Abstract: A simple, novel, and sensitive biosensor for the colorimetric detection of Sudan dyes was successfully prepared using Sudan III aptamer as a recognition element, hemin/G-quadruplex DNAzyme as a signal indicator, and hybridization chain reaction as a signal amplification strategy. Under optimized conditions, the sensitivity, accuracy and specificity of the method were evaluated.?Finally, the developed method was applied to detect Sudan III in food samples, and was validated by comparing it with the national standard method (GB/T 19681-2005). A good linear relationship was obtained between the absorbance at 450 nm and the concentration of Sudan III in the range of 0.5 to 250 ng/mL with correlation coefficient of 0.995, and the detection limit was 0.09 ng/mL. Specificity analysis demonstrated that this method could be used to detect Sudan I–IV. The recoveries of Sudan III from spiked real samples ranged from 84.3% to 101.6%, with relative standard deviations of 4.13%–8.36%. There was no significant difference in the spiked recoveries between the proposed method and the national standard method (P > 0.05). This method was simple, reliable, sensitive, and suitable for the detection of Sudan dyes in food samples.

Key words: Sudan dyes; aptamer; hybridization chain reaction; hemin/G-quadruplex DNAzyme; colorimetric biosensor