Delayed luminescence and motional harmonicity

Drying of biological structure sizably reduces the non-harmonic contributions to internal atomic fluctuations. Such a reduction takes place either when the "nude" structures are dried or when structures are dried embedded in a trehalose-water matrix (trehalose coating), although the last procedure better preserves the structure than the former. In this work we studied the effects that drying in the presence of trehalose has on the delayed fluorescence of bovine Achilles' tendon and compared the results with analogous ones obtained by drying in the absence of trehalose. In both cases the intensity of the delayed fluorescence signal increases by several orders of magnitude. However, the wavelength dependence of the signal remains the same as in wet samples for trehalose coated Achilles' tendon, while it results different for samples dried in the absence of the sugar. The reported results enable to conclude that the lack of non-harmonic contributions to internal atomic fluctuations, present in wet samples, makes to increase the yield of delayed fluorescence. Moreover, the reported findings indicate that the trehalose matrix gives to the Achilles' tendon a friendly environment in which the structure is better preserved than in the case of drying in the absence of sugar.