An electrochemical sensor for rapid determination of ractopamine based on a molecularly imprinted electrosynthesized o-aminothiophenol film.

A simple electrochemical sensor based on a molecularly imprinted polymer film as the recognition element was developed for ractopamine (RAC) detection. This is the first report of a RAC-imprinted film on a gold electrode surface, synthesized through an electrochemical method using o-aminothiophenol as the functional monomer. The imprinting mechanism and experimental parameters affecting the capability of the imprinted film are discussed here. The sensor was successfully applied with constant potential amperometry for RAC detection in an indirect process with potassium ferricyanide as an electrochemical probe. The sensor had a rapid equilibrium time (120 s), high binding affinity and selectivity towards RAC, and with good reproducibility and stability. Under the experimental conditions applied, a linear relationship between the relative amperometric response and RAC ranged from 2.0 × 10(-7) to 1.4 × 10(-6) mol L(-1), with a lower limit of detection (LOD) of 2.38 × 10(-8) mol L(-1) (signal to noise ratio = 3). The sensor was tested with feed samples spiked with trace amounts of RAC, with good recoveries between 87.4 and 90.5 %.

Covalent imprinted polymer for selective and rapid enrichment of ractopamine by a noncovalent approach.

A novel molecularly imprinted polymer (MIP) for the separation and concentration of ractopamine (RAC) was prepared by a covalent imprinting approach and the template was removed successfully by hydrolysis, so that four carboxylic acid groups were left in the cavities and could specifically rebind RAC through noncovalent interaction: hydrogen bonding. The conditions for synthesis of the MIP were optimized during the polymerization process, and a molar ratio of template-functional monomer complexes to cross-linker of 1:3 was confirmed. The adsorption capacity of the MIP was 4.1-fold that of the nonimprinted polymer, and the adsorption reaction reached equilibrium after 25 min at 50 mg L(-1) concentration. The results of the competitive adsorption test showed that the MIPs had specific recognition ability for the analyte RAC. In addition, the important factors affecting the efficiency of the method which was developed using the MIPs as a solid-phase sorbent for separation and determination of RAC combined with high-performance liquid chromatography with fluorescence detection were optimized. Under the optimum experimental conditions, the linear range of the calibration curve in the method was 0.05-5 µg L(-1) (R(2)=0.98) and the limit of detection (signal-to-noise ratio of 3) was 0.01 µg L(-1). The proposed method was applied to determination of RAC in spiked feedstuffs and urine samples, with recoveries ranging from 74.17 to 114.46% and relative standard deviation (n=3) below 4.55 in all cases.

Novel surface molecularly imprinted sol-gel polymer applied to the online solid phase extraction of methyl-3-quinoxaline-2-carboxylic acid and quinoxaline-2-carboxylic acid from pork muscle.

A new molecularly imprinted polymer (MIP), selective for major metabolites of quinoxaline-1,4-dioxides was firstly prepared by combining surface molecular imprinting technique with the sol-gel process. Methyl-3-quinoxaline-2-carboxylic acid (MQCA) was used as template, 3-aminopropyltriethoxysilane as functional monomer, and tetraethoxysilicane as cross-linker. The MIP was characterized by Fourier transform infrared and evaluated through static adsorption experiments. The results indicated that MIP had high adsorption capacity, fast binding kinetics for MQCA, and the polymer showed a high degree of cross-reactivity for quinoxaline-2-carboxylic acid (QCA). The MIP was then applied as a selective sorbent in an online solid phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC). For a 50-mL sample solution, enrichment factors of 1,349 and 1,046 for QCA and MQCA, respectively, and limits of detection (S/N=3) of 0.8 and 2 ng L(-1) for QCA and MQCA, respectively, were obtained (corresponding to 0.02 and 0.04 ng g(-1) in solid samples for final 100 mL of sample solutions of 5 g of pork). The sample preparation protocol was simplified and only included one step extraction with acetonitrile (MeCN) after the release of target analytes through acidic hydrolysis without further sample cleanup. The new MIP-SPE-HPLC method was successfully applied to the quantification of trace QCA and MQCA in pork muscle with good recoveries ranging from 67% to 80% and RSD below 8%.

