Artificial
living technologies are rapidly developing in several laboratories
around the world: in USA (Steen Rasmussen, James Bailey, Hans Ziock,
Los Alamos National Laboratory (LANL [1]); Liaohai Chen, Argone
National Laboratory), in Italy (Pier Luigi Luisi's group at RomaTre
University), in Germany (John S. McCaskill, Guenter von Kiedrowski,
Ruhr-Universitaet Bochum; Patrick Wagler, Protostreem GmbH), and in
European Center for Living Technology (headquarter in Venice). New
creating nano biorobots are planed to be used for nanomedicine,
nanoecology, and for future emerging new information technologies.
Despite of really useful benefits of these artificial living
technologies one can foresee also some possible dangerous events in the
case if these new creating artificial living cells might self-mutate
and escape to the natural biospheres. Vilnius University research group
is creating molecular electronics logic gates regulating the
photosynthesis, growing and dividing of artificial living cells and
nanobiorobots in the order to prevent the negative affects of these new
emerging artificial living information technologies. The molecular
electronics and spintronics logical devices which regulate
photosynthesis, self-assembling to the mobile computing structures,
selectively capturing and transporting nuclear, chemical and microbial
pollutions already were quantum mechanically designed in our previous
research [2].
The artificial minimal living cells (LANL scientists call them as
protocells) that are synthesized in USA Los Alamos National Laboratory
(LANL) [1] are only a few (4-6) nanometers in size. In their simplest
form, these cells consist of a micelle which acts as the container, a
light driven metabolism, and a genetic system, whose functions are all
very tightly coupled. The container consists of amphiphilic fatty acid
(FA) molecules that self-assemble into a micelle. The hydrophobic
interior of the micelle provides an alternative thermodynamic
environment from the aqueous or methanol exterior and acts as a
sticking point for the photosensitizer, fatty acid precursors (pFA)
(food), and the genetic material. Peptide nucleic acid (PNA) is chosen
as the genetic material as it is far less polar than RNA or DNA and
therefore should stick to the micelle, especially if hydrophobic chains
are added to the PNA backbone. It is also capable of undergoing the
same Watson-Crick pairing and replication as RNA and DNA. PNA is
similar to DNA but has a peptide-based backbone, as opposed to DNA's
sugar-phosphate backbone.
The first main goal of this research is to report the results of
quantum mechanical (QM) modeling of the self-assembly and charge
transfer in a minimal protocell [1] that might have implications for
the first living organism on the Earth arround 3.8-3.5 bilion years
ago. The climate in the Earth at that time was hot with intense UV
radiation therefore PNAs might were the most suitable for genome of
minimal living cells in comparison with RNA or DNA. This article uses a
collection of quantum mechanical tools and applies them to a variety of
protocell photosynthetic problems, while also providing a perspective
of the requirements for success in the synthesis of new forms of living
organisms.
The metabolism involves the photoexcitation of an electron in various
photosensitizers which are stabilized by the donation of an electron
from non-canonical PNA bases (for example, 8-oxo-guanine). The excited
electron is in turn used to cleave a fatty acid precursor to
yield another fatty acid molecule, thereby allowing the container to
grow until it reaches an unstable size and divides. The artificial
minimal cell could be fed PNA monomers or use an essentially identical
metabolism to convert a PNA precursor monomer into a true monomer,
thereby also providing the material to allow the double-stranded PNA
"gene" to replicate when it undergoes a random dehybridization to yield
two complementary single-stranded templates [1]. Finally, as the
different nucleobases have different electron donor and electron relay
capabilities, there is also a mechanism for natural selection, with
some bases and base orderings being superior to others in their ability
to facilitate the metabolism.
The artificial minimal living cell contains on the order of 103 atoms.
Due to its small size, all its processes, including its self-assembly
from component molecules, its absorption of light, and its metabolism
should in principle be investigated using quantum mechanical (wave)
theory.
Usually self-reproducing artificial living cells that are creating in
LANL and in other laboratories do not have the nanosize electronics
tools which might be able to regulate the growth and multiplication. It
is important to have possibility to stimulate or prevent uncontrolled
multiplication of artificial living organisms by installing different
molecular electronics devices. The second main goal of this research is
by using quantum mechanical experiments to predict the possibility of
biochemical experimental synthesis of molecular electronics controlled
artificial minimal living cells or nanobiorobots which might be used
for nanomedicine and nanoecology. It is presented in this research the
quantum mechanically designed molecular electronics OR logical gate for
the the regulation of artificial minimal living cell functions.
[1] S. Rasmussen, L. Chen, M. Nilsson, and S. Abe, Artificial Life, vol
9, 267-316 (2003).
[2] A. Tamulis, J. Tamuliene, V. Tamulis, "Quantum Mechanical Design of
Photoactive Molecular Machines and Logical Devices", in "Handbook of
Photochemistry and Photobiology", Vol. 3 "Supramolecular
Photochemistry", Ed. H.S. Nalwa, American Scientific Publishers,
495-553, 2003.