Monoliths with chiral surface functionalization for enantioselective capillary electrochromatography

The state-of-the-art in CEC enantiomer separations with monolithic capillary columns is comprehensively reviewed. The various types of monolithic columns comprising in situ organic polymer monoliths, molecularly imprinted polymer (MIP) monoliths, silica monoliths and monoliths made from particles are discussed with a focus on materials’ synthesis, chemistry and properties as well as column aspects. Monolithic MIP-type porous layer open-tubular (PLOT) columns are treated herein as well. From this survey of the literature, the authors come to the conclusion that monolithic silica capillaries appear to become the preferred column type for CEC enantiomer separations of low-molecular drugs and other chiral pharmaceuticals or chemicals.     

槲皮素分子印迹聚合物的合成及表征

目的利用分子印迹技术制备槲皮素分子印迹聚合物(MIPs)。方法以槲皮素为模板分子,丙烯酰胺为功能单体,乙二醇二甲基丙烯酸酯为交联剂,偶氮二异丁腈为引发剂,分别在无水乙醇和四氢呋喃为致孔剂的作用下,采用沉淀聚合法、本体聚合法制备槲皮素MIPs;利用紫外光谱、红外光谱选择模板分子与功能单体间的最佳配比;通过扫描电镜(SEM)考察了MIPs的微观结构。采用平衡和等温吸附实验对2种方法制备的MIPs的吸附平衡时间和最大吸附量进行考察,并对特异性吸附能力进行研究。结果沉淀聚合法制备的槲皮素MIPs具有均匀规则的球状结构,在吸附动力学和等温吸附实验中发现有较快的吸附速度和较大的吸附量,在芦丁和槲皮素的选择性吸附过程中聚合物对槲皮素具有较高的特异性识别能力。结论沉淀聚合法制备的MIPs以吸附量大、选择性强,为中药黄酮类复杂化学成分的分离、富集提供一种新的研究方法,同时也为其他中药化学成分的研究提供借鉴。     

Protein A immobilization and HIgG adsorption onto porous/nonporous and swellable HEMA-incorporated polyEGDMA microspheres

Both non swellable and swellable poly(EGDMA/HEMA) microbeads were produced by suspension copolymerization. These microbeads were modified by immobilization of a spacer-arm (hexamethylene diamine (HMDA)) and protein A. The optimal values for modifications were as follows: sodium periodate concentration, 1.0 mg ml^-1; HMDA concentration, 4 mg ml^-1; and glutaraldehyde concentration, 0.070 μg ml^-1. Adsorption of protein A onto the plain and periodate oxidized poly(EGDMA/HEMA) microbeads were very close to each other, and were 0.01-0.02 mg protein A on the 1-g Microbeads I and II, respectively. Protein A immobilization on poly(EGDMA/HEMA) microbeads were studied at different temperatures, times, and pHs using single protein solution containing different amounts of proteins. The optimal values for immobilization were as follows: the initial protein A concentration, 0.1 mg ml^-1; temperature, 25°C; pH, 9.5; and immobilization time, 120 min. Incorporation of protein A resulted in 1.420 and 1.825 mg protein A on the 1-g Microbeads I and II, respectively. HIgG adsorption capacity on the protein A-incorporated poly(EGDMA/HEMA) microbeads is 27 and 35 mg HIgG g^-1 polymer for Microbeads I and II, respectively.     

Effects of antioxidants on DNA-double strand breaks in human gingival fibroblasts exposed to methacrylate based monomers

Objective

(Co)monomers from dental resin composites have cytotoxic and genotoxic potential. In previous studies it has been demonstrated that antioxidants can decrease the cytotoxicity of various dental (co)monomers. In this study the effects of the antioxidants N-acetylcysteine (ACC) and ascorbic acid (Asc) on the number of DNA double-strand breaks (DSBs) in human gingiva fibroblasts (HGFs) were tested.

Methods

HGF was incubated with the (co)monomers bisphenol-A-glycidyl methacrylate (BisGMA), urethandimethacrylate (UDMA), ethylene glycol dimethacrylate (EGDMA) or 1,3-glyceroldimethacrylate (GDMA) with and without addition of antioxidants ACC and Asc. DNA-DSBs were determined using the γ-H2AX assay.

