Title: In Situ 3D Structural Determination of Soft Biomaterials by Computationally Assisted Polarized Raman Spectroscopy

Authors: Xiao-Han Xi, Hao Ma*, Sen Yan, Lin-Yuan Chen, Xin-Di Pei, Yan-Ti Liu, Ping-Shi Wang, Zi-Ang Nan, Xian-Kui Wei, Xiang Wang*, Bin Ren*

Abstract: Soft biomaterials, characterized by structural disorder and weak interactions, pose significant challenges for structural characterization by conventional methods, which typically rely on long-range crystalline order or strong electron scattering. Here, we report a computationally assisted polarized Raman spectroscopy strategy that enables direct, in situ determination of three-dimensional (3D) molecular structures and their intermolecular interactions, correlating molecular-scale orientations with macroscopic morphologies. We validated our approach using the well-characterized α-glycine crystal, achieving structural precision comparable to that of single-crystal X-ray diffraction (RMSD = 0.367 ± 0.003 Å). Extending our method to structurally complex peptides, we resolve biomaterial diphenylalanine structure (RMSD = 0.743 ± 0.009 Å) and determine Alzheimer’s-associated peptide (r-acAβ) assemblies at angstrom precision. Furthermore, our approach uniquely identified specific vibrational signatures associated with hydrogen bonding and hydrophobic interactions, linking the reversible switching of peptide self-assembly through environmental stimuli. This method provides a transformative structural characterization platform, offering critical insights into molecular assembly mechanisms and enabling the rational design of next-generation functional biomaterials.

Full-Link: https://pubs.acs.org/doi/10.1021/jacs.5c09396