Plasmonic Silver Nanoparticle-Amplified Green Spectrofluorometry for Trace Quantification of Doxycycline with Enhanced Sensitivity and Detection Limits

A rapid, simple, and highly sensitive spectrofluorometric approach was developed for the quantification of doxycycline (DOX) in methanol based on the fluorescence enhancement produced by silver nanoparticles (AgNPs). The proposed method exploits the interaction of doxycycline with the prepared AgNPs, resulting in a significant increase in the fluorescence intensity and consequently improving the analytical response. Therefore, under optimized experimental conditions, fluorescence emission was measured at 506 nm after excitation at 376 nm; the method exhibited linearity in the range of 25–1000 ng/ml and demonstrated detection and quantification limits of 8 and 25 ng/mL, respectively. The developed procedure was applied to the determination of doxycycline in commercial vibramycin capsules obtained from a local pharmacy. Validation was carried out in accordance with International Council for Harmonisation (ICH) guidelines, ensuring the method’s accuracy, precision, and robustness.