Biology subjects

Zustiak, S. P.

Publications and source records attributed to Zustiak, S. P..

3 recordsLinked to original sources

bioRxiv2025

Substituent-based Modulation of Self-Assembly and Immunogenicity of Amphipathic Peptides

Peptide-based biomaterials assembled through monomer-by-monomer self-assembly provide versatile platforms for biomedical applications due to their adjustable physicochemical properties, biocompatibility, and dynamic nature. The self-assembly process largely depends on primary sequence features, such as hydrophobicity, length, and charge, which influence the formation of various nanostructures, including fibrils and hydrogels. Amphipathic peptides, characterized by alternating polar and hydrophobic residues, are especially effective in forming supramolecular nanofibers stabilized by {pi}-{pi} interactions and hydrogen bonds. Chemical modifications, particularly on aromatic side chains, have proven to be a promising approach for controlling assembly morphology, stability, and biological activity. In organic chemistry, the use of chemical substituents, such as halogens, alkyl groups, or electron-donating and electron-withdrawing groups, has been widely employed to alter reactivity, stability, and molecular interactions for diverse applications, including catalysts, pharmaceuticals, and materials science. However, the influence of these substituents on peptide packing and in vivo immunogenicity remains relatively unexplored. In this study, we systematically examine how changes in the position and nature of substituents on benzyl groups attached to short amphipathic peptides affect self-assembly, fibril morphology, and immune responses. By introducing different electron-donating and withdrawing groups at the para-position of benzyl rings and modifying the chain length connecting the backbone to the aromatic moiety, we observe notable effects on fibril formation, molecular packing, and immunogenicity both in vitro and in vivo. Our results show that subtle chemical modifications are effective tools for designing tailored peptide nanomaterials with promising potential in vaccine delivery, tissue engineering, and regenerative medicine.

bioengineering↗

bioRxiv2024

Enantiomeric histidine-rich peptide coacervates enhance antigen delivery to T cells

Peptides and peptidomimetics that self-assemble via LLPS have recently emerged as building blocks for fabricating functional biomaterials due to their unique physicochemical properties and dynamic nature. One of lifes most distinctive signatures is its selectivity for chiral molecules and, to date, coacervates comprised of D-amino acids have not been reported. Here, we demonstrate that histidine-rich repeats of (GHGXY)4 (X=L/V/P) and their enantiomers undergo LLPS opening new avenues for enhancing coacervate stability. Through a series of biophysical studies, we find that LLPS kinetics, droplet size, fusion, and encapsulation efficiency are dictated by the primary sequence. Further, these coacervates can encapsulate therapeutic cargo which are then internalized via endocytic mechanisms. Finally, we show that the coacervates enhance antigen presentation to CD4+ and CD8+ T cells resulting in robust proliferation and production of functional cytokines. Collectively, our study describes the development and characterization of enantiomeric peptide coacervates as attractive vaccine delivery vehicles with tunable physicochemical properties. HIGHLIGHTSO_LID amino acid-peptides were used for the first time to construct phase separating coacervates C_LIO_LIChirality does not restrict LLPS or modulate other coacervate properties C_LIO_LIAntigen delivery using chiral coacervates enhances and prolongs presentation to T cells C_LI PROGRESS AND POTENTIALPeptides can undergo self-assembly via liquid-liquid phase separation (LLPS) to result in solute-rich coacervates that can serve as biomaterials. Using histidine-rich peptide repeats, this work demonstrates that peptides composed of entirely D-amino acids can form functional coaceravtes. The kinetics of LLPS and bulk properties of the droplets can be controlled through simple amino acid substitutions. The coacervates, while immunologically inert, exert an adjuvanting effect and enhance antigen presentation to T cells leading to proliferation and functional cytokine production. The materials showcased here possess high translational potential for combined delivery of immunomodulators and antigens for vaccine delivery against infectious diseases or cancer. The deliverables from this study will also inspire the development of chiral systems that will contribute to the knowledge of cellular processes associated with phase changes integral to both physiology and pathology.

bioengineering↗

bioRxiv2023

Evaluation of gelatin bloom strength on gelatin methacryloyl hydrogel properties

Gelatin methacryloyl (GelMA) hydrogels are widely used for a variety of tissue engineering applications. The properties of gelatin can affect the mechanical properties of gelatin gels; however, the role of gelatin properties such as bloom strength on GelMA hydrogels has not yet been explored. Bloom strength is a food industry standard for describing the quality of gelatin, where higher bloom strength is associated with higher gelatin molecular weight. Here, we evaluate the role of bloom strength on GelMA hydrogel mechanical properties. We determined that both bloom strength of gelatin and weight percent of GelMA influenced both stiffness and viscoelastic ratio; however, only bloom strength affected diffusivity, permeability, and pore size. With this library of GelMA hydrogels of varying properties, we then encapsulated Swan71 trophoblast spheroids in these hydrogel variants to assess how bloom strength affects trophoblast spheroid morphology. Overall, we observed a decreasing trend of spheroid area and Feret diameter as bloom strength increased. In identifying clear relationships between bloom strength, hydrogel mechanical properties, and trophoblast spheroid morphology, we demonstrate that bloom strength should considered when designing tissue engineered constructs.

bioengineering↗