Synthesis of polymer particles with specific lysozyme recognition sites by a molecular imprinting technique

To prepare silica beads covered with a lysozyme‐imprinted polymer layer, we polymerized acrylamide and acrylic acid or acrylamide and N,N‐dimethylaminopropylacrylamide with (NH₄)₂S₂O₈ in a phosphate buffer containing the lysozyme, surface‐modified silica beads, and crosslinkers; the result was the formation of a polymer layer with a lysozyme recognition site on the silica‐bead surface. By quantitative analysis of the supernatant of the solution containing the silica beads, we confirmed that modified silica beads, in contrast to unmodified silica beads, can selectively adsorb lysozymes. The process of binding and releasing the lysozyme to and from the modified silica beads can be repeated several times without degradation of the rebinding ability. A quartz‐crystal microbalance sensor fabricated with a molecularly imprinted polymer layer with a lysozyme recognition site was prepared. When a lysozyme aqueous solution was added to the solution in which the sensor was immersed, a high level of sensitivity and response was observed. High selectivity was also demonstrated by tests with other protein solutions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3378–3387, 2001     

分子印迹技术在甾类物质识别和分析中的应用

分子印迹技术在甾类分子识别和分析中的应用及取得的进展。     

Surface molecular imprinting of nylon fibers for chiral recognition of d‐phenyllactic acid

In the current work, synthetic polyamide nylon fibers were modified via the strategy of surface molecular imprinting to develop enantio‐selective adsorbent fabrics for chiral recognition of d ‐phenyllactic acid (d‐ PhLA). The nylon fibers were first modified by grafting of polyacrylamide and then the incorporated amide groups were converted into functional amino groups via treatment with NaOCl (Hofmann degradation). The amino‐functionalized nylon fibers (Ny‐NH₂) were interacted with the targeted d‐ PhLA enantiomer before crosslinking the amino‐containing grafted chains with glutaraldehyde crosslinker followed by leashing the template d‐ PhLA out of the formed surface polymeric matrix by lowering the pH to 1 to finally produce the desired enantio‐selective adsorbent fibers DP‐Ny. Different instrumental methods such as elemental analysis, Fourier transform infrared spectroscopy, XRD and TGA were employed to examine all the synthetic procedures. SEM was also utilized to observe the morphological appearances of both native and modified nylon fibers. Moreover, the optimum extraction of d‐ PhLA was found to occur at pH 7. Isotherm studies of the prepared DP‐Ny fibers obeyed the common Langmuir linear equation with q_m values 130 ± 2 and 75 ± 1 mg g^?1 in the case of d‐ PhLA and l‐ PhLA, respectively. Furthermore, the enantiomeric resolution of (±)‐PhLA racemate was successfully carried out by a column technique with enantiomeric excess reaching approximately 78%. © 2019 Society of Chemical Industry     

In situ polymerization preparation of chiral molecular imprinting polymers monolithic column for amlodipine and its recognition properties study

Amlodipine is a first-line therapeutic drug for hypertension and angina pectoris and its vasodilating effect only resides in the S-(-)-enantiomer. But mostly commercial chiral separating matrixes are not capable of enantio-separating of racemic amlodipine. The amlodipine’s the chiral molecular imprinting polymers monolithic column (CMIPMC) was firstly and successfully synthesized by in situ molecular imprinting technique, utilizing S-(-)-amlodipine as the template molecule, methacrylic acid (MAA) as a monomer, and the resulting monolithic colunm could be directly integrated into the high performance liquid chromatography (HPLC) systems. The scanning electron microscope (SEM) was employed to identify the micro-morphologic features of the obtained polymers. Further, the molecule-special recognition mechanism and special selective absorbent properties for the corresponding template were studied by chromatographic system and Scatchard analysis model, respectively. Meanwhile, the optimized chromatographic conditions for chiral separation of amlodipine enantimoers were established. The results showed the obtained CMIPMC had a high specific affinity and selectivity for the template molecule S-(-)-amlodipine, in which chiral separation of racemic amlodipine was achieved under optimized conditions. The mechanism investigation results showed that two kinds of binding sites prevail in the CMIPMC, besides the molecular shape complementation of template molecular and CMIPMC, hydrogen bond or ionic interaction seem to play an important role in the enantio-selective recognition of the CMIPMC. The research laid fundament for the study of expanding the amlodipine chiral separating medium.     

