Centre for Micro & Nano Devices, Department of Physics, COMSATS University Islamabad, Park Road Campus, Islamabad, 45550, Pakistan.
Department of Bioscience, COMSATS University Islamabad, Park Road Campus, Islamabad, 45550, Pakistan.
Sci Rep. 2020 Nov 24;10(1):20439. doi: 10.1038/s41598-020-77499-9.
This paper reports the enhanced performance of cholesterol oxidase (COx) conjugated CdSe/ZnS quantum dots (QDs) by using water-soluble mercaptoacitic acid (MAA) as linker. The functionalized MAA-CdSe/ZnS QDs conjugated in four different dilutions of cholesterol oxidase significantly affected QDs photoluminescence intensities, which affected the process of charge transfer from QDs to MAA. The conjugation of COx to MAA-QDs in increased dilutions resulted in the regain of PL intensities, which were attributed to the passivation of MAA HOMO/LUMO states. The electrochemical impedance spectroscopy and cyclic voltammetry of the conjugated QDs were performed to get study the charge transfer mechanism. The 1:1000 diluted COx conjugated MAA-CdSe/ZnS QDs was found to have the lowest charge transfer resistance of 228 Ω, the highest diffusion (~ 1.39 × 10 cm/s) and charge transfer rates (~ 4.5 × 10 s) between the electrode and the redox species. The current study demonstrated the sensitivity of electrochemical and optical based detection on the alkaline.
本文报道了胆固醇氧化酶（COx）通过使用水溶性巯基乙酸（MAA）作为连接物连接到 CdSe/ZnS 量子点（QDs）上，从而增强了其性能。功能化的 MAA-CdSe/ZnS QDs 以胆固醇氧化酶的四种不同稀释度进行共轭，显著影响了 QDs 的光致发光强度，从而影响了从 QDs 到 MAA 的电荷转移过程。在增加的稀释度下，COx 与 MAA-QDs 的共轭导致 PL 强度的恢复，这归因于 MAA HOMO/LUMO 态的钝化。对共轭 QDs 进行了电化学阻抗谱和循环伏安法研究，以研究电荷转移机制。发现 1:1000 稀释的 COx 共轭 MAA-CdSe/ZnS QDs 的电荷转移电阻最低，为 228 Ω，扩散率最高（约 1.39×10 cm/s），在电极和氧化还原物种之间的电荷转移速率最高（约 4.5×10 s）。本研究证明了基于电化学和光学的检测在碱性条件下的灵敏度。
