Hydrogel‐based surface‐enhanced Raman spectroscopy for food contaminant detection: A review on classification, strategies, and applications

Abstract Toward the challenge on reliable determination of food contaminants to ensure food safety and security, surface‐enhanced Raman spectroscopy (SERS) technology with single‐molecule sensitivity through their “fingerprint” Raman signal has been developed into a fundamental and important molecular toolkit for food industry. Currently, hydrogel is attracting great interests in SERS sensing as a functional and flexible material. In this perspective, we first introduce the classification of common hydrogel and strategies for the synthesis of SERS substrates. Next, we highlight the response characteristics of hydrogel, including temperature response and pH response. Finally, we summarize the applications of hydrogel‐based substrates for food contaminant detection and discuss its developing trends and challenges. Compared to traditional solid SERS substrates, hydrogel‐based substrates have encouraging characteristics, such as unique flexibility to adhere to food surfaces for direct target molecule collection, and the stable three‐dimensional network scaffold that prevents the aggregation of SERS hot spots, etc. These advantages suggest that hydrogel‐based substrates have great potential for food safety analysis and monitoring.