Quaternary Ammonium Polyamidoamine Dendrimer Modified Quantum Dots as Fluorescent Probes for p-Fluorophenoxyacetic Acid Detection in Aqueous Solution

Abstract

The wide use of pesticide p-fluorophenoxyacetic acid has caused the serious environmental contaminant. A novel fluorescent probe for sensitive detection of p-fluorophenoxyacetic acid in aqueous solutions based on 3.0G quaternary ammonium polyamidoamine (PAMAM) dendrimer modified quantum dots (QDs) (PAMAM@QDs) was reported. Through the solvent-evaporation method, quaternary ammonium PAMAM was employed to modify the QDs. Poloxamer 188 was used to improve the solubility and stability. The resultant PAMAM@QDs dispersed well in water. Fluorescence (FL) spectroscopic study showed that the FL intensity of the PAMAM@QDs was enhanced in the presence of p-fluorophenoxyacetic acid. Under optimal conditions, the enhanced FL intensity as a function of concentration matched very well in the range of 1 ~ 200 µg/mL of p-fluorophenoxyacetic acid, while the lower limits of detection were found to be 0.16 µg/mL. These results show that PAMAM@QDs is a promising luminescent probe for the detection of pesticides.

Inorganic nanoparticle-cored dendrimers for biomedical applications: A review

“…Similarly, Xu et al illustrated that 3.0G quaternary ammonium PAMAM dendrimer-modified QDs functioned as detectors for the pesticide p -fluorophenoxyacetic acid, exhibiting increased fluorescence intensity upon exposure. The fluorescence intensity enhancement was more pronounced in instances where the acidity of the pesticides was stronger [ 195 ].…”

Hemicyanine-Based Near-Infrared Fluorescence Off–On Probes for Imaging Intracellular and In Vivo Nitroreductase Activity

“…We used a hemicyanine skeleton as a fluorogenic backbone, introducing a nitro group as a selective NTR-responsive moiety and fluorescence quencher. NIR-HCy-NO 2 derivatives ( NIR-HCy-NO 2 2 and NIR-HCy-NO 2 3 ) are also designed to increase water solubility, which was achieved by introducing a sulfonate (-SO 3 − ) and quaternary ammonium group to the indolium part of NIR-HCy-NO 2 [ 27 , 28 ]. NIR-HCy-NO 2 showed a low fluorescence because of the interference of ICT by the nitro group and the reduction induced by NTR, which induced an enhancement in the fluorescence spectra due to the effect of ICT on the amine group.…”