Paper-based chip integrated with vitrified silk fibroin microneedle array for colorimetric detection of histamine in food

Early detection and analysis of pathogens in food are an effective way to curb food poisoning. Traditional detection methods require complex sample pre-treatment and high costs, and are not easy to implement point-of-care testing (POCT) for food safety. By preparing a patch of vitrified silk fibroin hollow microneedle array patch (SF-HMAP) and integrating it with a patterned paper-based chip using a 3D printing technology and a double-printed die fabrication process, a conceptual sensor in the form of a microneedle array paper chip has been successfully developed. During the preparation of the sensor, the vitrified SF-HMAP with a suitable diameter and height exhibits a complete and homogeneous structure and excellent mechanical properties, thus being able to meet the puncture detection of various food products. Meanwhile, rice paper with good color intensity and uniformity was selected as the patterned paper-based chip sensing layer and assembled with vitrified SF-HMAP to form a sensor, which can quickly absorb and transmit liquid into the solid gel within 9min. To validate the practicality of the conceptual sensor, the loading of copper nanoclusters (Cu NCs) probes in a patterned paper-based sensing layer enabled continuous visual fluorescence monitoring of histamine produced during the storage of fresh pork and fresh shrimp and color comparison with standard colorimetric cards for histamine detection, allowing semi-quantitative colorimetric detection of histamine in actual samples. The proposed portable conceptual sensor is adjustable and versatile, and offers a novel idea and approach for food safety detection.