Peptide Amphiphilic Supramolecular Nanogels: Competent Host for Notably Efficient Lipase‐Catalyzed Hydrolysis of Water‐Insoluble Substrates

Supramolecular self-assembled nanogels in water have been developed from peptide amphiphile hydrogelators. The micro-heterogenous surface of the nanogels was judiciously utilized to catalyze the hydrolysis of water-insoluble substrates like p-nitrophenyl-n-alkanoates with remarkable efficiency by CV lipase immobilized at the interface of the gel nanoparticles. The rate enhancement of CV lipase in the presence of nanogels was significantly high in comparison to aqueous buffer and other self-aggregating systems.

Abstract

The present work depicts the development of stable nanogels in an aqueous medium that were exploited for efficient surface-active lipase-catalyzed hydrolysis of water-insoluble substrates. Surfactant-coated gel nanoparticles (neutral NG1, anionic NG2, and cationic NG3) were prepared from peptide amphiphilic hydrogelator (G1, G2, and G3, respectively) at different hydrophilic and lipophilic balance (HLB). Chromobacterium viscosum (CV) lipase activity towards hydrolysis of water-insoluble substrates (p-nitrophyenyl-n-alkanoates (C4–C10)) in the presence of nanogels got remarkably improved by ~1.7–8.0 fold in comparison to that in aqueous buffer and other self-aggregates. An increase in hydrophobicity of the substrate led to a notable improvement in lipase activity in the hydrophilic domain (HLB>8.0) of nanogels. The micro-heterogeneous interface of small-sized (10–65 nm) nanogel was found to be an appropriate scaffold for immobilizing surface-active lipase to exhibit superior catalytic efficiency. Concurrently, the flexible conformation of lipase immobilized in nanogels was reflected in its secondary structure having the highest α-helix content from the circular dichroism spectra.

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