Synthesis of SBA-15 and pore-expanded SBA-15 and surface modification with tin for covalent lipase immobilization

The mesoporous silicas were extensively used in lipase immobilization due to the high specific area, pore diameter, and the possibility of surface modification. Due to this, the present work aimed to synthesize the SBA-15 with different pore diameters (S8 with 9.1 nm and S23 with 23 nm) and modify the silica surfaces with tin (SnS8 and SnS23), a little-explored technique for immobilization, for Burkholderia cepacia lipase immobilization by covalently bond between the functional group in the enzyme and the metal. The tin-modified silica (SnS23) derived from the pore expansion of the SBA-15 was the support with the largest pore size (25 nm) and led to the highest specific activity of the immobilized enzyme (SnS23B, 268 ± 12 U/mg). In the leaching tests, no lipase was detected in the buffer solution used for lipase desorption, indicating the strong interaction between lipases and modified silicas.