We have shown previously that carbohydrate-specific bacterial adhesion to a non-physiological surface can be photocontrolled by reversible E/Z isomerisation using azobenzene-functionalised sugars. Here, this approach is applied to the surface of human cells. We show not only that bacterial adhesion to the azobenzene glycoside-modified cell surface is higher in the E than in the Z state, but add...

The electric field applied between the tip of a scanning tunneling microscope and a metallic surface is shown to induce the reversible trans-cis isomerization of single azobenzene derivatives adsorbed on a Au(111) surface. The investigated molecule is symmetrically equipped with four tert-butyl groups, which decouple the azobenzene core from the metallic surface, facilitating the formation of h...

For many applications it would be desirable to be able to control the activity of proteins by using an external signal. In the present study, we have explored the possibility of modulating the activity of a restriction enzyme with light. By cross-linking two suitably located cysteine residues with a bifunctional azobenzene derivative, which can adopt a cis- or trans-configuration when illuminat...

The movement of a liquid droplet on a flat surface functionalized with a photochromic azobenzene may be driven by the irradiation of spatially distinct areas of the drop with different UV and visible light fluxes to create a gradient in the surface tension. In order to better understand and control this phenomenon, we have measured the wetting characteristics of these surfaces for a variety of ...

We have recently developed a technique that has great potential in producing proteins with photo-control of conformation and consequently activity (J. R. Kumita, O. S. Smart and G. A. Woolley, Proc. Natl. Acad. Sci. U. S. A., 2000, 97, 3803-3808). The method is based on incorporating two cysteine residues into the sequence of a polypeptide. An azobenzene derivative is subsequently used to produ...

We report a novel way to modulate the elastic modulus of azobenzene containing liquid crystal networks (LCNs) by exposure to light. The elastic modulus can cycle between different levels by controlling the illumination conditions. Exposing the polymer network to UV light near the trans absorption band of azobenzene gives a small reduction of the glass transition temperature thereby lowering the...

In this article are described dendritic structures containing photoactive groups at the surface or in the core. The observed supramolecular effects can be attributed to the nature of the photoactive group and their location in the dendritic architecture. The peripheric azobenzene groups in these dendrimeric compounds can be regarded as single residues that retain the spectroscopic and photochem...

The optical switching of coupled plasmons of silver nanoparticles derivatised with a photoisomerisable azobenzene ligand is presented. It is shown that nanoparticle clusters, linked with an azobenzene dithiol molecule, display switchable optical properties. The photoisomerisation of the linker molecule was used to vary the separation between nanoparticles, which was monitored by changes in the ...

Azobenzene derivatives are a unique class of photo-switch molecules with promising potential for nanoscale optical applications. We have studied the self-assembly and photo-induced mechanical switching azobenzene on Au(111) at single-molecule level by using scanning tunneling microscope (STM). 4,4′-Dibromo-azobenzene (Br-AB) assembled into two types well-ordered structures surfaces in trans-iso...

In order to allow spatial and temporal control of carbohydrate-specific bacterial adhesion, it has become our goal to synthesise azobenzene mannosides as photoswitchable inhibitors of type 1 fimbriae-mediated adhesion of E. coli. An azobenzene mannobioside 2 was prepared and its photochromic properties were investigated. The E→Z isomerisation was found to be highly effective, yielding a long-li...