Copper-free click biofunctionalization of silicon nitride surfaces via strain-promoted alkyne-azide cycloaddition reactions.
Cu-free "click" chemistry is explored on silicon nitride (Si(3)N(4)) surfaces as an effective way for oriented immobilization of biomolecules. An ω-unsaturated ester was grafted onto Si(3)N(4) using UV irradiation. Hydrolysis followed by carbodiimide-mediated activation yielded surface-bound active succinimidyl and pentafluorophenyl ester groups. These reactive surfaces were employed for the attachment of bicyclononyne with an amine spacer, which subsequently enabled room temperature strain-promoted azide-alkyne cycloaddition (SPAAC). This stepwise approach was characterized by means of static water contact angle, X-ray photoelectron spectroscopy, and fluorescence microscopy. The surface-bound SPAAC reaction was studied with both a fluorine-tagged azide and an azide-linked lactose, yielding hydrophobic and bioactive surfaces for which the presence of trace amounts of Cu ions would have been problematic. Additionally, patterning of the Si(3)N(4) surface using this metal-free click reaction with a fluorescent azide is shown. These results demonstrate the ability of the SPAAC as a generic tool for anchoring complex molecules onto a surface under extremely mild, namely ambient and metal-free, conditions in a clean and relatively fast manner.
Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB Wageningen, The Netherlands.
Radostina K
RK
Manova
Sidharam P
SP
Pujari
Carel A G M
CA
Weijers
Han
H
Zuilhof
Teris A
TA
van Beek
D000480:Alkynes / Q000737:chemistry*; D001386:Azides / Q000737:chemistry*; D057930:Click Chemistry; D004024:Dicyclohexylcarbodiimide / Q000737:chemistry; D004952:Esters; D005456:Fluorescent Dyes; D005461:Fluorine / Q000737:chemistry; D055772:Green Chemistry Technology; D057927:Hydrophobic and Hydrophilic Interactions; D007785:Lactose / Q000737:chemistry; D008856:Microscopy, Fluorescence; D056951:Photoelectron Spectroscopy; D017655:Silicon Compounds / Q000737:chemistry*; D013388:Succinimides / Q000737:chemistry; D013499:Surface Properties; D014466:Ultraviolet Rays; D014867:Water
D000480:Alkynes; D001386:Azides; D004952:Esters; D005456:Fluorescent Dyes; D017655:Silicon Compounds; D013388:Succinimides; D014867:Water; D005461:Fluorine; D004024:Dicyclohexylcarbodiimide; D007785:Lactose; C001426:N-hydroxysuccinimide; C032734:silicon nitride