Proteins have become components of "dry" electrical circuits
The idea of creating biological molecules suitable for integration directly into electronic circuits has long worried scientists' minds. Researchers at the University of Pennsylvania, working under the guidance of Professor Dawn Bonnell, have developed a method for forming such structures capable of functioning outdoors. Moreover, they also proposed a new technique of electron microscopy, which makes it possible to evaluate the electrical properties of these and similar devices.
Protein-graphite electrical circuits are bundles of spiral-shaped protein molecules containing photosensitive molecules specially deposited on the surface of graphite electrodes. When light hits the protein molecules, photons are converted into electrons, which are transmitted to the electrodes.
Previously, the functioning of such structures was tested under conditions of immersion in special solutions. However, it was not possible to evaluate their electrical properties, especially electrical capacitance, whereas knowledge of the electrical properties of biological molecules is a prerequisite for their use to create various devices.
Creating electrical circuits and devices based on silicon oxide is much easier than working with proteins, the measurement of the electrical properties of which must be carried out at the nanoscale. Since diagnostic systems with sufficient sensitivity still did not exist, scientists had to invent not only a method for synthesizing photovoltaic proteins capable of functioning in air, but also a technology for measuring their electrical properties.
To solve this problem, they upgraded the method of atomic force microscopy and called the developed technique "nanoresistance-torsional resonance microscopy" (torsional resonance nanoimpedance microscopy). The principle of operation of the atomic force microscope is to bring the thinnest tip of silicon oxide very close to the surface of the sample and measure the reaction of the tip, which provides spatial sensitivity from several nanometers to individual atoms.
In the method modernized by the authors, the silicon oxide tip was replaced with a metal one under the action of an alternating electric field. Observing the reaction of electrons to the approach of an electric field allows us to evaluate more complex interactions and parameters, including the electrical capacitance of the device under study.
The method of synthesis of self-assembling proteins and their fixation on the surface of graphite electrodes, successfully developed by the authors, in combination with the method of evaluating their electrical properties described above, can have a number of practical applications. The most obvious of them is the creation of solar panels. However, the researchers note that proteins can be changed in such a way that they react not to photons of light, but to the presence of certain chemical compounds, for example, toxins, by changing color or activating an electrical circuit. Similar schemes can be used to create various pocket gadgets.
Article by Kendra Kathan-Galipeau et al. Direct Probe of Molecular Polarization in De Novo Protein–Electrode Interfaces was published on May 25 in the online version of ACS Nano magazine.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of the University of Pennsylvania: Penn Researchers Develop Biological Circuit Components, New Microscope Technique for Measuring Them.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru14.06.2011