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
