Enhanced removal of bilirubin on molecularly imprinted titania film

Titania film imprinted by bilirubin molecule at the surface of quartz crystal was prepared using molecular imprinting and surface sol-gel process. The molecularly imprinted titania film was characterized by FTIR spectra, and the interaction between bilirubin and imprinted film was investigated using quartz crystal microbalance (QCM) technique. Compared with pure titania film, the molecularly imprinted titania film exhibits a much higher adsorption capacity for the target molecule, and the adsorption kinetic parameter estimated from the in situ frequency measurement is about 1.6×10(8) M(-1), which is ten times higher than that obtained on pure titania film. The photocatalytic measurements indicate that the bilirubin adsorbed on molecularly imprinted titania film can be completely removed under UV illumination. Moreover, our study indicates that the molecularly imprinted titania film possesses a better stability and reusability.     

Piezoelectric atrazine sensor based on a molecularly imprinted film of titanium dioxide

We have developed a piezoelectric sensor for the determination of atrazine. It is based on the modification of a molecularly imprinted film of TiO₂ that was placed on a quartz crystal via a surface sol?Cgel process. The resulting sensor exhibits high selectivity for atrazine, a re-usability that is better than that of other sensors, a response time of 3?min, a wider linear range (0.0005?C8?mM), and a lower detection limit (0.1???M). The analytical application of the atrazine sensor confirms the feasibility of atrazine determination.

水溶液中制备分子印迹聚合物微球及其分子识别特性 研究

采用聚乙烯醇400作为分散剂,利用模板分子与功能单体/聚合物残基之间的离子键(静电)相互作用形成复合物,用水溶液微悬浮聚合法制备了4-氨基吡啶(4-AP)和甲氧苄氨嘧啶(TMP)分子印迹聚合物微球,并通过色谱行为表征,比较了它们对各自的模板分子作用的强弱。结果表明,采用甲基丙烯酸为功能单体制备的分子印迹聚合物微球(MIMs),对带有氨基的模板分子主要靠离子键(静电)相互作用,且作用力的大小与氨基的个数有关,色谱研究表明,模板分子中氨基数目越多,这种作用越强,而且这种作用不是简单的加合,而是协同增强作用。     

分子印迹膜电化学传感器检测土壤中莠去津

本文报道了一种对莠去津有识别特性的分子印迹膜的制备,即在含和不含模板分子(莠去津)的情况下,通过循环伏安技术在金电极表面沉积2-巯基苯并咪唑,制备了2-巯基苯并咪唑聚合膜.利用循环伏安法对印迹和非印迹膜行为进行了评价,对分子印迹膜的影响因素进行了筛选和优化.实验表明,该分子印迹膜对莠去津具有良好的选择性和灵敏度.莠去津的还原峰电流与莠去津的浓度在 1.2 ×10 - 8mal/L～8.0 ×10 - 5mol/ L 范围内具有良好的线性关系( r=0.99862),检出限可达 3.0 ×10 - 9mol/ L.将此传感器用于土壤中莠去津的测定,回收率在90.8% ～ 98.2%之间,取得了很好的结果.     

Enhanced adsorption of radioactive strontium ions from aqueous solution by H2O2-modified attapulgite

Effective adsorption of Sr(II) onto H₂O₂-modified attapulgite in aqueous solution was investigated about kinetics and isothermal equilibrium adsorption. The adsorption equilibrium process of Sr(II) on adsorbents reached about 8 h at 40 °C. The adsorption kinetics followed the pseudo-second order equation and the isothermal adsorption data were fit well with the Langmuir isotherm model. The enhanced adsorption mechanism of H₂O₂-modified attapulgite for Sr(II) in aqueous solution was expatiated in detail. The H₂O₂ treatment for attapulgite is effective and as-made adsorbents can be applied for removal of Sr(II) in radioactive waste water.

