Plant nanobionic materials with a giant temperature response mediated by pectin-Ca ²⁺

Abstract

Conventional approaches to create biomaterials rely on reverse engineering of biological structures, on biomimicking, and on bioinspiration. Plant nanobionics is a recent approach to engineer new materials combining plant organelles with synthetic nanoparticles to enhance, for example, photosynthesis. Biological structures often outperform man-made materials. For example, higher plants sense temperature changes with high responsivity. However, these properties do not persist after cell death. Here, we permanently stabilize the temperature response of isolated plant cells adding carbon nanotubes (CNTs). Interconnecting cells, we create materials with an effective temperature coefficient of electrical resistance (TCR) of −1,730% K −1 , ∼2 orders of magnitude higher than the best available sensors. This extreme temperature response is due to metal ions contained in the egg-box structure of the pectin backbone, lodged between cellulose microfibrils. The presence of a network of CNTs stabilizes the response of cells at high temperatures without decreasing the activation energy of the material. CNTs also increase the background conductivity, making these materials suitable elements for thermal and distance sensors.temperature sensor | plant nanobionics | carbon nanotubes | iontronics | biomaterials M aterials that respond sensitively to temperature variations are used in several applications that range from electrical temperature sensors (1) to microbolometers for thermal cameras (2, 3). Existing high-performance temperature-sensitive materials, such as vanadium oxide, have temperature coefficient of electrical resistance (TCR) on the order of −6% K −1 at room temperature (4). These materials derive their properties from changes of their crystal structure during semiconductor to metal transitions (5). Higher sensitivities have been pursued by exploiting quantum effects (6-9), e.g., in carbon nanotube (CNT) composites (1). However, such composites reach lower TCRs because CNTs are embedded in an insulating polymeric matrix (1).Variations of the ambient temperature influence the biopotential of living plants (10,11). Experiments performed in vivo on a maple tree (Acer saccharum) showed an exponential correlation between the tree's branch electrical resistance and temperature (10). This behavior has been attributed to ionic conductivity occurring in plant cell walls (11). The plant cell wall has a highly complex macromolecular architecture with very dynamic structural and physiological properties (12). The cell wall, positioned outside the plasma membrane (13), is composed of carbohydrates such as cellulose microfibrils (14) with diameters as small as 3.0 nm (15) and hemicellulose interconnected with pectin. Pectins are composed of pectic polysaccharides rich in galacturonic acid that influence properties such as porosity, surface charge, pH, and ion balance and therefore are critical for ion transport within the cell wall. Pectins contain multiple negatively charged saccharides that bind cations, such as Ca 2+, that for...

Printable, Highly Sensitive Flexible Temperature Sensors for Human Body Temperature Monitoring: A Review

“…Shown in Fig. 2 c, Giacomo et al [ 76 ] proposed a biomimetic material with excellent temperature response sensitivity made of isolated plant cells and carbon nanotubes (MWCNT) using plant nano-biomimetic technology. Using CNTs as a channel to connect cells directly, creating a bionic material with an effective temperature resistivity (TCR) of , which is two orders of magnitude higher than the current best sensor, and the monitoring temperature range is 35–75 °C.…”

“…b The entire surface micrographs of PEO1500/PVDF/Gr [68]. c Schematic diagrams and scanning electron microscopy (SEM) images of cyberwood [76]. d SEM images of the CNT/PEDOT:PSS composite fibers with CNT contents of 40 wt% [75].…”

Rational Design Principles for the Transport and Subcellular Distribution of Nanomaterials into Plant Protoplasts

“…Besides nucleic acids, nanoparticles can also be functionalized with molecules such as fluorescent dyes for intracellular labeling in plants, active molecules for tracking and sensing purposes, and agrochemicals for crop health . Targeted delivery of nanoparticles to certain regions of plant tissue is also important for the creation of biomimetic systems such as light‐harvesting apparatuses, photonic devices, emission sources for near‐infrared communication to electronic devices, and carbon‐negative temperature and environmental sensors . We have previously shown that highly charged nanoceria, a nanoparticle‐based reactive oxygen species (ROS) scavenger, and certain polymer‐wrapped single‐wrapped carbon nanotubes (SWNTs) localized within the chloroplasts when introduced to plant mesophyll tissue, enabling photosynthetic rate augmentation and extending the photoactive lifetime of extracted chloroplasts .…”

Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors

“…Together with strain and pressure sensors, temperature‐sensitive devices, which can be stretchable and biocompatible at the same time, allow the implementation of noninvasive and unobtrusive systems for health monitoring. As proof of concept, our engineered elastomeric substrate is combined with a layer of pectin, a plant‐derived molecule recently reported to have large temperature–responsivity (see Device Fabrication section). The temperature sensor, consisting of a single pillar (acting as substrate), metal contacts, and the pectin layer (see Figure a), is mounted on a heating/cooling system (see Figure S14, Supporting Information).…”