Development of a Hybrid Enzyme-Based Porous Silicon Platform for Chemical Warfare Agent Detection

2004 ◽  
Vol 828 ◽  
Author(s):  
Sonia E. Létant ◽  
Bradley R. Hart ◽  
Staci R. Kane ◽  
Masood Z. Hadi ◽  
Sharon J. Shields ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Hydrolysis Product ◽  
Silicon Detector ◽  
Chemical Warfare Agent ◽  
Test System ◽  
Detection Scheme ◽  
Silicon Matrix ◽  
Sensing Applications ◽  
The Matrix ◽  
Target Molecules

ABSTRACTThe goal of our research is to combine porous silicon and enzymes in order to build hybrid platforms for extremely selective chemical sensing applications. For this, a new synthetic route to covalently anchor bio-molecules on photo-luminescent porous silicon (PL PSi) while preserving the optical properties of the matrix was developed. The hydride terminated porous silicon surface was covalently functionalized with t-butyloxycarbonyl protected amine by light-assisted hydrosysilation. Protein cross-linker chemistry was then used to extend the linker and immobilize various enzymes. The glu-coronidase enzyme/p-nitro-phenyl-beta-glucoronide substrate test system provided a proof of concept for an enzyme-based porous silicon detector. The enzymatic activity and the luminescence of the porous silicon platform were both retained after the functionali-zation procedure and, charge transfer between the products of the enzymatic breakdown and the silicon quantum dots was demonstrated. The organophosphorous hydrolase enzyme OPAA was then immobilized and tested on p-nitrophenyl-soman, a surrogate substrate for soman. The production of the hydrolysis product, p-nitrophenol, correlated with the reversible luminescence quenching of the porous silicon matrix demonstrating the relevance of the enzyme-based platform for detection applications. This detection scheme, although indirect, takes advantage of the extreme specificity of enzymes. The approach is general and can be implemented for a series of target molecules.

Nanoscale Silicon Microcavity Optical Sensors for Biological Applications

2000 ◽  
Vol 638 ◽  
Author(s):  
Selena Chan ◽  
Scott R. Horner ◽  
Benjamin L. Miller ◽  
Philippe M. Fauchet
Keyword(s):  
Porous Silicon ◽  
Optical Sensors ◽  
Average Pore Size ◽  
Internal Surface ◽  
Optical Biosensor ◽  
Device Fabrication ◽  
Luminescence Spectra ◽  
Average Pore ◽  
Detection Scheme ◽  
Sensing Applications

AbstractThe large surface area of porous silicon provides numerous sites for many potential species to attach, which makes it an ideal host for sensing applications. The average pore size can be easily adjusted to accommodate either small or large molecular species. When porous silicon is fabricated into a structure consisting of two high reflectivity multilayer mirrors separated by an active layer, a microcavity is formed. Multiple narrow and visible luminescence peaks are observed with a full width at half maximum value of 3 nm. The position of these peaks is extremely sensitive to small changes in refractive index, such as that obtained when a biological object is attached to the large internal surface of porous silicon. We demonstrate the usefulness of this microcavity resonator structure as a DNA optical biosensor which displays appropriate sensitivity, selectivity, and response speed. A probing strand of DNA is initially immobilized in the porous silicon matrix, and then subsequently exposed to its sensing complementary DNA strand. Red-shifts in the luminescence spectra are observed and detected for various DNA concentrations. The spectral shifts confirm successful recognition and binding of DNA molecules within the porous structure. Detailed device fabrication procedures and the results of extensive testing will be presented. The detection scheme has also been extended to include the detection of viral DNA, proteins, and potentially bacteria. This work will lead to the development of a “smart bandage”, where the detection of bacteria or viruses can be diagnosed and an antibiotic treatment can be recommended.

The magnetic structure of ferromagnetic filaments of a CoNi(P) alloy in a porous silicon matrix

2003 ◽  
Vol 29 (4) ◽  
pp. 263-266 ◽  
Author(s):  
R. S. Iskhakov ◽  
S. V. Komogortsev ◽  
L. A. Chekanova ◽  
A. D. Balaev ◽  
V. A. Yuzova ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Magnetic Structure ◽  
Silicon Matrix

Development of Silicon-Based UV-Photodetector Prototypes using Photoluminescent Nanocrystalline Silicon Overlayers

2000 ◽  
Vol 638 ◽  
Author(s):  
Carlos Navarro ◽  
Luis F. Fonseca ◽  
Guillermo Nery ◽  
O. Resto ◽  
S. Z. Weisz
Keyword(s):  
Porous Silicon ◽  
Active Zone ◽  
Silicon Detector ◽  
Nanocrystalline Silicon ◽  
Incident Radiation ◽  
Enhancement Effect ◽  
Type Silicon ◽  
Quantum Confinement Effects ◽  
Si Films ◽  
P Type

