Background: Lipases are excellent biocatalysts with dual ability of hydrolysis as
well as esterification with high efficiency and substrate specificity. However, in the pristine
form they have inherent limitations such as lack of reusability and limited thermal and pH
stability those restrict their uses in commercial applications. These limitations can be overcome by their immobilization
on the suitable supports.
Methods: In the present study a new poly(acrylic acid)-based functional nanogel was prepared by a simple
surfactant free emulsification method and functionalized to poly(acrylic azide) form by a simple chemical
protocol. Nanogels were characterized by X-Ray diffraction (XRD), Fourier Transform Infra Red (FTIR)
spectroscopy, and transmission electron microscopy (TEM) to get evidence of the network formation and post
reaction. The well characterized precursor nanogel and its functional derivatives were used as supports to
immobilize lipase (triacyl glycerin). The activity assay of the immobilized lipase was carried out by the standard
assay method. The catalytic potential of the immobilized lipase was evaluated in hydrolytic reactions using
p-nitrophenol palmitate as substrate.
Results: Immobilization enhanced the lipase activity and the structure of the nanogels made significant difference
in enhancing their activity as the lipase immobilized on poly(Acryl azide)-cl-divinylbenzene nanogel exhibited
the higher activity than the lipase immobilized on the precursor nanogel. Also, its activity was far
higher than the free lipase. The immobilized lipase exhibited thermal and pH stability, which is not possible
with the free lipase.
Conclusion: The lipase was immobilized by the covalent linkages. The immobilized lipase exhibited good activity,
storability and reusability. These results were dependent on the nanogel structure. Hence, a suitable
nanogel can be tailored to obtain the maximum gains of immobilization. The reported results have good technological