Xurography-Enabled Thermally Transferred Carbon Nanomaterial-Based Electrochemical Sensors on Polyethylene Terephthalate-Ethylene Vinyl Acetate Films.

A novel benchtop approach to fabricate xurography-enabled thermally transferred (XTT) carbon nanomaterial-based electrochemical sensors is proposed. Filtered nanomaterial (NM) films were transferred from Teflon filters to polyethylene terephthalate-ethylene vinyl acetate (PET-EVA) substrates by a temperature-driven approach. Customized PET-EVA components were xurographically patterned by a cutting plotter. The smart design of PET-EVA films enabled us to selectively transfer the nanomaterial to the exposed EVA side of the substrate. Hence, the substrate played an active role in selectively controlling where nanomaterial transfer occurred allowing us to design different working electrode geometries. Counter and reference electrodes were integrated by a stencil-printing approach, and the whole device was assembled by thermal lamination. To prove the versatility of the technology, XTT materials were exclusively made of carbon black (XTT-CB), multiwalled carbon nanotubes (XTT-MWCNTs), and single-walled carbon nanotubes (XTT-SWCNTs). Their electrochemical behavior was carefully studied and was found to be highly dependent on the amount and type of NM employed. XTT-SWCNTs were demonstrated to be the best-performing sensors, and they were employed for the determination of l-tyrosine (l-Tyr) in human plasma from tyrosinemia-diagnosed patients. High analytical performance toward l-Tyr (linear range of 0.5-100 µM, LOD = 0.1 µM), interelectrode precision (RSD ip,a = 3%, n = 10; RSD calibration slope = 4%, n = 3), and accurate l-Tyr quantification in plasma samples with low relative errors (≤7%) compared to the clinical declared values were obtained. The proposed benchtop approach is cost-effective and straightforward, does not require sophisticated facilities, and can be potentially employed to develop pure or hybrid nanomaterial-based electrodes.

Injection of oral medication into the skin confirmed by infrared spectroscopy.

"Skin popping" refers to the practice of injecting drugs, most commonly heroin, subcutaneously or into granulation tissue. Pharmaceutical tablets meant for oral consumption are modified into solutions for injection. Excipients-inactive substances that serve as vehicles for medication-are often not filtered out before injection and result in abscess formation, granulomatous inflammation, and scarring. Common excipients used in the production of pharmaceutical tablets include starch, microcrystalline cellulose, magnesium stearate, silica, and polyvinylpyrrolidone (PVP). Identification of these exogenous materials is valuable in confirming the diagnosis of skin popping, especially when patients may not be forthcoming about their drug use. We present a case of subcutaneous oral medication injection in which PVP and cellulose were identified by Fourier transform infrared spectroscopy. Considering the variable cutaneous manifestations of injection drug abuse, recognition of histopathologic and chemical characteristics of exogenous material from oral medications is helpful for diagnosis and intervention.

UPLC-Q-TOF-MS analysis of non-volatile migrants from new active packaging materials.

Ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry (MS) is a useful tool in the analysis of non-volatile compounds, and the use of a quadrupole-time-of-flight (Q-TOF) mass analyzer allows a high sensitivity and accuracy when acquiring full fragment mode, providing a high assurance of correct identification of unknown compounds. In this work, UPLC-Q-TOF-MS technology has been applied to the analysis of non-volatile migrants from new active packaging materials. The materials tested were based on polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH), and poly(ethylene terephthalate) (PET). The active packaging materials studied were one PP film containing a natural antioxidant, and two PP/EVOH films, two PET/EVOH films and one coextruded PP/EVOH/PP film containing natural antimicrobials. The chemical structure of several compounds was unequivocally identified. The analysis revealed the migration of some of the active substances used in the manufacture of active packaging, such as caffeine (0.07 ± 0.01 µg/g), carvacrol (0.31 ± 0.03 µg/g) and citral (0.20 ± 0.01 µg/g). Unintentionally added substances were also found, such as citral reaction compounds, or citral impurities present in the raw materials.

Evaluation of poly(ethylene-co-vinyl acetate-co-carbon monoxide) and polydimethylsiloxane for equilibrium sampling of polar organic contaminants in water.

