Deciphering Supramolecular Nucleopeptide-Based Hydrogel Formation through Unique Combination of NMR Methods and Molecular Dynamics Simulations

Abstract

Nucleopeptide-based hydrogels are attracting growing interest owing to their biocompatibility and wide range of applications, particularly in biotechnology. Their enhanced versatility compared to purely peptide-based systems enables fine-tuning of macroscopic properties to meet specific requirements. However, rational optimization of these materials requires a thorough understanding of their atomic-scale organization, which remains challenging due to the inherent nature of these amorphous, soft, and highly hydrated materials. In this context, nuclear magnetic resonance (NMR) spectroscopy emerges as a powerful technique for gaining valuable insights into both the isotropic and anisotropic phases of the samples. This work focuses on developing a unique combination of NMR methodologies to characterize the structural and dynamical parameters of these hydrogels. Fast-field cycling (FFC) NMR relaxometry is employed to probe the dynamical changes occurring during the gelation process and to elucidate the complex mechanisms driving the liquid-to-gel transition. Furthermore, solid-state NMR (ssNMR) experiments, performed on samples in protonated and deuterated solvents, provide key insights into the intermolecular interactions that structure the three-dimensional gel network. Molecular dynamics (MD) simulations corroborate these experimental findings and assess the stability and prevalence of various noncovalent interactions, while shedding light on the role of Watson–Crick pairing during the initial oligomerization steps.