We report a new ready-to-use sensor for simultaneous determination of paraquat (PQ) and glyphosate (GLY) based on a graphite screen-printed electrode modified with a dual-molecularly imprinted polymer coated on a mesoporous silica-platinum core.
Nanoscale imprinting significantly increases the specific
surface
area and recognition capabilities of a molecularly imprinted polymer
by improving accessibility to analytes, binding kinetics, and template
removal. Herein, we present a novel synthetic route for a dual molecularly
imprinted polymer (dual-MIP) of the carcinogen oxidative stress biomarkers
3-nitrotyrosine (3-NT) and 4-nitroquinolin-N-oxide (4-NQO) as coatings
on graphene quantum-dot capped gold nanoparticles (GQDs-AuNPs). The
dual-MIP was successfully coated on the GQDs-AuNPs core via a (3-mercaptopropyl)
trimethoxysilane (MPTMS) linkage and copolymerization with the 3-aminopropyltriethoxysilane
(APTMS) functional monomer. In addition, we fabricated a facile and
compact three-dimensional electrochemical paper-based analytical device
(3D-ePAD) for the simultaneous determination of the dual biomarkers
using a GQDs-AuNPs@dual-MIP-modified graphene electrode (GQDs-AuNPs@dual-MIP/SPGE).
The developed dual-MIP device provides greatly enhanced electrochemical
signal amplification due to the improved electrode-specific surface
area, electrocatalytic activity, and the inclusion of large numbers
of dual-imprinted sites for 3-NT and 4-NQO detection. Quantitative
analysis used square wave voltammetry, with an oxidation current appearing
at −0.10 V for 4-NQO and +0.78 V for 3-NT. The dual-MIP sensor
revealed excellent linear dynamic ranges of 0.01 to 500 μM for
3-NT and 0.005 to 250 μM for 4-NQO, with detection limits in
nanomolar levels for both biomarkers. Furthermore, the dual-MIP sensor
for the simultaneous determination of 3-NT and 4-NQO provides high
accuracy and precision, with no evidence of interference from urine,
serum, or whole blood samples.
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