The aim of the present study was to develop a passive absorptive equilibrium sampler that would enable the determination of the concentrations of polar organic compound (POC) in water more efficiently than existing techniques. To this end, a novel plastic material, poly(ethylene-co-vinyl acetate-co-carbon monoxide) (PEVAC), was evaluated and the results were compared with an existing silicone-based passive absorptive equilibrium device. Seven compounds (imidacloprid, carbendazim, metoprolol, atrazin, carbamazepine, diazinon, and chlorpyrifos), a mixture of pharmaceuticals, and pesticides with a logarithmic octanol-water partition coefficient ranging from 0.2 to 4.77 were selected as model substances for the experiments. The results showed that six of the seven selected POCs reached distribution equilibrium within 4 d in the two materials tested. A linear relation with a regression coefficient of more than 0.8906 between the established logarithmic absorbent-water partition coefficient and the calculated logarithmic dissociation partition coefficient of the selected compounds in the two polymers was observed. The correlation between these two coefficients was within one order of magnitude for the compounds that reached equilibrium in the two polymers, which demonstrates that both materials are suitable for mimicking biological uptake of POCs. The PEVAC material showed an enhanced sorption for all selected compounds compared to the silicone material and up to five times higher enrichment for the most polar compound. Fluorescence analysis of the sampler cross-section, following the uptake of fluoranthene, and proof that the sorption was independent of surface area variations demonstrated that the PEVAC polymer possessed absorptive rather than adsorptive enrichment of organic compounds.

Estudo da ação da saliva nas propriedades mecânicas de protetores bucais para esporte / Study on the effect of saliva on the mechanical properties of mouth protectors for sports

Introdução - A eficiência e a durabilidade de protetores bucais para esporte dependem diretamente da forma com que são usados, pois sempre se apresentam em condições básicas de presença ou ausência de saliva. Para observar se essa condição de uso interfere em suas propriedades mecânicas este trabalho observa através de modelo experimental de arcos dentais obtidos em epóxi, acoplados a uma máquina universal de ensaios Kratos programada para movimento de compressão, o comportamento mecânico de protetores bucais para esporte, confeccionados -m copolímero de etileno e acetato de vinila ? EVA, posicionados no arco superior. Material e Métodos - Foram formados dois grupos de estudo: protetores bucais secos e protetores bucais saturados em saliva artificial, sendo estes últimos obtidos através de análise de saturação com o auxilio de balança analítica para observação de ganho de massa. As propriedades mecânicas observadasforam força máxima e energia absorvida. Resultados - Os resultados foram submetidos a analise estatística t-student (p < 0,05). Observou-se que no grupo dos protetores bucais saturados com saliva houve redução da força máxima (p = 0,00) devido a plastificação do material, responsável pela redução das forças intermoleculares ocasionando maior deformabilidade do protetor atestado pelo aumento da energia absorvida (p = 0,05) quando comparado ao grupo dos protetores secos. Conclusão - Conclui-se que a presença da saliva altera o comportamento mecânico do protetor bucal confeccionado em EVA tornando-o mais dúctil, portanto diminuindo a probabilidadede fraturas dentais e/ou lesões em tecidos circunvizinhos.

Introduction - The efficiency and durability of mouth protectors for sports depend directly on the way they are used, mainly because of their frequent exposure to saliva. To analise if this condition of use affects their mechanical properties, this paper observes, through the use of an experimental model made of epoxy, connected to an universal testing machine Kratos programmed to compress, the mechanical behaviour of mouth protectors for sports, made of ethylene and vinyl acetate copolymer - EVA, positioned on the superior arch. Two groups of study were created: dry mouth protectors and artificial saliva saturated mouth protectors, the second of which was analised with the use of an analitical balance to measure the level of saturation through the gain of mass.The mechanical properties observed were maximal strength and absorbed energy. The results were submitted to t-student statistical analisis method (p < 0,05). It was observed that, in the saturated mouth protectors group, the maximal strength diminished (p = 0,00) due to the material plastification, that caused a reduction in the intermolecular force and consequently a bigger deformation of the protector, confirmed by the increase in the absorbed energy (p = 0,05) when compared to the dry protectors group. It was concluded that the presence of saliva changes the mechanical behaviour of the mouth protector made of EVA, making it more flexible and reducing the probability of dental fractures and/or injuries on adjacent tissues.

