scholarly journals Reusable and Mediator-Free Cholesterol Biosensor Based on Cholesterol Oxidase Immobilized onto TGA-SAM Modified Smart Bio-Chips

PLoS ONE ◽  
2014 ◽  
Vol 9 (6) ◽  
pp. e100327 ◽  
Author(s):  
Mohammed M. Rahman
Keyword(s):  
Free Cholesterol ◽  
Cholesterol Oxidase ◽  
Cholesterol Biosensor

scholarly journals An Electrochemical Cholesterol Biosensor Based on A CdTe/CdSe/ZnSe Quantum Dots—Poly (Propylene Imine) Dendrimer Nanocomposite Immobilisation Layer

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3368 ◽  
Author(s):  
Kefilwe Mokwebo ◽  
Oluwatobi Oluwafemi ◽  
Omotayo Arotiba
Keyword(s):  
Quantum Dots ◽  
Modified Electrode ◽  
Cholesterol Oxidase ◽  
Shell Growth ◽  
Modified Electrodes ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Poly Propylene ◽  
Cholesterol Biosensor

We report the preparation of poly (propylene imine) dendrimer (PPI) and CdTe/CdSe/ZnSe quantum dots (QDs) as a suitable platform for the development of an enzyme-based electrochemical cholesterol biosensor with enhanced analytical performance. The mercaptopropionic acid (MPA)-capped CdTe/CdSe/ZnSe QDs was synthesized in an aqueous phase and characterized using photoluminescence (PL) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), X-ray power diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy. The absorption and emission maxima of the QDs red shifted as the reaction time and shell growth increased, indicating the formation of CdTe/CdSe/ZnSe QDs. PPI was electrodeposited on a glassy carbon electrode followed by the deposition (by deep coating) attachment of the QDs onto the PPI dendrimer modified electrode using 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC), and N-hydroxysuccinimide (NHS) as a coupling agent. The biosensor was prepared by incubating the PPI/QDs modified electrode into a solution of cholesterol oxidase (ChOx) for 6 h. The modified electrodes were characterized by voltammetry and impedance spectroscopy. Since efficient electron transfer process between the enzyme cholesterol oxidase (ChOx) and the PPI/QDs-modified electrode was achieved, the cholesterol biosensor (GCE/PPI/QDs/ChOx) was able to detect cholesterol in the range 0.1–10 mM with a detection limit (LOD) of 0.075 mM and sensitivity of 111.16 μA mM−1 cm−2. The biosensor was stable for over a month and had greater selectivity towards the cholesterol molecule.

Enzyme Electrode with Collagen-Immobilized Cholesterol Oxidase for the Microdetermination of Free Cholesterol

1979 ◽  
Vol 12 (14) ◽  
pp. 1477-1488 ◽  
Author(s):  
Catherine Bertrand ◽  
Pierre R. Coulet ◽  
Danièle C. Gautheron
Keyword(s):  
Free Cholesterol ◽  
Cholesterol Oxidase ◽  
Enzyme Electrode

scholarly journals Filipin vs enzymatic localization of cholesterol in guinea pig, mink, and mallard duck testicular cells.

1994 ◽  
Vol 42 (12) ◽  
pp. 1539-1554 ◽  
Author(s):  
R M Pelletier ◽  
M L Vitale
Keyword(s):  
Guinea Pig ◽  
Lipid Droplets ◽  
Free Cholesterol ◽  
Cholesterol Oxidase ◽  
False Negative ◽  
Cholesterol Esters ◽  
Enzymatic Method ◽  
Mallard Duck ◽  
Cholesterol Levels ◽  
Testicular Cells

To test the validity of filipin cytochemistry for localization of cholesterol in testicular cells, we compared the results obtained by this technique with those obtained by a two-step enzymatic method involving cholesterol esterase and cholesterol oxidase. In all the animals models tested (guinea pig, mink, and mallard duck) the disappearance of subsurface filaments along Sertoli cell junctional membranes was accompanied by a significant increase in the number of filipin-cholesterol complexes/microns 2 in these membranes. Enzyme histochemistry allowed localization of free cholesterol in the limiting membrane of multivesicular bodies, in membranes within lysosomes, in mitochondrial membranes, and in junctional membranes, with or without subsurface filaments. The method also permitted selective visualization of cholesterol esters in lipid droplets. We conclude that filipin mapping of cholesterol induces false-negative cytochemical results. The enzymatic method is superior to filipin because it allows localization of free cholesterol in junctional membranes and of cholesterol esters in lipid droplets. This compartmentalization of the compounds may represent the basis of a system that helps to maintain constant free cholesterol levels in the testis.

Enzymatic Determination of Total Serum Cholesterol

1974 ◽  
Vol 20 (4) ◽  
pp. 470-475 ◽  
Author(s):  
Charles C Allain ◽  
Lucy S Poon ◽  
Cicely S G Chan ◽  
W Richmond ◽  
Paul C Fu
Keyword(s):  
Serum Cholesterol ◽  
Free Cholesterol ◽  
Cholesterol Oxidase ◽  
Total Serum ◽  
Total Serum Cholesterol ◽  
Enzymatic Method ◽  
Simultaneous Production ◽  
Enzymatic Determination ◽  
Production Of Hydrogen

Abstract An enzymatic method is described for determination of total serum cholesterol by use of a single aqueous reagent. The method requires no prior treatment of sample and the calibration curve is linear to 600 mg/dl. Cholesterol esters are hydrolyzed to free cholesterol by cholesterol ester hydrolase (EC 3.1.1.13). The free cholesterol produced is oxidized by cholesterol oxidase to cholest-4-en-3-one with the simultaneous production of hydrogen peroxide, which oxidatively couples with 4-aminoantipyrine and phenol in the presence of peroxidase to yield a chromogen with maximum absorption at 500 nm. The method is reproducible, and the results correlate well with those obtained by automated Liebermann—Burchard procedures (AA-2 and SMA 12/60) and the method of Abell et al. The present method affords better specificity than those previously reported and has excellent precision.

Automated enzymic measurement of total cholesterol in serum.

1978 ◽  
Vol 24 (1) ◽  
pp. 108-114 ◽  
Author(s):  
G S Rautela ◽  
R J Liedtke
Keyword(s):  
Hydrogen Peroxide ◽  
Total Cholesterol ◽  
Response Surface ◽  
Computer Analysis ◽  
Free Cholesterol ◽  
Cholesterol Oxidase ◽  
Cholesterol Esters ◽  
Direct Proportion ◽  
Analytical Test ◽  
Response Surface Designs

Abstract We describe a completely automated enzymic system for measuring total cholesterol in serum. All reagents are contained in an analytical test pack and the test is performed on Du Pont's Automatic Clinical Analyzer (aca), which mixes the sample (20 microliter) and reagents and performs the necessary absorbance measurements and calculations. In the procedure, cholesterol oxidase oxidizes free cholesterol. The oxidation step produces cholest-4-en-3-one and hydrochloride peroxidesterase hydrolyzes cholesterol esters and cholesterol in direct proportion to the amount of cholesterol present. N,N-Diethylaniline hydrochloride and 4-aminoantipyrine react with the hydrogen peroxide to produce a quinoneimine dye (lambda max = 553 nm). Interacting reagents have been optimized simultaneously (coöptimization) utilizing response surface designs coupled with computer analysis of the data. Reagent efficiency is high and analytical performance reliable.

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