Delayed luminescence from collagen as arising from soliton and small polaron states

With the aim to give more hints to a theoretical model that describes the phenomenon of delayed luminescence (DL) from biological systems as due to the collective electron states that are excited in macromolecular structures by external illumination, a spectral characterization of DL from bovine Achilles' tendons sample at different hydration states has been performed. Tendons are mainly composed by Type I collagen macromolecules which form a one‐dimensional system with the long‐range order and capability of self‐organization, so favoring the existence of such collective excitations. Modeling the crystal structure of collagen as a one‐dimensional chain whose unit cell is formed by a tripeptide, the ground state of the corresponding Hamitonian has been evaluated by a variational approach. The change in DL from bovine Achilles' tendons, depending on the water content of the sample, has been correlated to the change in the ground state of such one‐dimensional lattice from a soliton state, for samples close to native, to a small polaron state, for samples that are much more dry.