Preparation and characterization of molecularly imprinted silica monolith for screening sulfamethazine.

In this work, a novel approach of preparing molecularly imprinted film-derivatized silica monolith materials was developed by a two-step procedure. The silica monolithic support was first prepared by the sol-gel method with tetramethoxysilane as the precursor. Subsequently, vinyl groups were introduced onto the surface of silica monolith by immobilization of γ-methacryloxypropyltrimethoxysilane. The prepolymerization mixtures, consisting of methacrylic acid as a functional monomer, ethylene dimethacrylate as a crosslinker, sulfamethazine as a template molecule and an ionic liquid as porogen, were injected into the silica monolith immobilized vinyl groups to form the molecularly imprinted films on the surface of the vinyl functionalized silica monolith. The monolithic materials were characterized by SEM, Fourier transform IR and solid-state reflection UV spectra. The resulted imprinted materials were evaluated under CEC and HPLC mode. The results indicated that there were enough recognition sites on the surface of the imprinted film-derivatized monolithic materials for selectively recognizing sulfamethazine from the sulfonamide mixture. Ionic liquids, which was utilized as the porogens, could improve the flow-through property and the imprinting effect of the molecularly imprinted film-functionalized silica monolithic materials.

[Determination of six heavy metals elements in drinking water by inductively coupled plasma mass spectrometry].

An inductively coupled plasma mass spectrometry (ICP-MS) for determination of the contents of six elements, Cd, Cr, Pb, Zn, Cu and Ni in drinking water has been developed in the present work. The operating parameters were optimized. 45Sc, 72Ge, 115In and 209Bi were chosen as the internal elements and the effect of matrix, interface and fluctuation of instrument was overcome effectively. Collision/reaction technology was used to eliminate the interference of polyatomic ion. Satisfactory linearity of working curves of six elements was obtained, giving all their correlation coefficients over 0.9997. The determination limit of the analytes were in the range of 0.70-77.0 ng x L(-1). The RSD was between 0.47% and 1.69%. GBW08607 was determined and the result was in the range of the standard. Drinking water of four areas was determined, the recoveries of the sample were 92%-108%. The method is simple, quick, accurate and stable, and can be used as a reliable method to determine trace elements in drinking water.

Ultra-Stable UiO-66 Involved Molecularly Imprinted Polymers for Specific and Sensitive Determination of Tyramine Based on Quartz Crystal Microbalance Technology.

A rapid method was developed to determine the content of tyramine in food on the basis of the combination of molecular imprinting technique and the metal-organic frameworks. We developed the new molecular imprinted polymers based on metal-organic frameworks UiO-66 (named UiO-66@MIPs) as the sensing recognition element, the non-molecular imprinted polymers based on UiO-66 (named UiO-66@NIPs) was synthesized according the same steps without tyramine for comparison. The characterization of obtained UiO-66@MIPs was investigated through a series of characterization experiments. The results indicated that the octahedral shaped UiO-66 was encapsulated in the sol-gel polymer film, with a desirable thermal stability and possessed a specific surface area (SSA) of 994.3 m2·g-1. The imprinting factor of the UiO-66@MIPs for tyramine was 1.956 in static experiment. This indicates the synthesized UiO-66@MIPs have outstanding performance compered to UiO-66@NIPs on the static adsorption quantity and selective adsorption affinity. It's to make use of advantages of the synthetic materials to develop a quartz crystal microbalance (QCM) sensor for the sensitive detection of tyramine. The detection limit of the system was 61.65 µg·L-1 within measurable concentration range from 80 to 500 µg·L-1. The prepared QCM sensor was verified in selectivity and application. The UiO-66@MIPs possess good behavior on selectivity, absorptivity, and chemical stability, so the UiO-66@MIPs achieve accurate and rapid trace detection of biogenic amines in food combining with the quartz crystal microbalance.

Recent Progress on Luminescent Metal-Organic Framework-Involved Hybrid Materials for Rapid Determination of Contaminants in Environment and Food.

