O
group and peak at 3280 cm-1 indicated O-H group. The peak at 710 cm-1 represented CS
stretching. The IR spectra confirms successful functionalization of the Fe3O4-Au NC
with ME-MDDA linker. In this study, rGO-APTES have been used to modify screen
printed electrode (SPE) to serve as immobilization matrix for immunoassay interaction.
The result from RAMAN spectroscopy, Field Emission Scanning Electron Microscope
(FE-SEM) and Energy Dispersive X-ray Spectroscopy (EDX) confirmed rGO-APTES
modified SPE successfully reduced. Additionally, the morphology of rGO-APTES
modified SPE also revealed smoother surface and ready for immobilization of capture
antibody (Ab). The effective surface area value of rGO-APTES modified SPE also has
increase about 20 times larger compared to bare SPE of based on cyclic voltammetry
(CV) studies. Moreover, the ratio of Ipc/Ipa = 0.9867 showed electron transfer process
is towards reversible kinetics. The rGO-APTES modified SPE was further explored as
immunoassays matrix for Ab1 tagged with Fe3O4-Au NC (Ab1- Fe3O4-Au) and further
interact with Mycobacterium Tuberculosis ESAT-6-like protein EsxB were monitored
by differential pulse voltammetry (DPV) technique using 0.1 M PBS as electrolyte. As
a result, the decreased of peak current of Ab from 3.996 μA to 3.863 μA occurs after
immobilization on rGO-APTES modified SPE confirmed that electron transfer
resistance increased. At optimal condition, the DPV was studied in different concentration of Mycobacterium Tuberculosis ESAT-6-like protein EsxB. The DPV
current of immunosensor electrode increased as the Mycobacterium Tuberculosis
ESAT-6-like protein EsxB increased. In this study, the lowest TB concentration that
could be determined statistical by resulting immunosensor was calculated as 1.32
ng/mL. The Relative Standard Deviation (RSD) of the measurements for five
electrodes was 6.4% suggesting the precision and reproducibility of the immunosensor
was quite good. |
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