PREPARATION OF GLUTATHIONE IMPRINTED POLYMER

Glutathione imprinted polymer was prepared using 1-vinyl imidazole and ethylene glycol dimethacrylate as the functional monomer and crosslinker, respectively, in dimethyl sulfoxide. The adsorption selectivity of glutathione-imprinted polymer was tested by reduced glutathione, oxidized glutathione, and L-Gly-Leu-Tyr in 30% phosphate buffer (0.01 M, pH 5.0)–70% acetonitrile and binding affinity values were compared. Reusability of molecularly imprinted polymer particles was also investigated. Molecularly imprinted polymer particles were found to be stable and to maintain glutathione adsorption capacity at 95% when washed with methanol–acetic acid (10%) after seven usages. Functional monomer 1-vinyl imidazole and cross linker ethylene glycol dimethacrylate-based glutathione imprinted polymer could be used as solid phase extraction material for recognition of glutathione in biological samples.     

Decay resistance of wood treated with boric acid and tall oil derivates

In this study, the effect of two boric acid concentrations (1% and 2%) and four derivates of tall oil with varying chemical composition were tested separately and in combination. The tall oil derivates were chosen in a way that they consist of different amounts of free fatty, resin acids and neutral compounds. Decay tests using two brown rot fungi (Postia placenta and Coniophora puteana) were performed on both unleached and leached test samples. Boric acid showed a low weight loss in test samples when exposed to fungal decay before leaching, but no effect after leaching. The tall oil derivates gave better efficacy against decay fungi compared to control, but are not within the range of the efficacy needed for a wood preservative. Double impregnation with boric acid and tall oil derivates gave synergistic effects for several of the double treatments both in unleached and leached samples. In the unleached samples the double treatment gave a better efficacy against decay fungi than tall oil alone. In leached samples a better efficacy against brown rot fungi were achieved than in samples with boron alone and a nearly similar or better efficacy than for tall oil alone. Boric acid at 2% concentration combined with the tall oil derivate consisting of 90% free resin acids (TO-III) showed the best performance against the two decay fungi with a weight loss less than 3% after a modified pure culture test.     

Senescent leaf exudate increases mosquito survival and microbial activity

We conducted experiments to evaluate the effects of soluble components in senescent leaf material on the growth and development of the eastern tree hole mosquito, Aedes triseriatus (Say). Oak leaves that were either leached for three days to remove the labile nutrient fraction, or were not leached, served as basal nutrient inputs in each experiment.Mosquito performance in microcosms containing leachate only was significantly worse compared with microcosms containing leaf material in combination with either leachate or water, indicating the importance of leaf substrates to mosquito production.Adult mosquito biomass, emergence, and development time were significantly higher in microcosms containing unleached leaves compared with leached leaf material. Additions of leachate to leached leaf treatments enhanced adult production, but not to the level observed in unleached leaf treatments.Filtered and unfiltered leachate added substantial nitrogen and phosphorus to microcosms and significantly affected mosquito growth responses. Bacterial productivity and abundance were also significantly affected by leachate additions and filtering.Taken together, these results suggest that while leaves decline with respect to nutritional value during decomposition, they remain important components of the habitat as substrates for microbial growth and mosquito feeding, particularly when nutrients (here, leachate) enter the system. Our results also illustrate the importance of soluble leaf material, which enhances mosquito production through effects on microbial community dynamics.     

Synthesis of nano‐sized hydrogen phosphate‐imprinted polymer in acetonitrile/water mixture and its use as a recognition element of hydrogen phosphate selective all‐solid state potentiometric electrode

Herein, a new recipe is introduced for the preparation of hydrogen phosphate ion‐imprinted polymer nanoparticles (nano‐IIP) in acetonitrile/water (63.5:36.5) using phosphoric acid as the template. The nano‐IIP obtained was used as the recognition element of a carbon paste potentiometric sensor. The IIP electrode showed a Nernstian response to hydrogen phosphate anion; whereas, the non‐imprinted polymer (NIP)‐based electrode had no considerable sensitivity to the anion. The presence of both methacrylic acid and vinyl pyridine in the IIP structure, as well as optimization of the functional monomers‐template proportion, was found to be important to observe the sensing capability of the IIP electrode. The nano‐IIP electrode showed a dynamic linear range of 1 × 10^?5‐1 × 10^?1 mol L‐1, Nernstian slope of 30.6 ± (0.5) mV decade ^?1, response time of 25 seconds, and detection limit of 4.0 × 10^?6 mol L^?1. The utility of the electrodes was checked by potentiometric titration of hydrogen phosphate with La³⁺ solution.     

