RESUMEN
Restricted access molecularly imprinted polymers (RAMIPs) are hybrid materials that present selective binding sites for a template (or similar molecules), and an external hydrophilic layer that avoids the binding of proteins to the material, making them appropriate for the sample preparation of protein fluids. RAMIPs have been used successfully in online and offline solid phase extractions, but there is no application as a fiber in solid phase microextraction (SPME), to the best of our knowledge. In this paper, molecularly imprinted fibers were synthesized inside glass capillary tubes (0.53 mm i.d.), using diazepam and methacrylic acid as template and functional monomer, respectively. The MIP fibers were coated with a cross-linked bovine serum albumin (BSA) layer, resulting in RAMIP fibers that were used in the SPME of benzodiazepines directly from biological fluids. The BSA layer acts as a protective barrier that avoids the binding of proteins from the sample by an electrostatic repulsion mechanism. The protein exclusion capacity of the RAMIP fiber was about 98%, which is selective to benzodiazepines in comparison with other drugs (citalopram and fluoxetine). The SPME was optimized and the extraction conditions were set as follows: 1000 µL of the sample diluted with water (1 : 0.5, v : v), no pH adjustment, an extraction time of 20 min at 500 rpm, and elution with 200 µL of acetonitrile for 5 min at 500 rpm. The fibers were used in the SPME of benzodiazepines directly from plasma samples, followed by HPLC-DAD analyses. The method was linear for bromazepam (50-750 µg L-1), clonazepam (15-250 µg L-1), alprazolam (15-350 µg L-1), nordiazepam (100-2100 µg L-1) and diazepam (100-2600 µg L-1), with correlation coefficients higher than 0.97. Relative standard deviations (precision) and relative errors (accuracy) ranged from 0.5 to 20.0%, and -15.6 to 21.6%, respectively.
Asunto(s)
Benzodiazepinas/sangre , Ácidos Polimetacrílicos/química , Adsorción , Animales , Benzodiazepinas/química , Bovinos , Diazepam/química , Humanos , Cinética , Metacrilatos/química , Impresión Molecular/métodos , Ácidos Polimetacrílicos/síntesis química , Prueba de Estudio Conceptual , Albúmina Sérica Bovina/química , Microextracción en Fase Sólida/instrumentación , Microextracción en Fase Sólida/métodosRESUMEN
Medical cotton gauzes were modified by grafting poly(methacrylic acid) (PMAA) via free radical polymerization to obtain wound dressings with antimicrobial and drug delivery properties. The effect of several reaction parameters including monomer and initiator concentrations, reaction time, and temperature was studied. The grafting was confirmed by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), swelling studies, and scanning electron microscopy (SEM). The grafted cotton gauzes (gauze-g-PMAA) samples were loaded with ZnO nanoparticles to endow with antibacterial properties. Also, they were tested as drug eluting systems using nalidixic acid as antimicrobial agent. The antibacterial activity of the ZnO-loaded gauze-g-PMAA samples was evaluated against Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis). The PMAA-grafted gauzes showed antibacterial activity and inhibited the growth of both microorganisms. These results suggest that the PMAA-grafted cotton gauzes could be used in the biomedical area particularly as antimicrobial and drug-eluting wound dressings.
Asunto(s)
Antibacterianos/química , Vendajes , Celulosa/química , Fibra de Algodón , Sistemas de Liberación de Medicamentos , Ácidos Polimetacrílicos/química , Celulosa/síntesis química , Liberación de Fármacos , Escherichia coli/efectos de los fármacos , Ácido Nalidíxico/química , Ácido Nalidíxico/farmacología , Nanopartículas/química , Polimerizacion , Ácidos Polimetacrílicos/síntesis química , Staphylococcus epidermidis/efectos de los fármacos , Óxido de Zinc/química , Óxido de Zinc/farmacologíaRESUMEN
A molecularly imprinted polymer was developed and evaluated for selective determination of metronidazole (MNZ) in wastewater. This was achieved by using sodium methacrylate as monomer, toluene as porogen, ethylene glycol dimethacrylate as crosslinker, azobisisobutyronitrile as initiator and metronidazole as template molecule to generate the selectivity of the polymer for the compound, as well as non-imprinted polymers were synthesized. Two different polymerization approaches were used, bulk and emulsion and the polymers obtained by emulsion presented higher retention percentages the MIP 2-M presented the higher retention (83%). The performed method, was validated in fortified water, showing linearity from 10 up to 1000 ng/mL; limit of detection and quantification for compound were between 3 and 10 ng/mL, respectively. Finally, the method was applied in samples of a wastewater treatment plant in the city of San Luis Potosí, México, and the concentrations of MNZ in these samples were 84.1-114 ng/mL.
