RÉSUMÉ
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.
Sujet(s)
Carbone/composition chimique , Techniques électrochimiques , Nanostructures/composition chimique , Téréphtalate polyéthylène/analyse , Polyvinyles/analyse , TempératureRÉSUMÉ
A new method for determining solubility lines of drugs in polymers, based on low-frequency Raman spectroscopy measurements, is described and the results obtained by this method are compared with those obtained using a more classical method based on differential scanning calorimetry investigations. This method was applied to the paracetamol/PVP system using molecular and crystalline dispersions (MCD) rather than usual physical mixtures to reach faster the equilibrium saturated states and make the determination of the solubility line more rapid.
Sujet(s)
Acétaminophène/analyse , Polyvinyles/analyse , Pyrrolidines/analyse , Analyse spectrale Raman/méthodes , Acétaminophène/composition chimique , Analgésiques non narcotiques/analyse , Analgésiques non narcotiques/composition chimique , Polyvinyles/composition chimique , Pyrrolidines/composition chimique , Solubilité , Diffraction des rayons X/méthodesRÉSUMÉ
"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.
Sujet(s)
Excipients/analyse , Réaction à corps étranger/diagnostic , Injections intradermiques , Spectroscopie infrarouge à transformée de Fourier/méthodes , Troubles liés à une substance/diagnostic , Adulte , Analgésiques morphiniques/administration et posologie , Analgésiques morphiniques/effets indésirables , Cellulose/effets indésirables , Cellulose/analyse , Excipients/effets indésirables , Femelle , Réaction à corps étranger/induit chimiquement , Humains , Oxycodone/administration et posologie , Oxycodone/effets indésirables , Polyvinyles/effets indésirables , Polyvinyles/analyse , Pyrrolidines/effets indésirables , Pyrrolidines/analyse , Maladies de la peau/induit chimiquement , Maladies de la peau/diagnostic , Troubles liés à une substance/anatomopathologieRÉSUMÉ
Objective: The aim of the study was to evaluate whether the compositions of the ethylene vinyl acetate (EVA) membrane of two different contraceptive vaginal rings could influence the surface roughness, which is associated with the possible accumulation of vaginal biomass on the rings during use.Methods: We measured and compared the surface roughness of unused vaginal rings, NuvaRing and Ornibel, using a scanning electron microscope (SEM) and dedicated software that can convert SEM images into 3D models. Average roughness (Ra), average quadratic roughness (Rq) and mean height of the irregularities at 10 points (Rz) were calculated.Results: Different thicknesses of the EVA membranes between the two rings were noted. No significant differences were found between the two rings in the three evaluated values of surface roughness (NuvaRing vs Ornibel, respectively: Ra, 1.53 ± 0.14 vs 1.61 ± 0.14 µm, p = 0.141; Rq, 2.03 ± 0.25 vs 2.07 ± 0.16 µm, p = 0.688; Rz, 11.4 ± 3.1 vs 11.4 ± 2.4 µm, p = 0.987).Conclusion: The different composition of the vaginal rings' EVA membrane is not associated with different surface roughness. Ornibel is equivalent to NuvaRing in terms of surface roughness, despite the different composition of the membrane polymers.
Sujet(s)
Dispositifs contraceptifs féminins , Polyvinyles/analyse , Propriétés de surface/effets des médicaments et des substances chimiques , Biomasse , Désogestrel/analogues et dérivés , Association médicamenteuse , Éthinyloestradiol , Femelle , Humains , Microscopie électronique à balayage , Vagin/composition chimique , Vagin/microbiologieRÉSUMÉ
This paper presents the abundance and ubiquitous presence of microplastics in a protected coastal zone located in the southeast of Spain: The Mar Menor lagoon, an important tourist destination in this region. Seventeen sampling sites, corresponding to both intertidal and backshore points, were collected during winter 2017 and 2018, being situated in different protected areas according to international, European and Spanish environmental policies. The main objectives of the study were to examine microplastics in both protected and non-protected areas, and to test the importance of local activities on their presence. Northwest samples reported higher average microplastic concentrations than samples collected in the southeastern part of the coastal lagoon, likely due to the extensive use of sludge from wastewater treatment plants besides the fragmentation of low density polyethylene from plastic greenhouses, being microplastic films also higher for northwest than for southeast samples. Moreover, large inter-site differences observed in microplastic concentrations also demonstrated that local activities, mainly tourism and fishery, may play an important role as microplastic sources. The extensive amount of 17 different polymer types identified in this paper, much higher than most reported in similar studies, together with the variety of colors of microplastics most of them in a fragmented form (59.4%) and mainly detected in urban beaches, should be related to the geographical situation of this coastal lagoon, together with enormous environmental passives accumulated over the past 50 years. Only polyvinyl ester resins proved to be statistically higher in non-protected than in protected zones, probably related to their use in manufacturing boat hulls, although sources and pathways for microplastics are always difficult to assess. Measures to avoid microplastic pollution should be taken through educational programs, with also a clear commitment from plastic producers and transformers.
