Dilution of mixed micellar dispersions of egg phosphatidylcholine (PC) and sodium cholate beyond a critical value results in formation of cholate-containing PC vesicles. The structure of the resultant vesicles and some mechanistic aspects of this process have been investigated by the use of light scattering and nuclear magnetic resonance techniques. The main findings and conclusions are the following: Both the state of aggregation (micellar or vesicular) and the apparent equilibrium size distribution of micelles or vesicles obtained by dilution of the PC-cholate mixed micellar dispersions are a function of the cholate to PC molar ratio in the mixed aggregates (micelles or vesicles). When this effective ratio (Re) is higher than 0.4, the dispersion is micellar, and the size of the mixed micelles increases with decreasing Re; when Re less than 0.3, the dispersion is essentially vesicular, and the mean hydrodynamic radius of the vesicles is an increasing function of Re; in dispersions with 0.3 less than Re less than 0.4, mixed micelles and vesicles coexist. Addition of cholate to vesicular dispersions, to Re values below 0.3, results in vesicle size growth through a concentration-independent lipid-exchange mechanism. Addition of cholate to higher Re values results in micellization (solubilization) of the vesicles. On the other hand, dilution of vesicular dispersions does not affect the size of the vesicles. Apparent equilibration of a mixed micellar dispersion following dilution to Re values below 0.3 is slow (many hours). The overall process involves a series of three subsequent categories of steps: (i) a rapid (approximately 1-2 min) prevesiculation equilibration of micellar sizes.(ABSTRACT TRUNCATED AT 250 WORDS)

This communication describes the self-assembly of a tripeptide into a functional coating that resists biofouling. Using this peptide-based coating we were able to prevent protein adsorption and interrupt biofilm formation. This coating can be applied on numerous substrates and therefore can serve in applications related to health care, marine and water treatment.

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Peptidomimetic low‐molecular‐weight hydrogelators, a class of peptide‐like molecules with various backbone amide modifications, typically give rise to hydrogels of diverse properties and increased stability compared to peptide hydrogelators. Here, a new peptidomimetic low‐molecular‐weight hydrogelator is designed based on the well‐studied N ‐fluorenylmethoxycarbonyl diphenylalanine (Fmoc‐FF) peptide by replacing the amide bond with a frequently employed amide bond surrogate, the urea moiety, aiming to increase hydrogen bonding capabilities. This designed ureidopeptide, termed Fmoc—Phe—NHCONH—Phe—OH (Fmoc‐FuF), forms hydrogels with improved mechanical properties, as compared to those formed by the unmodified Fmoc‐FF. A combination of experimental and computational structural methods shows that hydrogen bonding and aromatic interactions facilitate Fmoc‐FuF gel formation. The Fmoc‐FuF hydrogel possesses properties favorable for biomedical applications, including shear thinning, self‐healing, and in vitro cellular biocompatibility. Additionally, the Fmoc‐FuF, but not Fmoc‐FF, hydrogel presents a range of functionalities useful for other applications, including antifouling, slow release of urea encapsulated in the gel at a high concentration, selective mechanical response to fluoride anions, and reduction of metal ions into catalytic nanoparticles. This study demonstrates how a simple backbone modification can enhance the mechanical properties and functional scope of a peptide hydrogel.

The self-assembly of a tripeptide into particles with different morphologies is described along with the particles application as antibiofouling and antimicrobial coatings.