The Capability of Silver Nanoparticles Modified 4-Amino-3-hydrazino-5-mercapto-1,2,4-triazole for Early Detection of Cortisol as a Stroke Biomarker

Silver nanoparticles modified with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AgNPs-AHMT) have been developed as colorimetric sensors for cortisol detection as a stroke biomarker. This method’s principle was based on AgNPs-AHMT aggregation with cortisol due to the hydrogen bonding interaction between the surfaces of AHMT and cortisol. This process caused the color change that can be seen with the naked eye. Then, it is confirmed by ultraviolet-visible (UV-Vis) spectroscopy, particle size analyzer (PSA), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The color of colloidal AgNPs-AHMT changed from yellow to brownish orange, giving a red shift in the localized surface plasmon resonance (LSPR) peak. The quantitative monitor for cortisol determination had good linearity in the range of cortisol concentrations of 1.0–50.0 nM, with a limit of detection (LOD) and a limit of quantification (LOQ) of 0.719 nM and 2.37 nM, respectively. The relative standard deviations (RSD %) for intra-day and inter-day were <3.2 % and <2.26 %, respectively. Moreover, this method was applied for cortisol detection in a saliva sample. So, the simple, rapid, and real-time strategy exhibited a promising potential for cortisol detection in a saliva sample.