Asunto(s)
Metronidazol/análisis , Impresión Molecular/métodos , Ácidos Polimetacrílicos/síntesis química , Aguas Residuales/química , Contaminantes Químicos del Agua/análisis , Adsorción , Límite de Detección , Metacrilatos/química , México , Nitrilos/química , Ácidos Polimetacrílicos/química , Propiedades de Superficie , Tolueno/químicaRESUMEN
Molecularly imprinted polymer nanoparticles (MIPNPs) with the ability to recognize coenzyme Q10 (CoQ10) were synthesised in order to be employed as sorbent in a dispersive micro-solid phase extraction (DMSPE) for the determination of CoQ10 in a liver extract. CoQ10 is a redox-active, lipophilic substance integrated in the mitochondrial respiratory chain which acts as an electron carrier, shuttling electrons from complex I (NADH-ubiquinone oxidoreductase) and II (succinate-ubiquinone oxidoreductase) to complex III (ubiquinol-cytochrome c reductase), for the production of cellular energy. The MIPNPs were synthesised by precipitation polymerization using coenzyme Q0 as the dummy template, methacrylic acid as the functional monomer, an acetonitrile: water mixture as the porogen, ethylene glycol dimethacrylate as the crosslinker and potassium persulfate as initiator. The nanoparticles were characterized by microscopy, capillary electrophoresis, dynamic light scattering, N2 adsorption-desorption isotherms, and infrared spectroscopy. The MIPNPs demonstrated the presence of selective cavities complementary to the quinone nucleus of CoQ10, leading to a specific recognition of CoQ10 compared with related compounds. In the liver extract the relative CoQ10 peak area (CoQ10 area/total peak area) increased from 4.6% to 25.4% after the DMSPE procedure. The recovery percentage of CoQ10 from the liver matrix was between 70.5% and 83.7% quantified against CoQ10 standard processed under the same conditions. The DMSPE procedure allows the elution of almost all the CoQ10 retained (99.4%) in a small volume (200µL), allowing the sample to be concentrated 2.5 times (LOD: 1.1µgg(-1) and LOQ: 3.7µgg(-1) of tissue). The resulted clean up of the sample, the improvement in peak shape and baseline and the reduction of interferences, evidence that the MIPNPs could potentially be applied as sorbent in a DMSPE with satisfactory results and with a minimum amount of sorbent (1mg).
Asunto(s)
Reactivos de Enlaces Cruzados/química , Metacrilatos/química , Ácidos Polimetacrílicos/química , Extracción en Fase Sólida/métodos , Ubiquinona/análogos & derivados , Adsorción , Animales , Bovinos , Hígado/química , Impresión Molecular , Nanopartículas , Polimerizacion , Ácidos Polimetacrílicos/síntesis química , Ubiquinona/química , Ubiquinona/aislamiento & purificaciónRESUMEN
This work reports the synthesis and characterization of a new material obtained by mixing the hybrid natural-synthetic chitosan-g-glycidyl methacrylate (CTS-g-GMA) biopolymer and xanthan gum (X). All materials were characterized by infrared spectroscopy (FTIR), X-ray diffraction, and thermal analysis (DSC and TGA) and the results were contrasted with those of the precursor materials. The swelling index of the hydrogels decreases when the GMA mass percentage increases. The X-ray diffraction patterns show that the hybrid hydrogels are amorphous in contrast to chitosan (CTS), which is semi-crystalline. FTIR analysis confirms the existence of physical interactions among constituents. Rheological properties, η, G', and G", were determined as a function of flow allowing one to conclude that (CTS-g-GMA)-X behaves as physical hydrogel. Additionally, we report viability of fibroblasts when cultured onto the synthesized hydrogels. This study shows that these hydrogels support cell viability and have potential for use in biomedical engineering applications.
Asunto(s)
Quitosano/química , Compuestos Epoxi/química , Metacrilatos/química , Ácidos Polimetacrílicos/síntesis química , Polisacáridos Bacterianos/química , Polisacáridos Bacterianos/síntesis química , Rastreo Diferencial de Calorimetría , Quitosano/síntesis química , Compuestos Epoxi/síntesis química , Fibroblastos/efectos de los fármacos , Humanos , Hidrogeles , Metacrilatos/síntesis química , Ácidos Polimetacrílicos/química , Ácidos Polimetacrílicos/farmacología , Polisacáridos Bacterianos/farmacología , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos XRESUMEN
The ethyl-4-dimethylaminobenzoate (EDAB) is widely used as a coinitiator of the camphorquinone (CQ), but in acidic circumstances it might present some instability, reducing the polymerization efficiency of the material. Considering this, new coinitiators are being evaluated. Hence, this study evaluated the kinetic of polymerization (KP), the degree of conversion (DC), and the rate of polymerization (RP ) of experimental resin adhesives containing 1,3-diethyl-2-thiobarbituric acid (TBA) as a coinitiator of the CQ. The experimental monomeric blend was prepared with bisphenol A glycidyl dimethacrylate, 2-hydroxyethyl methacrylate, and acidic monomers. CQ was added at 1 mol % as photoinitiator. Six groups were formulated: four containing concentrations of 0.1, 0.5, 1, and 2 mol % of TBA, one without coinitiator, and the last one containing 1 mol % of EDAB (control group). The KP and the RP were performed using real-time Fourier Transform infrared spectroscopy. The group without coinitiator has not formed a polymer, whereas the addition of TBA resulted in the conversion of monomers in polymer. The DC of the adhesives was as higher as the increase in the TBA content. The group with 2 mol % of TBA presented improved DC and reactivity (RP ) than the other groups and the control one. Hence, the TBA has performed as a coinitiator of the CQ for the radical polymerization of methacrylate resin adhesives and it has improved the DC and the reactivity of the materials. Thus, it is a potential coinitiator for the photopolymerization of dental materials.
