Surface functionalized thiol-ene waveguides for fluorescence biosensing in microfluidic devices

• Published in: Electrophoresis 2014-02, Vol.35 (2-3), p.282-288
• Main Authors: Feidenhans'l, Nikolaj A., Lafleur, Josiane P., Jensen, Thomas G., Kutter, Jörg P.
• Format: Article
• Language: English
• Subjects: Biosensing; Biosensing Techniques - instrumentation; Fluorescence; Microfluidic Analytical Techniques - instrumentation; Microfluidics; Polymers - chemistry; Refractometry; Spectrometry, Fluorescence - instrumentation; Sulfhydryl Compounds - chemistry; Surface functionalization; Surface Properties; Thiol-ene
• ISSN: 0173-0835; 1522-2683
• DOI: 10.1002/elps.201300271

Thiol‐ene polymers possess physical, optical, and chemical characteristics that make them ideal substrates for the fabrication of optofluidic devices. In this work, thiol‐ene polymers are used to simultaneously create microfluidic channels and optical waveguides in one simple moulding step. The reactive functional groups present at the surface of the thiol‐ene polymer are subsequently used for the rapid, one step, site‐specific functionalization of the waveguide with biological recognition molecules. It was found that while the bulk properties and chemical surface properties of thiol‐ene materials vary considerably with variations in stoichiometric composition, their optical properties remain mostly unchanged with an average refractive index value of 1.566 ± 0.008 for thiol‐ene substrates encompassing a range from 150% excess ene to 90% excess thiol. Microfluidic chips featuring thiol‐ene waveguides were fabricated from 40% excess thiol thiol‐ene to ensure the presence of thiol functional groups at the surface of the waveguide. Biotin alkyne was photografted at specific locations using a photomask, directly at the interface between the microfluidic channel and the thiol‐ene waveguide prior to conjugation with fluorescently labeled streptavidin. Fluorescence excitation was achieved by launching light through the thiol‐ene waveguide, revealing bright fluorescent patterns along the channel/waveguide interface.