Porous silicon based potentiometric triglyceride biosensor.
TL;DR: Enzyme solution-oxidized porous silicon-crystalline silicon structure was used to detect changes in pH during the hydrolysis of tributyrin as a shift in the capacitance-voltage (C-V) characteristics.
About: This article is published in Biosensors and Bioelectronics.The article was published on 2001-06-01. It has received 102 citations till now. The article focuses on the topics: Immobilized enzyme & Crystalline silicon.
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TL;DR: This work reviews the status of the various nanostructure-based biosensors and use of the self-assembly techniques and nano-electromechanical systems (NEMS) in bios Sensors is discussed.
506 citations
TL;DR: The potential of different porous silicon photonic crystals for biosensing in the context of its surface chemistry and nanostructure is discussed, both of which need to be optimized to obtain sensitive and stable devices.
155 citations
TL;DR: The impact of microfabricated devices has had an impact over a broad range of therapies and tissues, as well as offering ease of en masse fabrication, small device size, and facile incorporation of integrated circuit technology.
Abstract: By adapting microfabrication techniques originally developed in the microelectronics industry novel devices for drug delivery, tissue engineering and biosensing have been engineered for in vivo use. Implant microfabrication uses a broad range of techniques including photolithography, and micromachining to create devices with features ranging from 0.1 to hundreds of microns with high aspect ratios and precise features. Microfabrication offers device feature scale that is relevant to the tissues and cells to which they are applied, as well as offering ease of en masse fabrication, small device size, and facile incorporation of integrated circuit technology. Utilizing these methods, drug delivery applications have been developed for in vivo use through many delivery routes including intravenous, oral, and transdermal. Additionally, novel microfabricated tissue engineering approaches propose therapies for the cardiovascular, orthopedic, and ocular systems, among others. Biosensing devices have been designed to detect a variety of analytes and conditions in vivo through both enzymatic-electrochemical reactions and sensor displacement through mechanical loading. Overall, the impact of microfabricated devices has had an impact over a broad range of therapies and tissues. This review addresses many of these devices and highlights their fabrication as well as discusses materials relevant to microfabrication techniques.
112 citations
TL;DR: In this article, the authors trace the use of nanomaterials in biochemical sensor design and highlight capabilities and applications for nanoparticles based on gold, silver, magnetic, and semiconductor materials (quantum dots), used in optical (absorbance, luminescence, surface enhanced Raman spectroscopy, surface plasmon resonance), electrochemical, and mass sensitive sensors.
Abstract: There is little doubt that nanoparticles offer real and new opportunities in many fields, such as biomedicine and materials science. Such particles are small enough to enter almost all areas of the body, including cells and organelles, potentially leading to new approaches in nanomedicine. Sensors for small molecules of biochemical interest are of critical importance. This review is an attempt to trace the use of nanomaterials in biochemical sensor design. The possibility of using nanoparticles functionalized with antibodies as markers for proteins will be elucidated. Moreover, capabilities and applications for nanoparticles based on gold, silver, magnetic, and semiconductor materials (quantum dots), used in optical (absorbance, luminescence, surface enhanced Raman spectroscopy, surface plasmon resonance), electrochemical, and mass-sensitive sensors will be highlighted. The unique ability of nanosensors to improve the analysis of biochemical fluids is discussed either through considering the use of nanoparticles for in vitro molecular diagnosis, or in the biological/biochemical analysis for in vivo interaction with the human body.
111 citations
Cites background from "Porous silicon based potentiometric..."
...Moreover, estimation of triglyceride content in food has become important due to increased health awareness and stringent regulatory laws.(42) The conventional methods for triglycerides detection, such as colorimetric or fluorometric techniques, are based on enzymatic hydrolysis of triglycerides to glycerol and free fatty acids....
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TL;DR: The electrochemical response of lipase/nano-CeO 2 /ITO bioelectrode towards tributyrin, investigated using CV studies, exhibits linearity, detectionlimit and shelf life as 50 500mg/dL, 32.8 mg/dL and 12 weeks, respectively.
