Method of assembly of capacitive bio-sensor for bio-molecules detection

We developed a method of assembly for electrical micro-bio-sensor. The system is a part of a micro-fluidic device based on a capacitive biosensor. The bio-sensor is designed for bio-molecules (specifically DNA and protein) detection, quantification and recognition. Using the developed method we assembled series of fully functional demonstrators.DNASI

Low-Wavelengths SOI CMOS Photosensors for Biomedical Applications

INTRODUCTION : Biological agents may be characterized (in terms of quantity (or concentration), purity, nature) using optical ways like spectrometry, fluorometry and real-time PCR for example. Most of these techniques are based on absorbance or fluorescence. Indeed, many biological molecules can absorb the light when excited at wavelengths close to blue and ultraviolet (UV). For example, DNA, RNA and proteins feature an absorption peak in the deep UV, more precisely around 260 and 280 nm (Karczemska & Sokolowska, 2001). This work is widely focused on those wavelengths. A biological sample concentration measurement method can be based on UV light absorbance or transmittance, as already known and realized with high-cost and large-size biomedical apparatus. But, often, the difficulties come from the limitation for measuring very small concentrations (close to a few ng/µL or lower) since the measurement of such small light intensity variations at those low wavelengths requires a precise light source, and very efficient photodetectors. Reducing the dimensions of such a characterization system further requires a small light source, a miniaturized photosensor and a processing system with high precision to reduce the measurement variations. Some light-emitting diodes (LED) performing at those UV wavelengths have recently appeared and may be used to implement the light source. Concerning the optical sensor, while accurate but high-cost photosensors in technologies such as AlGaN and SiC provide high sensitivities in UV low wavelengths thanks to their semiconductor bandgap (Yotter & Wilson, 2003), the silicon-on-insulator (SOI) layers absorb the photons in that specific range thanks to an appropriate thickness of the silicon. Adding excellent performances of low power consumption, good temperature behavior and high speed (Flandre et al., 1999; 2001), the SOI technology allows the designers for integrating a specific signal processing integrated CMOS circuit to transform the photocurrent into a digital signal for example. This opens the possibility to build a low-cost, complete and portable microsystem, including the light source, the photodetector and a recipient for the sample to characterize […

Immunoassay using a biofunctionnalized alumina-coated capacitive biosensor: towards a microfluidic detection of the H5N1 Influenza virus

Influenza A viruses cause annual epidemics and occasional pandemics that spread worldwide. The nucleoprotein is essential for the survival of this virus and is thus well-conserved. We developed a quantitative electronic biosensor displaying a protein recognition thanks to the covalent grafting of anti-nucleoprotein antibodies. The detection device lies on interdigitated array microelectrodes (IDAM), covered with alumina (Al2O3) to protect the underlying aluminum and enhance the electrical coupling. As the dimensions of the IDAM can determine the sensitivity of the sensor, we processed 4 structures with varying electrode widths and spacings in the same silicon chip and assessed their individual performance. The sensing area of each sensor is 200*200 µm2 and the overall chip-size is 3*3 mm2. The sensor is mounted in a DIL-16-package partially encapsulated by resin

Transfection of Immortalized Keratinocytes by Low Toxic Poly(2-(Dimethylamino)Ethyl Methacrylate)-Based Polymers.

Skin carcinoma are among the most spread diagnosed tumours in the world. In this study, we investigated the transfection of immortalized keratinocytes, used as an in vitro model for skin carcinoma, using antisense technology and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA)-based polymers, with original architecture and functionalities. We tested PDMAEMA polymers with different structures: linear, with two (DEA-PDMAEMA) or three (TEA-PDMAEMA) arms. The cytotoxicity of these polymers was assessed over a wide range of apparent M(n) (from 7600 to 64 600). At a N/P ratio of 7.38, cytotoxicity increases with the M(n). Keratinocytes were transfected with a fluorescent oligonucleotide and then analyzed by flow cytometry. For the three architectures tested, the percentage of transfected cells and abundance of internalized oligonucleotide were closely related to the M(n) of the polymer. Confocal microscopy and FACS analyses showed a wide spread fine granular distribution of the oligonucleotide up to 3 days post-transfection. Then, we assessed the silencing efficiency of the polymers, targeting GFP in GFP expressing keratinocytes. The maximal silencing effect (±40%) was obtained using a DEA-PDMAEMA polymer (M(n)=30 300). These results suggest that PDMAEMA-based polymers can be efficiently used to transfect immortalized keratinocytes and, thus, open new perspectives in the therapy of skin carcinoma

Assessment of different functionalization methods for grafting a protein to an alumina-covered biosensor

The specificity of a biosensor is usually provided by the binding of biomolecules to the surface of the sensor. This critical step is sensitive to the nature of the material and the overall experimental conditions. Here, we provide a study of different bio-functionalization methods for a sensor covered by alumina

Light-triggered green fluorescent protein silencing in human keratinocytes in culture using antisense oligonucleotides coupled to a photoreactive ruthenium(II) complex

A photoreactive ruthenium(II) complex that contains two tetraazaphenanthrene (TAP) and one phenanthroline (phen) ligands was synthesized and then tethered to (antisense) oligonucleotides (Ru-ASO) to target a destabilized GFP (dGFP). The specificity of the photoreaction of this Ru-ASO conjugate was studied in vitro by polyacrylamide gel electrophoresis (PAGE) experiments in denaturing conditions. Other nonspecific Ru-ASO conjugates were also prepared and evaluated with human keratinocytes that expressed dGFP. An illumination-dependent cytotoxicity was observed for most Ru-ASO conjugates that varied from 10 to almost 40%, but only the specific Ru-ASO conjugate was able to significantly reduce GFP expression in illuminated cells.SCOPUS: ar.jFLWNAinfo:eu-repo/semantics/publishe