     

Remarkable enantioselectivity of molecularly imprinted TiO2 nano-thin films

TiO(2) nano-thin films with imprinted (R)- and (S)-enantiomers of propranolol, 1,1'-bi-naphthol, and 2-(4-isobutylphenyl)-propionic acid were fabricated on quartz plates by spin-coating their solutions with Ti(O-(n)Bu)(4) in a toluene-ethanol mixture (1:1, v/v). After template removal, the imprinted films showed better binding for original templates than to the corresponding enantiomers. The assessment of template incorporation, template removal, and re-binding was conducted through UV-vis measurements. Significant enhancement of enantioselectivity was achieved by optimization of the film thickness and by heat-treatment of the imprinted films. After subtraction of non-specific binding, the optimized films provided chiral recognition with the enantioselectivity of almost 100% for (R)-propranolol and 95% for (S)-propranolol.     

Hydrophilic molecularly imprinted polymers for bisphenol A prepared in aqueous solution

We have prepared a hydrophilic molecularly imprinted polymer (MIP) for the hydrophobic compound bisphenol A (BPA) in aqueous solution using 3-acrylamido-N,N,N-trimethylpropan-1-aminium chloride (AMTC) as the functional monomer. Under redox-polymerization conditions, BPA forms an ion-pair with AMTC, which was confirmed by ¹H-NMR titration. The imprinting effect in aqueous solution was evaluated by comparison of this material with the corresponding non-imprinted polymer (NIP) and with a control polymer (CP) bearing no AMTC. The MIP showed the highest activity among the three polymers, and the imprinting factors as calculated from the amount of BPA bound to the MIP divided by the amounts bound to NIP and CP, respectively, are 1.8 and 6.0. The MIP was selective for BPA in aqueous solution, while structurally related compounds are not recognized. Such a selectivity for a hydrophobic compound is rarely observed in aqueous medium because non-specific binding of BPA inevitably leads to hydrophobic interaction.

     

Hydrophilic molecularly imprinted polymers for bisphenol A prepared in aqueous solution

We have prepared a hydrophilic molecularly imprinted polymer (MIP) for the hydrophobic compound bisphenol A (BPA) in aqueous solution using 3-acrylamido-N,N,N-trimethylpropan-1-aminium chloride (AMTC) as the functional monomer. Under redox-polymerization conditions, BPA forms an ion-pair with AMTC, which was confirmed by ¹H-NMR titration. The imprinting effect in aqueous solution was evaluated by comparison of this material with the corresponding non-imprinted polymer (NIP) and with a control polymer (CP) bearing no AMTC. The MIP showed the highest activity among the three polymers, and the imprinting factors as calculated from the amount of BPA bound to the MIP divided by the amounts bound to NIP and CP, respectively, are 1.8 and 6.0. The MIP was selective for BPA in aqueous solution, while structurally related compounds are not recognized. Such a selectivity for a hydrophobic compound is rarely observed in aqueous medium because non-specific binding of BPA inevitably leads to hydrophobic interaction.

Synthesis of a molecularly imprinted polymer on mSiO2@Fe3O4 for the selective adsorption of atrazine

Atrazine contamination of water is of considerable concern because of the potential hazard to human health. In this study, a magnetic molecularly imprinted polymer for atrazine was prepared by the surface‐imprinting technique using Fe₃O₄ as the core, mesoporous silica as the carrier, atrazine as the template, and itaconic acid as the functional monomer. The magnetic molecularly imprinted polymer was characterized by Fourier‐transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, and vibration‐sample magnetometry. The binding properties of the magnetic molecularly imprinted polymer toward atrazine were investigated by adsorption isotherms, kinetics, and competitive adsorption. It was found that the adsorption equilibrium was achieved within 2 h, the maximum adsorption capacity of atrazine was 8.8 μmol/g, and the adsorption process could be well described by the Langmuir isotherm model and pseudo‐second‐order kinetic model. The magnetic molecularly imprinted polymer exhibited good adsorption selectivity for atrazine with respect to structural analogues, such as cyanazine, simetryne, and prometryn. The reusability of the magnetic molecularly imprinted polymer was demonstrated for at least five repeated cycles without a significant decrease in adsorption capacity. These results suggested that the magnetic molecularly imprinted polymer could be used as an efficient material for the selective adsorption and removal of atrazine from water samples.     

