Surface and Interface Control on Photochemically Initiated Immobilization

Abstract

Surface and interface properties are important in controlling the yield and efficiency of the photochemically initiated immobilization. Using a silane-functionalized perfluorophenyl azide (PFPA-silane) as the photoactive cross-linker, the immobilization of polymers was studied by adjusting the density of the surface azido groups. Dilution of the photolinker resulted in a gradual decrease in the density of surface azido groups as well as the thickness of the immobilized film. When a nonphotoactive silane was added to PFPA-silane, the film thickness decreased more rapidly, suggesting that the additive competed with PFPA-silane and effectively reduced the density of the surface azido groups. The effect of surface topography was studied by adding a nonphotoactive silane with either a shorter (n-propyltrimethoxysilane (PTMS)) or a longer spacer (n-octadecyltrimethoxysilane (ODTMS)). In most cases the long chain ODTMS shielded the surface azido groups, resulting in a more rapid decrease in film thickness as compared to PTMS treated under the same conditions. As the density of the surface azido groups decreased, the immobilized polymer changed from smooth films to patched structures and, eventually, single polymer molecules.

Silane coupling agent bearing a photoremovable succinimidyl carbonate for patterning amines on glass and silicon surfaces with controlled surface densities

“…Most of these methods can be categorized into two groups: (i) those based on photochemically generated radicals using aryl azides [15,16], benzophenones [17][18][19], anthraquinones [20], photosensitive amino acids [21], dye bleaching [22], or photocatalytic reactions [23] and (ii) those based on reactive functional groups protected by a photocleavable group, such as caged amines [24,25], caged carboxy groups [26,27], caged oximes [28], caged biotins [29], and caged aldehydes [30]. The former category of methods is superior in terms of its capability to immobilize a wide range of ligands.…”

Photogenerated Carbohydrate Microarrays

“…Furthermore, the technique is applicable to a variety of polymers. [11,12,[14][15][16] In this study, PFPA chemistry was first used to covalently attach poly(ethylene oxide) (PEO) to amino-functionalized glass slides. By treating the amino groups on the array glass slide with N-hydroxylsuccinimide-derivatized PFPA (NHS-PFPA), [17] a monolayer of PFPA was formed on the surface (Scheme 1).…”

Photochemically Initiated Single Polymer Immobilization

“…Consistent results were obtained from surfaces treated with PFPA-silane at concentrations of a few µM, or when more than 100 times of a non-photoactive silane were added. [45] This is because in principle only one attachment point is necessary to tether the polymer to the substrate. We therefore hypothesized that as the density of the surface azido groups decreases, the immobilized polymer would evolve from a uniform film to eventually isolated single molecules.…”