In situ single particle characterization of the themoresponsive and co-nonsolvent behavior of PNIPAM microgels and silica@PNIPAM core-shell colloids.

Poly(N-isopropylacrylamide) (PNIPAM) microgels and PNIPAM colloidal shells attract continuous strong interest due to their thermoresponsive behavior, as their size and properties can be tuned by temperature. The direct single particle observation and characterization of pure, unlabeled PNIPAM microgels in their native aqueous environment relies on imaging techniques that operate either at interfaces or in cryogenic conditions, thus limiting the observation of their dynamic nature. Liquid Cell (Scanning) Transmission Electron Microscopy (LC-(S) TEM) imaging allows the characterization of materials and dynamic processes such as nanoparticle growth, etching, and diffusion, at nanometric resolution in liquids.

Repulsive van der Waals forces enable Pickering emulsions with non-touching colloids.

Emulsions stabilized by solid particles, called Pickering emulsions, offer promising applications in drug delivery, cosmetics, food science and the manufacturing of porous materials. This potential stems from their high stability against coalescence and 'surfactant-free' nature. Generally, Pickering emulsions require that the solid particles are wetted by both phases and as a result, the adsorption free energy is often large with respect to the thermal energy (kBT).

Charging of poly(methyl methacrylate) (PMMA) colloids in cyclohexyl bromide: locking, size dependence, and particle mixtures.

We studied suspensions of sterically stabilized poly(methyl methacrylate) (PMMA) particles in the solvent cyclohexyl bromide (CHB; εr = 7.92). We performed microelectrophoresis measurements on suspensions containing a single particle species and on binary mixtures, using confocal microscopy to measure the velocity profiles of the particles.

A reduced SNARE model for membrane fusion.

Let's get together: A minimal model system was developed to mimic the SNARE-protein-mediated fusion of biological membranes (see picture). Fusion between two populations of liposomes is controlled by a pair of complementary lipidated oligopeptides that form noncovalent coiled-coil complexes and thereby force the membranes into close proximity to promote fusion. The model system displays the key characteristics of in vivo fusion events.