Preparation of carboxylatocalix[4]arene functionalized magnetic polyionic liquid hybrid material for the pre-concentration of phthalate esters.

In this work, we designed a novel hybrid material based on the polymerization of an ionic liquid on a magnetic core and further functionalized with carboxylatocalix[4]arene. Scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, thermal gravimetric-derivative thermogravimetric analysis, energy dispersive X-ray spectroscopy, X-ray diffractometer, and vibrating sample magnetometer were utilized to examine the physicochemical properties of the hybrid material obtained. The material was used as the adsorbent for magnetic solid-phase extraction of phthalate esters. To obtain the maximum pre-concentration efficiency, a series of parameters influencing the extraction efficiency, including sample pH, adsorbent amount, adsorption time, eluent type as well as salt addition, was examined systematically. Under the optimum conditions, a fast and feasible pre-concentration protocol for phthalate esters was established with satisfactory enrichment factors between 158.7 and 191.3. The limits of detection from high-performance liquid chromatographic analysis for the target analytes were in the range of 0.02-0.31 ng mL-1. The wide linear ranges varying from 0.1 to 100 ng mL-1 were achieved with correlation coefficients greater than 0.9977. To evaluate the feasibility of this method, it was successfully applied to analyse phthalate esters in multiple kinds of real samples including tap water, lake water, drinks, tonic lotions, and human serum samples. The results obtained demonstrated that the synthesized magnetic material had potential as a candidate in the pre-concentration field for phthalate esters due to the special properties stemming from its structure and components.

A magnetic hydrazine-functionalized dendrimer embedded with TiO2 as a novel affinity probe for the selective enrichment of low-abundance phosphopeptides from biological samples.

Dendrimers exhibit tunable terminal functionality and bio-friendly nature, making them of being promising materials for applications in the field of separation and enrichment. In this work, we prepared magnetic hydrazide-functionalized poly-amidoamine (PAMAM) dendrimer embedded with TiO2 for the enrichment of phosphopeptides. The novel affinity probe possessed superparamagnetism, realizing its rapid separation from sample solution. Electrostatic attraction and hydrogen bonding existed between PAMAM and phosphopeptides while Lewis acid-base interaction was originated between TiO2 and the targets. The combined synergistic strength of multiple binding interactions contributed to the highly selective enrichment of phosphopeptides. The specificity for the capture of phosphopeptides was reflected in quantities as low as 1:1000 mass ratio of phosphopeptides to non-phosphopeptides. The detection limit of ß-casein digests was low to 0.4 fmol, indicating the high sensitivity of the developed method. Fifteen and four phosphopeptides could be selectively captured from non-fat milk digests and human serum samples, which further confirmed the great potential of the affinity probe in the extraction of low-abundance phosphopeptides from real complex biological samples.

Design of a calix[4]arene-functionalized metal-organic framework probe for highly sensitive and selective monitor of hippuric acid for indexing toluene exposure.

In the present work, a novel metal-organic framework (MOF) fluorescent probe was prepared by post-synthetic modification of MIL-53-NH2(Al) with carboxylatocalix[4]arene (CC[4]A). The introduced CC[4]A could not only enhance the fluorescence performance and the recognition ability of the probe, but also sustain the high stability under UV light and moisture conditions. A method based on the as-synthesized CC[4]A@MIL-53-NH2(Al) probe was established for sensing hippuric acid. The detection limit was determined to be as low as 3.7 µg mL-1. Over the concentration range of 0.005-3 mg mL-1, the calibration curve was obtained with a satisfactory linearity (R2 = 0.993). The method was successfully used for rapid and highly selective direct monitor of hippuric acid in human urine. The sensor had great potential to be used as a simple diagnostic tool for hippuric acid in human urine which is regarded as a biological index of toluene exposure.

Highly Sensitive and Selective Sensing of Free Bilirubin Using Metal-Organic Frameworks-Based Energy Transfer Process.

Free bilirubin, a key biomarker for jaundice, was detected with a newly designed fluorescent postsynthetically modified metal organic framework (MOF) (UIO-66-PSM) sensor. UiO-66-PSM was prepared based on the aldimine condensation reaction of UiO-66-NH2 with 2,3,4-trihydroxybenzaldehyde. The fluorescence of UIO-66-PSM could be effectively quenched by free bilirubin via a fluorescent resonant energy transfer process, thus achieving its recognition of free bilirubin. It was the first attempt to design a MOF-based fluorescent probe for sensing free bilirubin. The probe exhibited fast response time, low detection limit, wide linear range, and high selectivity toward free bilirubin. The sensing system enabled the monitor of free bilirubin in real human serum. Hence, the reported free bilirubin sensing platform has potential applications for clinical diagnosis of jaundice.

