Development of Highly Sensitive and Selective Cholesterol Biosensor Based on Cholesterol Oxidase Co-Immobilized with α-Fe2O3 Micro-Pine Shaped Hierarchical Structures

2014 ◽  
Vol 135 ◽  
pp. 396-403 ◽  
Author(s):  
Ahmad Umar ◽  
Rafiq Ahmad ◽  
S.W. Hwang ◽  
S.H. Kim ◽  
A. Al-Hajry ◽  
...  
Keyword(s):  
Cholesterol Oxidase ◽  
Hierarchical Structures ◽  
Highly Sensitive ◽  
Cholesterol Biosensor

Bimetallic Co 2+ and Mn 2+ Hexacyanoferrate for Hydrogen Peroxide Electrooxidation and Its Application in a Highly Sensitive Cholesterol Biosensor

2019 ◽  
Vol 6 (5) ◽  
pp. 1567-1573 ◽  
Author(s):  
Manuel Antuch ◽  
Yasser Matos‐Peralta ◽  
Dayma Llanes ◽  
Frank Echevarría ◽  
Joelis Rodríguez‐Hernández ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Highly Sensitive ◽  
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.

scholarly journals Highly Sensitive Cholesterol Assay with Enzymatic Cycling Applied to Measurement of Remnant Lipoprotein-Cholesterol in Serum

2002 ◽  
Vol 48 (5) ◽  
pp. 737-741 ◽  
Author(s):  
Koji Kishi ◽  
Koji Ochiai ◽  
Yohsuke Ohta ◽  
Yahiro Uemura ◽  
Kazushi Kanatani ◽  
...  
Keyword(s):  
Cholesterol Oxidase ◽  
Lipoprotein Cholesterol ◽  
Cholesterol Concentration ◽  
Separation Procedure ◽  
Enzymatic Method ◽  
Healthy Individuals ◽  
Apo B ◽  
Remnant Lipoprotein ◽  
Enzymatic Cycling ◽  
Highly Sensitive

Abstract Background: Remnant lipoprotein-cholesterol (RLP-C) concentrations in sera of healthy individuals are very low (0.080–0.437 mmol/L), making conventional cholesterol methods poorly suited to this purpose. We have developed a highly sensitive cholesterol assay (CD method) and applied it to the RLP-C assay. Methods: The CD shuttled cholesterol reversibly between reduced and oxidized forms in the presence of thio-NAD and NADH. The production rate of thio-NADH correlated with the cholesterol concentration and was measured by the absorbance at 404/500 nm. This CD method was combined with an immunoaffinity separation procedure with specific monoclonal antibodies to apolipoprotein (apo) A1 and apo B-100 and used for RLP-C assay. Results were compared with a RLP-C method that uses cholesterol oxidase, peroxidase, and chromogenic substrate. Results: The CD method could detect 0.10 × 10−3 mmol/L cholesterol and was at least 5 times more sensitive than the conventional enzymatic method. Within- and between-day imprecision (as CVs) of the RLP-C assay with the CD method was <4%. Regression analysis of RLP-C assays with the new (y) and conventional (x) cholesterol methods yielded: y = 1.02x − 0.008 mmol/L (Sy|x = 0.0065 mmol/L; r = 0.997; n = 297). Conclusions: Serum RLP-C can be measured by the CD method. The CD method may be useful for other assays that require sensitive cholesterol measurements in biological materials.

scholarly journals Label-free highly sensitive probe detection with novel hierarchical SERS substrates fabricated by nanoindentation and chemical reaction methods

2019 ◽  
Vol 10 ◽  
pp. 2483-2496
Author(s):  
Jingran Zhang ◽  
Tianqi Jia ◽  
Yongda Yan ◽  
Li Wang ◽  
Peng Miao ◽  
...  
Keyword(s):  
Ag Nanoparticles ◽  
Enhancement Factor ◽  
Low Cost ◽  
Hierarchical Structures ◽  
Production Method ◽  
Copper Surface ◽  
Sers Substrate ◽  
Label Free ◽  
Sers Substrates ◽  
Highly Sensitive

Nanostructures have been widely employed in surface-enhanced Raman scattering (SERS) substrates. Recently, in order to obtain a higher enhancement factor at a lower detection limit, hierarchical structures, including nanostructures and nanoparticles, appear to be viable SERS substrate candidates. Here we describe a novel method integrating the nanoindentation process and chemical redox reaction to machine a hierarchical SERS substrate. The micro/nanostructures are first formed on a Cu(110) plane and then Ag nanoparticles are generated on the structured copper surface. The effect of the indentation process parameters and the corrosion time in the AgNO3 solution on the Raman intensities of the SERS substrate with hierarchical structures are experimentally studied. The intensity and distribution of the electric field of single and multiple Ag nanoparticles on the surface of a plane and with multiple micro/nanostructures are studied with COMSOL software. The feasibility of the hierarchical SERS substrate is verified using R6G molecules. Finally, the enhancement factor using malachite green molecules was found to reach 5.089 × 109, which demonstrates that the production method is a simple, reproducible and low-cost method for machining a highly sensitive, hierarchical SERS substrate.

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