Biosensors and Bioelectronics 25 (2009) 154–160 Contents lists available at ScienceDirect Biosensors and Bioelectronics journal homepage: www.elsevier.com/locate/bios Cold plasma functionalized TeraHertz BioMEMS for enzyme reaction analysis Abdennour Abbas a,b,c , Anthony Treizebre a , Philippe Supiot b , Nour-Eddine Bourzgui a , Didier Guillochon c , Dominique Vercaigne-Marko c , Bertrand Bocquet a,∗ a Institute of Electronics, Microelectronics and Nanotechnology (UMR-CNRS 8520), University of Lille1, F59655 Villeneuve d’Ascq, France b Laboratory of Process Engineering of Reactive Fluids-to-Materials Interactions (EA 3571), University of Lille1, F59655 Villeneuve d’Ascq, France c Laboratory of Biological Processes, Enzymatic and Microbial Engineering (EA 1026), University of Lille1, F59655 Villeneuve d’Ascq, France article info Article history: Received 19 April 2009 Received in revised form 14 June 2009 Accepted 16 June 2009 Available online 24 June 2009 Keywords: Biocatalysis BioMEMS Cold plasma Sub-TeraHertz spectroscopy Thin films abstract In this paper, we describe the development, functionalization and functionality testing of a Tera- Hertz (THz) Bio-MicroElectroMechanical System (BioMEMS) dedicated to enzyme reaction analysis. The microdevice was fabricated by mixing clean room microfabrication with cold plasma deposition. The first is used to build the microfluidic circuits and the THz sensor, while the later serves for the polymeriza- tion of allylamine using a homemade glow discharge plasma reactor for a subsequent immobilization of enzymatic biocatalysts. Thermal stability of the deposited plasma polymer has been investigated by infrared spectroscopy. Fluorescent detection confirmed the efficiency of the immobilization and the enzyme hydrolysis into the BioMEMS microchannels. For the first time, the progression of the hydrol- ysis reaction over time was monitored by the THz sensor connected to a vectorial network analyzer. Preliminary results showed that sub-THz transmission measurements are able to discriminate different solid films, various aqueous media and exhibit specific transmission behavior for the enzyme hydrolysis reaction in the spectral range 0.06–0.11THz. © 2009 Elsevier B.V. All rights reserved. 1. Introduction TeraHertz (THz) radiations are the bridging region between the microwave and the infrared spectrum, from 0.1 to 10THz. The extended notion includes some millimeter and submillimeter- waves, i.e. sub-THz frequencies. The use of THz spectroscopy in analytical biochemistry is becoming an exciting challenge since theoretical predictions showed that biomolecules should present multiple and specific resonances in the picosecond timescale, i.e. THz frequency range (Bykhovskaia et al., 2001; Lawrence et al., 1987; Van Zandt and Saxena, 1989). These specific features rely in low frequency collective vibrational and rotational modes involv- ing weak hydrogen bonds and other weak intramolecular and/or intermolecular interactions. Additionally, because of their low ener- gies (0.4–40 meV), THz waves are non-ionizing radiations, and thus represent a non-destructive analysis approach. Many experimental results confirmed the potential of THz waves for biosensing (Choi et al., 2002; Globus et al., 2006; Markelz et al., 2000; Nagel et al., 2002). Most of these studies have been conducted in the solid state, rather than in an aqueous media. The reason is that water exhibits a strong absorbance in the THz domain. To overcome this problem and enable the monitoring of biomolecules dynamics and reactions, ∗ Corresponding author. Tel.: +33 320 19 79 37; fax: +33 320 19 78 92. E-mail address: bertrand.bocquet@univ-lille1.fr (B. Bocquet). efforts have been focused on the use of microsystems to reduce the transmission path length. Microfluidic systems and BioMEMS have been used to draw microvolume of fluids until the THz sensor (Facer et al., 2001; Hefti et al., 1999; Nagel et al., 2006; Treizebré et al., 2005; Treizebré and Bocquet, 2008). Among the biological entities studied with THz radiations, the enzyme biocatalysis is one of the less explored topics. The enzyme activity can be investigated by THz since this activity is associ- ated with conformational changes that occur during the conversion of the substrate to the product, such as the protein hydrolysis into peptides after binding to a specific enzyme. To enable these measurements, one of the most crucial challenges is the devel- opment of a suitable interface with biological materials in order to immobilize the biocatalyst inside the BioMEMS microchannel and onto the THz probe. Many processes have been developed, that are principally related to wet chemistry. The drawback is that solution-based surface treatments usually need solvents, are costly and time-consuming and consequently unsuit for further industrial scale development. Plasma thin film deposition represents a promising alterna- tive for microdevices bio-functionalization, which could be easily integrated in the microfabrication process. Plasma-polymerized coatings have already been used in microsystems field, as a support for electronic or electromagnetic sensors (Hiratsuka et al., 2004), as a stationary phase on chromatography microcolumns (Lima et al., 2008) and as a structural material for microfluidic network 0956-5663/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.bios.2009.06.029