Encapsulation of GFP in Complex Coacervate Core Micelles

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Biophysics

Background:

• Protein encapsulation using polymers offers significant potential for applications in drug delivery, enzyme protection, and stabilization.
• Complex coacervate core micelles (C3Ms) are a promising structure for protein encapsulation, formed using polyelectrolytes.

Purpose of the Study:

• To investigate the encapsulation of enhanced green fluorescent protein (EGFP) within C3Ms formed by cationic-neutral diblock copolymers.
• To characterize the C3Ms and determine the encapsulation efficiency and capacity for EGFP.

Main Methods:

• Utilized two different sizes of cationic-neutral diblock copolymers: poly(2-methyl-vinyl-pyridinium)41-b-poly(ethylene-oxide)205 and poly(2-methyl-vinyl-pyridinium)128-b-poly(ethylene-oxide)477.
• Employed dynamic light scattering and fluorescence correlation spectroscopy (FCS) for characterization.
• Quantified encapsulated protein using mixtures of EGFP and nonfluorescent GFP.

Main Results:

• Identified a preferred micellar composition (PMC) with a positive charge composition of 0.65 for both copolymers.
• Determined micellar hydrodynamic radii of approximately 34 nm.
• Observed C3M formation above 100 nM EGFP at the PMC, irrespective of polymer length, with approximately 450 GFPs encapsulated per micelle.

Conclusions:

• Fluorescence correlation spectroscopy (FCS) is a suitable technique for characterizing protein-containing C3Ms.
• The study successfully demonstrated the encapsulation of EGFP within C3Ms, providing insights into their formation and capacity.
• The findings support the potential of C3Ms for protein stabilization and delivery applications.