Sujet(s)
Sédiments géologiques/composition chimique , Matières plastiques/analyse , Étangs/composition chimique , Polluants chimiques de l'eau/analyse , Surveillance de l'environnement , Matières plastiques/composition chimique , Matières plastiques/classification , Polyéthylène/analyse , Polyvinyles/analyse , Silice/analyse , Espagne , Polluants chimiques de l'eau/composition chimique , Polluants chimiques de l'eau/classificationRÉSUMÉ
This study aimed to investigate the effect of different polymers (polyethylene glycol 4000 and 6000 and Soluplus®) on the enhancement of solubility, dissolution, and stability of cefixime trihydrate as a selected class II model drug. Different solid dispersions have been prepared using conventional methods and supercritical fluid technology. The effect of co-solvent incorporation in supercritical fluid technology was also studied. Physicochemical properties for solid dispersions were investigated using Fourier transform infrared analysis, differential scanning calorimetry, thermogravimetric analysis, powder X-ray diffraction, and scanning electron microscopy. The solubility of the prepared solid dispersions increased except for those prepared with Soluplus® using supercritical fluid technology without co-solvent. The best enhancement in the release profile was recorded by Soluplus®-based solid dispersions prepared using a conventional method. The conventional methods of preparation and the presence of co-solvent in supercritical fluid technology converted cefixime into its amorphous form.
Sujet(s)
Antibactériens/composition chimique , Céfixime/composition chimique , Polyéthylène glycols/composition chimique , Polyvinyles/composition chimique , Antibactériens/analyse , Calorimétrie différentielle à balayage/méthodes , Céfixime/analyse , Chromatographie en phase supercritique/méthodes , Polyéthylène glycols/analyse , Polyvinyles/analyse , Solubilité , Spectroscopie infrarouge à transformée de Fourier/méthodes , Diffraction des rayons XRÉSUMÉ
OBJECTIVES: To assess the efficacy and effect on clinical signs of a polyvinylsiloxane (Tresident; Shütz Dental Group GmbH, Germany) compared with an irreversible hydrocolloid (Orthoprint; Zhermack SpA, Badia Polesine, Italy) for ocular impression-taking. METHODS: Twenty subjects were recruited (13 female and 7 male), with mean age 31.1±4.6 years (SD) (range 25.8-39.7). Subjects attended for 2 sessions, each of 1-hr duration, on 2 separate days. Each session was scheduled at the same time on each day. At each visit, the subject underwent an ocular impression procedure, using either Tresident or Orthoprint, in random order and to one eye only. Investigator 2 was blind to this assignment. Two experienced practitioners conducted the study, investigator 1 performed the ocular impression procedures and investigator 2 observed and assessed the clinical signs: logMAR visual acuity, ocular surface staining, tear break-up time (TBUT), and ocular hyperemia. RESULTS: Visual acuity was unaffected by either material; TBUT was marginally disrupted by both materials, but was not clinically significant according to published criteria; ocular redness increased with both materials; and corneal staining was significantly greater after Orthoprint impression. Less redness and clinically insignificant staining after impression-taking, with fewer clinical complications, was found after use of Tresident. CONCLUSIONS: Tresident offers a quicker, more effective, and clinically viable method of obtaining ocular impression topography compared with the traditional Orthoprint, and Orthoprint causes significantly more superficial punctuate staining of the corneal epithelium than Tresident.
