A smartphone-based inverse opal hydrogel film aptasensor for mycotoxin detection by the naked eye

Ochratoxin A (OTA), a carcinogenic mycotoxins, poses a significant threat to human health. The current detection methods exhibit advantages such as high sensitivity and good selectivity. However, The methods applicability for on-site detection remains hindered by complex operational procedures and the requirement for bulky testing instruments. Here, to address this limitation, we present a novel portable platform for naked-eye detection of OTA using photonic crystal (PC) inverse opal hydrogel films based on the smartphone. The inverse opal hydrogel film was fabricated by integrating hydrogel within PC templates, while a binding aptamer was employed to selectively recognize OTA. In the absence of OTA, the film displayed a vibrant red. With increasing OTA concentration, the diffraction peak progressively shifted toward the blue region of the spectrum. Leveraging a portable microscope, and captured the color change using a smartphone and developed a selfwritten algorithm to extract the H value of the image, enabling quantitative detection of OTA concentration. This portable platform has demonstrated exceptional reliability and convenience, boasting a remarkable detection limit of 1 mu g/mL. Furthermore, its versatility extends to the detection of other mycotoxins, making it a promising tool for broader mycotoxin detection applications.