Spatioselective functionalization of gold nanopillar arrays.

A process combining electrochemical nanofabrication by hard templating with the use of a masking strategy and surface functionalization methods, is developed to produce arrays of gold nanopillars of spatially-controlled surface chemistry. Therefore, a gold nanopillar array is first fabricated by performing metal electrochemical deposition into a track-etched membrane supported on a gold substrate. After dissolution of the membrane, a protective polymer layer is deposited on the array and partially etched to specifically reveal the top of the nanopillars. Then, a polythiolactone-based copolymer is grafted on the upper part of the nanopillars. Afterwards, the sacrificial polymer layer is dissolved to reveal the non-functionalized surface corresponding to the lower part of the gold nanopillars and the background surface. This surface is subsequently modified by a self-assembled monolayer (SAM) of alkylthiol molecules which leads to nanostructured surfaces with spatio-selective surface chemistry. The grafting of gold nanoparticles and of a bioadhesive peptide on the top and on the background of the nanopillar array, respectively, is performed to prove the versatility of the approach to produce bifunctionalized nanopillar arrays for biological, biosensing or (bio)catalysis applications.

Bifunctionalized Redox-Responsive Layers Prepared from a Thiolactone Copolymer.

The development of multifunctional surfaces is of general interest for the fabrication of biomedical, catalytic, microfluidic or biosensing devices. Herein, we report on the preparation of copolymer layers immobilized on gold surface and showing both free thiol and amino groups. These layers are produced by aminolysis of a thiolactone-based copolymer in the presence of a diamine, according to a one-step procedure. The free thiol and amino groups present in the modified copolymer layers can be successfully functionalized with respectively thiolated and carboxylic derivatives, in order to produce bifunctionalized surfaces. In addition, we show that the grafted thiolated derivative can be released by cleavage of the disulfide bond under mild reducing conditions. On the other hand, a side cross-linking reaction occurring during the grafting process and resulting in the formation of copolymer aggregates on the metal surface is evidenced. The methodology developed for the preparation of these bifunctionalized redox-responsive layers should be advantageously used to produce bioactive surfaces with drug loading/release properties.