Allergic contact dermatitis to copolymers in cosmetics--case report and review of the literature.

Copolymers or heteropolymers are large molecules with high molecular weights (>1000 D). They have been underestimated for a long time as to their sensitizing capacities. Allergic contact dermatitis to 6 copolymers in cosmetics and 1 in a medical dressing has been described; however, the nature of the hapten is still unknown. We report a case of allergic contact dermatitis to polyvinylpyrrolidone (PVP)/hexadecene copolymer in a purple-colored lipstick and review the literature on allergic contact dermatitis to 7 copolymers: PVP/hexadecene, PVP/eicosene, PVP/1-triacontene, methoxy polyethyleneglycol (PEG)-22/dodecyl glycols, methoxy PEG-17/dodecyl glycols, phthalic anhydride/trimellitic anhydride/glycols, and polyvinyl methyl/maleic acid anhydride.

Multidimensional chromatographic techniques for hydrophilic copolymers II. Analysis of poly(ethylene glycol)-poly(vinyl acetate) graft copolymers.

A large variety of hydrophilic copolymers is applied in different fields of chemical industry including bio, pharma and pharmaceutical applications. For example, poly(ethylene glycol)-poly(vinyl alcohol) graft copolymers that are used as tablet coatings are responsible for the controlled release of the active compounds. These copolymers are produced by grafting of vinyl acetate onto polyethylene glycol (PEG) and subsequent hydrolysis of the poly(ethylene glycol)-poly(vinyl acetate) graft copolymers. The poly(ethylene glycol)-poly(vinyl acetate) copolymers are distributed with regard to molar mass and chemical composition. In addition, they frequently contain the homopolymers polyethylene glycol and polyvinyl acetate. The comprehensive analysis of such complex systems requires hyphenated analytical techniques, including two-dimensional liquid chromatography and combined LC and nuclear magnetic resonance spectroscopy. The development and application of these techniques are discussed in the present paper.

Calibration models for the vinyl acetate concentration in ethylene-vinyl acetate copolymers and its on-line monitoring by near-infrared spectroscopy and chemometrics: use of band shifts associated with variations in the vinyl acetate concentration to improve the models.

The present study investigates calibration models for the vinyl acetate (VA) concentration in ethylene-vinyl acetate (EVA) copolymers and its on-line monitoring by near-infrared (NIR) spectroscopy and chemometrics. The key point in the present study is to make use of band shifts associated with concentration changes in the vinyl acetate (VA) for the improvement of the models. NIR spectra of EVA in melt and solid states were measured by a Fourier transform near-infrared (FT-NIR) on-line monitoring system and a FT-NIR laboratory system. Some of the bands in the NIR spectra for both states show significant shifts with the variations in the VA concentration. The peak shifts induced by the VA concentration changes are larger in the solid-state EVA than those in the melt-state EVA. We have developed calibration models for the VA concentration in the solid-state EVA and investigated how to improve the calibration models. The factor analysis of partial least squares (PLS) regression has suggested that the wavenumber shifts caused by the VA concentration changes affect the calibration models for the VA concentration in EVA. From the analysis, it has been proposed that the wavenumbers in the spectrum of one sample in nine EVA samples (VA concentration range: 0-41.1%) are shifted for the improvement of the calibration models, and the effects of the proposed method have been confirmed by using the PLS calibration models for the VA concentration in the solid EVA samples. As the next step, the effects of the wavenumber shift method have been explored for the calibration models for the VA concentration in the melt-state EVA. After that, the discrimination method using the score plots of PLS and the application sequence for the on-line monitoring to use the proposed wavenumber shift method were studied. The simulation results using the discrimination and wavenumber shift methods have shown that those methods are very effective to improve the predicted values of the calibration models for the on-line monitoring of the VA concentration in the melt-state EVA.