The high speed of contaminants growth needs the burgeoning of new analytical techniques to keep up with the continuous demand for monitoring and legislation on food safety and environmental pollution control. Metal-organic frameworks (MOFs) are a kind of advanced crystal porous materials with controllable apertures, which are self-assembled by organic ligands and inorganic metal nodes. They have the merits of large specific surface areas, high porosity and the diversity of structures and functions. Latterly, the utilization of metal-organic frameworks has attracted much attention in environmental protection and the food industry. MOFs have exhibited great value as sensing materials for many targets. Among many sensing methods, fluorometric sensing is one of the widely studied methods in the detection of harmful substances in food and environmental samples. Fluorometric detection based on MOFs and its functional materials is currently one of the most key research subjects in the food and environmental fields. It has gradually become a hot research direction to construct the highly sensitive rapid sensors to detect harmful substances in the food matrix based on metal-organic frameworks. In this paper, we introduced the synthesis and detection application characteristics (absorption, fluorescence, etc.) of metal-organic frameworks. We summarized their applications in the MOFs-based fluorometric detection of harmful substances in food and water over the past few years. The harmful substances mainly include heavy metals, organic pollutants and other small molecules, etc. On this basis, the future development and possible application of the MOFs have prospected in this review paper.

Synthesis of anionic ionic liquids@TpBd-(SO3)2 for the selective adsorption of cationic dyes with superior capacity.

The discharge of industrial printing and dyeing wastewater is one of the main reasons for the increasing water shortage and deterioration. The treatment of dyestuff wastewater is an issue and needs to be urgently solved. In this work, anionic ionic liquid functional covalent organic materials (COMs) were firstly synthesized and used for the selective adsorption of cationic dyes. First, a series of sulfonic acid group (SO3H)-functionalized anionic TpPa-SO3, TpBd-(SO3)2, and TpCR-(SO3)2 were prepared, respectively, and then imidazole was grafted onto TpBd-(SO3)2 to obtain ImI@TpBd-(SO3)2. The full characterization using X-ray diffraction, FT-IR spectroscopy, 13C cross-polarization magic-angle spinning NMR spectroscopy, zeta-potentials, BET surface and pore analysis indicated that these COMs and ImI@TpBd-(SO3)2 exhibited different morphologies, porosities, and potentials. The effects of the type of dye, adsorption time, initial dye concentration, and pH on the adsorption of dyes on ImI@TpBd-(SO3)2 were systematically investigated, respectively. The results revealed that ImI@TpBd-(SO3)2 possessed good adsorption performance for nine different cationic dyes with adsorption capacities in the range from 2865.3 mg g-1 for methylene blue (MB) to 597.9 mg g-1 for basic orange 2 (BO), but little adsorption for anionic and neutral dyes, revealing charge selectivity. The adsorption ratio of ImI@TpBd-(SO3)2 for MB was as high as 74.0% at 10 min by using 1.0 mg material, owing to the post modification of TpBd-(SO3)2 with imidazole. The adsorption of MB on ImI@TpBd-(SO3)2 was pH dependent. The adsorption isotherm and kinetics fitted well with the Freundlich and pseudo second-order kinetic model, respectively. Finally, the very outstanding advantages of superior selective adsorption, desorption, convenient preparation, and low density of ImI@TpBd-(SO3)2 predicted its research and application potential in dye wastewater recovery.

Construction of Persistent Luminescence-Plastic Antibody Hybrid Nanoprobe for In Vivo Recognition and Clearance of Pesticide Using Background-Free Nanobioimaging.

We prepared a specific adsorptive nanocarrier for pesticide due to its challenge to cleanup and low detoxification in the treatment after intake, whether intentional or by mistake. We modified the plastic antibody (molecularly imprinted polymer (MIP)) on the surface of persistent luminescence nanoparticle (La3Ga5GeO14: Cr3+, Zn2+, LGGO) as the specific adsorptive nanocarrier for toxic molecules and realized the nanocarrier was widely distributed for absorbing pesticide and real-time in vivo bioimaging. We used LGGO as the core and trichlorphon as the template to prepare the plastic antibody nanocarrier. After in vivo bioimaging and biodistribution of mice, LGGO@MIP could be distributed evenly in the gastrointestinal tract, circulated in the blood for a long time, and finally excreted to achieve the adsorption and removal of pesticide in the body. The LGGO@MIP nanocarrier prepared in this study opens a new way for the treatment of poisoning.