Increasing the adsorption capacity and selectivity of poly(vinyl alcohol) hydrogels by an alternative imprinting technique

In this work, we report an innovative alternative imprinting method for obtaining chemically crosslinked poly(vinyl alcohol) hydrogels with β‐cyclodextrin as template. The materials present high affinity toward the template that imprinted them, revealed by the higher sorption yield of β‐cyclodextrin and higher selectivity factors of the imprinted material, by comparing with the nonimprinted reference. The imprinting kinetic and mechanism has been demonstrated by adsorption studies, binding isotherms and Scatchard analysis and is in good correlation with the information regarding the morphology of the materials, determined by fluorescence microscopy and atomic force microscopy. By using a novel fluorescence spectroscopy method of the starting polymer solution, the optimum amount of imprinting template could be determined. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42024.     

Synthesis of polymer gel with chiral helical cavity by molecular imprinting using bifunctional vinyl monomers

The molecular imprinting method was applied for synthesizing gels with a chiral helical cavity using various bifunctional vinyl monomers, such as α-(benzyloxymethyl)acrylic acid derivatives as a monomer, and one-handed helical (+)-poly(diphenyl-2-pyridylmethyl methacrylate) as a template. The chiral gels were almost quantitatively prepared after removal of the template polymer by hydrolysis of the ester groups. The obtained gels exhibited chiral resolution powers toward various racemates, such as trans-stilbene oxide and Tröger's base, and the substituents on the phenyl group of the monomer significantly affected the recognition ability. The observed separation factors were higher than those of the gels prepared from the mono-functional vinyl monomer, methacrylic acid.     

Metal ion imprinted microsphere prepared by surface molecular imprinting technique using water-in-oil-in-water emulsions

A novel metal ion imprinted polymer was prepared by the surface molecular imprinting technique. Trimethylolpropane trimethacrylate (TRIM), zinc ions, and 1,12-dodecanediol-O,O′-diphenyl phosphonic acid (DDDPA) were used as the matrix-forming monomer, imprint molecule, and functional monomer, respectively. We have prepared Zn(II)-imprinted microspheres utilizing water-in-oil-in-water emulsions, which are spherically well defined and uniform. TRIM comprises of three polymerizable groups that serve to align the recognition sites produced on the polymer surface with better template effect. We conducted diagnostic zinc adsorption tests by using the Zn(II)-imprinted and unimprinted polymers in order to make an assessment on the effectiveness of TRIM-based and divinylbenzene-based imprinted polymers. The template effect of the TRIM-based polymer was enhanced by the high rigidity of the polymer matrix compared to that of the imprinted polymer whose matrix is divinylbenzene. In addition, the adsorption equilibrium constant was evaluated on the basis of the Langmuir analysis for the adsorption data. The method to prepare metal-imprinted microspheres on the surface of polymers crosslinked by TRIM is easy, and the adsorbent produced can be readily used without subsequent grinding or sieving. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1223–1230, 1999     

Novel surface modifying macromolecules (SMMs) blended polysulfone gas separation membranes by phase inversion technique

