Selective molecular recognition of polycyclic aromatic hydrocarbons using CdTe quantum dots with cyclodextrin as supramolecular nano-sensitizers in water

A simple fluorescence (FL) analysis method to polycyclic aromatic hydrocarbons (PAHs) has been reported using supramolecular nano-sensitizers combining of CdTe quantum dots (QDs) and cyclodextrins (CDs) as additive. The new fluorescence analysis pathway utilizes patent cyclodextrins and thioglycolic acid (TGA)-modified CdTe QDs which are easily prepared. It shows the fluorescent response of CdTe QDs towards different PAHs in the presence of CD via changing the numbers of CDs. These supramolecular nano-sensitizers are performed for the determination of phenanthrene and acenaphthene in water based on the response characteristics of different CDs. In comparison with acenaphthene, 9, 9-diflurofluorene produces a modest quenching of the fluorescence of CdTe in presence of gamma-CD. Under optimal conditions, the relative FL intensities of CdTe QDs are decreased linearly with increasing phenanthrene and acenaphthene in the range of 5 x 10(-7)-7.5 x 10(-5) M and 10(-7)-2.5 x 10(-5) M, with the corresponding detection limits (3 sigma) of 0.53 mu M (94.3 ng/mL) and 0.085 mu M (13.1 ng/mL), respectively. It is found that phenanthrene and acenaphthene decrease the FL intensity of the CdTe QDs with CDs in a concentration dependence that is best described by a Stern-Volmer-type equation. The possible mechanism is discussed. (c) 2008 Elsevier B.V. All rights reserved.