title: Localized, stepwise template growth of functional nanowires from an amino acid-supported framework in a microfluidic chip.
abstract: A spatially controlled synthesis of nanowire bundles of the functional crystalline coordination polymer (CP) Ag(I)TCNQ (tetracyanoquinodimethane) from previously fabricated and trapped monovalent silver CP (Ag(I)Cys (cysteine)) using a room-temperature microfluidic-assisted templated growth method is demonstrated. The incorporation of microengineered pneumatic clamps in a two-layer polydimethylsiloxane-based (PDMS) microfluidic platform was used. Apart from guiding the formation of the Ag(I)Cys coordination polymer, this microfluidic approach enables a local trapping of the in situ synthesized structures with a simple pneumatic clamp actuation. This method not only enables continuous and multiple chemical events to be conducted upon the trapped structures, but the excellent fluid handling ensures a precise chemical activation of the amino acid-supported framework in a position controlled by interface and clamp location that leads to a site-specific growth of Ag(I)TCNQ nanowire bundles. The synthesis is conducted stepwise starting with Ag(I)Cys CPs, going through silver metal, and back to a functional CP (Ag(I)TCNQ); that is, a novel microfluidic controlled ligand exchange (CP → NP → CP) is presented. Additionally, the pneumatic clamps can be employed further to integrate the conductive Ag(I)TCNQ nanowire bundles onto electrode arrays located on a surface, hence facilitating the construction of the final functional interfaced systems from solution specifically with no need for postassembly manipulation. This localized self-supported growth of functional matter from an amino acid-based CP shows how sequential localized chemistry in a fluid cell can be used to integrate molecular systems onto device platforms using a chip incorporating microengineered pneumatic tools. The control of clamp pressure and in parallel the variation of relative flow rates of source solutions permit deposition of materials at different locations on a chip that could be useful for device array preparation. The in situ reaction and washing procedures make this approach a powerful one for the fabrication of multicomponent complex nanomaterials using a soft bottom-up approach.
authors.affiliation: Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus Universitari de Bellaterra , 08193 Bellaterra, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Puigmartí-Luis
authors.forename: Marta
authors.initials: M
authors.lastname: Rubio-Martínez
authors.forename: Inhar
authors.initials: I
authors.lastname: Imaz
authors.forename: Benjamin Z
authors.initials: BZ
authors.lastname: Cvetković
authors.forename: Llibertat
authors.initials: L
authors.lastname: Abad
authors.forename: Angel
authors.initials: A
authors.lastname: Pérez Del Pino
authors.forename: Daniel
authors.initials: D
authors.lastname: Maspoch
authors.forename: David B
authors.initials: DB
authors.lastname: Amabilino