Lignin is the second most abundant polymer after cellulose in lignocellulosic biomass. Its aromatic composition and recalcitrant nature make its valorization a major challenge for obtaining low molecular weight aromatics compounds with high value-added from the enzymatic depolymerization of industrial lignins. The oxidation reaction of lignin polymer using laccases alone remains inefficient. Therefore, researches are focused on the use of a laccase-mediator system (LMS) to facilitate enzymatic depolymerization. Until today, the LMS system was studied using water-soluble lignin only (commercial lignins, modified lignins, or lignin model compounds). This work reports a study of three LMS systems to depolymerize the three major industrial lignins (organosolv lignin, Kraft lignin, and sodium lignosulfonate). We show that an enzymatic depolymerization of these lignins can be achieved by LMS using laccase from Trametes versicolor, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt as mediator and a cosolvent (25% of 1,4-dioxane) to enhance the solubilization of lignins.

This paper describes the impact of a physical immobilization methodology, using plasma polymerized 1,1,3,3, tetramethyldisiloxane, on the catalytic performance of β-galactosidase from Aspergillus oryzae in a microfluidic device. The β-galactosidase was immobilized by a polymer coating grown by Plasma Enhanced Chemical Vapor Deposition (PEVCD). Combined with a microchannel patterned in the silicone, a microreactor was obtained with which the diffusion through the plasma polymerized layer and the hydrolysis of a synthetic substrate, the resorufin-β-d-galactopyranoside, were studied. A study of the efficiency of the immobilization procedure was investigated after several uses and kinetic parameters of immobilized β-galactosidase were calculated and compared with those of soluble enzyme. Simulation and a modelling approach were also initiated to understand phenomena that influenced enzyme behavior in the physical immobilization method. Thus, the catalytic performances of immobilized enzymes were directly influenced by immobilization conditions and particularly by the diffusion behavior and availability of substrate molecules in the enzyme microenvironment.

Plasma Enhanced Chemical Vapour Deposition (PECVD) processes have been used for decades for surface processing in a wide range of industrial applications like semiconductor films, low-k films, barrier diffusion. Thin film deposition is especially of high interest for biomedical applications for the production of protective coatings, adhesion layers, hydrophilic or hydrophobic layers. Up to now, most of used processes are usually realized under low pressure. Actually, there is a great and increasing interest in the development of plasma sources operating at atmospheric pressure. The present work deals with plasma polymerisation of TMDSO and HMDSO with a Dielectric Barrier Discharge plasma jet at atmospheric pressure, the Plasma Gun developed in GREMI. Depending on parameters like voltage, frequency, carrier gas and monomer injection, the deposited polymer appears either as a gel-like coating or a transparent film with fringes. Deposits are characterized by Fourier Transformed IRspectroscopy and contact angle measurements. The precursor used was introduced in both liquid or gaseous state, in case TMDSO and only gaseous state in case of HMDSO. The liquid flow rate was regulated by a peristaltic pump (Ismatec) while the vapour flow was ensured by bubbling nitrogen or oxygen with a fixed flow rate of 10 sccm. Microscope slides and polished Silicon wafer (100) were used as substrates. The polymerized coatings have been obtained at frequencies between 500Hz and 4 kHz, for applied voltages between 14 and 20 kV and exposure times from 1 to 10 minutes. The deposition were realized with plasma tube edge-to-substrate distances ranging from 3 to 12 mm. Profilometer measurements revealed thicknesses comprised between 500 nm and 1.5 µm at the middle of the deposit. Deposited films analyses clearly show the efficiency of this atmospheric plasma-type TMDSO and HMDSO polymerisation and their similarity with those usually realized under low pressure RPECVD. The most interesting deposited films are obtained when the monomer is introduced under gaseous state, the samples clearly showing a better homogeneity. The influence of the transport gas is not evidenced. More experiments and analyses need to be achieved to complete these preliminary results. It must be stressed that multi-spot deposition has been obtained from plasma multi-jet delivered by a single Plasma Gun.

The present work deals with plasma polymerisation of TetraMethylDiSilOxane with a Dielectric Barier Discharge plasma jet at atmospheric pressure. Depending on parameters like voltage, frequency, carrier gas and monomer injection, the deposited polymer looks like gel film or transparent film with fringes. Deposits are characterized by Fourier Transformed IR spectroscopy and contact angle measurements. Keywords: Atmospheric pressure DBD plasma jet, Low temperature, Plasma polymerisation, TetraMethylDiSilOxane.