Drug release from cast films of ethylene vinyl acetate (EVA) copolymer: Stability of drugs by 1H NMR and solid state 13C CP/MAS NMR.

The study utilizes an oral biocompatible material based on ethylene vinyl acetate copolymer (EVA) designed to release drugs in vitro at therapeutic levels over several days. We examined the drug stability during film casting process using proton and solid state NMR techniques. The drug-loaded EVA films were prepared from the dry sheet obtained by solvent (dichloromethane) evaporation of polymer casting solutions. Drugs tested include chlorhexidine diacetate (CDA), doxycycline hydrochloride (DOH), tetracycline hydrochloride (TTH) and nystatin (NST). Drug release from the films was examined for at least 14 days in 10 ml ddH2O (NST in water/ethanol (4:1)) which was replaced daily. Changes in optical density were followed spectraphotometrically. Effect of temperature on rate measurements was studied and the energies of activation (E*) were calculated using Arrhenius plots. Effect of EVA copolymer composition on CDA release rate was also investigated. The enhanced rates with temperature increase may be attributed to the formation of channels with increased geometry in the polymer. The highest E* observed for CDA compared to DOH and TTH may be related to their average molecular weights. Spectral analyses for CDA and NST revealed that the chemical and physical structures of the drugs remained unaffected during the film casting process.

Novel composite poly(4-vinylpyridine)/polypropylene membranes with recognition properties for (S)-naproxen.

In the last few years, molecular imprinting technology has entered in different fields of chemistry, biochemistry, biotechnology and medicine. The technique allows us to introduce the molecular memory of the substrate to be recognized in a polymeric material during its preparation. In the present paper, molecularly imprinted enantioselective polymer membranes were prepared by photo-copolymerization of commercial polypropylene membranes with the functional monomer 4-vinylpyridine. The (S)-naproxen was used as a template molecule. Enantioselectivity studies in a dead-end filtration system showed the recognition properties of the imprinted membranes, which exhibited a selective transport of the (S)-enantiomer.

Highly stretched single polymers: atomic-force-microscope experiments versus ab-initio theory.

Experimental single-molecule stretching curves for three backbone architectures (single-stranded DNA, various types of peptides, polyvinylamine) are quantitatively compared with corresponding quantum-chemical (zero-temperature) ab-initio calculations in the high-force range of up to two nanonewtons. For high forces, quantitative agreement is obtained with the contour length of the polymers as the only fitting parameter. For smaller forces, the effects of chain fluctuations are accounted for by using recent theoretical results for the stretching response of a freely-rotating-chain model.

Solid-phase extraction of L-muscone from aqueous samples with Amberlite XAD-4 for gas chromatographic assay.

An efficient analytical method was devised for the accurate L-muscone assay in aqueous samples. It involves solid-phase extraction of L-muscone in adsorption mode using XAD-4 as the sorbent and dichloromethane modified with 10% (v/v) methanol as the eluting solvent. The gas chromatographic analysis of the eluate residue dissolved in toluene on a DB-5MS capillary column provided complete resolution of L-muscone from the co-extracted interferences. The overall method showed excellent linearity (r2 > or = 0.9994) in the range of 0.1 to 2.0 microg/mL with good intra- and inter-day precisions (% RSD = 2.5 to approximately 7.3) and with high extraction recovery rates (> or = 98.1%). When the present method was applied to a L-muscone herbal drink product, the within-batch RE (%) in the labeled concentration (1.5 microg/mL) for the three randomly chosen bottles were -2.4, -1.3 and -3.3 with high precision (% RSD < or = 3.1). The present method is considered to be suitable for quality control evaluation on liquid drinks and other complex formulations fortified with L-muscone.

Combination of SEC/MALS experimental procedures and theoretical analysis for studying the solution properties of macromolecules.

