Analytical Sciences

A Novel Fluorescent Probe for Copper Ions Based on Polymer-modified CdSe/CdS Core/Shell Quantum Dots

Zhong CAO,*,** Zheng GU,** Ju-Lan ZENG,* Jin-Hua LIU,** Qin DENG,** Jun-Bing FAN,** and Jian-Nan XIANG**

*Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation, School of Chemistry and Biological Engineering, Changsha University of Science and Technology, Changsha 410004, P. R. China
**State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China

Quantum dots (QDs) have become one of the most attractive fields of current research because of their unique optical properties. Novel copper-sensitive fluorescent fluoroionophores based on CdSe/CdS core/shell QDs modified with a polymer of MAO-mPEG were synthesized and characterized in the present work. A pH of 6.47 was optimally selected for measurements. By modifying QDs with MAO-mPEG, significant aqueous fluorescence quenching was observed upon binding with copper ions involving both reduced and oxidized environments, indicating great sensitivity and specificity for copper-ion sensing. No significant interfering effects from other metal ions, such as Ag⁺, Al³⁺, Ba²⁺, Ca²⁺, Cd²⁺, Co²⁺, Cr³⁺, Fe²⁺, Fe³⁺, Hg²⁺, K⁺, Mg²⁺, Mn²⁺, Na⁺, Ni²⁺, Pb²⁺, Sn²⁺, and Zn²⁺, were observed. The linear response range for Cu²⁺ was found to be 0.01 – 0.50 μM, and the limit of detection was evaluated to be 16 nM. The proposed method demonstrated improved sensitivity and selectivity characteristics for Cu(II) determinations based on CdSe/CdS core/shell QDs modified with MAO-mPEG by using a typical liquid-phase quenching assay, showing its potential application to multiplex sensing of different analytes through distinct ligand conjugation and functionalization of individual fluorophores.

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