Abstract: A new aptamer-adsorbed gold nanoparticles-based colorimetric method was developed for sensitive detection of histamine, by taking advantage of the facts: 1) histamine can specifically recognize histamine aptamer, leading to exposure of the surface of gold nanoparticles (AuNPs); 2) the imidazole structure of excess histamine can replace the citrate ions on the surface of AuNPs, and destroy the electrostatic interaction between the AuNPs, thereby leading to an aggregation phenomenon that causes a color change from red to blue. Based on the changes in the absorbance of AuNPs solutions, the limit of detection (LOD) was calculated to be 8.89 nmol/L, and the linear range was 50 nmol/L–1.2 μmol/L (R2 = 0.999). Meanwhile, a smart phone was used to take photos of the sample solutions, and the values of red (R), green (G) and blue (B) channels were obtained by the Image J software. Using G/R ratio as the detection signal, the LOD of the RGB method was 24.91 nmol/L, and good linearity was observed in the range from 150 nmol/L to 1.0 μmol/L (R2 = 0.997). In addition, this method has good selectivity to histamine. The recoveries of the spectrophotometric and RGB methods were 91.82%–102.27% and 98.96%–102.89% for spiked water samples and 89.77%–108.92% and 88.96%–109.82% for spiked fish samples, respectively. Both methods are simple, rapid and sensitive. Particularly, the RGB method, which can meet the requirements of on-site real-time detection without the need for any sophisticated instrumentation, is expected to be applied for sensitive monitoring of the freshness of animal-derived foods.

Key words: aptamer; gold nanoparticles; aggregation; histamine; colorimetric sensor; RGB