Ammonium-based Ionic Liquid: A Hydrophobic-Chain Ruler Towards Protein Aggregation and Disaggregation

Abstract

This study investigates the thermal-induced aggregation and ionic liquid-based disaggregation of Bone Morphogenetic Protein-2 (BMP-2) using ammonium-based ionic liquids. Spectroscopic techniques, including FTIR, DLS, and fluorescence spectroscopy, alongside electron microscopy, reveal that ionic liquids with longer alkyl chains (e.g., N8) promote the transformation of aggregated BMP-2 into amyloid fibrils with a hydrodynamic radius of 635 ± 43 nm. Conversely, shorter chain ionic liquids (e.g., N6, N4, N2) effectively disaggregate preformed BMP-2 aggregates, reducing their sizes to 520 ± 18 nm, 77 ± 11 nm, and 42 ± 5 nm, respectively. The disaggregation is attributed to the decreasing hydrophobicity of the ionic liquids as the alkyl chain length shortens, with N2 and N4 being the most effective disaggregating agents