Development of novel magnetic solid phase extraction materials based on Fe3O4/SiO2/poly(acrylamide-N,N'-methylene bisacrylamide)-Pluronic L64 composite microspheres and their application to the enrichment of natamycin.

Novel magnetic adsorbents based on Fe3O4/SiO2/poly(acrylamide-N,N'-methylene bisacrylamide) magnetic microspheres modified with non-ionic triblock copolymer surfactant were successfully prepared as a magnetic solid phase extraction adsorbent for the determination of trace natamycin in jam samples. The adsorbent was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transformed infrared spectroscopy, vibrating sample magnetometer, and X-ray diffractometer analysis, confirming that Pluronic L64 was effectively functionalized on the magnetic materials. Various experimental parameters affecting the extraction capacity were investigated including adsorbent amount, extraction time, desorption time, sample pH, and ionic strength. For recovery evaluations, the jam samples were spiked at two concentration levels of 100 and 200µgkg(-1) of natamycin and the recovery values were in the range of 78.8-93.4%. The relative standard deviations (RSD) for the recoveries were less than 3.5%. The novel magnetic solid phase extraction method provided several advantages, such as simplicity, low environmental impact, convenient extraction procedure, and short analysis time when used for natamycin analysis.

Preconcentration of synthetic phenolic antioxidants by using magnetic zeolites derived with carboxylatocalix[4]arenes combined with high performance liquid chromatography.

Here, we synthesized a novel organic-inorganic hybrid material combining carboxylatocalix[4]arenes and magnetic zeolites by covalent bonding. The complex was characterized by scanning electron microscopy, transmission electron microscopy, Fourier-transformed infrared spectroscopy, X-ray diffraction spectrometry, thermogravimetric analysis/differential thermal gravity analysis, and by using an X-ray photoelectron spectrometer and a vibrating sample magnetometer. The resulting magnetic composite was employed as a solid phase adsorbent to separate and preconcentrate synthetic phenolic antioxidants. Various interactions between the targets and the adsorbent contributed to the adsorption efficiency including hydrophobic interaction, hydrogen-bond interaction, and π-π complexation. The superparamagnetic participation in the process of synthesizing zeolites made the separation process of adsorbent from solutions convenient by an external magnetic field. Taking advantage of this property, this adsorbent could be recycled more than 30 times. The concentrations of the preconcentrated SPAs were determined directly by high-performance liquid chromatography. Various experimental parameters were optimized, according to which the method was evaluated. Finally, the prepared magnetic zeolite@carboxylatocalix[4]arene was successfully applied to identify synthetic phenolic antioxidants from juice and infant milk powder samples with high enrichment factors in the range of 41.9-92.5. The magnetic materials allowed rapid and simple preconcentration, implying their potential in the field of adsorption.

Preconcentration procedures for phthalate esters combined with chromatographic analysis.

Phthalate esters are endocrine disrupters or mutagens. They are widely used as plasticizers and can be usually found in environmental samples, such as food, soil and polluted air. However, it is difficult to directly determine phthalate esters owing to their relatively low concentration and complex matrices. Therefore, preconcentration and separation have become increasingly important. In recent years, many preconcentration methods have been successfully developed and widely used, such as liquid-liquid extraction, dispersive liquid-liquid microextraction and solid-phase extraction. These preconcentration methods for phthalate esters can be applied to various real samples, water, soil, air, food and cosmetics. The aim of this paper is to review recent literature studies (primarily from the last five years) about preconcentration techniques for phthalate esters coupled with chromatographic analysis. The following text describes several preconcentration approaches, including liquid-liquid extraction, dispersive liquid-liquid microextraction, cloud point extraction, solid-phase extraction, solid-phase microextraction and stir bar sorptive extraction. Their advantages and disadvantages are also summarized.

High efficiency and stable dye-sensitized solar cells with an organic chromophore featuring a binary pi-conjugated spacer.

We employed a binary spacer of orderly conjugated 3,4-ethyldioxythiophene and thienothiophene to construct a wide-spectral response organic chromophore for dye-sensitized solar cells, exhibiting a high power conversion efficiency of 9.8% measured under irradiation of 100 mW cm(-2) air mass 1.5 global (AM1.5G) sunlight and an excellent stability.