Acetabularia 

The numerous experimental data accumulated on DL of biological systems showed the strong correlation of the properties of DL with the state of the system. 

Biosystems posses specific delayed photoluminescence whose properties differ significantly from those of similar devitalised organisms, and both are different from non-living systems and depend on the physical, chemical, physiological and other conditions and pre-history of the samples. 

At present there are only few theoretical models of this phenomenon, but neither can explain in a self-consistent way the wide range of the kinetics of DL, including exponential, simple hyperbolic and much more complicated time decays, and its correlation with the conditions of experiments.

 Based on the previous theoretical studies of the nonlinear mechanisms of charge and energy transfer in biological systems and coherent collective electron states in the solid state systems of the reduced dimensionality, the possible role of electro-solitons in the photoluminescence of biological systems has been considered. 

In the result, the soliton model of the DL has been developed. This model takes into account the experimental fact that the DL lasts from few seconds to few hours, which indicates that to a great extent it is related to the long-living photoinduced excitations in the system.

Collagenous Tissues

DL from ox Achilles’ tendon is found to depend on the order parameters of the collagen fibres and on both water content and the temperature, which affect those parameters. Together with these measurements  the dielectric permittivity has been measured  in the frequency range 500Hz-10MHz as a function of the water content. Moreover the values of dielectric permittivity for low frequency are very high, like in some ferroelectric materials, and can not be explained using classical models. Changes in the dielectric permittivity as a function of the water content are similar to changes of the total number of photons emitted in DL experiments.

A correlated solitons model is in progress with the aim  to describe both qualitatively and quantitatively the main features of the DL and of dielectric permittivity in this system.