Implantable Hydrogel Electrochemical Sensor for Early Warning and Fingerprinting of Environmental Pollutant Stresses in Plants

Ubiquitous environmental pollution exerts severe adverse impacts on plant growth, development, and yield, jeopardizing global food security as well as human life and health. Traditional plant health monitoring relies on phenotypic observation and excised tissue testing, suffering from sample destructiveness and time lag in results. Whereas emerging plant wearable sensors mainly provide output signals that are indirect, comprehensive responses to plant physiological processes, failing to specifically capture early endogenous stress signals. Herein, a hydrogel-integrated multiplexed electrochemical sensor (HIMES) with high sensing performance, good flexibility (Young’s modulus = 18.27 MPa), and excellent biocompatibility was developed, which enables 24-day in situ monitoring of four core stress-responsive signaling molecules (H 2 O 2, salicylic acid, abscisic acid, indole-3-acetic acid) in tomato stems under exposure to environmentally relevant concentrations of four pollutants (Cd 2+, PFOS, atrazine, sulfadiazine). The HIMES achieved ultraearly pollution stress warning within 1–2 days of pollutant exposure, >10 days ahead of visible phenotypic damage, and established a pollutant-specific signal fingerprint library based on the temporal response characteristics of the signaling molecules for rapid pollutant typing. This study provides a powerful platform for the early diagnosis of environmental pollution, pollution source identification, and dynamic assessment of ecological risks for plants.