Results

Asc induced at 500 μM significant more DNA-DSBs in HGFs compared with controls (4.92 (1.28) vs. 1.62 (0.67); foci/cell mean (standard deviation), n = 3). Most DNA-DSBs were found after incubation of HGFs with 90 μM BisGMA (4.05 (0.56)) and 2720 μM EGDMA (5.36 (1.59)). The addition of 100 μM Asc or 500 μM ACC leaded to a statistical significant reduction of DNA-DSBs in HGFs for all tested (co)monomers. After incubation of HGFs with 2720 μM EGDMA and 500 μM ACC the foci/cell decrease from 5.36 (1.59) to 1.9 (1.17) (controls: 1.12 (0.24)). After incubation of HGFs with 90 μM BisGMA and 100 μM Asc the foci/cell decrease from 4.05 (0.56) to 1.96 (0.59) (controls: 1.12 (0.24)).

Significance

All tested (co)monomers can induce DNA-DSBs but addition of antioxidants (Asc or ACC) leads to reduction of DNA-DSBs.     

Determination of haloperidol in biological samples using molecular imprinted polymer nanoparticles followed by HPLC-DAD detection

In this study an extraction procedure using molecular imprinted polymer nanoparticles for the determination of haloperidol in biological samples is proposed. The haloperidol imprinted polymer nanoparticles were synthesized successfully by precipitation polymerization in a flask containing haloperidol as a template, ethyleneglycoldimethacrylate as a crosslinking agent, methacrylic acid as a functional monomer, and 2,2′-azobisisobutyronitrile as an initiator. The leached and unleached polymer nanoparticles have been characterized by infrared spectroscopy and scanning electron microscopy. The effect of different variables such as the pH of solution, uptake and elution time, type, and the least amount of eluent for elution of haloperidol from polymer was evaluated. Extraction efficiencies more than 97% were obtained by elution of the polymer with 1.5 mL of methanol–acetic acid–trifluoroacetic acid 79.9:20:0.1. Under optimal conditions maximum adsorption capacity was obtained 153.84 mg g⁻¹. The detection limit of the proposed procedure was between 0.2 and 0.35 μg L⁻¹. Finally this method was applied to the determination of haloperidol in plasma and urine samples and satisfactory results were achieved (RSD < 6.9%).     

Occupational methacrylate and acrylate allergy from glues

Background:  Glues and sealants are important causes of methacrylate and acrylate allergy.
Aim:  This study aimed to analyse patterns of allergic patch test reactions to acrylic monomers in relation to exposure in patients sensitized from glues.
Patients/Methods:  We screened the patch test files at the Finnish Institute of Occupational Health from 1994 to 2006 for allergic reactions in the 'Methacrylate series' and analysed the clinical records of sensitized patients. Only patients who had handled acrylic glues at work were included.
Results:  10 patients had allergic reactions to acrylic monomers and had been sensitized from glues at work. 9 of them had used anaerobic sealants, 3 cyanoacrylate-based instant adhesives, and 1 patient a bi-component instant adhesive. All the patients reacted to 2-hydroxyethyl methacrylate (2-HEMA) and ethyleneglycol dimethacrylate (EGDMA); reactions to 2-hydroxypropyl methacrylate, triethyleneglycol dimethacrylate, and tetrahydrofurfuryl methacrylate were also common. The first 4 methacrylates were found in the glues used by the patients. Ethyl cyanoacrylate (ECA) gave no reactions, but 1 patient reacted weakly to her own ECA-based glue.
Conclusion:  2-HEMA and EGDMA are good screeners for contact allergy to anaerobic sealants and also detected a single case deriving from bi-component acrylic glue.     

Biomonitoring of urinary metabolites of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) following human consumption of cooked chicken

Human risk assessment of exposure to 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) through the diet may be improved by conducting biomonitoring studies comparing metabolism in humans and rodents. Eleven volunteers ingested a meal of cooked chicken containing 4 -OH-PhIP and PhIP in amounts of 0.6 and 0.8mug/kg, respectively and urine was collected for the next 16h. The large number of PhIP metabolites was by treatment of the urine samples with hydrazine hydrate and hydrolytic enzymes reduced to three substances, 4'-OH-PhIP, PhIP and 5-OH-PhIP of which the first is a biomarker for detoxification and the last a biomarker for activation. The eleven volunteers eliminated large amounts of 4'-OH-PhIP in the urine. The majority of which could be accounted for by the presence of 4'-OH-PhIP in the fried chicken, showing that PhIP only to a small extent (11%) was metabolised to 4'-OH-PhIP. A larger fraction of the PhIP exposure, 38%, was recovered as PhIP and the largest fraction (51%) was recovered as 5-OH-PhIP suggesting that PhIP in humans to a large extent is metabolised to reactive substances. In rats, less than 1% of the dose of PhIP was eliminated as 5-OH-PhIP, suggesting that human cancer risk from exposure to PhIP is considerable higher than risk estimations based on extrapolation from rodent bioassays.     

