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Article

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

1
Department of Applied Chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein 2028, Johannesburg, South Africa
2
Centre for Nanomaterials Science Research, University of Johannesburg, Doornfontein 2028, Johannesburg, South Africa
*
Author to whom correspondence should be addressed.
Sensors 2018, 18(10), 3368; https://doi.org/10.3390/s18103368
Received: 18 August 2018 / Revised: 24 September 2018 / Accepted: 6 October 2018 / Published: 9 October 2018
(This article belongs to the Special Issue Development of Enzymatic Electrochemical Biosensors and Applications)
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. View Full-Text
Keywords: Cholesterol; electrochemical biosensors; quantum dots; poly (propylene imine) dendrimer; cholesterol oxidase Cholesterol; electrochemical biosensors; quantum dots; poly (propylene imine) dendrimer; cholesterol oxidase
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MDPI and ACS Style

Mokwebo, K.V.; Oluwafemi, O.S.; Arotiba, O.A. An Electrochemical Cholesterol Biosensor Based on A CdTe/CdSe/ZnSe Quantum Dots—Poly (Propylene Imine) Dendrimer Nanocomposite Immobilisation Layer. Sensors 2018, 18, 3368. https://doi.org/10.3390/s18103368

AMA Style

Mokwebo KV, Oluwafemi OS, Arotiba OA. An Electrochemical Cholesterol Biosensor Based on A CdTe/CdSe/ZnSe Quantum Dots—Poly (Propylene Imine) Dendrimer Nanocomposite Immobilisation Layer. Sensors. 2018; 18(10):3368. https://doi.org/10.3390/s18103368

Chicago/Turabian Style

Mokwebo, Kefilwe V.; Oluwafemi, Oluwatobi S.; Arotiba, Omotayo A. 2018. "An Electrochemical Cholesterol Biosensor Based on A CdTe/CdSe/ZnSe Quantum Dots—Poly (Propylene Imine) Dendrimer Nanocomposite Immobilisation Layer" Sensors 18, no. 10: 3368. https://doi.org/10.3390/s18103368

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