The sensitive cortisol
detection by an electrochemical
sensor based
on silver nanoparticle-doped molecularly imprinted polymer was successfully
improved. This study describes the method development for cortisol
detection in both aqueous solution and biological samples using molecularly
imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-histidine methyl ester)-coated pencil graphite electrodes
modified with silver nanoparticles (AgNPs) by differential pulse voltammetry
(DPV). The cortisol-imprinted pencil graphite electrode (PGE) has
a large surface area because of doped AgNPs with enhanced electroactivity.
The prepared molecularly imprinted polymer was characterized by scanning
electron microscopy. The DPV response of the synthesized electrode
with outstanding electrical conductivity was clarified. Cortisol-imprinted
polymer-coated PGEs (MIP), cortisol-imprinted polymer-coated PGEs
with AgNPs (MIP@AgNPs), and nonimprinted polymer-coated PGEs with
AgNPs (NIP@AgNPs) were evaluated for sensitive and selective detection
of cortisol in aqueous solution. Five different cortisol concentrations
(0.395, 0.791, 1.32, 2.64, and 3.96 nM) were applied to the MIP@AgNPs,
and signal responses were detected by the DPV with a regression coefficient
(R
2) value of 0.9951. The modified electrode
showed good electrocatalytic activity toward cortisol for the linear
concentration range from 0.395 to 3.96 nM, and a low limit of detection
was recorded as 0.214 nM. The results indicate that the MIP@AgNPs
sensor has great potential for sensitive and selective cortisol determination
in biological samples.