Haibing Li

para-Sulfonatocalix[6]arene-modified silver nanoparticles electrodeposited on glassy carbon electrode: preparation and electrochemical sensing of methyl parathion.

In this paper, a new electrochemical sensor, based on modified silver nanoparticles, was fabricated using one-step electrodeposition approach. The para-sulfonatocalix[6]arene-modified silver nanoparticles coated on glassy carbon electrode (pSC(6)-Ag NPs/GCE) was characterized by attenuated total reflection IR spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), etc. The pSC(6) as the host are highly efficient to capture organophosphates (OPs), which dramatically facilitates the enrichment of nitroaromatic OPs onto the electrochemical sensor surface. The combination of the host-guest supramolecular structure and the excellent electrochemical catalytic activities of the pSC(6)-Ag NPs/GCE provides a fast, simple, and sensitive electrochemical method for detecting nitroaromatic OPs. In this work, methyl parathion (MP) was used as a nitroaromatic OP model for testing the proposed sensor. In comparison with Ag NPs-modified electrode, the cathodic peak current of MP was amplified significantly. Differential pulse voltammetry was used for the simultaneous determination of MP. Under optimum conditions, the current increased linearly with the increasing concentration of MP in the range of 0.01-80microM, with a detection limit of 4.0nM (S/N=3). The fabrication reproducibility and stability of the sensor is better than that of enzyme-based electrodes. The possible underlying mechanism is discussed.

Luminescence switching of CdTe quantum dots in presence of p-sulfonatocalix[4]arene to detect pesticides in aqueous solution.

A simple, rapid, and sensitive identification method of fenamithion and acetamiprid is developed using supramolecular nano-sensitizers combining of CdTe quantum dots (QDs) and p-sulfonatocalix[4]arene as additive by fluorescent spectroscopic technique in water. Depending on p-sulfonatocalix[4]arene, the selectivity of CdTe QDs is tuned between fenamithion and acetamiprid. The luminescence of free CdTe QDs is quenched selectively to fenamithion. While in the presence of p-sulfonatocalix[4]arene, it shows that the fluorescence intensity of QDs is enhanced selectively to acetamiprid due to the cooperation of QDs and p-sulfonatocalix[4]arene. Based on the response characteristics of the QDs, a fluorescent method is performed for tuning selective determination of the pesticides. Under optimum conditions described, it is found that the pesticides effect on the luminescence of the CdTe QDs in concentrations dependence are described by a Stern-Volmer-type equation or a Langmuir binding isotherm equation in the range of 0-10(-4)M (fenamithion) and 0-10(-3)M (acetamiprid), with the corresponding detection limits (3sigma) of 1.2 x 10(-8)M (fenamithion) and 3.4 x 10(-8)M (acetamiprid), respectively. The possible mechanism is discussed.