This work describes a chemically well defined method for patterning ligands to self-assembled monolayers (SAMs) of alkanethiolates on gold. This method begins with monolayers presenting a nitroveratryloxycarbonyl (NVOC)-protected hydroquinone which is photochemically irradiated to reveal a hydroquinone group. The resulting hydroquinone is then oxidized to the corresponding benzoquinone, providing a site for the Diels-Alder mediated immobilization of ligands. The rate constant for the photochemical deprotection is 0.032 s(-1) (with an intensity of approximately 100 mW/cm(2) between 355 and 375 nm), corresponding to a half-life of 21 s. The hydroquinone is oxidized to the benzoquinone using either electrochemical or chemical oxidation and then functionalized by reaction with a cyclopentadiene-tagged ligand. Two methods for patterning the immobilization of ligands are described. In the first, the substrate is illuminated through a mask to generate a pattern of hydroquinone groups, which are elaborated with ligands. In the second method, an optical microscope fit with a programmable translational stage is used to write patterns of deprotection which are then again elaborated with ligands. This technique is characterized by the use of well-defined chemical reactions to control the regions and densities of ligand immobilization and will be important for a range of applications that require patterned ligands for biospecific interactions.

Natural inspiration: A bioinspired functional material in the form of a hydrogel created by cross‐linking an engineered version of calmodulin, a protein which undergoes a conformational change in response to ligand binding (see schematic representation), with a four‐armed poly(ethylene glycol) molecule terminated with acrylate groups decreased in volume by 20 % when treated with the ligand trifluoperazine. Multiple cycles of gel swelling and shrinkage were possible.

Sea urchins and sea cucumbers, like other echinoderms, control the tensile properties of their connective tissues by regulating stress transfer between collagen fibrils. The collagen fibrils are spindle-shaped and up to 1 mm long with a constant aspect ratio of approx. 2000. They are organized into a tissue by an elastomeric network of fibrillin microfibrils. Interactions between the fibrils are regulated by soluble macromolecules that are secreted by local, neurally controlled, effector cells. We are characterizing the non-linear viscoelastic properties of sea cucumber dermis under different conditions, as well as the structures, molecules and molecular interactions that determine its properties. In addition, we are developing reagents that will bind covalently to fibril surfaces and reversibly form cross-links with other reagents, resulting in a chemically controlled stress-transfer capacity. The information being developed will lead to the design and construction of a synthetic analogue composed of fibres in an elastomeric matrix that contains photo- or electro-sensitive reagents that reversibly form interfibrillar cross-links.

This manuscript reports the application of the selective-withdrawal coating technique to the microencapsulation of insulin-producing pancreatic islets within thin poly(ethylene glycol) coatings. These polymer coatings permit the islets to respond to changes in glucose concentration by producing insulin with a dose-response profile that is substantially similar to that of unencapsulated islets. Furthermore, the hydrogel capsules exclude the large molecules of the immune system. These results suggest that the microencapsulation technique-which combines droplet formation from a flow of two immiscible fluids with polymerization chemistries-has the characteristics required for the transplantation of islets for the treatment of Type I diabetes.