Colorimetric sensors based on silver nanoparticles (AgNPs) have attracted significant interest across various fields due to their unique properties and diverse applications. However, AgNPs can face challenges in terms of stability under certain chemical or environmental conditions, which may affect their performance as colorimetric sensors. In contrast, Ag@Ag₂O nanostructures offer superior stability and the ability to control particle size, making them the preferred choice for specific applications that require enhanced stability and reliable performance over time. This study presents a one-pot biosynthesis of Ag@Ag₂O nanostructures using banana peel extract, followed by surface modification with methionine (Ag@Ag₂O-Met). The surface modification of Ag@Ag₂O nanoparticles using methionine improved its stability, enhanced sensitivity and selectivity of determination. The morphology of the hybrid nanostructure was investigated using XRD, FESEM, FTIR, TEM, and AFM techniques. To the best of our knowledge, no previous studies have reported the determination of uric acid (UA) and epinephrine (EP) using colorimetric sensing method approach. Developing sensitive and selective methods for the determination of EP in the presence of UA, with low limits of detection and high accuracy and precision, has been a significant challenge. The fabricated Ag@Ag₂O-Met nanocomposite was employed for the colorimetric detection of UA and EP. The experimental parameters were investigated and optimized. The method provided linear dynamic ranges of ????? μM and ???? μM for UA and EP, respectively, with detection limits of ??? μM for UA and ?? μM for EP. The findings demonstrate that this approach offers a broad linear range and lower detection limits, making it suitable for the determination of these analytes in various biological samples.