Fabrication and investigation of gold (III) ion‐imprinted functionalized silica particles

Au (III) ion‐imprinted mesoporous silica particles (Au‐Si‐Py) was manufactured by the condensation reaction of (3‐Aminopropyl)triethoxysilane (AT)and 2‐pyridinecarboxaldehyde (Py). The obtained AT‐Py Schiff base ligand was then coordinate with the template gold ions and the polymerizable gold‐complex was allowed to gel in presence of tetraethoxysilane (TEOS) and then the coordinated gold ions were leached out of the obtained silica matrix using acidified thiourea solution. During the synthetic steps, the obtained materials were investigated utilizing advanced instrumental and spectral methods. Moreover, the morphological structure of both Au (III) ions imprinted Au‐Si‐Py and non‐imprinted NI‐Si‐Py silica particles were visualized using scanning electron microscope (SEM). Various adsorption experiments had been carried out using both Au‐Si‐Py and NI‐Si‐Py to examine their potential for selective extraction of gold ions under different conditions     

Towards the rational development of molecularly imprinted polymers: 1H NMR studies on hydrophobicity and ion-pair interactions as driving forces for selectivity

The preparation of molecularly imprinted polymers (MIP) based on non-covalent interactions has become a widely used technique for creating highly specific sorbent materials predominantly used in separation chemistry. A crucial factor in a successful imprinting protocol is the optimisation of the template/functional monomer interaction in the pre-polymerisation mixture, eventually leading to a maximum of high-affinity binding sites in the resulting polymer matrix. In order to develop more efficient preparation technologies for imprinted polymers, two separate pre-polymerisation complexes were investigated by NMR spectroscopic techniques in order to identify the types of interactions occurring in the pre-polymerisation mixture, and their implications for the subsequently formed imprinted polymer. In particular, hydrophobic effects have been followed by NMR spectroscopy and their contribution to the selectivity of the resulting MIP has been investigated. The 2,4-D imprint system is used as an example to fundamentally study whether observations at the pre-polymerisation stage correlate with properties of the finally prepared MIP, and which parameters govern success of an imprinting protocol.     

Synthesis of cholesterol imprinted polymeric particles

The aim of this study is to prepare cholesterol-imprinted polymeric particles. N-Methacryloyl-(L)-tyrosinemethylester (MAT) was chosen as the complexing monomer. In the first step, functional monomer MAT was synthesized by the reaction of L-tyrosine methylester and methacryloyl chloride and characterized by FTIR and NMR. Then, cholesterol was complexed with MAT in different mol ratios and the cholesterol-imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-(L)-tyrosine methylester) [MIP] particles were synthesized by bulk polymerization. After that, the template molecules (i.e., cholesterol) were removed using chloroform. MIP particles were characterized by elemental analysis, FTIR, SEM, swelling tests and surface area measurements. Cholesterol adsorption experiments were performed in a batch experimental set-up. Adsorption medium was methanol or intestinal mimicking solution. Stigmasterol and estradiol were used as competing molecules in selectivity tests. Obtained results were as follows: swelling ratio of MIP and non-imprinted (NIP) particles were 60.8% and 44.1% in water. With the increase in the amount of MAT in the polymerization medium, incorporation of MAT was increased (16.6-78.0 micromol/g). SEM photographs showed the surface roughness and porosity. Specific surface area of NIP and MIP particles were found as 19.2 and 31.5 m(2)/g, respectively. Template molecules (i.e., cholesterol) were removed from the polymer structure in the ratio of 76-84% of the initial concentration. Cholesterol adsorption increased with the increase in cholesterol concentration up to 1.5 mg/mL. MIP particles prepared using higher amounts of cholesterol exhibit significantly higher capacity to the NIP particles (i.e., control polymer). MIP particles were 3.09 and 3.60 times selective with respect to the stigmasterol and estradiol, respectively. Reusability of MIP particles was also investigated. MIP particles showed negligible loss in the cholesterol adsorption capacity after five adsorption-desorption cycles with the same adsorbent.     