Sujet(s)
Colloïdes/analyse , Conjonctive/composition chimique , Maladies de la conjonctive/diagnostic , Cornée/métabolisme , Élastomères/analyse , Polyvinyles/analyse , Siloxanes/analyse , Coloration et marquage/méthodes , Larmes/composition chimique , Adulte , Conjonctive/anatomopathologie , Maladies de la conjonctive/métabolisme , Cornée/anatomopathologie , Femelle , Études de suivi , Humains , Mâle , Méthode en simple aveugleRÉSUMÉ
The Fenton reaction as an oxidative degradation process was used for industrial chemical wastewater (ICW) pretreatment. The biodegradation of pretreated ICW was performed, in aqueous environment under aerobic condition, by a defined fungal consortium. The central composite design (CCD) was used to study the effect of nitrogen and phosphorus addition and the concentration of the pollution on the removal of polyvinyl alcohol (PVA) and organic compounds. The interaction between parameters was modeled using the response surface methodology (RSM). Results of optimization showed COD, PVA and color removal yields of 97.8%, 98.5% and 99.75%, respectively with a supplementof 1.4â¯gL-1 of (NH4)2SO4, 1.2â¯gL-1 of KH2PO4 and 75% of concentrated ICW. Enzymatic analysis proved that laccase and lignin peroxidase were involved in the biodegradation with 45 UIL-1 and 450 UIL-1, respectively. Furthermore, the analysis of metabolic products using Fourier transforms infrared spectroscopy (FTIR) and nuclear magnetic resonance (1HNMR) showed clearly the mineralization of organic compounds and the formation of formic acid and ethanol. Therefore, the effective treatment of ICW was achieved by developing an integrated chemical and biological process which met the requirement for a safety effluent respectful for environment without risks for public health.
Sujet(s)
Champignons/croissance et développement , Peroxyde d'hydrogène/composition chimique , Fer/composition chimique , Polyvinyles/analyse , Eaux usées/composition chimique , Polluants chimiques de l'eau/analyse , Purification de l'eau/méthodes , Aspergillus/croissance et développement , Dépollution biologique de l'environnement , Chaetomium/croissance et développement , Déchets industriels/analyse , Consortiums microbiens , Rhizopus/croissance et développementRÉSUMÉ
The objectives of this study were to explore sodium dodecyl sulfate (SDS) and Soluplus on the crystallization inhibition and dissolution of felodipine (FLDP) extrudates by bottom-up and top-down approaches. FLDP extrudates with Soluplus and SDS were prepared by hot melt extrusion, and characterized by polarized light microscopy, differential scanning calorimetry, and fourier transform infrared spectroscopy. Results indicated that Soluplus inhibited FLDP crystallization, and the whole amorphous solid dispersions (ASDs) were binary FLDP-Soluplus (1:3) and ternary FLDP-Soluplus-SDS (1:2:0.15â¼0.3 and 1:3:0.2â¼0.4) extrudates. Internal SDS (5%-10%) decreased glass transition temperatures of FLDP-Soluplus-SDS ternary ASDs without presenting molecular interactions with FLDP or Soluplus. The enhanced dissolution rate of binary or ternary Soluplus-rich ASDs in the nonsink condition of 0.05% SDS was achieved. Bottom-up approach indicated that Soluplus was a much stronger crystal inhibitor to the supersaturated FLDP in solutions than SDS. Top-down approach demonstrated that SDS enhanced the dissolution of Soluplus-rich ASDs via wettability and complexation with Soluplus to accelerate the medium uptake and erosion kinetics of extrudates, but induced FLDP recrystallization and resulted in incomplete dissolution of FLDP-rich extrudates. In conclusion, top-down approach is a promising strategy to explore the mechanisms of ASDs' dissolution, and small amount of SDS enhances the dissolution rate of polymer-rich ASDs in the nonsink condition.
