Design of gold nanoparticle based colorimetric sensor for detection of biogenic amines in micelles with improved sensitivity

A rapid, highly sensitive colorimetric nanosensor based on citrate-capped gold nanoparticles (Cit-AuNPs) is presented for screening total biogenic amines (TBAs) as a practical indicator of food quality and safety. Individual BAs like putrescine (PUT), histamine (HTM), spermine (SPM), and spermidine (SPD) were first investigated in aqueous and micellar media to elucidate the sensing mechanism, evaluate sensitivity, optimization of parameters and confirm uniform optical responses. Electrostatic and hydrogen-bonding interactions between the amines and Cit-AuNPs induce nanoparticle aggregation, triggering a distinct color change from burgundy red to dark grey accompanied by a surface plasmon resonance shift from 520 to 700 nm. The nanosensor was comprehensively characterized by UV–Vis spectroscopy, FTIR, SEM-EDX, dynamic light scattering, and zeta potential, validating surface chemistry, size, morphology, and colloidal stability. Detection limits of 0.842–2.018 μg/mL in aqueous medium were enhanced nearly tenfold (0.008–0.067 μg/mL) in a micellar environment. The method was applied to Labeo rohita fish muscle, TBAs (as HTM equivalents) ranging from 141.99 to 654.33 mg/kg, with excellent precision (RSD <0.1%) were calculated. Further the method's practical applicability was confirmed using HTM spiked samples, which demonstrated high accuracy and precision with recoveries of 96.26–101.65%, low standard deviations (0.002–0.006 mg/kg), and %RSD below 0.4%, highlighting the sensor as a fast, reliable, and cost-effective tool for food freshness and safety screening .