Erythrocyte membrane bioinspired near-infrared persistent luminescence nanocarriers for in vivo long-circulating bioimaging and drug delivery.

Combination of biological entities with functional nanostructure would produce the excellent systemic drug-delivery vehicles that possess the ability to cross the biological barriers. Herein, from a biomimetic point of view, erythrocyte membrane bioinspired optical nanocarrier is fabricated by integrating Red blood cell (RBC) membrane vesicle with near-infrared persistent luminescence nanophosphors (PLNPs). The triple-doped zinc gallogermanate nanostructures with super-long near-infrared persistent luminescence (ZGGO) are used as optical emission center, mesoporous silica coated on the PLNPs (ZGGO@mSiO2) is employed for drug delivery, and the RBC membrane vesicle is introduced for biomimetic functionalization to ensure the developed nanocarriers bypass macrophage uptake and systemic clearance. Owing to the coating of natural erythrocyte membrane along with membrane lipids and associated membrane proteins, the proposed bioinspired nanocarriers have exhibited cell-mimicking property. Retaining the applicability of PLNPs core that favored in vitro excitation, the developed RBC-ZGGO@mSiO2 biomimetic nanocarriers have demonstrated intense fluorescence, super-long persistent luminescence, monodispersed nanosize, red light renewability, and excellent biocompatibility. In vivo mice bioimaging and biodistribution study demonstrate the erythrocyte membrane bioinspired nanoprobe loaded with doxorubicin as ideal nanocarriers for long-circulating bioimaging, in situ real-time monitoring and drug delivery. We believe the PLNPs-based biomimetic nanocarriers offer a promising nano-platform for diagnostics and therapeutics application.

Bifunctional supported ionic liquid-based smart films for dyes adsorption and photodegradation.

Herein, novel bifunctional smart films containing poly(styrene-butyl acrylate-ionic liquids) (P(S-BA-ILs)) and TiO2 were first prepared by a simple cast method and then used to demonstrate a superior bifunction of adsorption/desorption for dyes due to the property of reversible wettability switching and photodegradation under ultraviolet (UV) irradiation due to the addition of TiO2. The glass transition temperature (Tg) of P(S-BA-ILs) latex was characterized using a differential scanning calorimeter (DSC). The surface properties of films (P(S-BA-ILs)-TiO2) were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), attenuated total (internal) reflection Fourier transform infrared spectroscopy (ATR-FTIR), and water contact angle (WCA) measurements. The results showed that the films displayed reversible wettability switching of hydrophobicity (124.5 ±â€¯2°)/hydrophilicity (10.5 ±â€¯2°) and hydrophobicity (35.1 ±â€¯2°)/hydrophilicity (93.1 ±â€¯2°) triggered by pH and temperature, respectively. Additionally, the films exhibited large adsorption capacities for pollutants at different pH: brilliant red (BR) (6.6 mg cm-3) at pH 1, methylene blue (MB) (12.4 mg cm-3) and phenol (1.1 g cm-3) at pH 11, and metal ions As, Mo and Sb (1.11, 1.57, and 1.25 mg cm-3) at pH 1, as well as superior reusability and excellent in situ photodegradation performance. The convenient preparation of the smart films as well as the good bifunction of adsorption and photodegradation for dyes predicts potential for application to curb water pollution.

Spherical covalent organic frameworks as advanced adsorbents for preconcentration and separation of phenolic endocrine disruptors, followed by high performance liquid chromatography.

