Mild Photochemical Biofunctionalization of Glass Microchannels

• Published in: Langmuir Vol. 33; no. 35; pp. 8624 - 8631
• Main Authors: Carvalho, Rui Rijo, Pujari, Sidharam P, Gahtory, Digvijay, Vrouwe, Elwin X, Albada, Bauke, Zuilhof, Han
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.09.2017
• Subjects: atomic force microscopy; bioactive compounds; DNA, Catalytic; esters; fluorescence microscopy; G-Quadruplexes; glass; Hemin; Horseradish Peroxidase; Hydrogen Peroxide; Laboratorium voor Organische chemie; Laboratory for Organic Chemistry; Organic Chemistry; Organische Chemie; oxidation; peroxidase; Photochemical Processes; photochemistry; scanning electron microscopy; silica; silicon; VLAG; wavelengths; X-ray photoelectron spectroscopy
• ISSN: 0743-7463; 1520-5827; 1520-5827
• DOI: 10.1021/acs.langmuir.6b03931

The ability to locally modify the inside of microfluidic channels with bioactive molecules is of ever-rising relevance. In this article, we show the direct photochemical coupling of a N-hydroxysuccinimide-terminated ω-alkene onto hydrogen-terminated silicon oxide, and its subsequent functionalization with a catalytically active DNAzyme. To achieve this local attachment of a DNAzyme, we prepared hydrogen-phenyl-terminated glass (H-Φ-glass) by the reaction of glass with H-SiPhCl2. The presence of a radical-stabilizing substituent on the Si atom (i.e., phenyl) enabled the covalent modification of bare glass substrates and of the inside of glass microchannels with a functional organic monolayer that allowed direct reaction with an amine-functionalized biomolecule. In this study, we directly attached an NHS-functionalized alkene to the modified glass surface using light with a wavelength of 328 nm, as evidenced by SCA, G-ATR, XPS, SEM, AFM and fluorescence microscopy. Using these NHS-based active esters on the surface, we performed a direct localized attachment of a horseradish peroxidase (HRP)-mimicking hemin/G-quadruplex (hGQ) DNAzyme complex inside a microfluidic channel. This wall-coated hGQ DNAzyme effectively catalyzed the in-flow oxidation of 2,2′-azino-bis­(3-ethylbenzothiazoline-6-sulfonate) [ABTS] in the presence of hydrogen peroxide. This proof-of-concept of mild biofunctionalization will allow the facile preparation of modified microchannels for myriad biorelevant applications.