Abstract: Lipase has been immobilized onto sol gel derived nanostuctured cerium oxide (Nano-CeO 2 , 35nm)lm deposited onto indium tin oxide (ITO) coated glass plate for tributyrin detection. The Nano-CeO 2 /ITO electrode and lipase/nano-CeO 2 /ITO bioelectrode have been characterized using scanningelectron microscopy (SEM) and cyclic voltammetry (CV). The electrochemical response of lipase/nano-CeO 2 /ITO bioelectrode towards tributyrin, investigated using CV studies, exhibits linearity, detectionlimit and shelf life as 50 500mg/dL, 32.8mg/dL and 12 weeks, respectively. The value of the apparentMichaelis Menten constant ( K appm ) obtained as 22.27mg/dL (0.736mM) for lipase/nano-CeO 2 /ITO bio-electrode indicates high afnity of lipase with tributyrin. Attempts have been made to detect triglycerideconcentration in serum samples.© 2009 Elsevier B.V. All rights reserved. 1. IntroductionEstimation of triglycerides (triacylglycerols) is extremelyimportant since its high concentration [normal range in men(40 160mg/dl) and in women (35 135mg/dl)] can cause hyper-lipidemia [1 3] . Apart from coronary diseases, hyperlipidemiais associated with several disorders including diabetes mellitus,nephrosis, liver obstruction and endocrine. Moreover, estimationof triglycerides content in food has become important due toincreased health awareness and stringent regulatory laws [4]. Theconventionalmethodsfortriglyceridesdetectionsuchascolorimet-ricoruorometrictechniquesarebasedonenzymatichydrolysisoftriglycerides to glycerol and free fatty acids [5 7] .Most triglyceride biosensors reported till date are based onmulti-enzymes wherein a biochemical reaction depends uponenzyme kinetics of the other enzymatic reaction. McGowan etal. have described an enzymatic method for serum triglyceridedetection that involves simultaneous catalysis of four bio-enzymes(lipase, glycerol kinase, l-a-glycerophosphate oxidase and per-oxidase) [8]. These methods are, however, time-consuming,complicated and expensive. Basu et al. have recently fabricated apH-based biosensor for triglycerides detection using silicon and anelectrolyte insulator semiconductor capacitor (EISCAP) [9]. Microreactor packed with immobilized lipase has been used for triglyc-eride detection using ion sensitive eld effective transistor (ISFET)
86 citations
Cites background or methods from "Porous silicon based potentiometric..."
...have fabricated porous silica based potentiometric pH dependant triglyceride biosensor [4]....
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...478 pH/mM [9] Porous silica Lipase Physical Potentiometric 6 months – 30 mV [4] Iridium nano-particle modified carbon Lipase, GDH,* -NAD Physical 0–10 mM Electrochemical – – 7....
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...Moreover, estimation of triglycerides content in food has become important due to increased health awareness and stringent regulatory laws [4]....
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References
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TL;DR: The development of an ion-sensitive solid-state device that combines the principles of an MOS transistor and a glass electrode and can be used for measurements of ion activities in electrochemical and biological environments is described.
Abstract: The development of an ion-sensitive solid-state device is described. The device combines the principles of an MOS transistor and a glass electrode and can be used for measurements of ion activities in electrochemical and biological environments. Some preliminary results are given.
1,841 citations
TL;DR: A biosensor has been developed based on induced wavelength shifts in the Fabry-Perot fringes in the visible-light reflection spectrum of appropriately derivatized thin films of porous silicon semiconductors based on Binding of molecules induced changes in the refractive index of the porous silicon.
Abstract: A biosensor has been developed based on induced wavelength shifts in the Fabry-Perot fringes in the visible-light reflection spectrum of appropriately derivatized thin films of porous silicon semiconductors. Binding of molecules induced changes in the refractive index of the porous silicon. The validity and sensitivity of the system are demonstrated for small organic molecules (biotin and digoxigenin), 16-nucleotide DNA oligomers, and proteins (streptavidin and antibodies) at pico- and femtomolar analyte concentrations. The sensor is also highly effective for detecting single and multilayered molecular assemblies.