Poly(hydroxyethyl methacrylate)-based co-polymeric hydrogels for transdermal delivery of salbutamol sulphate

Various co-polymeric hydrogels for transdermal delivery of salbutamol sulphate were synthesized using 2-hydroxyethyl methacrylate (HEMA), methacrylic acid (MAA) and N-[3-(dimethylamino)propyl]methacrylamide (DMAPMA) in the presence of ammonium persulphate (APS) and N,N,N′,N′-tetramethylethylenediamine (TEMED) as redox free radical initiator and ethyleneglycol dimethacrylate (EGDMA) as a cross-linker. The synthesized co-polymeric hydrogels were characterized using FT-IR spectral studies and swelling studies. It was observed that percentage swelling of co-polymeric hydrogel increased with the increasing concentration of DMAPMA and methacrylic acid. Salbutamol sulphate, a well-known vasodilator, was labeled with ^99mTc(technetium) and loaded on circular discs of various hydrogels. In vitro permeation of radiolabelled salbutamol sulphate was carried out using a Franz diffusion cell in phosphate-buffered saline (PBS, pH 7.4) as dissolution medium through mice skin. It was observed that drug release from the co-polymeric hydrogel carriers increased on increasing the amount of DMAPMA in the polymeric carriers, while it decreased on increasing the amount of MAA content. The local toxicity studies of DMAPMA-containing hydrogel patches were carried out in rabbits. Drug-loaded patches applied on rabbit skin showed no toxicity, even after 1 week of studies.     

Off into a thinning fog

Both non-swellable and swellable poly(EGDMA/HEMA) microbeads were produced by suspension copolymerization. These microbeads were modified by immobilization of a spacer-arm (hexamethylene diamine, HMDA) and fibronectin. The optimal values for modifications were as follows: the sodium periodate concentration 1.0 mg ml^-1; the HMDA concentration 4 mg ml^-1; and the glutaraldehyde concentration 0.070 μg ml^-1. Adsorption of fibronectin onto the plain and periodate-oxidized poly(EGDMA/HEMA) microbeads were very similar, and were 0.025-0.035 mg fibronectin per g polymer, respectively. Fibronectin immobilization on poly(EGDMA/HEMA) microbeads were studied at different temperature, time and pH using single protein solution containing different amount of proteins. The optimal values for immobilizations were as follows: the initial fibronectin concentration 0.1 mg ml; temperature + 25°C; pH 7; the immobilization time 120 min. Both fibroblastic 3T3 and epithelial MDBK cells were attached to these unmodified and modified microbeads. The attachments of both 3T3 and MDBK cells, especially to the fibronectin-immobilized swellable microbeads, were very high. Almost 96% of the 3T3 cells available in the cell culture medium did attach to these microbeads (2345 ± 98 cells per mg of polymer).     

Occupational allergic contact dermatitis from 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate in a modified acrylic structural adhesive

Acrylates have a broad area of application in various products including glues, sealants and adhesives. Whereas anaerobic acrylic sealants arc well-known sensitizers, acrylate glues that cure in air have only seldom been reported as allergens. Here a patient sensitized to such a glue, and developing hand dermatitis that spread to the lower arms, chest, neck and face, is presented. Her glue was analyzed by gas chroma tography/mass spectrometry (GC/MS) and contained 24,6% 2-hydroxyethyl methacrylate (2-HEMA) and 0.4% ethylene glyol dimethacrylate (EGDMA). These 2 acrylate compounds, as well as her glue, provoked an allergic patch test reaction. Also many other acrylate compounds, e.g., tetrahydrofurfuryl methacrylate, gave an allergic reaction indicating cross-allergy. The patient could not continue in her previous workplace because of severely-relapsing skin symptoms.