Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


From Bacterium to Semiconductor

Proteins of photosynthetic bacteria can be used to generate photocurrent. How to do that – this can be learnt from the article by Russian researchers.

Researchers from different countries are accommodating to their purposes proteins of photosynthesis system bacteria. They are used as an active component of the photocurrent generation chain in the sensory and energy-storing systems.

In Russia, the problem is being addressed by specialists of the Lomonosov Moscow State University, Institute of Problems of Chemical Physics (Russian Academy of Sciences), Moscow Institute of Applied-Physics and the Institute of Chemical Physics (Russian Academy of Sciences). The researchers built proteins of reactionary center for purple bacteria photosynthesis into porous nano-crystalline films of titanium oxide.

Proteins of the photosynthesis system (bacteriochlorophyll, bacteriopheophytin and ubiquinones) – are natural solar energy bioaccumulators. Excited bacteriochlorophyll molecule transmits electron along the chain to other proteins of photosystem. These proteins attract attention of biophysicists due to high quantum yield of reaction of primary charge division and relative stability of these charges. As of today, there exist two different approaches to creation of hybrid light-storing and sensitive devices based on bacterial proteins. For elements of the first type, a layer of photosensitive molecules are applied on a metal (golden or platinum) or graphite plate. At that, the proteins should be orientated on the plate surface in a certain way. Depending on the protein disposition on the electrode, there occurs either a cathodic charge (in this case, the electron is carried from the electrode to proteins), or an anodic charge, if there occurs reverse direction current.

In the devices of the second type, the proteins are applied on meso-porous semicoductors made of metal oxide. In such systems, excited protein molecules transmit very quickly, within fractions of a picosecond, an electron into the semiconductor’s conduction band. Besides, the pores are so tightly stuffed with proteins, that the special procedure of their orientation may be omitted. Proteins will get orientated spontaneously on the electrode hydrophobic surface, the donor section being turned to the semiconductor.

The photocurrent density is directly dependent on both the porous film structure and on the quantity of protein molecules on the electrode. Therefore, the Russian researchers tried to obtain thick film (4 micrometers thick) made of titanium o?ide. The researchers selected a structure which is optimal to maximum protein sorbtion.

The TiO2 meso-porous films are obtained from nano-crystalline powders, which are added into special paste. They were applied on glass with a conducting covering of titanium- indium oxide. The film was dried up and calcined for 30-60 minutes at 550 degrees. Calcination adds mechanical strength to films. Then the plate was soaked in the photosynthetic proteins solution, and the main electrode was ready. The researchers managed to get a film with small pores and large specific surface area (300 m2/g). Thanks to the film depth and porosity, a lot of proteins get stuck to it, their concentration in the sample being 160 times higher than that in the solution. Proteins on the main electrode preserve activity even after the two week keeping in a refrigerator. Illuminating the electrode by red light, which only proteins react to, generates the anodic photocurrent of almost 2 microamperes. Titanium o?ide also reacts to white light, but presence of the photosynthesis system proteins in the electrode increases the photocurrent by more than twice.

The researchers note that nano-porous semiconductors possess not only a very high sorbing ability, but also tremendous energy diversity of surface states, which significantly impacts the electron transmission process.

Nadezda Markina | alfa
Further information:

More articles from Physics and Astronomy:

nachricht First results of NSTX-U research operations
26.10.2016 | DOE/Princeton Plasma Physics Laboratory

nachricht Scientists discover particles similar to Majorana fermions
25.10.2016 | Chinese Academy of Sciences Headquarters

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Greater Range and Longer Lifetime

26.10.2016 | Power and Electrical Engineering

VDI presents International Bionic Award of the Schauenburg Foundation

26.10.2016 | Awards Funding

3-D-printed magnets

26.10.2016 | Power and Electrical Engineering

More VideoLinks >>>