In this article an attempt was made to fabricate defect‐free asymmetric polysulfone (PSf) membranes for the separation of oxygen and nitrogen. The approach is based on the enhanced delayed demixing by blending surface modifying macromolecules (SMMs) in the casting solution and by immersing the cast film in isopropanol for a certain period before it is immersed in water. Different SMMs, including hydrophobic and charged SMMs, were synthesized, characterized, and blended to the host PSf. It was found that the charged SMM could indeed contribute to the removal of defective pores from the skin layer and enhancement of oxygen/nitrogen selectivity. The experimental results were further interpreted based on the shift of the phase boundary line on the polymer/solvent/nonsolvent triangular diagram, which occurred when SMMs were blended to PSf, due to the change in the polymer/nonsolvent interaction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Switchable cholesterol recognition system with Diels–Alder reaction using molecular imprinting technique on self‐assembled monolayer

Molecular imprinting was conducted using a method to form a polymeric coating on a self‐assembled monolayer (SAM). This molecular imprinting system was able to obtain an on–off function using the Diels–Alder reaction. Cholesterol was used as a target compound and the SAM was formed using thiol compound on a gold plate. Epoxy resin was used to form the polymeric coating. Covalent bonding method was used in molecular imprinting. The formed molecular imprinting system recognized cholesterol better than analogs of cholesterol. Epoxy resin curing agent with furan group was synthesized to form the molecular imprinting system. Using the Diels–Alder reaction between the furan group and phenylmaleimide, this molecular imprinting system offers a switchable function. © 2019 Society of Chemical Industry     

Alumina/zirconia ceramic membranes fabricated by temperature induced forming technique

It is well known that the fabrication technique of porous ceramic composites has a significant effect on their microstructure and properties. In the present study, alumina/zirconia ceramic composites doped with magnesia were fabricated by temperature induced forming technique using tri-ammonium citrate and polyacrylic acid (PAA) as dispersant and gelling agents, respectively. The zirconia content was up to 20 wt% and added at the expense of alumina while the magnesia content was up to 2 wt% over the total mass. The optimum amount of ammonium citrate tribasic needed for dispersing the ceramic slurry was determined by measuring zeta potential of slurries. The prepared green alumina/zirconia composites were subjected for solid state sintering at 1550 °C for 1 h. The densification parameters, phase composition, average pore diameter, microstructure and cold crushing strength of sintered alumina/zirconia ceramics were investigated by the suitable techniques. The results revealed that the addition of tri-ammonium citrate to ceramic slurries enhanced the zeta potential which reached ?28.3 mV by adding 1 wt.-%. The bulk density was decreased while the apparent porosity was increased with the increase of zirconia content. The apparent porosities of sintered porous composites were in the range of 38.8–48.5%. The average pore diameter for the composite containing 15% zirconia was 1.79 μm and pore volume was 0.11 ml/g. The obtained microstructure exhibited zirconia grains located on the grain boundaries of Al₂O₃ matrix. The existence of zirconia in addition to magnesia hindered the growth and deformation of the matrix. The cold crushing strength of porous composites was decreased from 16.0 to 8.5 to MPa by increasing the zirconia content from 5 to 20 wt.-%.     

Preparation and gas separation properties of asymmetric polysulfone membranes by a dual bath method

Defect-free skinned asymmetric gas separation membranes were prepared by a dual bath coagulation method that is a wet/wet phase inversion technique. The membranes were cast from a polysulfone/N,N-dimethylacetamide solution. In two sequent nonsolvent baths, the first bath using iso-propanol (IPA) leads to the formation of a dense skin top layer and the second bath using water makes the actual polymer precipitation. The top skin layer thickness was governed by changing the immersion time of the first IPA bath. We suggest that the growth rate of the skin layer is to be determined by a diffusion process.     

