In Vivo Real-time Multiplex Detection of Plant Signalling Molecules using Surface-Enhanced Raman Scattering Nanosensor

To understand the biological and chemical dynamics of plants is essential in agriculture, and various sensor technologies have been studied. 'Plant signalling molecules' released against stimuli are drawing attention as a key to understand plant's status under stressors. Surface-enhanced Raman scattering (SERS)-based nanosensor has shown strong potential for its non-invasiveness and capability of real-time detection from fingerprint spectra. In our research, we fabricated PDDA-capped Ag nanoshell (AgNS@PDDA) and introduced it into plants through stoma. Due to AgNS@PDDA's optical activity in NIR, it was possible to evade chlorophyll’s autofluorescence and obtain SERS signals with fine quality. Also, PDDA polymer effectively attracted signalling molecules by coulombic interaction.<br/>Then, we studied the plant's reaction against biotic and abiotic stress with SERS signal monitoring. When plants leaf was under wound stress or cold stress, nasturlexin B, extracellular ATP and glutathione were successfully detected <i>in vivo </i>environment. Meanwhile, biotic stress was studied for the plants infected with fungal disease. <i>F. Graminearum</i> was injected into the plant, and signaling molecules was monitored with nanosensors according to the elapsed days after injection. Even only 2 hours after the fungi injection, when no lesion was detectable, SERS signals of eATP and salicylic acid related to systemic acquired resistance were successfully detected.