Interest in nanostructures, artificial compartments and smart materials is steadily increasing as a result of beneficial applications in sensors, tissue engineering, nanoreactors and drug delivery systems. Block copolymers, peptide-based hybrid materials, expressed protein-like copolymers, and peptides that selfassemble in aqueous solution fulfill the demands of such applications while providing maximum biocompatibility. Herein, we focus on the formation of self-assembled particles using an amphiphilic amino acid (AA) sequence derived by solid-phase peptide synthesis (SPPS) and describe its purification and characterisation. The prepared undecamer features a repetitive L-tryptophan and D-leucine [LW-DL] motif representing the hydrophobic block, and an N-terminally attached hydrophilic (lysine or acetylated lysine) section. For peptides containing charged lysine, aggregation into micelles and a minor fraction of peptide particles was observed. Charge shielding with anionic counter ions shifted the equilibrium towards the larger peptide aggregates, with their size depending on the counter ion's position in the Hofmeister series. Similarly, the corresponding uncharged (acetylated) peptide was also demonstrated to assemble into micelles and subsequently into peptide particles, termed 'peptide beads', which we hypothesise to be multicompartment micelles. The formation of the peptide beads was studied as a function of temperature and solvent composition by means of electron paramagnetic resonance (EPR), dynamic and static light scattering, fluorimetry and electron microscopy. The results suggest an equilibrium between single peptide molecules, micelles, and peptide beads. Interestingly once formed the peptide beads show high mechanical stability and preserve their shape and dimensions even after isolation from solution.

In this article, we review the recent advances in the field of block copolymer membranes. We discuss the similarities and differences between natural membranes and their polymeric counterparts, pointing out the advantages of the latter in applications for biosciences and biomaterials. Membrane properties are discussed in terms of functionality and responsiveness, and the most interesting application possibilities are highlighted.

Biocompatible, self-assembled nanostructures are attracting ever more attention, in particular in aqueous media for biomedical applications. Here, we present the successful, solid-phase peptide synthesis (SPPS) and characterization of short amino acid sequences with amphiphilic character with the aim of gaining insight into their self-assembled, supramolecular structures. The peptide design includes three parts: (a) a charged lysine part, (b) an acetylated lysine part, and (c) a constant hydrophobic rodlike helix, based on gramicidin A (gA). By stepwise replacement of free lysine (K) with acetylated lysine (X) we generated a library of a total of 10 peptides, Ac-X(8)-gA and K(m)X(8-m)-gA (m ranging from 0 to 8). By using point mutations, we adjusted the degree of acetylation (DA) and thus the overall amphiphilicity of the peptides, which led to a change in the secondary structure in the aqueous environment from a β-sheet to an α-helix. This transition generated a significant change in the morphology of the self-assembled structures from fibers to micelles. Two different regions were observed for the conformation of the hydrophilic part of the peptide: one region, a β-sheet-like secondary structure, inducing fiber formation (high DA), the other an α-helical-like secondary structure, generating micelle formation (moderate and low DA). The micellar structures depended on the degree of acetylation, which influenced their critical micelle concentration (cmc). These morphology regions were determined by a combination of circular dichroism, dynamic light scattering, surface tension, and transmission electron microscopy, which allowed us to correlate the generated supramolecular architectures with the fine changes obtained by means of the point mutation strategy.

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Short, amphiphilic peptides self‐assemble into vesicles due to dimerization. These additional interactions lead to the formation of stable peptide membranes. The vesicles demonstrate pH responsiveness and the ability to encapsulate hydrophobic and hydrophilic moieties within their structure, and therefore may be used as an advanced, biodegradable, drug‐delivery system.