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1.
Different strategies for the preparation of efficient and robust immobilized biocatalysts are here reviewed. Different physico-chemical approaches are discussed.i.- The stabilization of enzyme by any kind of immobilization on pre-existing porous supports.ii.- The stabilization of enzymes by multipoint covalent attachment on support surfaces.iii.- Additional stabilization of immobilized-stabilized enzyme by physical or chemical modification with polymers.These three strategies can be easily developed when enzymes are immobilized in pre-existing porous supports. In addition to that, these immobilized-stabilized derivatives are optimal to develop enzyme reaction engineering and reactor engineering. Stabilizations ranging between 1000 and 100,000 folds regarding diluted soluble enzymes are here reported.  相似文献   
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This review critically evaluates the plastic accumulation challenges and their environmental (primarily) and human (secondarily) impacts. It also emphasizes on their degradation and fragmentation phenomena under marine conditions. In addition, it takes into account the leachability of the various chemical substances (additives) embedded in plastic products to improve their polymeric properties and extend their life. Regardless of their effectiveness in enhancing the polymeric function of plastic products, these additives can potentially contaminate air, soil, food, and water. Several findings have shown that, regardless of their types and sizes, plastics can be degraded and/or fragmented under marine conditions. Therefore, the estimation of fragmentation and degradation rates via a reliable developed model is required to better understand the marine environmental status. The main parameter, which is responsible for initiating the fragmentation of plastics, is sunlight/UV radiation. Yet, UV- radiation alone is not enough to fragment some plastic polymer types under marine conditions, additional factors are needed such as mechanical abrasion. It should be also mentioned that most current studies on plastic degradation and fragmentation centered on the primary stages of degradation. Thus, further studies are needed to better understand these phenomena and to identify their fate and environmental effects.  相似文献   
4.
A novel type of magnetic molecularly imprinted polymer was prepared for the selective enrichment and isolation of chelerythrine from Macleaya cordata (Willd) R. Br. The magnetic molecularly imprinted polymers were prepared using functional Fe3O4@SiO2 as a magnetic support, chelerythrine as template, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross‐linker. Density functional theory at the B3LYP/6‐31G (d, p) level with Gaussian 09 software was applied to calculate the interaction energies of chelerythrine, methacrylic acid and the complexes formed from chelerythrine and methacrylic acid in different ratios. The structural features and morphology of the synthesized polymers were characterized by using Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, and vibration sample magnetometry. Adsorption experiments revealed that the magnetic molecularly imprinted polymers possessed rapid kinetics, high selectivity, and a higher binding capacity (7.96 mg/g) to chelerythrine than magnetic molecularly non‐imprinted polymers (2.36 mg/g). The adsorption process was in good agreement with the Langmuir adsorption isotherm and pseudo‐second‐order kinetics models. Furthermore, the magnetic molecularly imprinted polymers were successfully employed as adsorbents for the extraction and enrichment of chelerythrine from Macleaya cordata (Willd) R. Br. The results indicated that the magnetic molecularly imprinted polymers were suitable for the selective adsorption of chelerythrine from complex samples such as natural medical plants.  相似文献   
5.
Discriminative detection of invasive and noninvasive breast cancers is crucial for their effective treatment and prognosis. However, activatable probes able to do so in vivo are rare. Herein, we report an activatable polymeric reporter (P-Dex) that specifically turns on near-infrared (NIR) fluorescent and photoacoustic (PA) signals in response to the urokinase-type plasminogen activator (uPA) overexpressed in invasive breast cancer. P-Dex has a renal-clearable dextran backbone that is linked with a NIR dye caged with an uPA-cleavable peptide substrate. Such a molecular design allows P-Dex to passively target tumors, activate NIR fluorescence and PA signals to effectively distinguish invasive MDA-MB-231 breast cancer from noninvasive MCF-7 breast cancer, and ultimately undergo renal clearance to minimize the toxicity potential. Thus, this polymeric reporter holds great promise for the early detection of malignant breast cancer.  相似文献   
6.
Functional polymers with a metal–coordination interaction have been fabricated for sample pretreatment. Poly(N‐4‐vinyl‐benzyl iminodiacetic acid‐co‐methacrylic acid‐co‐styrene)‐modified magnetic nanoparticles were prepared and used as solid‐phase extraction adsorbents for the analysis of quinolones by tuning the metal–coordination interaction. In the construction of the polymer‐based adsorbents, functional monomer (N‐(4‐vinyl)‐benzyl iminodiacetic acid) and comonomers (methacrylic acid and styrene) were fabricated onto the magnetic nanoparticles by free radical polymerization. Factors affecting the performance of the adsorbents were investigated, and the results revealed that Fe3+ played a vital role in the formation of metal–coordination adsorbents. Compared with other compounds, the resultant adsorbents displayed good selectivity to quinolones due to the metal–coordination complex (N‐4‐vinyl‐benzyl iminodiacetic acid‐Fe3+‐quinolones). Interestingly, the captured quinolones could be rapidly released by manipulating the metal–coordination interaction with Cu2+. The linearity range for analysis of the test quinolones was 0.025–2.0 μg/mL (R2 > 0.999), and the recovery varied from 80.0 to 100.7%. Further, the proposed adsorbents were combined with high‐performance liquid chromatography for the analysis of quinolones in real urine samples. The results demonstrated that the prepared adsorbents have good selectivity and sensitivity for quinolones, showing great potential for drug analysis in real samples.  相似文献   
7.