Polysiloxane films obtained from a cold remote nitrogen plasma polymerization of 1,1,3,3-tetramethyldisiloxane monomer mixed with oxygen show attractive properties and can be used for many applications. These films can also be modified in-situ by the (nitrogen+oxygen) remote plasma. An increase of the atomic oxygen concentration in the plasma leads to carbon removal and to an enhancement of the cross-linking of the Si–O–Si chains. The uppermost layer tends towards a silica structure while the core of the coating remained unchanged. By successive (deposition/plasma treatment) sequences, it was possible to obtain multilayer coatings which were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and contact angles measurements. The efficiency of such multilayer coatings to protect carbon steel against corrosion in NaCl 0.5M was also investigated from polarization curves and Electrochemical Impedance Spectroscopy (EIS).

Over the years, immobilization of biologically active species such as enzymes onto solid support gave rise to a wide range of analytical and industrial applications. The development of fast, simple and efficient immobilization strategies is becoming of great importance in specific Biological Micro-Electromechanical Systems (BioMEMS) manufacturing. Thus, the current work focuses on an original methodology and mild procedure for β-galactosidase immobilization. Using as support either silicon or a thin film obtained from polymerization of 1,1,3,3-tetramethyldisiloxane (ppTMDSO) deposited by Plasma Enhanced Chemical Vapor Deposition in afterglow mode, the strategy developed here consisted in adsorption of β-galactosidase followed by its overcoating by the same siloxane plasma polymer. After sample washing, the enzymes were characterized to be efficiently entrapped within the porous polymer matrix while allowing the penetration and hydrolysis of the synthetic substrate ortho-nitrophenyl-β-d-galactopyranoside (o-NPG) with stability over at least 8 assays. The entrapment procedure allowed obtaining bio-functionnal coatings where β-galactosidase was expected to be included in the plasma-polymerized films while preserving its native structure and its activity. This latter was modulated by mass transfer limitations of the substrate according to the thickness of the ppTMDSO coatings. The dry-process-based-preparation of such a thin bio-functional film (from ∼200 nm to ∼650 nm) is fast and compatible with biochip or microreactor fabrication processes while avoiding the use of lot of chemicals and multi-step treatments commonly encountered in enzyme immobilization procedures.

Thin films of organosilicon materials produced by plasma-assisted deposition are frequently used because of their multifunctional character, but few comparative studies into their growth on structured surfaces are available. Two types of CVD processes, plasma-enhanced (PE)CVD and remote plasma-enhanced (RPE)CVD are taken as typical operating conditions. Polymer films of thicknesses ranging from 0.25 to 1.2 mu m are obtained by both processes from the tetramethylsiloxane (TMDSO) precursor, on silicon substrates microstructured with a set of patterns (trenches, holes, and columns) with various spacings, and with vertical dimensions of 1.3 or 1.45 mu m. Analysis by scanning electron microscopy (SEM) of the samples is carried out after sample cleavage. The effects of pattern size and shape, defined by the aspect ratio parameter, on the local growth rate are studied more specifically for trenches for both PECVD and RPECVD processes

The aim of this work is to study the transformation of plasma polymerised tetramethyldisiloxane (ppTMDSO) films deposited by microwave induced RPECVD through exposure to a N-2/O-2 microwave plasma afterglow in a duplex reactor. The film thickness, structure and composition of the as-deposited or transformed ppTMDSO films are determined by profilometry, interferometry, Fourier transform infrared and X-ray photoelectron spectroscopies. The analysis of the post-treatment effect is carried out through a combination of results obtained from FTIR study and subsequent optical interferometry study during CF4 etching of deposits. A carbon removal and an enhancement of cross-linking of the Si-O-Si chains are shown. We also propose a model to determine the transformed layer depth with taking the film contraction into account for the first time for this family of polymers.

Plasma polymerized allylamine (ppAA) films were deposited in a radio-frequency glow discharge plasma reactor using a continuous-wave mode and varying the discharge power from 15 to 125 W. The deposition rate reached 26 nm . min(-1) and was constant within at least half an hour of process. The chemical structure and elemental composition of the deposited films were investigated by Fourier transform infrared and X-ray photoelectron spectroscopies, whereas surface properties were analyzed by atomic force microscopy and surface free energy measurement. A special focus is given to the stability of ppAA in aqueous media and primary amine quantification. The use of fluorescent microscopy and UV-Visible spectroscopy enabled us to detect and quantify the primary amine, respectively. All the studied parameters varied widely with enhanced power with a transition point around 50 W. Over this value, the results remain relatively unchanged.