Synthesis and evaluation of uniformly sized nalidixic acid-imprinted nanospheres based on precipitation polymerization method for analytical and biomedical applications

For the first time in this work, uniform molecularly imprinted polymer (MIP) nanoparticles were prepared using nalidixic acid as a template. The MIP nanoparticles were successfully synthesized by precipitation polymerization applying methacrylic acid (MAA) as a functional monomer and trimethylolpropane trimethacrylate (TRIM) as a cross-linking monomer at different mole ratios. The morphology, binding, recognition, selectivity, and in vitro release behaviors of obtained particles were studied. The produced polymers were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetric. Furthermore, their morphology was analyzed accurately by scanning electron microscopy, photon correlation spectroscopy, and Brunauer-Emmett-Teller analysis. The nanospheres and microspheres with mean diameter values of 94 nm, 256 nm, and 1.2 μm were obtained using nalidixic acid-MAA-TRIM various mole ratios. Among the MIPs, the product with nalidixic acid-MAA-TRIM mole ratio of 1:12:12 established nanospheres with the lowest polydispersity index (0.003), an average pore diameter (12 nm), and the highest specific surface area (280 m(2) g(-1)) and selectivity factor (10.4). Results from binding experiments demonstrated that the imprinted nanospheres with a 94-nm mean diameter and a binding capacity of 28 mg of nalidixic acid per gram of polymer had higher specific affinity to nalidixic acid in contrast with the other imprinted nanospheres, microspheres, and nonimprinted particles. However, the binding performance of imprinted nanospheres in human serum was estimated using high-performance liquid chromatography analysis (binding approximately 98% of nalidixic acid). In addition, release experiments proved to be successful in the controlled release of nalidixic acid during a long period. The 20% of loaded nalidixic acid was released from the imprinted nanospheres within the first 20 h, whereas the remaining 80% was released in the after 120 h. The nalidixic acid release kinetics from the MIPs was highly affected by properties of the particles.     

Synthesis of molecularly imprinted polymers using a functionalized initiator for chiral-selective recognition of propranolol

We present a new concept of synthesis for preparation of molecularly imprinted polymers using a functionalized initiator to replace the traditional functional monomer. Using propranolol as a model template, a carboxyl-functionalized radical initiator was demonstrated to lead to high-selectivity polymer particles prepared in a standard precipitation polymerization system. When a single enantiomer of propranolol was used as template, the imprinted polymer particles exhibited clear chiral selectivity in an equilibrium binding experiment. Unlike the previous molecular imprinting systems where the active free radicals can be distant from the template-functional monomer complex, the method reported in this work makes sure that the actual radical polymerization takes place in the vicinity of the template-associated functional groups. The success of using functional initiator to synthesize molecularly imprinted polymers brings in new possibilities to improve the functional performance of molecularly imprinted synthetic receptors.     

Recognition of the Different Structural Forms of the Capsid Protein Determines the Outcome following Infection with Porcine Circovirus Type 2

Porcine circovirus type 2 (PCV2) capsid protein (CP) is the only protein necessary for the formation of the virion capsid, and recombinant CP spontaneously forms virus-like particles (VLPs). Located within a single CP subunit is an immunodominant epitope consisting of residues 169 to 180 [CP(169–180)], which is exposed on the surface of the subunit, but, in the structural context of the VLP, the epitope is buried and inaccessible to antibody. High levels of anti-CP(169–180) activity are associated with porcine circovirus-associated disease (PCVAD). The purpose of this study was to investigate the role of the immune response to monomer CP in the development of PCVAD. The approach was to immunize pigs with CP monomer, followed by challenge with PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV). To maintain the CP immunogen as a stable monomer, CP(43–233) was fused to ubiquitin (Ub-CP). Size exclusion chromatography showed that Ub-CP was present as a single 33-kDa protein. Pigs immunized with Ub-CP developed a strong antibody response to PCV2, including antibodies against CP(169–180). However, only low levels of virus neutralizing activity were detected, and viremia levels were similar to those of nonimmunized pigs. As a positive control, immunization with baculovirus-expressed CP (Bac-CP) resulted in high levels of virus neutralizing activity, small amounts of anti-CP(169–180) activity, and the absence of viremia in pigs following virus challenge. The data support the role of CP(169–180) as an immunological decoy and illustrate the importance of the structural form of the CP immunogen in determining the outcome following infection.     

