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Bonding and in‐channel microfluidic functionalization using the huisgen cyclization


The bonding of layers of silicone elastomers during the manufacturing of microfluidic devices is often accomplished using plasma oxidation. The process can be costly, may require a clean room and materials that ensure the flatness of the bonding layers and, as a consequence of hydrophobic recovery, can lead to high variability in the degree of adhesion. As importantly, the process precludes incorporation of chemical functionalities that work as anchors to immobilize biomolecules within the microfluidic channel. We hypothesized that it would be possible to fabricate microfluidic channels using the Huisgen 1,3‐dipolar cycloaddition of azides to alkynes to crosslink silicones and form PDMS elastomers and, in a subsequent step, bond one PDMS layer to another simply by heating, with the added advantage of producing microfluidic channels with embedded chemical functionalities. After thermal bonding, the microfluidic devices underwent cohesive failure (rupture of the elastomer layer) at ∼145 kPa during pressure tests, but did not exhibit adhesive failure (delamination), showing that the azide–alkyne reaction provides a strong bond between elastomer layers. Furthermore, the internal microfluidic channel surfaces retained alkyne and azide functionality during the process, as shown by the grafting of one or more fluorescent dyes, through Huisgen cyclization. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017

The metal‐free Huisgen cyclization between azides and alkynes permits both assembly and (bio)functionalization of microfluidic devices. The Huisgen cyclization reaction can be used to cure silicone rubbers simply by heating. Azide‐ and alkyne‐rich elastomers, respectively, formed strong adhesive bonds simply by catalyst‐free thermal welding. The assembly of microfluidic devices using this approach avoids many of the problems associated with silicones and, additionally, provides azide, and alkyne functionality on the inside surfaces of the microchannel that may be used to tether (bio)molecules.

Authors:   Talena Rambarran, Ferdinand Gonzaga, Ayodele Fatona, Michael Coulson, Sokunthearath Saem, Jose Moran‐Mirabal, Michael A. Brook
Journal:   Journal of Polymer Science Part A: Polymer Chemistry
Year:   2017
Pages:   n/a
DOI:   10.1002/pola.28930
Publication date:   28-Dec-2017
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