Size-exclusion chromatography (SEC) with dual detection, i.e., employing refractive index (RI) and multiangle light-scattering (MALS) detectors, has been applied to study the solution properties of two very different polymer-solvent systems at 25 degrees C: poly(N-vinylcarbazole) (PVCz) in an organic solvent THF that is a very good solvent and a system under theta conditions that is formed by polyvinylpyrrolidone (PVP) in water containing a 0.1 M concentration of NaNO(3). In both cases, the analysis of a single highly polydisperse sample obtained by free radical polymerization is enough for obtaining molecular weight and radius of gyration calibration curves, molecular weight distributions (MWD) (and thus, molecular weight averages), molecular dimensions, scaling laws coefficients and unperturbed dimensions. Extrapolation to theta conditions produces values of the characteristic ratio of the unperturbed dimensions C(n)=(o)/nl(2)=15.9 and 14, respectively, for PVCz and PVP. Unperturbed dimensions are also theoretically calculated with different models such as Kuhn equivalent chain, worm-like chain and rotational isomeric states model. Conformational parameters required for this last model were taken from the literature in the case of PVCz; however, they are calculated by molecular dynamics simulations in the case of PVP. Theoretical values obtained with the RIS model are in good agreement with the experimental results.

Drebrin is a widespread actin-associating protein enriched at junctional plaques, defining a specific microfilament anchorage system in polar epithelial cells.

Using immunoblotting, immunprecipitation with subsequent fragment mass spectrometry, and immunolocalization techniques, we have detected the actin-binding ca. 120-kDa protein drebrin, originally identified in - and thought to be specific for - neuronal cells, in diverse kinds of human and bovine non-neuronal cells. Drebrin has been found in numerous cell culture lines and in many tissues of epithelial, endothelial, smooth muscle and neural origin but not in, for example, cardiac, skeletal and certain types of smooth muscle cells, in hepatocytes and in the human epithelium-derived cell culture line A-431. By double-label fluorescence microscopy we have found drebrin enriched in actin microfilament bundles associated with plaques of cell-cell contact sites representing adhering junctions. These drebrin-positive, adhering junction-associated bundles, however, are not identical with the vinculin-containing, junction-attached bundles, and in the same cell both subtypes of microfilament-anchoring plaques are readily distinguished by immunolocalization comparing drebrin and vinculin. The intracellular distribution of the drebrin- and the vinculin-based microfilament systems has been studied in detail by confocal fluorescence laser scanning microscopy in monolayers of the polar epithelial cell lines, MCF-7 and PLC, and drebrin has been found to be totally and selectively absent in the notoriously vinculin-rich focal adhesions. The occurrence and the possible functions of drebrin in non-neuronal cells, notably epithelial cells, and the significance of the existence of two different actin-anchoring junctional plaques is discussed.

The clinical, histologic, and ultrastructural presentation of polyvinyl sponge (Ivalon) breast prostheses removed for massive fluid accumulation.

The current study describes what we believe is the first report of bilateral massive seromas associated with open-cell Ivalon sponges. Additionally, the gross, histologic, and ultrastructural features consistent with previous reports of polyvinyl alcohol prostheses are presented. Despite the reported chemical inertness of polyvinyl alcohol, this material may incite a biologic response in some patients, leading to dense fibrosis and occasional foreign-body giant-cell reaction. It is postulated that the molecular breakdown products of the polyvinyl alcohol polymer may create an osmotic gradient across the periprosthetic capsule, which may lead to intracapsular fluid accumulation, as presented in this case.

Influence of physicochemical and biological parameters on drug release from microspheres adhered on vesical and intestinal mucosa.

The object of our work is to develop mucoadhesive microspheres to be applied into the urinary bladder. In the present study the microspheres were prepared and the release of a model drug after their adhesion to mucosa was evaluated. The microspheres were prepared by solvent evaporation method using Eudragit RL or hydroxypropylcellulose as matrix polymers and one out of five different polymers as mucoadhesives or non-mucoadhesive references. A method for the evaluation of the drug release from microspheres adhered on guinea pig urinary bladder and small intestine mucosa was developed and the influence of the following parameters on this process was followed: mucoadhesion strength of polymeric films, swelling of polymers and the drug release from microspheres. The results showed that the detachment forces were decreasing in the following order: CMCNa > Carbopol 934P > HPC > EE.HCl = PVP/VA. Carbopol swelled to the largest volume among all polymers and the drug release from microspheres was more retarded when Eudragit RL was used as matrix polymer. When comparing the results of pipemidic acid release from microspheres adhered on intestinal mucosa with detachment forces, similar ratios among the mucoadhesive polymers can be seen. On the other hand, differences between two mucosae were observed. These differences are due to the amount of mucus on mucosa and might also be influenced by the charge of mucus. The goal of our work at this point of investigation was achieved by microspheres containing carboxymethylcellulose as mucoadhesive and Eudragit RL as matrix polymer because they provide the longest release time from microspheres adhered on vesical mucosa and sufficient high strength of mucoadhesion.

