Silica-embedded CdTe quantum dots functionalized with rhodamine derivative for instant visual detection of ferric ions in aqueous media.

Graphical abstract A new hydrophilic ratiometric hybrid sensor has been developed for the visual detection of Fe3+ with the fluorescence color changing from red to yellow and a lower detection limit of 26.5 nM. Highlights • A novel hydrophilic ratiometric sensor for instant visual detection of Fe3+. • The fluorescence response occurs instantaneously and reaches stability less than one second. • The detection limit of Fe3+ is as low as 26.5 nM. • The paper sensor has been prepared for the visual and on-site detection of Fe3+. Abstract A novel hydrophilic ratiometric fluorescence sensor for instant visual detection of Fe3+ was successfully prepared by integrating silica-embedded CdTe quantum dots (QDs) with rhodamine derivative. The rich hydrophilic group and large specific surface area of CdTe@SiO 2 QDs favored the adsorption of rhodamine derivative on silica and improvement of its water solubility. The results proved that the ratiometric fluorescence sensor shows a much higher selectivity towards Fe3+ with the detection limit as low as 26.5 nM than other typical cations and anions in aqueous solution. Moreover, the fluorescence response occurs instantaneously and reaches stability less than one second. Additionally, a simple and rapid paper-based analytical device was designed for on-site and visual detection of Fe3+ in actual water samples. Hence, this study provided a good candidate for the on-site and visual sensing of Fe3+ in the environmental analysis. [ABSTRACT FROM AUTHOR]