Why sol gel process is necessary After mixing protein dye with gelatin ? 2.2.2. Preparation of sol-gel matrix Tetraethoxysilane (TEOS) were used as precursors for the sol-gel glass. TEOS (7 ml), 3.0 ml of distilled water and 0.1 ml of 0.04 M HC1 were mixed together and sonicated for 20 min. The resulting product was diluted with an equal volume of distilled water. The resulting mixture (0.5 ml) was mixed with 0.25 ml sodium borate buffer solution (pH 9) and (0.1 ml, 0.2 ml) bR solution to create a film-forming solution. Triethanolamine (TEA) was chosen as sensitizing additives. The concentration of chemical additives was in the range of 0.010.4 M. For the preparation of chemically modified films, bR solution was mixed with TEA, before mixing with the sol mixture, and afterwards 0.02 ml of the bR-chemical additives mixture was added to 0.12 ml of the sol mixture [7,8].