Sujet(s)
Chimie pharmaceutique/méthodes , Félodipine/composition chimique , Polyéthylène glycols/composition chimique , Polyvinyles/composition chimique , Dodécyl-sulfate de sodium/composition chimique , Calorimétrie différentielle à balayage/méthodes , Cristallisation/méthodes , Félodipine/analyse , Félodipine/pharmacocinétique , Polyéthylène glycols/analyse , Polyéthylène glycols/pharmacocinétique , Polyvinyles/analyse , Polyvinyles/pharmacocinétique , Dodécyl-sulfate de sodium/analyse , Dodécyl-sulfate de sodium/pharmacocinétique , Solubilité , Spectroscopie infrarouge à transformée de Fourier/méthodesRÉSUMÉ
Most of scientific papers concern the qualitative or semi-quantitative analysis of aroma-active terpenes in liquid food matrices. Therefore, the procedure based on solid-phase microextraction and two-dimensional gas chromatography-time-of-flight mass spectrometry for determination of monoterpenes in fresh berries was developed. The optimal extraction conditions using divinylbenzene-carboxen-polydimethylsiloxane fiber were: temperature of 50°C, extraction time of 26min, equilibrium time of 29min. The developed procedure provides a high recovery (70.8-99.2%), good repeatability (CV<10.4%), high linearity (r>0.9915) and offers practical advantages over currently used methods: reliability of compounds identification, simplicity of extraction and at least one order of magnitude lower detection limits (0.10-0.011µg/L). The method was successfully applied to determine monoterpenes in 27 berry samples of different varieties and 4 berry products. Tukey's test revealed that monoterpenes content is a reliable indicator of fruit maturity and origin. It suggests that the method may be of interest to researchers and food industry.
Sujet(s)
Fruit/composition chimique , Chromatographie gazeuse-spectrométrie de masse/méthodes , Monoterpènes/analyse , Microextraction en phase solide/méthodes , Polydiméthylsiloxanes/analyse , Chromatographie gazeuse-spectrométrie de masse/normes , Polyvinyles/analyse , Reproductibilité des résultats , Microextraction en phase solide/normes , Température , Terpènes/analyseRÉSUMÉ
In a solid dispersion (SD), the drug is generally dispersed either molecularly or in the amorphous state in polymeric carriers, and the addition of a surfactant is often important to ensure drug release from such a system. The objective of this investigation was to screen systematically polymer-surfactant and polymer-drug-surfactant miscibility by using the film casting method. Miscibility of the crystalline solid surfactant, poloxamer 188, with two commonly used amorphous polymeric carriers, Soluplus® and HPMCAS, was first studied. Then, polymer-drug-surfactant miscibility was determined using itraconazole as the model drug, and ternary phase diagrams were constructed. The casted films were examined by DSC, PXRD and polarized light microscopy for any crystallization or phase separation of surfactant, drug or both in freshly prepared films and after exposure to 40°C/75% RH for 7, 14, and 30 days. The miscibility of poloxamer 188 with Soluplus® was <10% w/w, while its miscibility with HPMCAS was at least 30% w/w. Although itraconazole by itself was miscible with Soluplus® up to 40% w/w, the presence of poloxamer drastically reduced its miscibility to <10%. In contrast, poloxamer 188 had minimal impact on HPMCAS-itraconazole miscibility. For example, the phase diagram showed amorphous miscibility of HPMCAS, itraconazole, and poloxamer 188 at 54, 23, and 23% w/w, respectively, even after exposure to 40°C/75% RH for 1 month. Thus, a relatively simple and practical method of screening miscibility of different components and ultimately physical stability of SD is provided. The results also identify the HPMCAS-poloxamer 188 mixture as an optimal surface-active carrier system for SD.
Sujet(s)
Vecteurs de médicaments/pharmacocinétique , Itraconazole/pharmacocinétique , Poloxamère/pharmacocinétique , Polyéthylène glycols/pharmacocinétique , Polyvinyles/pharmacocinétique , Tensioactifs/pharmacocinétique , Vecteurs de médicaments/analyse , Itraconazole/analyse , Poloxamère/analyse , Polyéthylène glycols/analyse , Polymères/analyse , Polymères/pharmacocinétique , Polyvinyles/analyse , Solubilité , Tensioactifs/analyse , Diffraction des rayons XRÉSUMÉ
MAIN CONCLUSION: A mixture of resins based on aliphatic esters and carboxylic acids occurs in distantly related genera Peperomia and Roridula , serving different functions as adhesion in seed dispersal and prey capture. According to mechanical characteristics, adhesive secretions on both leaves of the carnivorous flypaper Roridula gorgonias and epizoochorous fruits of Peperomia polystachya were expected to be similar. The chemical analysis of these adhesives turned out to be challenging because of the limited available mass for analysis. Size exclusion chromatography and Fourier transform infrared spectroscopy were suitable methods for the identification of a mixture of compounds, most appropriately containing natural resins based on aliphatic esters and carboxylic acids. The IR spectra of the Peperomia and Roridula adhesive resemble each other; they correspond to that of a synthetic ethylene-vinyl acetate copolymer, but slightly differ from that of natural tree resins. Thus, the pressure sensitive adhesive properties of the plant adhesives are chemically proved. Such adhesives seem to appear independently in distantly related plant lineages, habitats, life forms, as well as plant organs, and serve different functions such as prey capture in Roridula and fruit dispersal in Peperomia. However, more detailed chemical analyses still remain challenging because of the small available volume of plant adhesive.