Chiral recognition by molecularly imprinted polymers in aqueous media

Summary Molecularly imprinted polymers were prepared using 2-vinylpyridine and/or methacrylic acid as functional monomers in a self-assembly imprinting protocol. The resulting polymers were analyzed in aqueous media, and the effects from the pH of the mobile phase and the degree of added organic solvent were investigated. The results are indicative of the importance of ionic bonds in conjunction with hydrophobic interactions in the formation of the complexes between the analyte and the polymers.     

Selective recognition of 4-nitrophenol from aqueous solution by molecularly imprinted polymers with functionalized tetratitanate whisker composites as support

Three kinds of molecularly imprinted polymers (MIPs) were obtained with surface molecular imprinting technique on functionalized potassium tetratitanate whisker (F-PTW). The results of adsorption experiments indicated that MIP prepared using PTW modified with N-(2-aminoethyl)-3-(trimethoxysilyl)propylamine (AAPTS) (F-PTW A) as support [MIP(1)] was superior to the other two polymers, then MIP(1) was selected to analyze the 4-nitrophenol (4-NP) adsorption process from aqueous solution in this study. AAPTS offered hydrophilic exterior that allowed to self-assemble with the template 4-NP through intermolecular interaction rather than based on the interactions between the functional monomers and template. Equilibrium adsorption data were analyzed by the Langmuir and Freundlich isotherm models at various temperatures. Kinetic properties were successfully investigated by pseudo-first-order model, pseudo-second-order model, intraparticle diffusion equation, initial adsorption rate, half-adsorption time. A diffusion-controlled process as the essential adsorption rate-controlling step was also proposed. The performance of such imprinted polymer was further demonstrated by high-performance liquid chromatography, and the results showed that the selectivity of MIP(1) exhibited higher affinity for template 4-NP over competitive phenolic compounds than that of non-imprinted polymer NIP(1). MIP(1) could be reused four times without significant loss in the adsorption capacity.     

Enhanced adsorption of roxarsone onto humic acid modified goethite from aqueous solution

The adsorption of roxarsone (ROX) on the humic acid modified goethite (HA-α-FeOOH) was evaluated for several potential environmental factors. Results showed that 1) ROX had a higher adsorption capacity onto HA-α-FeOOH than unmodified α-FeOOH; 2) the adsorption of ROX increased with a decrease in pH; 3) the high ionic strength significantly inhibited the adsorption capacity of HA-α-FeOOH; and 4) a higher temperature yielded greater adsorption, since the process for ROX to be adsorbed by HA-α-FeOOH was a spontaneous endothermic reaction. The maximum adsorption capacity of ROX was found to be 80.71?mg?·?g^?1, when the temperature was 308?K. Meanwhile, the inhibitory effects of ionic strength and PO₄^3? on the adsorption of ROX onto HA-α-FeOOH were enhanced with an increase in concentration. In addition, the adsorption equilibrium data obeyed Langmuir isotherm model and the kinetic data were well described by the pseudo-second-order kinetic model. From the infrared spectra of HA-α-FeOOH, it could be deduced that the ROX adsorption onto HA-α-FeOOH was achieved via the ion exchange between the arsenic acid and the carboxyl group on adsorbent, as well as the formation of As-O-Fe bond between Fe-O and arsenic acid ions.     

Enantioseparation on molecularly imprinted monoliths--preparation and adsorption isotherms

In this paper we report the synthesis of monolithic molecularly imprinted polymers (monolithic MIPs) for the chromatographic separation of Z-phenylalanine by “in situ” polymerisation. Four different functional monomers were used for the preparation and the columns were tested with a standard mobile phase of 1% acetic acid in acetonitrile. 4-Vinylpyridine has shown the best separation performance with a resolution factor R>1 and was chosen for a further improvement of the imprinted stationary phase, which leads to a resolution factor R=2.06. All monoliths investigated have surface areas of around 400 m² g⁻¹. The columns containing 4-vinylpyridine as functional monomer were characterised by frontal analysis and peak fitting method. These methods allow the determination of the adsorption isotherm which quantify the separation potential of the imprinted monoliths.     