Molecular surface recognition by a computer vision-based technique

Correct docking of a ligand onto a receptor surface is a complexproblem, involving geometry and chemistry. Geometrically acceptablesolutions require close contact between corresponding patchesof surfaces of the receptor and of the ligand and no overlapbetween the van der Waals spheres of the remainder of the receptorand ligand atoms. In the quest for favorable chemical interactions,the next step involves minimization of the energy between thedocked molecules. This work addresses the geometrical aspectof the problem. It is assumed that we have the atomic coordinatesof each of the molecules. In principle, since optimally matchingsurfaces are sought, the entire conformational space needs tobe considered. As the number of atoms residing on molecularsurfaces can be several hundred, sampling of all rotations andtranslations of every patch of a surface of one molecule withrespect to the other can reach immense proportions. The problemwe are faced with here is reminiscent of object recognitionproblems in computer vision. Here we borrow and adapt the geometrichashing paradigm developed in computer vision to a central problemin molecular biology. Using an indexing approach based on atransformation invariant representation, the algorithm efficientlyscans groups of surface dots (or atoms) and detects optimallymatched surfaces. Potential solutions displaying receptor-ligandatomic overlaps are discarded. Our technique has been appliedsuccessfully to seven cases involving docking of small molecules,where the structures of the receptor-ligand complexes are availablein the crystallo-graphk database and to three cases where thereceptors and ligands have been crystallized separately. Intwo of these three latter tests, the correct transformationshave been obtained.     

Adsorption and degradation of norfloxacin by a novel molecular imprinting magnetic Fenton-like catalyst

In this study, a novel magnetically separable adsorbent, molecular imprinting magnetic γ-Fe₂O₃/crosslinked chitosan composites (MIPs), were prepared by a microemulsion process. Adsorption and Fenton-like oxidative degradation of a model pharmaceutical pollutant norfloxacin (NOR) by using MIPs were investigated. Various characterization methodswere used to study the properties ofMIPs, and it is suggested that the hydroxyl groups are the main adsorption sites for NOR. MIPs present better selective adsorption for NOR than its reference antibiotic sulfadiazine. The NOR adsorption data can be well fitted by Langmuir isotherm model and pseudosecond- order kinetic model. The optimum pH range for NOR adsorption is 7-10. In addition, the MIP-catalyzed Fenton-like system (MIPs/H₂O₂) exhibits remarkably faster removal rate for NOR than the case of γ-Fe₂O₃/ H₂O₂. The result indicates that MIPs will be a good functional material in decontamination of pharmaceutical wastewaters since MIPs can be magnetically recycled after the treatment.     

Preparation of biofuel from argemone seed oil by an alternative cost-effective technique

In this experiment, argemone oil, toxic and highly viscous oil, was treated in two different processes to use this as an adulterer to petroleum diesel. Firstly oil was passed through several processes to lower it viscosity and to improve its properties. The resultant oil, refined argemone oil (RAO), was compared with traditional transesterified biodiesel (TEO) prepared from crude argemone oil. Results indicated that RAO had properties closer to those of TEO and important properties like viscosity, acid value, iodine value and pour point of RAO were also within the acceptable range. Engine testing revealed that up to 42% increment in engine runtime was recorded when only 10% RAO was added to the petroleum diesel, and this is probably the most feasible technique to convert argemone oil to biofuel additive with petroleum diesel. GC–MS analysis revealed the presence of methyl esters of several saturated and unsaturated fatty acids in both RAO and TEO. However, methyl eicosanoate was present in the highest concentration in these oils.     

Fabrication of polysulfone asymmetric hollow‐fiber membranes by coextrusion through a triple‐orifice spinneret

Polysulfone (PSf) asymmetric hollow‐fiber membranes, which have a dense outer layer but a loose inner layer, were tentatively fabricated by coextrusion through a triple‐orifice spinneret and a dry/wet‐phase inversion process. Two simple polymer dopes were tailored, respectively, for the dense outer layer and the porous inner layer according to the principles of the phase‐inversion process. By adjusting the ratio of the inner/outer extrusion rate, the hollow‐fiber membranes with various thicknesses of outer layers were achieved. The morphology of the hollow‐fiber membranes was exhibited and the processing conditions and the water permeability of the membrane were investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 259–266, 2004     

Molecular recognition of amines by a chiral Zn(II) porphyrin complex

Equilibria of the reactions of a Zn(II) `picket-fence' porphyrin complex bearing optically active substituents with chiral amines were studied. Stability constants were determined by spectrophotometric titration in dichloromethane solution. Chiral recognition in the complexation of amine to the α,β,α,β-isomer of the complex was observed for 1-(1-naphthyl)ethylamine with the ratio of the binding constant of K_S/K_R=2.4.     

