The role of structural reorganization in charge carrier transfer in DNA molecule

A model of hole transfer in DNA molecules has been proposed, which takes into account changes in the reorganization energy and orbital coupling between the neighboring bases during the charge transfer in different molecular sequences. It is shown that the rate of hole transfer by the superexchange and hopping transfer mechanisms is limited by the relaxation of the geometries of nucleobases participating in charge migration and the dynamics of solvent molecules. The rate of charge transfer in the DNA molecule is found to be dependent on the height of the potential barriers between the nucleotide and the molecular sequences. The inclusion of the interchain charge transfer, which is characterized by weak coupling between the nucleotides located in opposite strands, does not affect the general charge transport in DNA. The increase in the number of the parallel components of the hopping mechanism leads to a rise in the charge transfer rate in the double helix.     

Determination with a microelectrode of membrane potential of giant human erythrocytes obtained by La(3+)-induced fusion

The effect of La3+ on the fusion of erythrocytes of blood stored for a week at +4 degrees C was studied. It was shown that the fusion of erythrocytes begins after one day of storage of blood. The most intensive fusion of erythrocytes was observed on day 4 of blood storage. As a result, giant cells with a size of 100 microns and more arise. The electrical potential of giant cells was measured using a microelectrode and was -6.6 +/- 1.5 mV.     

The role of structural reorganization in charge carrier transfer in a DNA molecule

The model proposed for hole transfer in DNA molecules with different configurations allows for the changes in the reorganization energy during charge transfer in a nucleotide strand with variations in the degree of orbital overlap in neighboring nucleotide pairs in different molecular sequences. The rate of hole transfer occurring in a DNA molecule through the superexchange and hopping transfer mechanisms is limited by the vibrational relaxation of the geometry of the nucleotide bases, as well as by the dynamics of solvent molecules. The rate of charge transfer in the DNA molecule depends on the height of the potential barrier between the donor fragment and the molecular bridge and on the positional arrangement of nucleobase pairs and their number in the molecular bridge. Inclusion of the interstrand charge transfer, which is characterized by a small degree of orbital overlap in the nucleobases of the opposite strands, does not affect the total charge transfer in the DNA molecule. An increase of the number of parallel components (processes) in the hopping mechanism entails an increase in the rate of charge transfer in the double helix.     

Dynamics of charge carrier transfer in a DNA molecule

An equivalent electric circuit has been developed which describes the charge transfer in DNA molecule. A computer simulation of the charge carrier transfer dynamics in the molecule has been performed based on this circuit. It was found that the switching time of a molecular junction lies in the femtosecond range and depends on the frequency of the input electric signal. An increase in the frequency of the input signal in the range from 1 GHz to 4 THz and a reduction of temperature lead to a decrease in the current passing through the DNA molecule. It has been shown that the sequence of the DNA base pairs defines the rate of localization and delocalization of holes and controls the signal propagation rate in the DNA molecule.     

Dynamics of transfer of charge carriers in DNA molecule

An equivalent electrical circuit of DNA molecule is suggested and used to model the charge transfer dynamics in the molecule. Its switching time is shown to be in the femtosecond time range and to depend on the frequency of input electric signal. Raising the input signal frequency from 1 GHz to 4 THz and lowering the temperature decrease the current through DNA. The switching rate of DNA molecule is determined by the processes of delocalization and localization of holes, which is achieved by variation in the base sequence and length.