Investigation of thermal effects and physical parameters on crosslinking by different riboflavin solutions and UV-A

Abstract

Riboflavin-Dextran and Riboflavin-Dextrin solutions have the ability to create crosslinks between fibrilles in the biological tissues. These solutions cause the generation of free oxygen radicals by the excitement of UV light without harming the biological tissues. These oxygen radicals are formed to tide amino groups of the collagen fibrilles by covalent bond. Dextran is a type of polysaccharide consisting glucose molecules (glucan). It has so complex structure that includes lots of chains of different lengths. In medicine, dextran is used as drop to decrease the viscosity of blood and volume expander in anemia. It is the product of sucrose fermentation of a bacterium named leuconostoc mesenteroides. Due to the fact that obtainment of dextran is not straightforward, it is considerably high-priced. Dextran also plays an important role in keratoconus treatment. Despite successful results, there can be unexpected effects as edema, loss of vision etc. Dextrin is a group of low molecular weight carbohydrates produced by the hydrolysis of starch or glycogen. Its structure has polymers of D-glucose units. Unlike dextran, it is simple to obtain hydroxyl groups. According dextrin. According to our studies, dextrin can be used in keratoconus treatment instead of dextran alternatively. In our research, the absorption and emission spectra of the solutions were measured by the UV-A and steady-state fluorescence techniques at different temperatures. Their physical parameters were determined. As temperature change has significant effect on biological systems, dextran and dextrin is compared about temperature increment during the treatment. Furthermore, it is investigated correlation between unexpected impacts of treatment and temperature increase of itself.