Macroporous silicon based capacitive affinity sensor—fabrication and electrochemical studies (original) (raw)
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Porous silicon as functionalized material for immunosensor application
Talanta, 2007
Recently, for sensor application, porous silicon has received a great deal of attention due to the high specific surface area and the easy fabrication using some established processes of the usual silicon technology. We herein, report the development of a novel immunosensors based on porous silicon for antigen detection. The multilayer immunosensor structure was fabricated following the successive steps: APTS self-assembled monolayer (SAM) layer, glutaaldehyde linker, anti-rabbit IgG binding. The insulating properties of the aminopropyl-triethoxysilane (APTS) monolayer were studied with cyclic voltammetry and the molecular structure was characterized with Fourier-transform infrared (FTIR) technique. The binding between antibody and different antigen concentration (rabbit IgG) was monitored by measuring the capacitance-voltage curve of the antibody functionalized EIS structure. A detection limit of 10 ng/ml of antigen can be detected.
IEEE Sensors Journal, 2000
In this paper, an interdigitated electrode-less, highperformance macroporous silicon-based impedance biosensor has been reported first time for the detection of E.ColiO157. Macroporous silicon of three different pore thickness of around 3, 8, and 12 m and 55% porosity have been fabricated on a 10-20 -cm wafer using hydrofluoric acid (HF) and dimethyl sulfoxide (DMSO). The samples are next thermally oxidized for partial oxidation of silicon crystallites followed by optimized silanization and antibody immobilization. Two simple gold coated aluminium electrodes of 2 mm by 1 mm dimensions and 1 mm spacing have been fabricated similar to our previous report.
Towards the Development of Electrical Biosensors Based on Nanostructured Porous Silicon
Materials, 2010
The typical large specific surface area and high reactivity of nanostructured porous silicon (nanoPS) make this material very suitable for the development of sensors. Moreover, its biocompatibility and biodegradability opens the way to the development of biosensors. As such, in this work the use of nanoPS in the field of electrical biosensing is explored. More specifically, nanoPS-based devices with Al/nanoPS/Al and Au-NiCr/nanoPS/Au-NiCr structures were fabricated for the electrical detection of glucose and Escherichia Coli bacteria at different concentrations. The experimental results show that the current-voltage characteristics of these symmetric metal/nanoPS/metal structures strongly depend on the presence/absence and concentration of species immobilized on the surface.
Immobilization of antibodies onto a capacitance silicon-based transducer
Sensors and Actuators B: Chemical, 1993
The feasibility of a capacitive immunosensor, consisting of an antibody-layer fixed onto the top oxide layer of a heteros~ucture-bid EIS (electrolyte insulator ~miconductor) silicon has been studied. For such a biosensor, the sensitive layer that'contains the active species must act as an el~tri~lly-bl~kin~ capacitor. Fu~he~ore, the layer containing the immunospecies must keep its recognizing ability and a configuration allowing also a dielectric character. An attempt to solve such a problem consists in the antibodies (anti-a-fetoprotein) grafting onto silica through three different spacing reagents: aminosilane, cyanosilane and heteropolysilsesquioxanes membranes. Promising results have been obtained with polysiloxane membranes, but these compounds do not allow the direct detection of the antibody-antigen interaction.
Potentiometric Biosensors Based on Silicon and Porous Silicon
nsti.org
We report fabrication of potentiometric biosensors with silicon for the estimation of triglycerides and urea based on enzymatic reactions. The sensor is an ElectrolyteInsulator-Semiconductor capacitor (EISCAP) that shows a shift in the measured CV with changes in the pH of the ...
Porous silicon-based biosensor for pathogen detection
Biosensors and Bioelectronics, 2005
A porous silicon-based biosensor for rapid detection of bacteria was fabricated. Silicon (0.01 ohm cm, p-type) was anodized electrochemically in an electrochemical Teflon cell containing ethanoic hydrofluoric acid solution to produce sponge-like porous layer of silicon. Anodizing conditions of 5 mA/cm 2 for 85 min proved best for biosensor fabrication. A single-tube chemiluminescence-based assay, previously developed, was adapted to the biosensor for detection of Escherichia coli. Porous silicon chips were functionalized with a dioxetane-Polymyxin B (cell wall permeabilizer) mixture by diffusion and adsorption on to the porous surface. The reaction of -galactosidase enzyme from E. coli with the dioxetane substrate generated light at 530 nm. Light emission for the porous silicon biosensor chip with E. coli was significantly greater than that of the control and planar silicon chip with E. coli (P < 0.01). Sensitivity of the porous silicon biosensor was determined to be 10 1 -10 2 colony forming units (CFU) of E. coli. The porous silicon-based biosensor was fabricated and functionalized to successfully detect E. coli and has potential applications in food and environmental testing.
Tuning the Pore Size and Surface Chemistry of Porous Silicon for Immunoassays
physica status solidi (a), 2000
To use porous silicon as an optical interferometric biosensor, the pores must be sufficiently large to allow easy ingress of reagents and the layer must also display Fabry-Perot optical cavity modes. Here the detection antibody is rabbit IgG and the analyte is a-rabbit IgG conjugated to horseradish peroxidase (HRP). For this model system, the pores should be >50 nm in diameter. Such diameters have been obtained in 0.05 W cm n-type silicon using anodisation followed by chemical etching in ethanolic KOH and also by anodising 0.005 W cm p-type material. The latter also displays optical cavity modes. The silicon surface is oxidised in ozone, silanised using aminopropylmethoxysilanes with one, two or three methoxy groups, and cross linked to IgG using glutaraldehyde. High specific binding is found for mono-, di-and tri-methoxy silanes, but the lowest nonspecific binding is found for silanisation with the tri-methoxy silane.