A two-site chemical recognition test strip for colorimetric detection of histamine based on polydopamine coated gold nanoparticles

Histamine (HA) is a biogenic amine formed during the metabolism of microorganisms, excessive intake of which can cause headache, diarrhea, and, in severe cases, food poisoning. The commonly used instrumental detection methods are expensive and time-consuming, making it challenging to realize on-site inspection. In this work, we reported a colorimetric test strip-based detection method for HA by chemical recognition of the amine and imidazole groups of HA. Polydopamine-coated gold nanoparticles that were modified with carboxyl group-terminated polyethylene glycol (Au@PDA-C NPs) were utilized as labels to capture HA through the NHS/EDC reaction between HA and the carboxyl group of the Au@PDA-C NPs. The chelate from nitrilotriacetic acid (NTA) and Cu²⁺ at the T-line could then specifically bind the imidazole moiety of HA in the complex of HA and Au@PDA-C NPs, enabling the T-line to present the colorimetric characteristics of Au@PDA-C NPs. The gray value of the T-line in the test strip showed a good linear relationship with the HA concentration in the range of 0~100 µg/mL, with the standard curve equation of Y=27.94X+463.0 and the correlation coefficient of R² = 0.944. The detection limit and quantification limit of HA were 1.16 µg/mL (S/N = 3) and 3.88 µg/mL (S/N = 10), respectively. The two-site chemical recognition method could also achieve specific detection of HA in commercially available samples, showing potential application as an on-site analysis tool for HA.