A new class of microwires can be assembled by dielectrophoresis from suspensions of metallic nanoparticles. The wires are formed in the gaps between planar electrodes and can grow faster than 50 micrometers per second to lengths exceeding 5 millimeters. They have good ohmic conductance and automatically form electrical connections to conductive islands or particles. The thickness and the fractal dimension of the wires can be controlled, and composite wires with a metallic core surrounded by a latex shell can be assembled. The simple assembly process and their high surface-to-volume ratio make these structures promising for wet electronic and bioelectronic circuits.

In applications such as flavor encapsulation, drug delivery, and biomedical devices, microencapsulation is developing into an increasingly effective method for the protection and delivery of active ingredients. Herein, we show that spider-silk proteins are well-suited for producing responsive microcapsules with high mechanical stability. Emulsion interfaces are harnessed to induce the controlled self-assembly of these proteins into predominantly b-sheet configurations, resulting in a mechanically stable thin polymer shell. Capsules transferred into a continuous phase can readily encapsulate large molecules, while allowing small molecules to permeate freely. The capsules demonstrate good chemical stability, which is attributed to the b-sheet-rich structure of the self-assembled spider-silk proteins. These microcapsules represent a new class of biomimetic materials, exhibiting functionalities that can be further modified and controlled on the molecular level.

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We have conducted reversible addition−fragmentation chain transfer (RAFT) polymerization of n-hexyl methacrylate solubilized in a microemulsion using dodecyltrimethylammonium bromide as surfactant and 2-cyanoprop-2-yl dithiobenzoate (1) as the RAFT agent. The resulting latex particles are stable and much smaller, ranging from 18 to 30 nm depending on the mole ratio of RAFT agent 1 to the free radical initiator, 2,2‘-azobis(2-amidinopropane) hydrochloride (V50), than those produced by conventional microemulsion polymerization. The molecular weight increases linearly with conversion, and the polydispersity remains low when the number of RAFT agent molecules used is in excess of the initial number of swollen micelles. The RAFT technique can be successfully used in microemulsion polymerization to produce stable dispersions of small particles containing low molecular weight polymers. This is believed to be the first report of RAFT polymerization in microemulsion.

The assembly of colloidal particles at a liquid/liquid interface is a useful technique for the formation of a large variety of structures. Recently, we created a new method which uses liquid/liquid interfaces to assemble recombinant silk proteins into thin-shelled microcapsules. These microcapsules are mechanically stable and well suited to applications such as enzyme therapy and artificial cells. In this paper the permeability properties of these microcapsules are investigated using a novel measurement technique. It is found that the microcapsules are polydisperse in their permeabilities, but for all measured microcapsules the permeability is in the range required to protect encapsulants from immunoglobulin proteins, while allowing small molecules to enter the capsule freely.