As a promising generation of porous micro-materials, covalent organic frameworks (COFs) have great potentials for applications in separation and adsorption. In the present study, an advanced food-safety inspection method involving COFs as the adsorbents of solid phase extraction (SPE) is proposed for sensitive and accurate determination of target hazardous substances. Typical spherical TpBD COFs with large surface area and superior chemical stability were utilized as adsorbents for the preconcentration of phenolic endocrine disruptors (PEDs), followed by high performance liquid chromatography (HPLC) analysis. The well-prepared TpBD COFs were encapsulated in SPE cartridges and applied in food research, namely, for the separation and enrichment of four target endocrine disruptors in food samples. The possible factors influencing the SPE performance including the composition of the sample solvent, sample solution pH, sample flow rate, composition of the eluent, and the volume of the eluent were investigated and optimized. Due to the porous architecture and superior surface area of spherical TpBD, the enrichment of analytes via a COF-filled SPE column gave extremely low detection limits of 0.056-0.123 µg L-1 along with a wide linear range of 0.5-100 µg L-1 for all the analytes. Nine parallel determinations of the mixed standard with a concentration of 10 µg L-1 produced the relative standard deviations of 2.23-3.08%, indicating the excellent repeatability of the COF-SPE assay. This study can open up a new route for the employment of COFs as efficient SPE adsorbents for the enrichment and quantification of trace/ultra-trace hazardous materials in complex food samples.

Fabrication of mesoporous La3Ga5GeO14:Cr3+,Zn2+ persistent luminescence nanocarriers with super-long afterglow for bioimaging-guided in vivo drug delivery to the gut.

Infection by pathogens has always been a major threat to human health, and various drugs have been explored and designed to kill pathogens in the past decades. However, pathogens are evolving faster than the development of new antibiotics, and increasing doses are resulting in increasing side effects and toxicity; this has prompted us to exert effort toward the development of advanced drug carriers for precise delivery of antibiotics. In this study, with the involvement of persistent luminescence nanophosphors (PLNPs) as the emission core, we propose an antibiotic nanocarrier for in vivo delivery of vancomycin to intestinal bacteria via bioimaging guidance. The synthesized PLNPs were coated with mesoporous silica for vancomycin adsorption (NPs@SiO2@Van) and used as an efficient nanocarrier for direct vancomycin delivery and in vivo imaging with low cytotoxicity toward MC38 cell lines. Additionally, we detected the luminescence signals of NPs@SiO2@Van during their use as nanocarriers for vancomycin and accurately obtained the biodistribution of NPs@SiO2@Van in situ and in real time with neglectable auto-fluorescence from the animal body. For the first time, bioimaging-guided in vivo drug delivery to gut bacteria was realized in the present work. The outstanding luminescence features and excellent biocompatibility and structural stability of PLNPs may open new horizons in the development of nanocarriers for nano-diagnosis/therapy and in vivo studies of intestinal microorganisms.

Fabrication of porous covalent organic frameworks as selective and advanced adsorbents for the on-line preconcentration of trace elements against the complex sample matrix.

Herein, for the first time, the typical porous Covalent Organic Frameworks (COFs) CTpBD with superior chemical stability and large surface area were applied as sorbents for solid phase extraction of trace ions via flow injection followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The well-prepared and fully-characterized CTpBD COFs were filled in solid phase extraction cartridge as novel and robust adsorbents for element analysis. Separation and enrichment of Cr (III), Mn (II), Co (II), Ni (II), Cd (II), V (V), Cu (II), As (III), Se (IV), and Mo (VI) was then carried out, and the contents were measured by ICP-MS. Owing to the large surface area and instinctive porous structure of CTpBD, preconcentration of the target trace elements via COF-filled on-line SPE column has achieved low detection limits of 2.1-21.6ngL-1 along with a wide linearity range at 0.05-25µgL-1 for all target ions. The relative standard deviations (RSD) of 1.2%-4.3% obtained via 11 parallel determinations at the sample concentration of 100ngL-1 revealed excellent repeatability of the developed methods Our proposed methods have been successfully utilized for trace element analysis in environmental and food samples.

Upconversion Nanophosphor-Involved Molecularly Imprinted Fluorescent Polymers for Sensitive and Specific Recognition of Sterigmatocystin.