A highly selective molecularly imprinted polymer sorbent was synthesized and employed for the simultaneous determination of six sulfonamide antibiotic residues (sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole, sulfamerazine, and sulfamethizole) in milk samples. Multi‐analyte imprinted particles were used as a sorbent in solid‐phase extraction. Sulfonamides were separated on a high‐performance liquid chromatography column (Merck–Lichrospher RP18e, 5 μm 250 × 4 mm) and further identified and quantified by diode array detection. Several parameters including required loading of the molecularly imprinted polymer sorbent, mass of milk, volume, and type of elution solvent, as well as time for absorption and elution were investigated to obtain optimal experimental conditions. For comparison purpose, a non‐imprinted polymer was applied under the optimum conditions. The validation study according to the European Union Decision 2002/657/EC was based on the investigation of linearity, selectivity, stability, limits of detection and quantitation, decision limit, detection capability, trueness, precision, and ruggedness according to Youden's approach. The decision limit and detection capability values in the milk were achieved from 101.9 to 113.5 μg/kg and from 114.4 to 135.4 μg/kg, respectively, depending on the target sulfonamide drug. Finally, the optimized protocol was successfully applied to commercial milk samples and human breast milk.  相似文献   
8.
Internal plasticization of polyvinyl chloride (PVC) using thermal azide‐alkyne Huisgen dipolar cycloaddition between azidized PVC and electron‐poor acetylenediamides incorporating a branched glutamic acid linker resulted in incorporation of four plasticizing moieties per attachment point on the polymer chain. A systematic study incorporating either alkyl or polyethylene glycol esters provided materials with varying degrees of plasticization, with depressed Tg values ranging from ?1 °C to 62 °C. Three interesting trends were observed. First, Tg values of PVC bearing various internal plasticizers were shown to decrease with increasing chain length of the plasticizing ester. Second, branched internal plasticizers bearing triethylene glycol chains had lower Tg values compared to those with similar length long‐chain alkyl groups. Finally, thermogravimetric analysis of these internally plasticized PVC samples revealed that these branched internal plasticizers bearing alkyl chains are more thermally stable than similarity branched plasticizers bearing triethylene glycol units. These internal tetra‐plasticizers were synthesized and attached to PVC‐azide in three simple synthetic steps. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1821–1835  相似文献   
9.
Poly[9,9′‐dihexylfluorene‐2,7‐diyl)‐6,6″‐(2,2′:6′,2″‐terpyridine)] (LaPPS75) and its complexes with neodymium were synthesized and characterized. Magnetic measurements showed that the noncomplexed polymer presented a ferromagnetic contribution due to the formation of π stacking, and that in absence of those, the ferromagnetic behavior is suppressed. The pristine polymer, the complexed one and a low‐molecular‐weight model compound with the same structure of the complexed site in the parent polymer were studied. The observed behavior found is presented and discussed, the most important finding was that when a conjugated chain is used as a host for the metallic ion, an amplification of four times for the magnetization is achieved, using the same metallic content for complexed polymer and model compound for comparison. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 304–311  相似文献   
10.
A new approach was developed for synthesis of certain A3B3‐type of double hydrophilic or amphiphilic miktoarm star polymers using a combination of “grafting onto” and “grafting from” methods. To achieve the synthesis of desired miktoarm star polymers, acetyl protected poly(ethylene glycol) (PEG) thiols (Mn = 550 and 2000 g mol?1) were utilized to generate A3‐type of homoarm star polymers through an in situ protective group removal and a subsequent thiol–epoxy “click” reaction with a tris‐epoxide core viz. 1,1,1‐tris(4‐hydroxyphenyl)ethane triglycidyl ether. The secondary hydroxyl groups generated adjacent to the core upon the thiol–epoxy reaction were esterified with α‐bromoisobutyryl bromide to install atom transfer radical polymerization (ATRP) initiating sites. ATRP of N‐isopropylacrylamide (NIPAM) using the three‐arm star PEG polymer fitted with ATRP initiating sites adjacent to the core afforded A3B3‐type of double hydrophilic (PEG)3[poly(N‐isopropylacrylamide)] (PNIPAM)3 miktoarm star polymers. Furthermore, the generated hydroxyl groups were directly used as initiator for ring‐opening polymerization of ε‐caprolactone to prepare A3B3‐type of amphiphilic (PEG)3[poly(ε‐caprolactone)]3 miktoarm star polymers. The double hydrophilic (PEG)3(PNIPAM)3 miktoarm star polymers showed lower critical solution temperature around 34 °C. The preliminary transmission electron microscopy analysis indicated formation of self‐assembly of (PEG)3(PNIPAM)3 miktoarm star polymer in aqueous solution. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 146–156  相似文献   
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