Paper-based colorimetric sensor for histamine detection using dopamine-functionalized, size-varied gold nanoparticles.

Histamine, a prominent biogenic amine (BA), is commonly associated with allergic reactions and is a key culprit in foodborne illnesses stemming from spoiled food consumption. The detection of histamine is paramount for meeting food safety standards and ensuring quality control. In this study, an innovative method employing the direct integration of dopamine onto citrate-reduced gold nanoparticles (DCt-AuNPs) embedded within filter paper to create a paper-based colorimetric sensor for histamine detection was developed. Various sizes of DCt-AuNPs (13, 15, 27, and 39 nm) were synthesized, and their dimensions were controlled by adjusting the precursor molar ratio (MR). This adjustment led to size variations, influencing the localized surface plasmon resonance (LSPR) peaks (518, 520, 526, and 530 nm) and resulting in distinct optical properties. The interaction between these nanoparticles and histamine concentrations (ranging from 1 ppm to 100 ppm) was monitored by observing changes in the LSPR absorbance spectra and color. Histamine induced DCt-AuNP aggregation through interactions of its amino and imidazole groups via ligand exchange and interparticle crosslinking, thereby changing the solution color from red to blue. The size variance of DCt-AuNPs significantly impacted the colorimetric response to histamine. Among the sizes tested, the 15 nm DCt-AuNP paper sensor exhibited the lowest detection limit of 2.38 µM and a linear detection range of 20-70 ppm. Remarkably, this sensor boasted rapid detection, clocking in under 1 min, coupled with exceptional selectivity toward histamine analytes, highlighting its potential for real-world applications.