Originated from the bottom-up synthetic strategy, molecularly imprinted polymers (MIPs) possess the inherent ability of selective and specific recognition and binding of the target analytes, with their structural cavities that can match the target molecules in respect to size, shape, and functional groups. Herein, based on the high selectivity of MIPs and the fluorescence properties of the ß-NaYF4:Yb3+, Er3+ upconversion nanoparticles, MIPs with both specificity and fluorescent signals are fabricated to recognize trace sterigmatocystin (ST) with high selectivity and sensitivity. The structure analogue of ST, 1,8-dihydroxyanthraquinone (DT), was employed as the template molecule, acrylamide as the functional monomer, 3-methacryloyloxypropyltrimethoxysilane as the crosslinking agent, and a new molecular imprinting technique of non-aqueous sol-gel method is used to synthesize a molecularly imprinted material with high selectivity to ST. Under optimal conditions, the fluorescence enhancement of fluorescent MIPs increased as the concentration of ST increased. In the range of 0.05⁻1.0 mg L-1, fluorescence enhancement and the concentration showed a good linear relationship with a detection limit of 0.013 mg L-1. Real sample analysis achieved the recoveries of 83.8⁻88.8% (RSD 5.1%) for rice, 82.1⁻87.5% (RSD 4.6%) for maize, and 80.6⁻89.2% (RSD 3.0%) for soybeans, respectively, revealing the feasibility of the developed method.

Preparation and Evaluation of Core⁻Shell Magnetic Molecularly Imprinted Polymers for Solid-Phase Extraction and Determination of Sterigmatocystin in Food.

Magnetic molecularly imprinted polymers (MMIPs), combination of outstanding magnetism with specific selective binding capability for target molecules, have proven to be attractive in separation science and bio-applications. Herein, we proposed the core⁻shell magnetic molecularly imprinted polymers for food analysis, employing the Fe3O4 particles prepared by co-precipitation protocol as the magnetic core and MMIP film onto the silica layer as the recognition and adsorption of target analytes. The obtained MMIPs materials have been fully characterized by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), vibrating sample magnetometer (VSM), and re-binding experiments. Under the optimal conditions, the fabricated Fe3O4@MIPs demonstrated fast adsorption equilibrium, a highly improved imprinting capacity, and excellent specificity to target sterigmatocystin (ST), which have been successfully applied as highly efficient solid-phase extraction materials followed by high-performance liquid chromatography (HPLC) analysis. The MMIP-based solid phase extraction (SPE) method gave linear response in the range of 0.05⁻5.0 mg·L-1 with a detection limit of 9.1 µg·L-1. Finally, the proposed method was used for the selective isolation and enrichment of ST in food samples with recoveries in the range 80.6⁻88.7% and the relative standard deviation (RSD) <5.6%.

Influence of Kluyveromyces marxianus on proteins, peptides, and amino acids in Lactobacillus-fermented milk.

With increasing application of yeast in fermented milk, in order to study the effect of yeast on milk protein during the fermentation process, the effects of the presence of Kluyveromyces marxianus in milk fermented by Streptococcus thermophilus and Lactobacillus bulgaricus were investigated. After fermentation, the amino acid, protein, and peptide contents were analyzed by ultra-performance liquid chromatography, two-dimensional gel electrophoresis, and liquid chromatography-mass spectrometry, respectively. After the addition of K. marxianus for fermentation, 25 protein spots changed significantly. These were mostly caseins and bovine serum proteins, and the content of total free amino acids increased by 16.30%; ten types of bioactive peptides were identified. Furthermore, the number of peptide types in milk fermented by K. marxianus increased significantly compared with milk fermented by Lactobacillus. K. marxianus is considered to promote proteometabolism in milk when added with Lactobacillus, generate flavor compounds, and improve the digestion and absorption character of milk.

Multiwalled carbon nanotubes as sorbent for on-line coupling of solid-phase extraction to high-performance liquid chromatography for simultaneous determination of 10 sulfonamides in eggs and pork.

