Encapsulation of lysozyme in hybrid vesicles to protect from thermal challenges

Abstract

This study explores the formation of hybrid vesicles (HVs) through the co-assembly of dipalmitoyl phosphatidylcholine (DPPC) and the triblock copolymer F127. Our findings demonstrate that HVs offer enhanced stability compared to pure copolymer micelles and phospholipid vesicles. To evaluate their functional properties, we encapsulated the thermolabile protein lysozyme within the HVs. A range of characterization techniques such as dynamic light scattering (DLS), electron microscopy, circular dichroism (CD) spectroscopy, and high-sensitivity differential scanning calorimetry (HSDSC) revealed that the HVs' size increased modestly with higher F127 content and protein encapsulation. Despite these size changes, the vesicles retained their spherical morphology and smooth surface characteristics. Importantly, HVs demonstrated superior stability in terms of dilution and storage, which we attribute to the hydrophobic interactions between the phospholipid and copolymer. Moreover, HVs effectively shield lysozyme from thermal denaturation and unfolding, even under challenging stress conditions.

Keywords: Block copolymer; Circular dichroism; Hydrophobic association; Liposomes; Protein unfolding, fluorescence; Stabilization.