Biomimetic Formation and Tuning of a Cell Surface Heparan Sulfate Network: Approach on Deciphering the Glycosaminoglycans Code

The cell surface glycocalyx is a complex and dynamic network of glycoproteins and proteoglycans that plays a pivotal role in life activities. Its three-dimensional architecture is composed of various glycosaminoglycans (GAGs) mediating various biological functions. Exploring the structure of GAGs and its interaction with proteins or the GAGs code is of great significance for revealing the molecular mechanisms of biological processes. However, the structural complexity of the glycocalyx at both cellular and tissue scales poses challenges for accurate representation, while conventional planar sensors inadequately capture its multiscale spatial characteristics, thereby limiting precise analysis of dynamic GAG-protein interactions. In this study, a three-dimensional ordered interference substrate with surface-modified heparin was constructed to simulate the fine topological structure of the glycocalyx. On this ordered porous layer interferometry (OPLI) platform, combined with experimental and computer simulation methods, the effects of heparin density, spatial distribution, and chain length on the binding behavior of SARS-CoV-2 spike protein were systematically investigated. The experimental results show that a medium heparin density can maximize the binding strength of the spike protein. The affinity of heparin for spike protein can be enhanced by increasing the density of the three-dimensional spatial distribution. Molecular docking and thermodynamic experiments suggest that hydrogen bonds rather than electrostatic interactions play a crucial role in the binding strength. This study recreates the glycocalyx microenvironment, providing a highly biomimetic platform that not only deepens the molecular understanding of viral infection but also lays a methodological foundation for GAG code analysis and drug development.