Development of an alternative technique for sampling stack gas by using zeolite 3A

One of the primary prerequisites for accurate fuel-combustion stack-gas analysis is efficient moisture removal. At present moisture is generally removed by using moisture traps or coolers, but this arrangement has not proved very efficient. An alternative method has been developed by using a packed column of zeolite 3A selectively to remove the moisture without adversely affecting the composition of the dry flue gas. Column performance was analysed to find the optimum time and operating conditions. The technique works well under controlled laboratory conditions, but needs further development before it is ready for routine field use.     

Polymer electrolyte membranes having sulfoalkyl grafts into ETFE film prepared by radiation‐induced copolymerization of methyl acrylate and methyl methacrylate

Polymer electrolyte membranes (PEMs) containing alkylsulfonic acid grafts can be prepared by radiation‐induced graft copolymerization of methyl acrylate (MA) and methyl methacrylate (MMA) into a poly(ethylene‐co‐tetrafluoroethylene) film followed by sulfonation of the MA units in the copolymer grafts using an equimolar complex of chlorosulfonic acid and 1,4‐dioxane (ClSO₃H‐Complex). PEMs with MA/MMA copolymer grafts that are 33%–79% MA units were prepared by preirradiation with a dose of 20 kGy and grafting in bulk comonomers at 60°C. The grafted films are treated with ClSO3H‐Complex to obtain PEMs with ion exchange capacity of 0.36‐0.81 mmol/g (sulfonation degrees of 20%–40%) and proton conductivity of 0.04‐0.065 S/cm. These values can be controlled by changing the MA content the sulfonation occurring at an α‐carbonyl carbon. The PEMs with higher MMA content showed higher durability in water (80°C) and under oxidative conditions (3% H₂O₂) at 60°C. This is because the PMMA grafts in the PEMs have no proton at an α‐carbonyl carbon, which is considered to be a trigger of the degradation of grafting polymers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Biomimic recognition and catalysis by an imprinted catalysts: a rational design of molecular self-assembly toward predetermined high specificity

This article presents an original work contributing to the rational design of imprinted catalyst by molecular self-assembly toward predetermined high specificity. Assembling with p-nitrophenyl phosphate as the transition state analogue (TSA) of p-nitrophenyl acetate esterolysis and 1-vinylimidazole as the functional monomer, the imprinted catalyst was prepared. An increase in the amount of assembled monomer results in a higher activity of hydrolysis, which, however, does not lead to an improvement of specificity. The best specificity is shown at the optimal self-assembly (corresponding to a stoichiometric interaction of monomer-TSA). Higher or lower an amount of assembled monomer would lead to a dramatic decrease in this specificity. Related information indicates that these may be a result of increasing specific interaction between the TSA and binding sites, which make the catalyst capable of selectively recognizing the transition state and promoting the conversion from reactant to the transition state.     

Fluorescence upconversion properties of a chiral polybinaphthyl induced by two‐photon absorption

The fluorescence properties of a chiral polymer based on optically active polybinaphthyls were studied in tetrahydrofuran solution. One‐photon excited fluorescence of the polymer was located in the range of ～ 596 nm and the corresponding lifetime was ～ 4.38 ns. From the excitation spectra and emission spectra excited at 800 nm, the upconversion fluorescence emission was observed. When excited by using 800 nm fs laser pulses with different input irradiances, the peak fluorescence intensity of the solution provides square dependence with the input irradiance power, giving an evidence for two‐photon excited fluorescence. Furthermore, open aperture Z‐scan measurements were performed at different irradiation intensities to confirm two‐photon absorption property of the solution at 800 nm excitation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012