Inhibition of protein aggregation by zwitterionic polymer-based core-shell nanogels

Robin Rajan,Kazuaki Matsumura

doi:10.1038/srep45777

Abstract

Protein aggregation is a process by which misfolded proteins polymerizes into aggregates and forms fibrous structures with a β-sheet conformation, known as amyloids. It is an undesired outcome, as it not only causes numerous neurodegenerative diseases, but is also a major deterrent in the development of protein biopharmaceuticals. Here, we report a rational design for the synthesis of novel zwitterionic polymer-based core-shell nanogels via controlled radical polymerization. Nanogels with different sizes and functionalities in the core and shell were prepared. The nanogels exhibit remarkable efficiency in the protection of lysozyme against aggregation. Addition of nanogels suppresses the formation of toxic fibrils and also enables lysozyme to retain its enzymatic activity. Increasing the molecular weight and degree of hydrophobicity markedly increases its overall efficiency. Investigation of higher order structures revealed that lysozyme when heated without any additive loses its secondary structure and transforms into a random coil conformation. In contrast, presence of nanogels facilitates the retention of higher order structures by acting as molecular chaperones, thereby reducing molecular collisions. The present study is the first to show that it is possible to design zwitterionic nanogels using appropriate polymerization techniques that will protect proteins under conditions of extreme stress and inhibit aggregation.

Highlights

Protein aggregation is a process by which misfolded proteins polymerizes into aggregates and forms fibrous structures with a β-sheet conformation, known as amyloids
Protein aggregation is a serious problem in the growing field of protein biopharmaceuticals[1] and has hampered the development of protein-based biological formulations
The polymers were characterized by NMR (Figure S1) and gel permeation chromatography (GPC)

Summary

Introduction

Protein aggregation is a process by which misfolded proteins polymerizes into aggregates and forms fibrous structures with a β-sheet conformation, known as amyloids It is an undesired outcome, as it causes numerous neurodegenerative diseases, but is a major deterrent in the development of protein biopharmaceuticals. The deposition of amyloid like fibrils has been associated with various neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases[4,5] Many compounds such as arginine[6], proline[7], osmolytes[8], and quinones[9] have been reported to suppress protein aggregation; excessively large amounts of these reagents are required, which limits their widespread application. Nanogels are nanosized hydrogels formed by hydrophobic, electrostatic, covalent, and coordinate bonds[14] Their small size results in large and tuneable surface areas, which allow for easy encapsulation of molecules. One interesting feature of zwitterionic polymers is its anti-biofouling www.nature.com/scientificreports/

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