Label-free sensing of thrombin based on quantum dots and thrombin binding aptamer

• Published in: Talanta (Oxford) Vol. 107; pp. 140 - 145
• Main Authors: Zhang, Xiangyuan, Hu, Ruoxin, Shao, Na
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 30-03-2013
• Subjects: Aptamers, Nucleotide - chemistry; Binding; cadmium; Cadmium - chemistry; Cadmium Compounds - chemistry; Cadmium tellurides; CdTe quantum dots; Charging; Detection; detection limit; electrostatic interactions; Fluorescence; Fluorescence recovery; Fluorescent Dyes - chemistry; G-Quadruplexes; Humans; Label-free; Limit of Detection; oligonucleotides; Quantum Dots; Quenching; Spectrometry, Fluorescence - methods; Tellurium - chemistry; Thrombin; Thrombin - analysis; Thrombin binding aptamer; Thrombin binding aptamer; Fluorescence recovery; Thrombin; CdTe quantum dots; Label-free
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2013.01.003

A facile and sensitive label-free approach for detection of thrombin based on CdTe quantum dots (QDs) and thrombin binding aptamer (TBA) is presented. The crude QDs can be “activated” with fluorescence enhancement by adding extra Cd2+ to the solution in basic medium. As a result, the positively charged Cd2+-activating CdTe QDs could interact with the negatively charged TBA, leading to fluorescence quenching. When thrombin was added, TBA was induced to form a G-quadruplex structure and combined specifically with its target, releasing the QDs with a recovery of the fluorescence intensity. The sensing approach is based on the strongly specific interactions between TBA and thrombin over the electrostatic interactions between TBA and positively charged QDs. Based on the fluorescence enhancement of QDs, selective detection of thrombin was successfully achieved. A linear response for thrombin was observed in the range from 1.4nM to 21nM with a detection limit of 0.70nM.
► Label-free aptamer based detection of thrombin is realized using CdTe QDs. ► Easy to operate as the complicated cross-linking reactions were eliminated. ► Turn-on sensing mode could reduce background signal and improve sensitivity. ► Serum sample analysis was achieved, requiring no pretreatment or separation. ► This work may offer a relatively general approach to other analytes detection.