<p>Sensitive and reliable quantification of Ochratoxin A (OTA) in food is essential for ensuring food safety and protecting public health. In this study, a dual-mode colorimetric and Surface-Enhanced Raman Spectroscopy (SERS) biosensor was developed by integrating DNAzyme-responsive hydrogel and Au@Pt@4-MBN nanozyme for signal amplification. Upon introduction of OTA, a specific cascade reaction was triggered, activating the generated DNAzymes and leading to the disintegration of the hydrogel network and the subsequent release of encapsulated nanozymes. The extent of hydrogel disintegration exhibited a positive correlation with OTA concentration, enabling straightforward quantitative detection. The biosensor demonstrated excellent sensitivity, with detection limits of 0.0668 ng mL⁻¹ (colorimetric) and 0.0342 ng mL⁻¹(SERS). When applied to spiked corn samples, it achieved high recoveries of 98.70%-100.93% (colorimetric) and 95.6%-104.27% (SERS), confirming its reliability. The method also demonstrated high practical applicability for authentic non-spiked samples, with a positive detection rate of 10% that was consistent with the results of the national standard method. This robust platform offers significant potential for sensitive mycotoxin monitoring in food and environmental safety.</p> Graphical Abstract <p></p>