Sujet(s)
Adhésifs/composition chimique , Magnoliopsida/composition chimique , Peperomia/composition chimique , Polyvinyles/composition chimique , Adhésifs/analyse , Animaux , Chromatographie sur gel , Écosystème , Fruit/composition chimique , Fruit/physiologie , Insectes/physiologie , Magnoliopsida/classification , Magnoliopsida/physiologie , Peperomia/physiologie , Feuilles de plante/composition chimique , Feuilles de plante/physiologie , Phénomènes physiologiques des plantes , Polyvinyles/analyse , Dispersion des graines/physiologie , Spécificité d'espèce , Spectroscopie infrarouge à transformée de FourierRÉSUMÉ
An enzyme free glucose sensor was prepared by a molecular imprinting method (MIP). The procedure was developed by in situ preparation of a new polyvinyl acetate (PVA) electrode reinforced by MnO2/CuO loaded on graphene oxide (GO) nanoparticles (PVA/MnO2@GO/CuO). The nanocomposite was modified in the presence of glucose and then imprinted. A carbone paste method with voltammetry was used in the fabrication of the sensor from prepared MIP nanocomposite. PVA/MnO2@GO/CuO electrode was characterized by X-ray diffraction, FT-IR spectroscopy and scanning electron microscopy. Electrocatalytic activity of the electrode toward glucose oxidation was then investigated by cyclic voltammetry in alkaline medium. The results show that the response of PVA/MnO2@GO/CuO MIP is much higher than PVA/MnO2@GO/CuO non-imprinted electrode toward glucose oxidation. The detection limit was 53µM, and the sensor responses are linear for concentrations from 0.5 to 4.4mM. Relative standard deviations for intra- and inter-day determination were less than 6.0%. The relative recoveries for different samples were 96%.
Sujet(s)
Cuivre/composition chimique , Glucose/composition chimique , Composés du manganèse/composition chimique , Empreinte moléculaire/méthodes , Nanoparticules/composition chimique , Oxydes/composition chimique , Électrodes , Graphite/composition chimique , Oxydoréduction , Polyvinyles/analyseRÉSUMÉ
This study for the first time demonstrates combined application of mixture experimental design and artificial neural networks (ANNs) in the solid dispersions (SDs) development. Ternary carbamazepine-Soluplus®-poloxamer 188 SDs were prepared by solvent casting method to improve carbamazepine dissolution rate. The influence of the composition of prepared SDs on carbamazepine dissolution rate was evaluated using d-optimal mixture experimental design and multilayer perceptron ANNs. Physicochemical characterization proved the presence of the most stable carbamazepine polymorph III within the SD matrix. Ternary carbamazepine-Soluplus®-poloxamer 188 SDs significantly improved carbamazepine dissolution rate compared to pure drug. Models developed by ANNs and mixture experimental design well described the relationship between proportions of SD components and percentage of carbamazepine released after 10 (Q10) and 20 (Q20) min, wherein ANN model exhibit better predictability on test data set. Proportions of carbamazepine and poloxamer 188 exhibited the highest influence on carbamazepine release rate. The highest carbamazepine release rate was observed for SDs with the lowest proportions of carbamazepine and the highest proportions of poloxamer 188. ANNs and mixture experimental design can be used as powerful data modeling tools in the systematic development of SDs. Taking into account advantages and disadvantages of both techniques, their combined application should be encouraged.
