Surface functionalization of germanium ATR devices for use in FTIR-biosensors

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• 作者：Sabrina Devouge ; José ; phine Conti ; André ; a Goldsztein ; Emmanuel Gosselin ; Alain Brans ; Michel Voué ; Joë ; l De Coninck ; Fabrice Homblé ; Erik Goormaghtigh ; Jacqueline March ; -Brynaer
• 关键词：Germanium ; ATR crystal ; FTIR biosensors ; Thin film ; Phenyl azide ; Photografting ; BlaR-CTD protein ; Non-fouling surface
• 刊名：Journal of Colloid and Interface Science
• 出版年：2009
• 出版时间：15 April 2009
• 年：2009
• 卷：332
• 期：2
• 页码：408-415
• 全文大小：811 K

文摘

Biosensors based on intrinsic detection methods have attracted growing interest. The use of Fourier transform infra-red (FTIR) spectroscopy with the attenuated internal total reflection (ATR) mode, in the biodetection context, requires appropriate surface functionalization of the ATR optical element. Here, we report the direct grafting of a thin organic layer (about 20 Å depth) on the surface of a germanium crystal. This covering, constructed with novel amphiphilic molecules 2b (namely, 2,5,8,11,14,17,20-heptaoxadocosan-22-yl-3-(triethoxysilyl) propylcarbamate), is stable for several hours under phosphate buffered saline (PBS) flux and features protein-repulsive properties. Photografting of molecule 5 (namely, O-succinimidyl 4-(p-azidophenyl)butanoate) affords the activated ATR element, ready for the covalent fixation of receptors, penicillin recognizing proteins BlaR-CTD for instance. The different steps of the previous construction have been monitored by water contact angle (θ_w) measurements, spectroscopic ellipsometry (covering depth), X-ray photoelectron spectroscopy (XPS) by using a fluorinated tag for the control of surface reactivity, and FTIR-ATR spectroscopy for the structural analysis of grafted molecules. Indeed, contrarily to silicon device, germanium device offers a broad spectral window (1000–4000 cm⁻¹) and thus amide I and II absorption bands can be recorded. This work lays the foundations for the construction of novel FTIR biosensors.