Cyclic Polymers as Nanoscale Platforms for Enzyme Encapsulation and Transport

Area of Science:

• Polymer Chemistry
• Nanotechnology
• Biomaterials

Background:

• Cyclic polymers (CPs) form ring structures without chain ends and can create nanostructures for encapsulating molecules.
• While CPs encapsulate small molecules, drugs, and nucleic acids, their interaction with proteins/enzymes remains unexplored.

Purpose of the Study:

• To investigate the formation of nanoscale self-assemblies between poly(hydroxy butyrate)-based CPs and a model enzyme, lysozyme.
• To evaluate the enzyme-stabilizing capabilities and controlled release potential of these CP-enzyme nanostructures.

Main Methods:

• Nonsolvent-induced phase separation to promote CP-lysozyme interactions.
• Characterization of nanoparticle properties (hydrodynamic diameter, shape, surface charge) using techniques like dynamic light scattering.
• Assessment of enzyme conformation and activity via circular dichroism spectroscopy and ELISA.
• Electron paramagnetic resonance (EPR) spectroscopy for spatial localization of encapsulated enzyme.
• Cytotoxicity assays on various cell lines.
• Intracellular transport studies using fluorescently labeled lysozyme.

Main Results:

• Poly(hydroxy butyrate)-based CPs form stable nanoscale self-assemblies with lysozyme, acting as enzyme-stabilizing platforms.
• Nanoparticle characteristics are dependent on CP molecular weight (M_n), with larger CPs forming assemblies at lower critical association concentrations.
• Lysozyme encapsulation preserves enzyme conformation and activity, enabling sustained release.
• Electron paramagnetic resonance confirms spatial immobilization of lysozyme within the CP scaffold.
• CP nanoparticles demonstrate minimal cytotoxicity and promote intracellular uptake of enzymes.

Conclusions:

• This study reports the first instance of enzyme encapsulation within a cyclic polymer scaffold.
• CP-based nanoparticles offer a promising platform for enzyme stabilization, controlled release, and intracellular delivery.
• The biocompatibility and efficacy of these nanostructures highlight their potential in therapeutic and biotechnological applications.