This paper focuses on the immobilization of a proteolytic enzyme, trypsin, on plasma polymerized allylamine (ppAA) films. The later have been deposited onto silicon substrate by means of radiofrequency glow discharge. The covalent attachment of the enzyme was achieved in three steps: (i) activation of the polymer surface with glutaraldehyde (GA) as a linker, (ii) immobilization of trypsin and (iii) imino groups reduction treatment. The effects and efficiency of each step were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Fluorescent spectroscopy was used to evaluate the change of the biological activity following the immobilization steps. The results showed that enzyme immobilization on GA-modified substrate increases the enzyme activity by 50% comparing to adsorbed enzymes, while the imino reduction treatment improves the enzyme retention by about 30% comparing to untreated samples. In agreement with XPS and AFM data, UV-vis absorption spectroscopy, used to quantify the amount of immobilized enzyme, showed that allylamine plasma polymer presents a high adsorption yield of trypsin. Although the adsorbed enzymes exhibit a lower activity than that measured for enzymes grafted through GA linkers, the highest catalytic activity obtained was for the enzymes that underwent the three steps of the immobilization process.

The development of more complex biochips in terms of functionality requires some technological evolutions. A high frequency biological micro-electro-mechanical-system dedicated to biological analysis is a typical case of this requirement for providing compatibility between high frequency propagation and microfluidic circulation. Mixed fabrication technologies using silicon and polymers appear to be a good alternative. We have developed a promising deposition process of an organosilicon polymer by remote afterglow plasma technology, also called plasma polymerized tetramethyldisiloxane (ppTMDS). This technique allows us to obtain high deposition rate values in the range of 160 S angstrom s(-1) and a thick layer up to 140 mu m without any crack. Moreover, this process is compatible with high throughput microelectronic designs and it is done near room temperature. This last point is very interesting for further development of surface bio-functionalization, for example. We have characterized this siloxane polymer by physico-chemical analysis. The roughness has been optimized, thus allowing the realization of high frequency waveguides. The ppTMDS permittivity presents a low dispersive characteristic and constitutes one of the best low-loss polymers up to 1 THz.

Cover: AFM scans (5µm × 5µm) of 500 nm thick films as deposited on Si from processes a) RFICP (full vertical scale: 12.6 nm), b) MIRA (full vertical scale: 44.9 nm), and c) DECRP (full vertical scale: 27.7 nm). Further details can be found in the Full Paper by P. Supiot,* C. Vivien, A. Granier, A. Bousquet, A. Mackova, D. Escaich, R. Clergereaux, P. Raynaud, Z. Stryhal, and J. Pavlik on page 100.

We propose a new technology for high throughput bioMEMS based on a mixed technology polymer on silicon. This technology is compatible with microelectronic processes, the electromagnetic propagation, the microfluidic circulation and the biological solutions. We use a new process and a new polymer deposited by a "cold" plasma technique. We can use it for a surface functionalization or for the encapsulation with plasma assisted wafer bonding

Five hundred nanometer thick organosilicon coatings are prepared on Si substrates in parallel by the plasma-assisted polymerisation of hexamethyldisiloxane (HMDSO) in an RF-inductively coupled plasma (RFICP) and distributed electron cyclotron resonance plasma (DECRP) at low pressure (0.27 Pa) and of tetramethyldisiloxane (TMDSO) premixed with oxygen in an N-2 microwave induced remote afterglow (MIRA) at 560 Pa. The structure of these different films is analyzed by different techniques, such as Fourier-transform infrared spectroscopy, Rutherford backscattering spectrometry, atomic force microscopy, ellipsometry, and contact angle measurements. Results of the film composition (at least 30% carbon content), optical properties, and morphology indicate a low cross-linking degree accompanied by short chain length for RFICP and DECRP films, in contrast to a high-molecular-weight structure observed for the MIRA film. Carbon removal is achieved within the same plasma reactors by further oxygen-containing plasma treatment per-formed in the RF-ICP (3.33 Pa), DECRP (0.27 Pa, -200 V biased substrate), and MIRA (N-2/O-2 (98.7:1.3, 560 Pa)) reactors. The same measurements are carried out on the treated samples in order to detect the main changes in film composition, optical properties, and morphology. The evolution of surface energy is also studied. The results are discussed according to film structure and process specificity.

The purpose of the present work is to determine the growth rate of an organosilicon film during the deposition process. The films are obtained from the chemical decomposition of the 1,1,3,3 TetraMethylDiSilOxane (TMDSO) monomer premixed with oxygen by reaction in the far remote afterglow of a nitrogen microwave discharge. The process control, i.e. the knowledge about the relation between film thickness and deposition duration can only be achieved through in situ diagnostics. In this aim, the optical intensity of a laser beam signal after reflection on the substrate is monitored during deposition. The relevance of the analysis method has been tested for thicknesses close to 17 micrometers. The reproducibility of the signal is discussed according to the film properties. A first determination of the surface roughness has been proposed after comparison with theoretical reflectance. The resulting temporal evolution of the signal is compared with the film's thickness determined by profiler measurements for different deposition durations. Linearity of the growth rate deduced from reflected signal with the effective one has been demonstrated.