A Matter of Charge: Electrostatically Tuned Coassembly of Amphiphilic Peptides.

Coassembly of peptide biomaterials offers a compelling avenue to broaden the spectrum of hierarchically ordered supramolecular nanoscale structures that may be relevant for biomedical and biotechnological applications. In this work coassemblies of amphiphilic and oppositely charged, anionic and cationic, β-sheet peptides are studied, which may give rise to a diverse range of coassembled forms. Mixtures of the peptides show significantly lower critical coassembly concentration (CCC) values compared to those of the individual pure peptides.

Decoupling Charge and Side Chain Effects in Hierarchical Organization of Cationic PFX Peptide and Alginate.

We have successfully created self-assembled membranes by combining positively charged (Pro-X-(Phe-X)-Pro) PFX peptides with negatively charged alginate. These PFX/alginate membranes were formed by three different peptides that contain either X = Arginine (R), Histidine (H), or Ornithine (O) as their charged amino acid. The assemblies were compared to membranes that were previously reported by us composed of X = lysine (K).

Self-assembly at the interface of λ-carrageenan and amphiphilic and cationic peptides: More than meets the eye.

Self-assembly of macroscopic membranes at the interface between self-assembling peptides and aqueous polymer solutions of opposite charge has been explored mostly due to the membranes' unique hierarchical structure of three distinct regions, including a layer of perpendicular fibers. We report here on the formation and characterization of self-assembled membranes made with λ-carrageenan and the cationic β-sheet peptides, Pro-Lys-(Phe-Lys)-Pro (PFK). Using SAXS, SEM, ITC, and rheology, we compared these membranes' morphology and physical properties to membranes made with alginate.

Native Glucagon Amyloids Catalyze Key Metabolic Reactions.

Glucagon is a prominent peptide hormone, playing central roles in the regulation of glucose blood-level and lipid metabolism. Formation of glucagon amyloid fibrils has been previously reported, although no biological functions of such fibrils are known. Here, we demonstrate that glucagon amyloid fibrils catalyze biologically important reactions, including esterolysis, lipid hydrolysis, and dephosphorylation.

Time matters for macroscopic membranes formed by alginate and cationic β-sheet peptides.

Hierarchically ordered planar and spherical membranes (sacs) were constructed using amphiphilic and cationic β-sheet peptides that spontaneously assembled together with negatively charged alginate solution. The system was found to form either a fully developed membrane structure with three distinct regions including characteristic perpendicular fibers or a non-fully developed contact layer lacking these standing fibers, depending on the peptide age, membrane geometry and membrane incubation time. The morphological differences were found to strongly depend on fairly-long incubation time frames that influenced both the peptide's intrinsic alignment and the reaction-diffusion process taking place at the interface.

Sensing Exposure Time to Oxygen by Applying a Percolation-Induced Principle.

The determination of food freshness along manufacturer-to-consumer transportation lines is a challenging problem that calls for cheap, simple, reliable, and nontoxic sensors inside food packaging. We present a novel approach for oxygen sensing in which the exposure time to oxygen-rather than the oxygen concentration per se-is monitored. We developed a nontoxic hybrid composite-based sensor consisting of graphite powder (conductive filler), clay (viscosity control filler) and linseed oil (the matrix).

Hydrogels composed of hyaluronic acid and dendritic ELPs: hierarchical structure and physical properties.

Hydrogels that mimic the native extracellular matrix were prepared from hyaluronic acid (HA) and amine-terminated dendritic elastin-like peptides (denELPs) of generations 1, 2, and 3 (G1, 2, and 3) as crosslinking units. The physical properties of the hydrogels were investigated by rheology, scanning electron microscopy, swelling tests, small-angle X-ray scattering (SAXS), and model drug loading and release assays. Hydrogel properties depended on the generation number of the denELP, which contained structural segments based on the repeating GLPGL pentamer.