Anaesthetic uptake and washout characteristics of patient circuit tubing with special regard to current decontamination techniques.

The amounts of halothane and isoflurane trapped after exposure for up to 3 h at 2 MAC in commonly used anaesthesia circuit tubing were quantitated by gas chromatography. The decontaminating effects of procedures such as flushing with oxygen, thermal disinfection and/or routine storage were assessed in a similar way. After halothane exposure, anaesthetic content was highest in silicone (398 +/- 55 mg 100 g-1). Lower quantities were found in all other tubings investigated (electrically conductive latex: 64 +/- 4, conductive rubber: 62 +/- 4, polyethylene-vinyl-acetate (PEVA): 293 +/- 10 and 149 +/- 17 for non-conductive corrugated and spiral tubes, respectively, polysulfone (Hytrel): 155 +/- 10 mg 100 g-1). The isoflurane contents were substantially lower (silicone: 278 +/- 23; others: 55 +/- 7, 61 +/- 6, 163 +/- 9 and 86 +/- 8, 74 +/- 4 mg 100 g-1). The tubings' content did not correlate with the material's partition coefficient as full saturation was not achieved during exposure. Decontamination procedures reduced the content of volatile anaesthetics to a variable extent. Conductive latex and rubber showed the highest residual content, even after thermal disinfection and subsequent storage. Twenty-minute flushing with oxygen (8 l min-1) decreased effluent gas concentrations below 5 p.p.m. in all tubings. With silicone, after 1 h flushing, halothane concentrations still exceeded 10 p.p.m. (isoflurane: 8 p.p.m.). It is concluded that urgent decontamination by a 20-min flush warrants the safe re-use of previously 'contaminated' conductive rubber and latex as well as polysulfone tubings in critical situations, e.g. in malignant hyperthermia patients if disposable tubing is not immediately available.(ABSTRACT TRUNCATED AT 250 WORDS)

The migration of tobacco-specific nitrosamines into the saliva of chewers of nicotine-containing chewing gum.

In many countries nicotine-containing chewing gum (Nicorette) is used to help to break the habit of smoking. Saliva was collected every 5 min from chewers of nicotine chewing gum and analysed for tobacco-specific nitrosamines. Detectable levels of tobacco-specific nitrosamines were found in all samples collected between 5 and 15 min after chewing had started. The levels of N'-nitrosonornicotine ranged from 0.4 to 19 ng/g of saliva and those for the sum of N'-nitrosoanatabine plus N'-nitrosoanabasine from 1.3 to 46 ng/g. 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone was not detected in the saliva. The nicotine chewing gum was found to contain up to 380 ng tobacco-specific nitrosamines/g of chewing gum.

[Determination of dibutyltin compounds in polyvinyl chloride resin by capillary gas chromatography].

Dibutyltin compounds (DBTC) in polyvinyl chloride resin (PVC) were examined by capillary gas chromatography using a flame photometric detector (FPD). DBTC was extracted with a carbon tetrachloride-methanol (2:1) mixture under reflux. The extract was mixed with a hydrobromic acid solution. Dibutyltin dibromide was converted to dibutyldipentyltin (DBDPeT) by the Grignard reaction with pentylmagnessium bromide and then subjected to gas chromatography. A linear correlation between the amount of tin and peak height was observed in the range of 7.8 to 250 pg of tin on log-log paper. Recoveries of DBTC added to PVC were 92.6-108.1%. The results show that this procedure is more useful and sensitive (the detection limit is 3-4 pg, as tin) than previous methods reported.