Ultrasensitive copper(II) detection using plasmon-enhanced and photo-brightened luminescence of CdSe quantum dots.

Yang-Hsiang Chan, Jixin Chen, Qingsheng Liu, Stacey E Wark, Dong Hee Son, James D Batteas

Department of Chemistry, Texas A&M University, PO Box 30012, College Station, Texas 77842-3012, USA.

Analytical chemistry 2010 May 1

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Here, we present a simple platform for the use of the enhanced emission of 16-mercaptohexadecanoic acid (16-MHA) capped CdSe quantum dots (QDs) as a probe for ultrasensitive copper(II) detection. In this study, the photoluminescence (PL) of the QDs was first enhanced by Ag nanoprisms which were self-assembled on Si surfaces and then further increased by photobrightening. Using this approach, the control and different analytes could be readily probed all on a single platform using fluorescence microscopy. The enhanced PL intensity of CdSe QDs was selectively quenched in the presence of Cu(2+), accompanied by the emergence of a new red-shifted luminescence band. The quenching mechanism was found to be due to a cation exchange mechanism as confirmed by X-ray photoelectron spectroscopy (XPS) measurements. Herein, we have demonstrated that this simple methodology can offer a rapid and reliable detection of Cu(2+) with a detection limit as low as 5 nM and a dynamic range up to 100 muM in a fixed fast reaction time of 5 min. The potential applications of this technique were tested in two ways, for mixed-ion solutions and in physiological fluids, and both experiments exhibited good selectivity toward Cu(2+).

Citation

Yang-Hsiang Chan, Jixin Chen, Qingsheng Liu, Stacey E Wark, Dong Hee Son, James D Batteas. Ultrasensitive copper(II) detection using plasmon-enhanced and photo-brightened luminescence of CdSe quantum dots. Analytical chemistry. 2010 May 1;82(9):3671-8