Sujet(s)
Chimie pharmaceutique/méthodes , , Poloxamère/synthèse chimique , Polyéthylène glycols/synthèse chimique , Polyvinyles/synthèse chimique , Poloxamère/analyse , Polyéthylène glycols/analyse , Polyvinyles/analyse , Plan de rechercheRÉSUMÉ
The aim of the current study is to develop amorphous solid dispersion (SD) via hot melt extrusion technology to improve the solubility of a water-insoluble compound, felodipine (FEL). The solubility was dramatically increased by preparation of amorphous SDs via hot-melt extrusion with an amphiphilic polymer, Soluplus® (SOL). FEL was found to be miscible with SOL by calculating the solubility parameters. The solubility of FEL within SOL was determined to be in the range of 6.2-9.9% (w/w). Various techniques were applied to characterize the solid-state properties of the amorphous SDs. These included Fourier Transform Infrared Spectrometry spectroscopy and Raman spectroscopy to detect the formation of hydrogen bonding between the drug and the polymer. Scanning electron microscopy was performed to study the morphology of the SDs. Among all the hot-melt extrudates, FEL was found to be molecularly dispersed within the polymer matrix for the extrudates containing 10% drug, while few small crystals were detected in the 30 and 50% extrudates. In conclusion, solubility of FEL was enhanced while a homogeneous SD was achieved for 10% drug loading.
Sujet(s)
Chimie pharmaceutique/méthodes , Félodipine/composition chimique , Polyéthylène glycols/composition chimique , Polyvinyles/composition chimique , Félodipine/analyse , Polyéthylène glycols/analyse , Polyvinyles/analyseRÉSUMÉ
Vinyl acetate is polymerized in the living way under the irradiation of blue light-emitting diodes (LEDs) or sunlight without photocatalyst at ambient temperature. 2-(Ethoxycarbonothioyl)sulfanyl propanoate is exclusively added and acts as initiator and chain transfer agent simultaneously in the current system. Poly(vinyl acetate) with well-regulated molecular weight and narrow molecular weight distribution (D < 1.30) is synthesized. Near quantitative end group fidelity of polymer is demonstrated by nuclear magnetic resonance (NMR) and matrix-assisteed laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).
Sujet(s)
Lumière , Processus photochimiques , Polyvinyles/composition chimique , Polyvinyles/synthèse chimique , Polyvinyles/analyse , Spectrométrie de masse MALDI/méthodesRÉSUMÉ
OBJECTIVES: Vinyl polysiloxane (VPS) is elastomeric dental impression material which, despite having very few reports of adverse reactions, has shown high levels of cytotoxicity that is difficult to be interpreted without referencing to the positive control material. Therefore, in this study, positive control VPS was developed using sodium lauryl sulfate (SLS) for the reference of cytotoxicity test. MATERIALS AND METHODS: The positive control VPS with SLS was formed with a different proportion of SLS (0, 1, 2, 4, 8 and 16 wt%) added to the base. The cytotoxicity test was then carried out using the extractions or dilutions of the extractions from each of the test samples using murine fibroblast cells (L929). RESULTS: The final product of positive control VPS behaved similar to commercially available VPS; being initially liquid-like and then becoming rubber-like. Ion chromatography showed that the level of SLS released from the product increased as the proportion of added SLS increased, consequently resulting in an increased level of cytotoxicity. Also, the commercially available VPS was less cytotoxic than the positive control VPS with more or equal to 2 wt% of SLS. However, even the VPS with the highest SLS (16 wt%) did not cause oral mucosa irritation during the animal study. CONCLUSIONS: The positive control VPS was successfully produced using SLS, which will be useful in terms of providing references during in vitro cytotoxicity testing.
