Metal-Organic Framework-Based Biosensor for Detecting Hydrogen Peroxide in Plants through Color-to-Thermal Signal Conversion.

Plant biotic or abiotic stresses, such as pathogens, mechanical damage, or high temperature, can increase intracellular H 2 O 2 concentration, damaging proteins, lipids, and DNA. Most current H 2 O 2 detection methods require the separation or grinding of plant samples, inducing plant stresses, and the process is complicated and time-consuming. This paper constructed a metal-organic framework (MOF)-based biosensor for real-time, remote, and in situ detection of exogenous/endogenous H 2 O 2 in plant organs through color-to-thermal signal conversion. By simply spraying horseradish peroxidase, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and the precursor of zeolite imidazolate frameworks-8 (ZIF-8), ZIF-8 biosensors were formed in situ on a plant root, petiole, or leaf. This biosensor could report sub-micromolar H 2 O 2 in plants since the oxidation products, ABTS • + , emitted heat when they absorbed energy from near-infrared (NIR) light. Due to the plant's low absorption in the NIR region, the ZIF-8 biosensor allowed for remote thermal sensing of H 2 O 2 transport or biotic/abiotic stresses in plants with a high signal-to-noise ratio combining NIR laser and thermometer. Our biosensor can be used for the future development of plant sensors for monitoring plant signaling pathways and metabolism that are nondestructive, minimally invasive, and capable of real-time, in situ analysis.