Selective adsorption of modified nucleoside cancer biomarkers by hybrid molecularly imprinted adsorbents

Modified adenosine nucleosides have been proposed to be potential DNA‐based biomarkers for early diagnosis of tumor and a promising tool for the development of noninvasive prediction systems. However, the low concentration of modified adenosine nucleosides in physiological fluids makes them challenging for both quantitative and qualitative determination. Therefore, materials, which are potentially useful for selective adsorption of nucleobase‐containing compounds, were obtained. To obtain the adsorbents, the silica gel particles were coated layer‐by‐layer with films of the polymers with different combinations of polymers containing thymine groups. Next, the microspheres were irradiated with UV light in the presence of 2’‐deoxyadenosine or 5’‐deoxy‐5’‐(methylthio)adenosine, as template molecules, which resulted in the photodimerization of thymine moieties and molecular imprinting of adsorbed modified adenosine compounds. The selectivity of the adsorption was significantly enhanced by the photoimprinting process. Eventually, the imprinted particles have shown an improved ability to recognize mainly 2’‐deoxyadenosine and 5’‐deoxy‐5’‐(methylthio)adenosine molecules. The best performing adsorbent was obtained using modified natural polysaccharides. The studied materials could serve as promising adsorbents of biomarkers for tumor diagnostics.     

聚苯胺分子印迹膜电化学传感器检测氯霉素

以苯胺为功能单体和交联剂,氯霉素(chloramphenicol,CAP)为模板分子,采用电化学聚合法(循环伏安法)在金电极上合成了对CAP具有快速响应能力的聚苯胺分子印迹膜;结合差示脉冲伏安法建立了针对氯霉素的检测方法,并将所制备的聚苯胺分子印迹膜用作电化学传感器以测定氯霉素眼药水中的氯霉素.结果表明,所制备的聚苯胺分子印迹膜具有制备简单、响应快速、灵敏度高、再生性能良好等特点;其对氯霉素眼药水中的氯霉素的检测结果令人满意,有望用于实际样品中氯霉素的检测.     

Decontamination of bisphenol A from aqueous solution by graphene adsorption

The decontamination of bisphenol A (BPA) from aqueous solution by graphene adsorption was investigated. The maximum adsorption capacity (q(m)) of graphene for BPA obtained from a Langmuir isotherm was 182 mg/g at 302.15 K, which was among the highest values of BPA adsorption compared with other carbonaceous adsorbents according to the literature. Both π-π interactions and hydrogen bonds might be responsible for the adsorption of BPA on graphene, and the excellent adsorption capacity of graphene was due to its unique sp(2)-hybridized single-atom-layer structure. Therefore, graphene could be regarded as a promising adsorbent for BPA removal in water treatment. The kinetics and isotherm data can be well described by the pseudo-second-order kinetic model and the Langmuir isotherm, respectively. The thermodynamic studies indicated that the adsorption reaction was a spontaneous and exothermic process. Besides, the presence of NaCl in the solution could facilitate the adsorption process, whereas the alkaline pH range and higher temperature of the solution were unfavorable.     

Development of molecularly imprinted polymeric nanofibers by electrospinning and applications to pesticide adsorption

Novel polystyrene‐based molecularly imprinted polymer nanofibers were synthesized through the electrospinning technique. The molecularly imprinted polymers were prepared using a non‐covalent approach and atrazine as template. For comparison, nonimprinted polymer nanofibers were also synthesized. The morphology of the synthesized nanofibers was characterized using scanning electron microscopy. The adsorption of pesticides, atrazine, atrazine desisopropyl, atraton, carboxin, linuron, and chlorpyrifos was studied under equilibrium (batch) conditions. To describe the adsorption capability of the synthesized polymers, Langmuir and Freundlich models were used. The Freundlich model provided a better mathematical approximation of the sorption characteristic for polymers nanofibers. To evaluate the adsorption capacity in the presence of interferents experiments on river water samples spiked with a mixture of six pesticides were also performed. The results obtained for the highest concentration levels investigated, show a greater amount of pesticide adsorbed on molecularly imprinted polymers and non‐imprinted polymers compared to those obtained using commercial stationary phases used as reference.