Polymersome stomatocytes: controlled shape transformation in polymer vesicles.

We report here a controllable shape transformation of polymer vesicles (polymersomes) constructed from block copolymers of which the hydrophobic part is a high-molecular-weight glassy segment. Control over the shape transformation is obtained by kinetic manipulation of the phase behavior of this glassy hydrophobic segment. Kinetic manipulation of the phase behavior of polymer membranes allows for different shapes of polymersomes to be captured at specific times, which directly translates into physically robust nanostructures that are otherwise unobtainable.

Smart nanocontainers and nanoreactors.

We highlight recent advances in the synthesis of nanocarriers and nanoreactors from synthetic and biological building blocks with emphasis on the stimulus-responsive regulation of their function.

Site-specific immobilization of DNA in glass microchannels via photolithography.

For the first time, a microchannel was photochemically patterned with a functional linker. This simple method was developed for the site-specific attachment of DNA via this linker onto silicon oxide surfaces (e.g.

Stimulus responsive peptide based materials.

In this tutorial review we give an introduction into the field of stimulus responsive peptide based materials illustrated by some recent and current developments. We have tried to categorize them according to the stimulus the materials are responsive to, being pH, temperature, metal ions, enzymes and light. Because we have focused on the structural changes that these stimuli effect we have further classified the topics according to the secondary structures that are involved.

Effect of the diacetylene position on the chromatic properties of polydiacetylenes from self-assembled peptide amphiphiles.

Three diacetylene-containing peptide amphiphiles, with exactly the same structure, except for the position of the diacetylene moiety within the hydrophobic tail, were investigated on their assembly behavior, polymerization characteristics, and chromatic properties. After polymerization it was found that the color and, thus, the conjugation length of the polydiacetylenes was dependent both on mobility and on packing of the groups on both sides of the triple bonds. The polydiacetylene with the highest conjugation length and most stable structure was obtained when the diacetylenes were positioned in the middle of the hydrophobic tail.

Elastin-based stimuli-responsive gold nanoparticles.

Gold nanoparticles covered with ligands consisting of only a single repeat of the elastin-based pentapeptide VPGVG exhibit a stimuli-responsive behaviour.

Preparation of biodegradable liquid core PLLA microcapsules and hollow PLLA microcapsules using microfluidics.

Biodegradable PLLA capsules with a narrow size distribution were prepared using a microfluidics platform. With this technique, an oil-in-water emulsion was produced in which the polymer, a hydrophobic non-volatile non-solvent and a hydrophobic model drug were dissolved in the organic phase. The polymer precipitated at the droplet interface, yielding a drug deliverable microcapsule of which the release of this model drug was investigated.

Flash chemistry extensively optimized: high-temperature Swern-Moffatt oxidation in an automated microreactor platform.

The generally accepted benefits of small lateral dimensions of microreactors (1 microm to 1 mm) enable a different way of performing synthetic chemistry: Extremely short contact times in the millisecond range can circumvent the need for performing highly exothermic and fast reactions at very low temperatures. In order to fully exploit this technology, such fast processes need to be redesigned and investigated for optimal reaction conditions, which can differ drastically from the ones traditionally applied. In a comprehensive study, we optimized the selective Swern-Moffatt oxidation of benzyl alcohol to benzaldehyde by varying five experimental parameters, including reaction time and temperature.

Aza-dibenzocyclooctynes for fast and efficient enzyme PEGylation via copper-free (3+2) cycloaddition.

A strained aza-dibenzocyclooctyne was prepared via a high-yielding synthetic route. Copper-free, strain-promoted click reaction with azides showed excellent kinetics, and a functionalised aza-cyclooctyne was applied in fast and efficient PEGylation of enzymes.

Polypeptide-polymer bioconjugates.

