Manipulating the Surface Chemistry of Quantum Dots for Sensitive Ratiometric Fluorescence Detection of Sulfur Dioxide

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• 作者：Huihui Li ; Houjuan Zhu ; Mingtai Sun ; Yehan Yan ; Kui Zhang ; Dejian Huang ; Suhua Wang
• 刊名：Langmuir
• 出版年：2015
• 出版时间：August 11, 2015
• 年：2015
• 卷：31
• 期：31
• 页码：8667-8671
• 全文大小：334K
• ISSN：1520-5827

文摘

Herein, we report a novel approach to the rapid visual detection of gaseous sulfur dioxide (SO₂) by manipulating the surface chemistry of 3-aminopropyltriethoxysilane (APTS)-modified quantum dots (QDs) using fluorescent coumarin-3-carboxylic acid (CCA) for specific reaction with SO₂. The CCA molecules are attached to the surface amino groups of the QDs through electrostatic attraction, thus the fluorescence of CCA is greatly suppressed because of the formation of an ion-pair complex between the ATPS-modified QDs and CCA. Such an interaction is vulnerable to SO₂ because SO₂ can readily react with surface amino groups to form strong charge-transfer complexes and subsequently release the strongly fluorescent CCA molecules. The mechanism has been carefully verified through a series of control experiments. Upon exposure to different amounts of SO₂, the fluorescent color of the nanoparticle-based sensor displays continuously changes from red to blue. Most importantly, the approach owns high selectivity for SO₂ and a tolerance of interference, which enables the sensor to detect SO₂ in a practical application. Using this fluorescence-based sensing method, we have achieved a visual detection limit of 6 ppb for gaseous SO₂.