The Radical Formation of Diphthalocyanine Complexes of Lanthanum(III), Neodymium(IIl) and Yttrium(III) with p-Benzoquinone

Three species of neodymium(III) phthalocyanine: PcNdPcH (λ max = 345 and 636 nm), radical PcNdPc (324, 470 and 676 nm) and PcNdCH₃COO (336 and 675 nm) were obtained from a crude neodymium(III) phthalocyanine mixture by column chromatography on silica gel. The diphthalocyanine complexes of lanthanum (III), neodymium(III) and yttrium(III) were oxidized to the radical with p-benzoquinone and the reaction rate was increased with the decrease of an ionic radius, e.g. the rate was increased with the decrease of the distance of two macrocycles in the complex.     

Computer-simulation-based selection of optimal monomer for imprinting of tri-O-acetyl adenosine in a polymer matrix: calculations for benzene solution

Molecular imprinting is a promising way to create polymer materials that can be used as artificial receptors, and have anticipated use in synthetic imitation of natural antibodies. In case of successful imprinting, the selectivity and affinity of the imprint for the substrate molecules are comparable with those of natural counterparts. Various calculation methods can be used to estimate the effects of a large range of imprinting parameters under different conditions, and to find better ways to improve polymer characteristics. However, one difficulty is that properties such as hydrogen bonding can be modeled only by quantum methods that demand a lot of computational resources. Combined quantum mechanics/molecular mechanics (QM/MM) methods allow the use of MM and QM for different parts of the modeled system. In present study this method was realized in the NWChem package to compare estimations of the stability of tri-O-acetyl adenosine–monomer pre-polymerization complexes in benzene solution with previous results under vacuum.     

Determination of total aluminum, chromium, copper, iron, manganese, and nickel and their fractions leached to the infusions of black tea, green tea, Hibiscus sabdariffa, and Ilex paraguariensis (mate) by ETA-AAS

Total aluminum, chromium, copper, iron, manganese, and nickel were determined in black tea, green tea, Hibiscus sabdariffa, and Ilex paraguariensis (mate) by electrothermal atomic absorption spectrometry after nitric/perchloric acid digestion. In each case, one ground sample of commercially available leafy material was prepared and three 0.5-g subsamples were run in parallel. The infusions were also analyzed and the percentage of each element leached into the liquor was evaluated. The obtained results indicated that hibiscus and mate contained lower levels of aluminum (272±19 μg/g and 369±22 μg/g, respectively) as referred to black tea (759±31 μg/g) or green tea (919±29 μg/g) and suggested that mate drinking could be a good dietary source of essential micronutrient manganese (total content 2223±110 μg/g, 48.1% leached to the infusion). It was also found that the infusion of hibiscus could supply greater amounts of iron (111±5 μg/g total, 40.5% leached) and copper (5.9±0.3 μg/g total, 93.4% leached) as compared to other infusions. Moreover, it was found that the percentage of element leached to the infusion was strongly related to the tannins content in the beverage (correlation coefficients >0.82 with the exception for nickel); for lower tannins level, better leaching was observed.     

Novel fluorescent sensor using molecularly imprinted silica microsphere‐coated CdSe@CdS quantum dots and its application in the detection of 2,4,6‐trichlorophenol from environmental water samples