Creating bioconjugates by combining polymers with peptides and proteins is an emerging multidisciplinary field of research that has enjoyed increased attention within the scientific community. This critical review provides an overview of the strategies employed for the construction of these materials and will highlight the underlying synthetic methods used. This review is therefore relevant for chemists, material scientists and chemical biologists facing the challenge of constructing polypeptide-polymer bioconjugates in a controlled fashion (269 references).

Synthetic cells and organelles: compartmentalization strategies.

The recent development of RNA replicating protocells and capsules that enclose complex biosynthetic cascade reactions are encouraging signs that we are gradually getting better at mastering the complexity of biological systems. The road to truly cellular compartments is still very long, but concrete progress is being made. Compartmentalization is a crucial natural methodology to enable control over biological processes occurring within the living cell.

Polymeric monosaccharide receptors responsive at neutral pH.

We present the first detailed report of the synthesis of Wulff-type styrenic monomers and their polymerization by radical addition-fragmentation chain transfer (RAFT) methods. The resulting polymers and block copolymers exhibit sugar-responsive solubilization in aqueous buffer solutions (pH = 7.4-7.

Patterns of diacetylene-containing peptide amphiphiles using polarization holography.

The polarization dependence of a diacetylene polymerization was studied. For this purpose, peptide amphiphile fibers with a diacetylene moiety, which could only polymerize in the direction of the fiber, were employed. If nonaligned samples were illuminated with polarized light, only the fibers parallel to the polarization direction of the light were polymerized.

Synergy between chemo- and bio-catalysts in multi-step transformations.

Cascade synthetic pathways, which allow multi-step conversions to take place in one reaction vessel, are crucial for the development of biomimetic, highly efficient new methods of chemical synthesis. Theoretically, the complexity introduced by combining processes could lead to an improvement of the overall process; however, it is the current general belief that it is more efficient to run processes separately. Inspired by natural cascade procedures we successfully combined a lipase catalyzed amidation with palladium catalyzed coupling reactions, simultaneously carried out on the same molecule.

"Clickable" elastins: elastin-like polypeptides functionalized with azide or alkyne groups.

Elastin-like polypeptides (ELPs) functionalized with azide or alkyne groups were produced biosynthetically and coupled via the Cu-catalyzed azide-alkyne cycloaddition to a variety of (bio)molecules.

Single-step azide introduction in proteins via an aqueous diazo transfer.

The controlled introduction of azides in proteins provides targetable handles for selective protein manipulation. We present here an efficient diazo transfer protocol that can be applied in an aqueous solution, leading to the facile introduction of azides in the side chains of lysine residues and at the N-terminus of enzymes, e.g.

A three-enzyme cascade reaction through positional assembly of enzymes in a polymersome nanoreactor.

Porous polymersomes based on block copolymers of isocyanopeptides and styrene have been used to anchor enzymes at three different locations, namely, in their lumen (glucose oxidase, GOx), in their bilayer membrane (Candida antarctica lipase B, CalB) and on their surface (horseradish peroxidase, HRP). The surface coupling was achieved by click chemistry between acetylene-functionalised anchors on the surface of the polymersomes and azido functions of HRP, which were introduced by using a direct diazo transfer reaction to lysine residues of the enzyme. To determine the encapsulation and conjugation efficiency of the enzymes, they were decorated with metal-ion labels and analysed by mass spectrometry.

Enzymes containing porous polymersomes as nano reaction vessels for cascade reactions.

Polystyrene(40)-b-poly(isocyanoalanine(2-thiophen-3-yl-ethyl)amide)(50) (PS-PIAT) polymersomes have the unique property of being sufficiently porous to allow diffusion of small (organic) substrates while retaining large biomolecules such as enzymes inside. Herein we report on the encapsulation and protection of glucose oxidase (GOx) and horse radish peroxidase (HRP) in PS-PIAT polymersomes and the successful employment of these functionalised nanoreactors in a cascade reaction. The demonstrated concept allows for further application in other enzymatic cascade reactions, bio-organic hybrid systems and biosensing devices.