Design and Evaluation of Hydrophobic Ion-Pairing Complexation of Lysozyme with Sodium Dodecyl Sulfate for Improved Encapsulation of Hydrophilic Peptides/Proteins by Lipid-Polymer Hybrid Nanoparticles

Abstract

Hydrophobic ion-pairing (HIP) complexation-based approach has been employed to reduce aqueous solubilities of peptide and protein drugs. The solubility of a protein molecule is due to presence of charged amino acids present on the surface. HIP complexation is a technique to complex ionizable functional groups of protein and peptide molecules with oppositely charged functional groups of a complex forming agent. The main objective of this study was to formulate and evaluate HIP complexes of lysozyme with sodium dodecyl sulfate (SDS) as an ion paring agent. Results of % binding effciency shown that the formation of HIP complexes were dependent on pH of lysozyme solution and molar ratio of lysozyme to SDS. Aqueous solubilities of HIP complexes were very low compared to lysozyme alone. The e¬ffect of HIP complexation on enzymatic activity of lysozyme was also studied. Further, lipid-polymer hybrid nanoparticles (LPNs) loaded with lysozyme and lysozyme:SDS HIP complex were prepared by using a solid-in-oil-in-water (s/o/w) emulsion solvent evaporation method and characterised with respect to morphology, size and encapsulation efficiency. We observed significant improvement in encapsulation efficiency for lysozyme:SDS HIP complex-loaded LPNs. This study demonstrates a novel approach of formulating protein-loaded nanoparticles which can also be employed for delivery of proteins.