In this study, a high fluorescence sensitivity and selectivity, molecularly imprinted nanofluorescent polymer sensor (MIP@SiO₂@QDs) was prepared using a reverse microemulsion method. 2,4,6‐Trichlorophenol (2,4,6‐TCP) was detected using fluorescence quenching. Tetraethyl orthosilicate (TEOS), quantum dots (QDs) and 3‐aminopropyltriethoxysilane (APTS) were used as cross‐linker, signal sources and functional monomer respectively. The sensor (MIP@SiO₂@QDs) and the non‐imprinted polymer sensor (NIP@SiO₂@QDs) were characterized using infra‐red (IR) analysis, X‐ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The selectivity of MIP@SiO₂@QDs was examined by comparing 2,4,6‐TCP with other similar functional substances including 2,4‐dichlorophenol (2,4‐DCP), 2,6‐dichlorophenol (2,6‐DCP) and 4‐chlorophenol (4‐CP). Results showed that MIP@SiO₂@QDs had better selectivity for 2,4,6‐TCP than the other compounds. Fluorescence quenching efficiency displayed a good linear response at the 2,4,6‐TCP concentration range 5–1000 μmol/L. The limit of detection (LOD) was 0.9 μmol/L (3σ, n = 9). This method was equally applicable for testing actual samples with a recovery rate of 98.0–105.8%. The sensor had advantages of simple pretreatment, good sensitivity and selectivity, and wide linear range and could be applied for the rapid detection of 2,4,6‐TCP in actual samples.     

Antimicrobial activity of glycosidase inhibitory protein isolated from Cyphomandra betacea Sendt. fruit

Broad-spectrum antimicrobial activity of an invertase inhibitory protein (IIP) isolated from Cyphomandra betacea ripe fruits is documented. Minimal inhibitory concentration (MIC) values were determined by agar macrodilution and broth microdilution assays. This IIP inhibited the growth of xylophagous and phytopatogenic fungi (Ganoderma applanatum, Schizophyllum commune, Lenzites elegans, Pycnoporus sanguineous, Penicillium notatum, Aspergillus niger, Phomopsis sojae and Fusarium mango) and phytopathogenic bacteria (Xanthomonas campestris pvar vesicatoria CECT 792, Pseudomonas solanacearum CECT 125, Pseudomonas corrugata CECT 124, Pseudomonas syringae pv. syringae and Erwinia carotovora var carotovora). The IIP concentration required to completely inhibit the growth of all studied fungi ranged from 7.8 to 62.5 microg/ml. Phytopatogenic bacteria were the most sensitive, with MIC values between 7.8 and 31.25 microg/ml. Antifungal and antibacterial activities can be associated with their ability to inhibit hydrolytic enzymes. Our results indicate the possible participation of IIP in the plant defense mechanism and its potential application as a biocontrol agent against phytopathogenic fungi and bacteria.     

Synthesis and iron(III)-chelating properties of novel 3-hydroxypyridin-4-one hexadentate ligand-containing copolymers

Iron overload is a critical clinical problem that can be prevented by the use of iron-specific chelating agents. An alternative method of relieving iron overload is to reduce the efficiency of iron absorption from the intestine by administering iron chelators, which can bind iron irreversibly to form nontoxic, kinetically inert complexes that are not absorbed and are therefore excreted in the feces. A series of polymeric chelators with various iron binding capacities were therefore prepared as nonabsorbable iron-selective additives. A novel 3-hydroxypyridin-4-one hexadentate ligand CP254 has been synthesized and incorporated into polymers by copolymerisation with N, N-dimethylacrylamide (DMAA), and N, N'-ethylene-bis-acrylamide (EBAA) using (NH4)2S2O8 as the initiator. The physicochemical properties of CP254 were determined, namely, log K = 33.2 and pFe(3+) = 27.24. The chelating capacity of the CP254-DMAA copolymers was determined at physiological pH. The iron(III) chelation was found to achieve 80% capacity after 1 h and was virtually complete after 5 h, which is much quicker than that of the commercially available chelating resin Chelex100. The chelating copolymers were found to be readily regenerated and reusable. The copolymers possess a high selectivity for iron(III). The conditional affinity (log K') for iron(III) at pH 7.46 was determined to be 26.55, which is not significantly different to that of the hexadentate ligand CP254 (log K' = 26.47). In vitro perfusion studies indicate that the polymeric chelators described in this study can reduce iron absorption from the intestine.     