Sujet(s)
Matériaux empreinte dentaire/toxicité , Polyvinyles/toxicité , Siloxanes/toxicité , Dodécyl-sulfate de sodium/toxicité , Tensioactifs/toxicité , Animaux , Lignée cellulaire , Chromatographie d'échange d'ions , Cricetinae , Matériaux empreinte dentaire/analyse , Fibroblastes/effets des médicaments et des substances chimiques , Test de matériaux , Mesocricetus , Souris , Muqueuse de la bouche/effets des médicaments et des substances chimiques , Polyvinyles/analyse , Siloxanes/analyse , Dodécyl-sulfate de sodium/analyse , Sulfates/analyse , Tensioactifs/analyse , Facteurs tempsRÉSUMÉ
Soluplus, a graft copolymer of polyethylene glycol, vinyl caprolactam and vinyl acetate, is designed to solubilize poorly soluble active pharmaceutical ingredients. A straightforward aqueous gel permeation chromatography method that exploits both size exclusion and adsorption modes of separation was used to separate and quantify the related residual vinyl caprolactam monomer and caprolactam impurity present in Soluplus. This methodology offers a single step analysis of caprolactam and the residual vinyl caprolacatam monomer, yielding similar results to reversed-phase chromatography measurements, which are time-consuming and may involve multi-step sample preparation. The results of this study demonstrate that gel permeation chromatography provides a viable option to traditional reversed-phase chromatography in the quantitative analysis of residual caprolactam and vinyl caprolactam monomers and can be extended to other monomer-polymeric systems.
Sujet(s)
Azépan-2-one/isolement et purification , Polyéthylène glycols/analyse , Polyvinyles/analyse , Chromatographie sur gel , Chromatographie en phase liquide à haute performance , Limite de détection , Rapport signal-bruit , Solutions , Solvants/analyseRÉSUMÉ
Induction of chirality in achiral aggregates of an oligo(p-phenylenevinylene) has been used to detect the enantiomeric excess in acids used in the resolution of chiral compounds. The chiral acids which induce helicity in the aggregates are present at only 10% of the concentration of the chromophore, whose chiroptical activity can be detected using circular dichroism spectroscopy. An ee of 10% in mixtures of (+) and (-) acids has been clearly evidenced in a series of samples using only 1.5 µg and concentration of approximately 10 µM of the chiral compound. The composition of both carboxylic and phosphoric acid derivatives can be detected, thanks to their binding to the dimerised core ureidotriazine unit attached at one end of the oligo(p-phenylenevinylene) which induces a preferred twist in the aggregated aromatic rod. This chiral arrangement is reflected in the Cotton effects that the assemblies show. The sign of the induced dichroic signal can be affected by the substituents around a stereogenic centre of otherwise identical configuration, and can lead to ambidextrous assemblies as seen in Cotton effects at different positions for different acids. While this technique can be used to detect enantiomeric excess, screening of the pure enantiomers is wise prior to the use of the method to detect scalemic mixtures. This supramolecular approach to evaluation of chiral content in samples could also be applied to other types of aggregates based on achiral molecules which show sensitivity to molecular chiral inducers.
Sujet(s)
Acides carboxyliques/composition chimique , Acides phosphoriques/composition chimique , Polyvinyles/composition chimique , Dichroïsme circulaire , Dimérisation , Éphédrine/composition chimique , Liaison hydrogène , Structure moléculaire , Composés organiques du phosphore/composition chimique , Polyvinyles/analyse , Quinine/composition chimique , Stéréoisomérie , Triazines/composition chimiqueRÉSUMÉ
A direct immersion solid phase microextraction (DI-SPME) method was developed for the analysis of dentin monomers in saliva. Dentine monomers, such as triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA) and 2,2-bis-[4-(2-hydroxy-3-methacryloyloxypropoxy) phenyl]-propane (Bis-GMA), have a high molecular weight and a low vapor pressure. The polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber with a medium polarity was employed for DI-SPME, and 215 nm of detection wavelength was found to be optimum in the chromatogram of HPLC measurement. The calibration range for DI-SPME was 0.30-300 µg/mL with correlation coefficients (r) greater than 0.998 for each analyte. The DI-SPME method achieved good accuracy (recovery 96.1-101.2%) and precision (2.30-8.15% CV) for both intra- and inter-day assays of quality control samples for three target compounds. Method validation was performed on standards dissolved in blank saliva, and there was no significant difference (p>0.2) between the DI-SPME method and the liquid injection method. However, the detection limit of DI-SPME was as low as 0.03, 0.27 and 0.06 µg/mL for TEGDMA, UDMA and Bis-GMA, respectively. Real sample analyses were performed on commercial dentin products after curing for the leaching measurement. In summary, DI-SPME is a more sensitive method that requires less sample pretreatment procedures to measure the resin materials leached in saliva.