Ultrasonic-driven chemical reduction synthesis of alizarin complexone-modified gold nanoparticles for dual-signal colorimetric and fluorometric sensing of histamine in seafood products.

Alizarin complexone-modified gold nanoparticles (Au-NPs) were synthesized using a proposed ultrasonic irradiation-assisted chemical reduction method. Ultrasonic irradiation powers, reaction time and alizarin complexone concentration had been proven to be the main parameters for controlling the nucleation and growth of Au-NPs. In the synthesized ultrasonic irradiation-assisted chemical reduction conditions, Au-NPs had a spherical oriented morphology with a uniform size of 17.84 ± 1.37 nm and are shiny red with a surface plasmon resonance (SPR) of 535 nm. A rapid colorimetric and fluorometric dual-mode detection strategy for selective detection of histamine in seafood was developed based on the self-assembly of Au-NPs-Ni (II) complexes. Ni (II) can capture the histamine molecules close to Au-NPs surfaces, making changes in the colorimetric and fluorometric responses of the solution. The quantitative analysis of histamine was realized through the variation of dual-signal colorimetric and fluorometric responses. Such Au-NPs sensor offered good detection sensitivity for histamine with a detection limit (LOD) of 59.32 μmol L and 116.20 μmol L and wide linear response within the range of 10-10000 μmol L (R = 0.9952) and 100-5000 μmol L (R = 0.9947) for colorimetric and fluorometric measurement, respectively. Recoveries ranging from 94.99 to 103.29 % and 97.67-106.88 % for colorimetric and fluorometric assay were obtained, showing low levels of matrix effects. Particularly, the results of the dual-mode sensor were also validated by comparing with the HPLC method for improving the assay accuracy and dependability. Ultimately, the developed Au-NPs colorimetric and fluorometric probe performs excellently in practical applications, with promising results for detecting histamine in seafood products.