Water-in-oil-in-water emulsions are examples of double emulsions, in which dispersions of small water droplets within larger oil droplets are themselves dispersed in a continuous aqueous phase. Emulsions occur in many forms of processing and are used extensively by the foods, cosmetics and coatings industries. Because of their compartmentalized internal structure, double emulsions can provide advantages over simple oil-in-water emulsions for encapsulation, such as the ability to carry both polar and non-polar cargos, and improved control over release of therapeutic molecules. The preparation of double emulsions typically requires mixtures of surfactants for stability; the formation of double nanoemulsions, where both inner and outer droplets are under 100 nm, has not yet been achieved. Here we show that water-in-oil-in-water double emulsions can be prepared in a simple process and stabilized over many months using single-component, synthetic amphiphilic diblock copolypeptide surfactants. These surfactants even stabilize droplets subjected to extreme flow, leading to direct, mass production of robust double nanoemulsions that are amenable to nanostructured encapsulation applications in foods, cosmetics and drug delivery.

Polymer-mediated self-assembly of functionalized Pd and SiO2 nanoparticles provides highly active hydrogenation and Heck coupling catalysts.

Block copolymer micelles have been used extensively as carriers for therapeutic drugs and diagnostic molecules. Here, we report the synthesis of nonionic, block copolypeptides, K P x (rac-L) y , which have a "reversed" rod-coil structure composed of a hydrophilic, rod-like, α-helical segment attached to a disordered, racemic hydrophobic segment. The self assembly of these block copolypeptides in water was studied, and their compositions were optimized to identify a sample, K P 100 (rac-L) 10 , which is able to form well defined micelles that are very stable against dilution, high temperatures, and various media. Micelle structure was determined using a combination of electron microscopy and dynamic light scattering measurements. The potential of these micelles as drug delivery carriers was evaluated by encapsulation of the anticancer drug camptothecin. The drug containing micelles were found to be stable.Micelles are widely used to disperse materials for a range of food, 1 cosmetic, 2 and pharmaceutical 3 applications. These nanoscale assemblies are composed of amphiphilic molecules that self-assemble in water. 3 Block copolymers make up a large class of micelle forming molecules, 2,4,5 and include those containing polypeptide segments, which can be enzymatically degraded to natural metabolites and possess ordered conformations not found in conventional polymers. Numerous "rod-coil" micelles have been prepared using α-helical hydrophobic polypeptides conjugated to hydrophilic polyethylene glycol (PEG) segments, such as PEG-b-poly (γ-benzyl-L-glutamate) 6,7 and PEG-b-poly(β-benzyl-L-aspartate). 8 β-strand polypeptide segments have also been used to facilitate interchain interactions and increase micelle stability. 9 Here, we report the synthesis of poly(rod-coil block copolymers where the rod-like component is the hydrophilic segment. Use of disordered racemic hydrophobic segments was found to favor formation of spherical micelles in water that can entrap cargos and possess a nonionic, PEG-like corona potentially useful for drug delivery applications ( Figure 1A). 10 We previously reported that homopolypeptides of diethylene glycol modified lysine residues, K P , are nonionic, water soluble, and thermally stable α-helices. 11 These segments were used to prepare rod-rod amphiphilic diblock copolypeptides, K P x -b-poly(L-leucine), K P x L y , which were found to self-assemble into micron-sized vesicles and sheets in water * demingt@seas.ucla.edu .Supporting Information Available: Synthesis, experimental procedures, and additional data on the assemblies. This material is available free of charge via the Internet at http://pubs.acs.org. NIH Public Access Author ManuscriptMacromolecules. Author manuscript; available in PMC 2011 July 1. where assembly morphology was strongly directed by the preferred packing of α-helical poly(L-leucine) segments. 12 The K P x L y vesicles were stable under a variety of solution conditions and able to encapsulate small hydrophilic molecules. To disfavor formation of membranes a...

Antimicrobial properties of a long‐chain, synthetic, cationic, and hydrophobic amino acid block copolymer are reported. In 5 and 60 min time‐kill assays, solutions of K100L40 block copolymers (poly(l‐lysine·hydrochloride)100‐b‐poly(l‐leucine)40) at concentrations of 10–100 µg mL−1 show multi‐log reductions in colony forming units of Gram‐positive and Gram‐negative bacteria, as well as yeast, including multidrug‐resistant strains. Driven by association of hydrophobic segments, K100L40 copolymers form viscous solutions and self‐supporting hydrogels in water at concentrations of 1 and 2 wt%, respectively. These K100L40 preparations provide an effective barrier to microbial contamination of wounds, as measured by multi‐log decreases of tissue‐associated bacteria with deliberate inoculation of porcine skin explants, porcine open wounds, and rodent closed wounds with foreign body. Based on these findings, amino acid copolymers with the features of K100L40 can combine potent, direct antimicrobial activity and barrier properties in one biopolymer for a new approach to prevention of wound infections.

Inside Front Cover: Designed for local application to exposed tissues, a synthetic lysine‐leucine biopolymer, K100L40, provides a combination of direct microbicidal activity and barrier properties. These amino acid block copolymers are active against Gram‐positive and Gram‐negative bacteria, as well as yeast. Driven by association of water insoluble leucine segments, they form viscous solutions and hydrogels that are effective barriers against microbial contamination of tissues. These materials represent a new approach to the prevention of life‐threatening infections that can complicate surgery and trauma. This is reported by Michael P. Bevilacqua, Daniel J. Huang, Brian D. Wall, Shalyn J. Lane, Carl K. Edwards, III, Jarrod A. Hanson, Diego Benitez, Joseph S. Solomkin, and Timothy J. Deming, article number https://doi.org/10.1002/mabi.201600492.