AbstractThe maximum photoresponse of a normal silicon photodetector, that uses a p-n junction as the active zone, is obtained when the incident radiation wavelength is around 750nm. This response diminishes significantly when the incident radiation is near or in the UV region. Meanwhile, nanocrystalline silicon (nc-Si) films with high transparency above 650nm and high absorbance in the UV can be prepared. By quantum confinement effects, a fraction of this absorbed UV energy is re-emitted as visible photons that can be used by the junction. We study the enhancement of the UV-photoresponse of two silicon detector prototypes with a silicon p-n junction active zone and with a photoluminescent nc-Si overlayer. One prototype is made with a porous silicon/n-type silicon/p-type silicon/p++-silicon/metal configuration and the other with an Eu-doped Si-SiO2 overlayer instead of the porous silicon one. The comparison between both prototypes and the control is presented and discussed stressing on the enhancement effect introduced by the photoluminescent overlayers, stability and reproducibility.

EVIDENCE FOR ENERGY TRANSFER BETWEEN Eu3+ AND Tb3+ IN POROUS SILICON MATRIX

2003 ◽  
Author(s):  
A. MOADHEN ◽  
H. ELHOUICHET ◽  
B. CANUT ◽  
C. S. SANDU ◽  
M. OUESLATI ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Porous Silicon ◽  
Silicon Matrix

Polypyrrole-functionalized porous silicon for gas sensing applications

2006 ◽  
Vol 26 (5-7) ◽  
pp. 1072-1076 ◽  
Author(s):  
V. Vrkoslav ◽  
I. Jelínek ◽  
G. Broncová ◽  
V. Král ◽  
J. Dian
Keyword(s):  
Porous Silicon ◽  
Gas Sensing ◽  
Sensing Applications

Porous Silicon Nanostructured Materials for Sensing Applications: Molecular Assembling and Electrochemical or Optical Evaluation

2016 ◽  
Vol 1812 ◽  
pp. 77-82
Author(s):  
J. Márquez ◽  
M. De la Cruz-Guzmán ◽  
L.F. Cházaro ◽  
G. Palestino
Keyword(s):  
Porous Silicon ◽  
Optical Sensors ◽  
Detection Threshold ◽  
Environmental Pollutants ◽  
High Sensitivity ◽  
Hybrid Nanostructures ◽  
Specular Reflectance ◽  
Sensing Applications ◽  
Fluorescent Ligands ◽  
Hybrid Devices

ABSTRACTPorous silicon (PSi) combines the potential of miniaturization with a very large surface area. The PSi surface can be chemically modified resulting in a high sensitivity (low detection threshold) device for chemical and biomolecular sensing. In previous work, we have shown that redox proteins and fluorescent ligands can be infiltrated into PSi (PSiMc) structures. The hybrid devices have shown interesting new properties produced by the coupling of the individual properties of PSi nanostructures and the modifiers. In this work, we have obtained a PSiMc/redox protein bioelectrode, which presents a quasi-reversible electrochemical response. This effect was attributed to the semiconducting nature of the PSi substrate and to the functional groups of the crosslinking molecules (MPTS), which together produce a capacitive effect on the device. On the other hand, the chemical modification of PSiMc with fluorescent ligands allowed us to fabricate fluorescent PSi hybrid nanostructures, which were tested for the detection of environmental pollutants such as heavy metals (specifically Hg2+). We found that the selectivity of this optical device depends on the selected recognizing molecule. The captured metal induces the formation of a metallic complex that shows higher fluorescence compared with the sensor device. These results demonstrate the viability of using porous silicon as optical sensors and electrochemical biosensors. The infiltration of fluorescent recognizing molecules and proteins into the PSi matrix were evaluated by specular reflectance, FTIR spectroscopy, fluorescence spectroscopy and cyclic voltammetry.

Cu-Si Nanocomposites Based on Porous Silicon Matrix

2009 ◽  
Vol 151 ◽  
pp. 222-226 ◽  
Author(s):  
Hanna Bandarenka ◽  
Aliaksandr Shapel ◽  
Marco Balucani
Keyword(s):  
Porous Silicon ◽  
Elemental Composition ◽  
Porous Layer ◽  
Copper Film ◽  
Silicon Matrix ◽  
Fine Grained ◽  
Displacement Deposition

Cu-Si nanocomposites formed by an immersion displacement deposition of Cu into porous silicon (PS) matrix have been experimentally studied. SEM and AES were used to investigate the structure and elemental composition of Cu-Si samples. The top part of the Cu-PS samples is shown to demonstrate the following structure: large faceted Cu grains at the top, a porous fine-grained copper film underneath the large grains, and the copper pointed rods extended from the surface into the PS layer. The top part of the silicon skeleton of the PS layer is converted into the copper by the etching followed by Cu displacement deposition. The porosity of the porous layer and displacement deposition times are found to form Cu-Si nanocomposites of various structures and various Cu-Si contents because of various extent of the silicon skeleton transformation into copper.

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