Biocatalytic Conversion Efficiency of Steapsin Lipase Immobilized on Hierarchically Porous Biomorphic Aerogel Supports

Abstract

Hierarchically porous alumino-siloxane aerogels (ALS-PG) with a rare structural architecture were developed through a biotemplating method using pollen grains of Hibiscus rosa-sinensis. The unique structure of the Hibiscus rosa-sinensis pollen makes it an attractive biotemplate, by replicating all levels of macro- and mesoscale morphological features. The micromorphological analysis exposed funnelshaped macrochannels between the mesoporous aerogel framework that are difficult to design artificially. The N2 sorption analyses confirmed hierarchical trimodal pore size distribution with an average mesopores diameter (ca. 3.9, 8.7, 26.6 nm), high BET/Langmuir surface area (497/664 m2 g−1) and large pore volume (1.6788 cm3 g−1) than the corresponding nontemplated aerogels and xerogels counterpart. Beneficial properties of this sophisticated hierarchical porous structure was examined and confirmed by the immobilization of steapsin lipase. Hierarchically porous ALS-PG showed enhanced loading and immobilization efficiency (32.3 mg g−1 and 74.21%) when compared to non templated ALS-WO-PG (11.2 mg g−1 and 41.40%). It was further improved with the methyl (MTMS@ALSPG) (69.8 mg g−1 and 96.87%) and amino propyl (APTMS@ALS-PG) (65.1 mg g−1 and 94.96%) surface modifications. Additionally, it showed enhanced catalytic performance for hydrolytic, esterification, and transesterification reactions. It is anticipated that this hierarchically porous aerogel supports can suitably hold the biocatalyst and can solve critical problems associated with its native state for technological applications