Grafting of oligosaccharides onto synthetic polymer colloids

A new method to form colloidally stable oligosaccharide-grafted synthetic polymer particles has been developed. The oligosaccharides, of weight-average degree of polymerization approximately 38, were obtained by enzymatic debranching of amylopectin. Through the use of a cerium(IV)-based redox initiation process, oligosaccharide chains are grafted onto a synthetic polymer colloid comprising electrostatically stabilized poly(methyl methacrylate) or polystyrene latex particles swollen with methyl methacrylate monomer. Ce(IV) creates a radical species on these oligosaccharides, which then propagates, initially with aqueous-phase monomer, then with the methyl methacrylate monomer inside the particles. Ultracentrifugation, NMR, and total starch analyses together prove that the grafting process has occurred, with at least 7.7 wt % starch grafted and a grafting efficiency of 33%. The surfactant used in latex preparation was removed by dialysis, resulting in particles colloidally stabilized with only linear starch as a steric stabilizer. The debranched starch that comprises these oligosaccharides is found to be a remarkably effective colloidal stabilizer, albeit at low electrolyte concentration, stabilizing particles with very sparse surface coverage.     

The use of molecularly imprinted sol-gels in pharmaceutical separations

This paper illustrates the potential of the sol-gel process to imprint the pharmaceutical active--N-[N-[(1S)-1-carboxssy-3-phenylpropyl]-l-lysyl]-L-proline, (lisinopril dihydrate). This template exhibits unique difficulties such as limited solubility in non-polar and most polar porogens with multiple functionality evident in its 4 pKa values. Selectivity for this template was achieved using a 3-monomer sol-gel system utilising solid phase extraction (SPE). Analysis of the template and its related substances was achieved using HPLC. The effect of solvent polarity on the rebinding of the template was studied. Through optimisation of porogen and extraction solvent, the imprinted material (MIP) demonstrated enhanced selectivity, for the template, over a non-imprinted material (NIP). Selectivity was also illustrated for the original template over two of its related substances. The effect of starting monomer ratio on selectivity was studied to determine the interactions, which could best be exploited to further enhance selectivity.     

The rational use of hydrophobic effect-based recognition in molecularly imprinted polymers

A novel molecularly imprinted polymer (MIP) system selective for D-phenylalanine is described where polymerization is performed in aqueous solution. The unique polymer system comprises a hydrophobic moiety-selective functional monomer, polymerizable beta-cyclodextrin, an electrostatic interacting functional monomer, 2-acryloylamido-2-methylpropane sulfonic acid (AMPSA), and the crosslinking agent N,N'-diacryloylpiperazine. Chromatographic evaluation of polymer-ligand recognition characteristics demonstrated ligand selectivity by the MIP and that optimal recognition was achieved through a balance of hydrophobic and electrostatic ligand-polymer interactions, indicating that recognition in these systems is regulated by enthalpy-entropy compensation. The imprinting effect was shown to be sufficient to reverse the inherent selectivity of cyclodextrin for L-phenylalanine.     

Direct rapid synthesis of MIP beads in SPE cartridges

Selecting optimal compositions for non-covalent molecularly imprinted polymers (MIPs) and screening for appropriate rebinding conditions necessitates synthesising a large number of polymers. This is extremely labour-intensive and usually results in very limited "optimisation" in studies of MIPs. Here, a new method is proposed for rapid synthesis of MIPs in a beaded form that can be used directly in many different performance evaluation studies. The method is based on synthesis of spherical particles by suspension polymerisation in liquid fluorocarbon [Mayes, A., Mosbach, K., 1996. Molecularly imprinted polymer beads: suspension polymerisation using a liquid perfluorocarbon as the dispersing phase. Anal. Chem. 68, 3769-3774]. The polymers were directly polymerised under UV light in solid phase extraction (SPE) cartridges, then washed and extracted in the same cartridges where they had been synthesised, resulting in a rapid and automatable process that requires no transfer or manipulation of the polymer particles. The particles were similar in terms of size, morphology and functional performance to particles obtained by suspension polymerisation in fluorocarbon solvent using a conventional reactor. In this initial study, 36 polymers were synthesised to study the effect of a variation in the type and amount of four different functional monomers, methacrylic acid (MAA), acrylic acid (AA), hydroxyethyl methacrylate (HEMA) and 2-vinylpyridine (2-VPy), for the imprinting of propranolol and morphine. The performance of polymers synthesised using MAA was as expected, but those synthesised with AA as functional monomer showed more surprising rebinding properties as a function of monomer to cross-linker ratios, demonstrating the potential value of pragmatic synthesis and screening approaches to polymer optimisation.