rose transistor 01.12.2015

A living organism, in which its own cell tissues are supplemented with artificial materials, which half consists of wires and microcircuits, is a common character in science fiction films and books. And despite advances in prosthetics, despite advances in neuroscience trying to bridge the gap between electronics and the brain, it still seems that such bionic beings, if they do occur, will be in the very distant future. However, researchers from the University of Linköping Magnus Berggren and colleagues report that they have managed to grow a cyborg rose that can change the color of the leaves with an electrical signal.

The initial idea that arose in Berggren's laboratory almost 15 years ago was to "eavesdrop" on the biochemical processes occurring in the plant and, if possible, learn to control them. Here, of course, we can recall genetic engineering, which allows you to interfere with the genetic program of the body, turn on or off certain genes, achieving the desired physiological effect at the right time. The successes of genetic engineering can hardly be overestimated, and they are especially great just with plants that are easier to work with and whose genome can withstand quite strong shakes. However, in Sweden, the prospects for genetically modified plants - if we talk about their practical application in agriculture - are much more modest than, for example, in the United States. So the researchers thought about what could be an alternative to genetic engineering methods, and as a result they decided to create not a genetically modified, but an electronic plant.

The task was to supply the plant organism with wires, so to speak, without surgery, so that they would form themselves right on the spot. To do this, it was necessary to find a polymer that would, firstly, be biocompatible, secondly, would dissolve in water, and thirdly, would allow recording what is happening inside the plant and sending signals inside it. From the solution, monomer molecules would rise through the plant vessels and polymerize in them, forming the very wires that would run through the entire plant, from roots to leaves. More than twelve organic substances were tried, but everything ended either with a blockage of the root system, or the molecules, once in the rose, were not assembled into conductive structures. In the end, the authors of the work settled on PEDOT-S:H, a water-soluble organic compound that is used in printed electronics.

Rising through the vascular system of the plant, the PEDOT-S:H molecules lost a hydrogen atom, and due to the released sulfur atom, they formed polymer chains 10 cm long. Using gold electrodes connected to a rose, it was possible to show that the plant works like a transistor, and that performance is quite comparable to that of a simple transistor assembled only from polymer molecules. In another experiment, the leaves of live, uncut roses were impregnated with a PEDOT solution with cellulose nanofibers using a vacuum setup - as a result, the researchers were able to change the color of the leaves (not the petals!) In the blue-green range by applying current of different voltages. (It is also worth emphasizing that here the organic electronics were formed not from the roots through the stem, but directly in the leaf.) The results of the experiments are published in Science Advances.

The designers of the "cyborg rose" themselves believe that their experiments will serve as the basis for further research, and that in the future, with the help of such organic wires, it will be possible to regulate the hormonal background in agricultural crops, stimulating growth, fertility, etc. Of course, one can ask a question how such an operation affects the plant itself, and whether it will die prematurely due to the presence of organic electronics in itself.

However, according to Magnus Berggren, the experimental plants with which they experimented with changing the color of the leaves are still alive, and the leaves are still with them. And yet, one cannot discount the opinion of skeptics who believe that we are “only” an outstanding work of art that has no practical prospects, and, one way or another, such electronic plants have yet to prove their advantages over genetically modified ones.