Deciphering Supramolecular Nucleopeptide-Based Hydrogel Formation through Unique Combination of NMR Methods and...

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.