1,392 citations
TL;DR: In this article, the pore size distribution of porous silicon was investigated on different types of substrates and under different experimental conditions, and it was shown that porosity is strongly dependent on the type and resistivity of the original silicon substrate and on the electrochemical parameters used during anodization processes.
Abstract: Porosities of porous silicon layers formed on different types of substrates and under different experimental conditions are compared with and related to the pore size distribution determined by gas adsorption experiments. Results show that porous layers formed on lightly P-doped silicon exhibit a network of very narrow pores, of radii less than 2 nm. Porous films formed on heavily doped silicon present larger radii, ranging between 2 and 9 nm according to the experimental conditions. Larger porosities and larger pore sizes are obtained by increasing the forming current density or by decreasing the HF concentration. Heavily P-doped porous silicon layers are homogeneous in depth and generally present a quite sharp pore size distribution. With heavily N-doped silicon, an increase in porosity with increasing thickness is found, which corresponds to an increase in pore size, leading to a broadening of size distributions. This porosity gradient is attributed to a chemical dissolution of the layer occurring during anodization. In addition, a strong dependence of porosity with small variations in doping level is found. Porous silicon is a material obtained by anodic oxidation of monocrystalline silicon in concentrated hydrofluoric acid solutions. Several papers (1-4) have shown that this material is one of the promising candidates for use in silicon on insulator (SOI) structures in integrated circuit technology. In all the proposed applications, the oxidation properties of porous silicon are used to obtain thick insulating layers of silica in relatively short periods of time. The properties of the material are very dependent on the type and resistivity of the original silicon substrate and on the electrochemical parameters used during the anodization processes. Porous silicon is often characterized by its porosity, mainly due to the existence of a so-called optimal porosity of about 56%, for which good silicon dioxides are obtained with minimum strains and volume expansion (5), which is necessary to obtain fully oxidized structures. However, porosity values alone are not enough to characterize the material as quite different properties can be obtained for materials of the same porosity if the substrate resistivity and preparation conditions are properly chosen. Other parameters to be considered when a better characterization of porous structures is required are pore size and pore size distribution. Both porosity and pore size determine altogether the size of the silicon walls in the porous material, so that properties like crystalline quality (6), optical response (7), thermal behavior (8), and oxidation mechanism (9) are very dependent on both porosity and pore size. It has been shown in a previous paper (10) that it was possible using gas adsorption techniques to determine accurately the pore size and pore distribution of radii in the porous silicon layers. That work was limited to porous silicon layers prepared on (111) heavily P-doped substrates. The aim of the present work is to study (100) substrates and investigate other kinds of resistivity and different electrochemical preparation conditions. Experimental
526 citations
445 citations
TL;DR: In this article, an analysis of the quasi-equilibrium characteristics of an electrolyte-oxide-semiconductor (EOS) system has been carried out by initially considering two limiting cases: an ideal unblocked interface between the electrolyte and the oxide is assumed.
Abstract: In order to provide an improved understanding of ion-sensitive field-effect transistors (ISFET's) an analysis of the quasi-equilibrium characteristics of an electrolyte-oxide-semiconductor (EOS) system has been carried out. The characteristics of this system are examined by initially considering two limiting cases. In the first case, an ideal unblocked interface between the electrolyte and the oxide is assumed. Electrochemical processes of ion exchange dominates and consequently, a Nernstian response is experienced. The second limiting case assumes a totally blocked interface such that the behavior of the EOS system is dictated by electrostatic factors. The analysis is then generalized to examine the case of an electrolyte-pyrogenic SiO 2 -Si system using a site binding model to describe the ionic adsorption processes at the electrolyte-pyrogenic SiO 2 interface. The C-V characteristics and changes in flat-band voltage of the EOS system in response to pH are examined. Analytical results show that in general, the response does not obey the classical Nernst equation. Correlation of theoretical and experimental results yields excellent agreement suggesting that the models used in this study can provide an adequate description of the physical processes.
241 citations