The sulfonamides (SAs) have been widely used as effective chemotherapeutics and growth promoters in animals' feeding, but their residues could be a potential danger to human health due to their carcinogenic potency and possible antibiotic resistance. Development of a simple and sensitive method for the determination of SAs residues in food of animal origin, therefore, is of great significance. An on-line solid-phase extraction (SPE) method using multiwalled carbon nanotubes as sorbent coupled with high-performance liquid chromatography (HPLC) for simultaneous determination of 10 sulfonamides (SAs) in eggs and pork was developed. The adsorptive potential of carbon nanotubes for solid-phase extraction of sulfonamides was investigated for the first time in the present paper. To on-line interface solid-phase extraction with HPLC, a conventional sample loop on the six-port injector valve of the HPLC was replaced by a preconcentration column packed with carbon nanotubes. The analytes in water solution were preconcentrated onto the preconcentration column and subsequently eluted with mobile phase of methanol-water (22:78). The developed on-line solid-phase extraction method for HPLC permitted the current HPLC separation and the next preconcentration proceeded in parallel, and thus allows one determination finished within 35 min. The RSD of 10 SAs for nine replicate measurements of a standard mixture of 1 microgl(-1) were in the range of 2.5-7.8%. The method was applied to the determination of trace sulfadiazin (SDZ), sulfamerazine (SMR), sulfadimidine (SDMD), sulfathiazole (STZ), sulfamoxol (SMO), sulfamethizole (SMT), sulfamethoxypyridazine (SMP), sulfachlorpyridazine (SCP), sulfadoxin (SDX) and sulfisoxazole (SIA) in eggs and pork. The results indicated that the proposed method was simple, cost-effective and sensitive.

Synthesis of GdAlO3:Mn4+,Ge4+@Au Core-Shell Nanoprobes with Plasmon-Enhanced Near-Infrared Persistent Luminescence for in Vivo Trimodality Bioimaging.

The rise of multimodal nanoprobes has promoted the development of new methods to explore multiple molecular targets simultaneously or to combine various bioimaging tools in one assay to more clearly delineate localization and expression of biomarkers. Persistent luminescence nanophosphors (PLNPs) have been qualified as a promising contrast agent for in vivo imaging. The easy surface modification and proper nanostructure design strategy would favor the fabrication of PLNP-based multifunctional nanoprobes for biological application. In this paper, we have proposed novel multifunctional core-shell nanomaterials, applying the Mn4+ and Ge4+ co-doped gadolinium aluminate (GdAlO3:Mn4+,Ge4+) PLNPs as the near-infrared persistent luminescence emission center and introducing the gold nanoshell coated on the PLNPs to enhance the luminescence efficiency via plasmon resonance. Our developed core-shell nanoprobes have demonstrated the excellent features of ultrabrightness, superlong afterglow, good monodispersity, low toxicity, and excellent biocompatibility. The well-characterized nanoprobes have been utilized for trimodality in vivo imaging, with near-infrared persistent luminescence for optical imaging, Gd element for magnetic resonance imaging, and Au element for computed tomography imaging.

Preparation and evaluation of a molecularly imprinted sol-gel material for on-line solid-phase extraction coupled with high performance liquid chromatography for the determination of trace pentachlorophenol in water samples.

A highly selective imprinted amino-functionalized silica gel sorbent was prepared by combining a surface molecular imprinting technique with a sol-gel process for on-line solid-phase extraction-HPLC determination of trace pentachlorophenol (PCP) in water samples. The PCP-imprinted amino-functionalized silica sorbent was characterized by FT-IR, SEM, nitrogen adsorption and the static adsorption experiments. The imprinted functionalized silica gel sorbent exhibited high selectivity and offered a fast kinetics for the adsorption and desorption of PCP. The prepared sorbent was shown to be promising for on-line solid-phase extraction for HPLC determination of trace levels of PCP in environmental samples. With a sample loading flow rate of 5 ml min(-1) for 2 min, an enhancement factor of 670 and a detection limit (S/N = 3) of 6 ng l(-1) were achieved at a sample throughput of five samples h(-1). The precision (RSD) for nine replicate on-line sorbent extractions of 10 microgl(-1) PCP was 3.8%. The sorbent also offered good linearity (r = 0.9997) for on-line solid-phase extraction of trace levels of PCP. The method was applied to the determination of PCP in local lake water, river water and wastewater samples.