A simple and sensitive surface molecularly imprinted polymers based fluorescence sensor for detection of λ-Cyhalothrin.

In this study, surface molecularly imprinted YVO4:Eu(3+) nanoparticles with molecular recognitive optosensing activity were successfully prepared by precipitation polymerization using λ-Cyhalothrin (LC) as template molecules, methacrylic acid and ethylene glycol dimethacrylate as the polymerization precursors which could complex with template molecules, and the material has been characterized by SEM, TEM, FT-IR, XRD, TGA and so on. Meanwhile, the as-prepared core-shell structured nanocomposite (YVO4:Eu(3+)@MIPs), which was composed of lanthanide doped YVO4:Eu(3+) as fluorescent signal and surface molecular imprinted polymers as molecular selective recognition sites, could selectively and sensitively optosense the template molecules. After the experimental conditions were optimized, two linear relationship were obtained covering the concentration range of 2.0-10.0 µM and 10.0-90.0 µM, and the limit of detection (LOD) for LC was found to be 1.76 µM. Furthermore, a possible mechanism was put forward to explain the fluorescence quenching of YVO4:Eu(3+)@MIPs. More importantly, the obtained sensor was proven to be suitable for the detection of residues of LC in real examples. And the excellent performance of this sensor will facilitate future development of rapid and high-efficiency detection of LC.

Sedimentation and associated trace metal enrichment in the riparian zone of the Three Gorges Reservoir, China.

Impoundment of the Three Gorges Reservoir has created an artificial riparian zone with a vertical height of 30 m and a total area of 349 km(2), which has been subjected to seasonal inundation and exposure due to regular reservoir impoundment and the occurrence of natural floods. The significant alteration of hydrologic regime has caused numerous environmental changes. The present study investigated the magnitude and spatial pattern of sedimentation and metal enrichment in a typical section of the riparian zone, composed of bench terraces with previous agricultural land uses, and explored their links to the changed hydrologic regime. In particular, we measured the total sediment depths and collected surface riparian sediments and down-profile sectioned riparian soils (at 5 cm intervals) for trace metal determination. Our analysis showed that the annual average sedimentation rates varied from 0.5 to 10 cm·yr(-1) and they decreased significantly with increasing elevation. This lateral distribution was principally attributed to seasonal variations in water levels and suspended sediment concentrations. Enriched concentrations of trace metals were found both in the riparian sediments and soils, but they were generally higher in the riparian sediments than in riparian soils and followed a similar lateral decreasing trend. Metal contamination assessment showed that the riparian sediments were slightly contaminated by Ni, Zn, and Pb, moderately contaminated by Cu, and moderately to strongly contaminated by Cd; while riparian soils were slightly contaminated by As, and moderately contaminated by Cd. Trace metal enrichment in the riparian sediments may be attributed to external input of contaminated sediments produced from upstream anthropogenic sources and chemical adsorption from dissolved fractions during pure sediment mobilization and after sink for a prolonged flooding period due to reservoir impoundment.

Preparation of thermal-responsive magnetic molecularly imprinted polymers for selective removal of antibiotics from aqueous solution.

A novel thermal-responsive magnetic molecularly imprinted polymers (TMMIPs), maghemite/silica/poly (N-isopropylacrylamide-co-acrylamide-co-ethylene glycol dimethacrylate) (γ-Fe(2)O(3)/SiO(2)/P (NIPAm-co-AAm-co-EGDMA)), were developed as a potential effective adsorbent for selectively remove sulfamethazine (SMZ) exist in aquatic environments, which has been recognized as a warranting considerable issue. Free radical polymerization of NIPAm, AAm and EGDMA was performed in dimethyl sulfoxide/water (DMSO/H(2)O) (v/v=9/1) with 2,2'-azobisisobutyronitrile (AIBN) as initiator to coat γ-Fe(2)O(3)/SiO(2)/3-(methacryloxyl) propyl trimethoxysilane (MPS) microspheres through the capture of oligomers with the aid of vinyl groups on their surfaces. The unique aspect of TMMIPs was that they combined molecular recognition, magnetic separation and thermo-responsiveness. The got material was characterized by SEM, TEM, FT-IR and VSM. Batch mode adsorption studies were carried out to investigate the specific adsorption equilibrium, kinetics, and selective recognition ability of TMMIPs. Reversible recognition and release of template molecule were realized by changing environmental temperatures. Several other antibiotics were selected as model analytes to evaluate the selective recognition performance of TMMIPs. The TMMIPs have good temperature response, selectivity and reusability, making them possible in applying for antibiotics separation and controlled release.