Monitoring plant physiology with organic electrochemical transistors

Plants are the basis of food, providers of oxygens and regulators of the ecosystem. Plants
convert solar energy into chemical energy with the process of photosynthesis where carbon
dioxide is converted to sugar molecules. Sugars are not only the energy source in plants but
also important signalling molecules, involved in regulation of physiology including stress
responses. Currently there are no methods that allow real time monitoring of sugar transport
in plants. Sugar detection is based on enzymatic assays, chromatography and/or mass
spectrometry; all of these methods require sample collection and preparation. Organic
electrochemical transistors (OECTs) are ideal tools for interfacing with organisms, since they
can translate complex biological input to an electronic readout signal. OECT sensors can
operate in complex media and they can directly detect products from the biological unit. In
my group we are developing sugars sensors based on the organic electrochemical transistor
for monitoring plant processes in-vitro and in-vivo. In a first example we measure the export
of glucose in real time, from isolated chloroplasts, with a temporal resolution of 1min. The
OECT based platform is able to distinguish the metabolic phase of the chloroplast prior
isolation from the plant. In another example we are developing implantable OECT-based
sugar sensors for in-vivo, real time monitoring of sugar transport in trees. The OECTs sensors
show high device to device reproducibility, stability during the operation in the in-vivo
environment and most importantly they do not cause a significant wound response from the
plant. The sensors revealed kinetics of sugars transport that were not observed before. Our
work contributes to establishing the OECT-based sensors as powerful tools for monitoring
processes in plants, in real time both, in in-vivo and in-vitro systems.