Peptide Sequence Determines Structural Sensitivity to Supramolecular Polymerization Pathways and Bioactivity

Abstract

Pathways in supramolecular polymerization traverse different regions of the system's energy landscape, affecting not only their architectures and internal structure but also their functions. We report here on the effects of pathway selection on polymerization for two isomeric peptide amphiphile monomers with amino acid sequences AAEE and AEAE. We subjected the monomers to five different pathways that varied in the order they were exposed to electrostatic screening by electrolytes and thermal annealing. We found that introducing electrostatic screening of E residues before annealing led to crystalline packing of AAEE monomers. Electrostatic screening decreased intermolecular repulsion among AAEE monomers thus promoting internal order within the supramolecular polymers, while subsequent annealing brought them closer to thermodynamic equilibrium with enhanced βsheet secondary structure. In contrast, supramolecular polymerization of AEAE monomers was less pathway dependent, which we attribute to side-chain dimerization. Regardless of the pathway, the internal structure of AEAE nanostructures had limited internal order and moderate β-sheet structure. These supramolecular polymers generated hydrogels with lower porosity and greater bulk mechanical strength than those formed by the more cohesive AAEE polymers. The combination of dynamic, less ordered internal structure and bulk strength of AEAE networks promoted strong cell−material interactions in adherent epithelial-like cells, evidenced by increased cytoskeletal remodeling and cell spreading. The highly ordered AAEE nanostructures formed porous hydrogels with inferior bulk mechanical properties and weaker cell−material interactions. We conclude that pathway sensitivity in supramolecular synthesis, and therefore structure and function, is highly dependent on the nature of dominant interactions driving polymerization.

Supramolecular polymers: Dynamic assemblies of “dancing” monomers

“…Tuning the amplitude of supramolecular motion and selecting the necessary operative mechanisms will require a deeper understanding of dynamics so that monomer design and pathway-dependent polymerization strategies can be implemented. 21,22 In our view, experimental techniques that come to mind to help us get there include multinuclear and multiphase NMR 23 and advanced optical techniques such as STORM 10,12 to analyze the "polymerized state" of monomers, high resolution atomic scale cryo-electron microscopy, 24 hydrogen-deuterium exchange kinetics via mass spectroscopy, 25 and thermo-analytical methods 26 that can provide information on cohesive energy among monomers. New theories on supramolecular dynamics are of course also important, as are all-atom MD simulations 27 and artificial intelligence 28 to provide insights on internal structure of supramolecular polymers varying in dynamic behavior and this way inform monomer design.…”

Transformable nano-antibiotics for mechanotherapy and immune activation against drug-resistant Gram-negative bacteria

“…On the other hand, bacterial immunotherapy based on organic nanostructures is emerging (24)(25)(26)(27). Assembly of nanofibrils from peptide/protein has been found to regulate the phenotype of immune cells (28)(29)(30)(31)(32), astrocytes (33), and epithelial-like cells (34). Therefore, the outer membrane targeted in situ morphology transformation of nano-antibiotics is anticipated to be but one effective approach for outer membrane disruption and antigen release, and the newly formed peptide nanofibrils and released antigens should enable the subsequent activation of host innate and adaptive immune system.…”

Supramolecular presentation of bioinstructive peptides on soft multilayered nanobiomaterials stimulates neurite outgrowth

“…24 Furthermore, their peptide sequence can be rationally designed and customized to impart any biofunctionality to enable desired cellular responses. 6,25 In the literature one can find several studies that highlight the bottom-up nanofabrication of tunable PA-derived supramolecular matrices to control cell-biomaterial interactions for multiple tissue engineering strategies, 26,27 including nerve tissue regeneration. 28,29…”