Asunto(s)
Procesos Fotoquímicos , Fotoiniciadores Dentales/química , Ácidos Polimetacrílicos/síntesis química , Resinas Sintéticas/síntesis química , Tiobarbitúricos/química , Alcanfor/análogos & derivados , Alcanfor/química , Ácidos Polimetacrílicos/química , Resinas Sintéticas/químicaRESUMEN
Maleimide groups are synthesized on the surface of PE films by means of two different routes, from oxidized and anhydride-grafted PE films. Maleimide groups covalently bonded to the surface of PE film were used as photopolymerization initiators of acrylic acid (AA) and glycidyl methacrylate (GMA). The formation of poly (acrylic acid) (PAA) and poly (glycidyl methacrylate) (PGMA) covalently bonded to the modified PE film surface by the photopolymerization process was demonstrated by ATR-FTIR, gravimetry, and SEM results. The thickness of the polymer layers formed in the polymerization depends on the irradiation time. The PAA layer formed in the polymerization is thinner than 250 nm, whereas that of PGMA in some case is thicker than 3 mum.
Asunto(s)
Maleimidas/química , Fármacos Fotosensibilizantes/química , Polietileno/química , Resinas Acrílicas/síntesis química , Resinas Acrílicas/química , Ciclización , Radicales Libres/química , Estructura Molecular , Tamaño de la Partícula , Ácidos Polimetacrílicos/síntesis química , Ácidos Polimetacrílicos/química , Espectroscopía Infrarroja por Transformada de Fourier , Propiedades de Superficie , Factores de TiempoRESUMEN
The formation of a novel interpolyelectrolyte complex (IPEC) between basic butylated methacrylate copolymer and kappa-carrageenan was investigated and the product formed was characterized. Turbidity measurements and elemental analyses pointed to a 1:1 interaction of the repeating units. These results and FT-IR confirmed IPEC formation. Electronic microscopy images, particle size determination by image analysis and N(2) (77K) adsorption measurements were consistent with a porous material. This IPEC formed presented very good flowability and compactibility. Two maxima were observed in the swelling behaviour as a function of pH. The performance of the IPEC as a matrix for controlled release of drugs was evaluated, using ibuprofen as a model drug. Release profiles were properly represented by a mathematical model, which indicates that the system releases ibuprofen in a zero-order manner. These profiles could be controlled by conveniently modifying the proportion of the IPEC in the tablets.
Asunto(s)
Antiinflamatorios no Esteroideos/química , Carragenina/síntesis química , Portadores de Fármacos , Ibuprofeno/química , Ácidos Polimetacrílicos/síntesis química , Química Farmacéutica , Preparaciones de Acción Retardada , Composición de Medicamentos , Concentración de Iones de Hidrógeno , Cinética , Modelos Químicos , Tamaño de la Partícula , Porosidad , Solubilidad , Propiedades de Superficie , Comprimidos , Tecnología Farmacéutica/métodosRESUMEN
This study investigated the relationship between the solubility, salivary sorption, and degree of conversion of dimethacrylate-based polymeric matrixes. Six polymeric matrixes produced by mixing bis-GMA, TEGDMA and UDMA dimethacrylate monomers were studied. Photoactivation was induced by camphoroquinone/ethyl N,N-dimethyl-4-aminobenzoate. The specimens were light-cured using an irradiance of 850 mW/cm(2) for 20 s. The solubility and sorption (microg/mm(3)) were measured after immersion in artificial saliva (neutral pH) for 7 days. The degree of conversion (%) was obtained by using a FT-IR spectrometer equipped with an attenuated total reflectance crystal (ATR). The degree of conversion varied from 39.15 +/- 6.30 to 65.57+/- 4.80, and was influenced by the viscosity of the monomers present in the polymeric matrixes. The solubility of polymeric matrixes varied between 13.64 +/- 0.39 and 25.08 +/- 0.83, and was strongly influenced by the degree of conversion (Pearson, r = -0.9587, p < 0.01). No correlation was found between salivary sorption and the degree of conversion (p = 0.3918). Salivary sorption was only dependent on the chemical and physical structures of the monomers presented in the polymeric matrixes.
Asunto(s)
Ensayo de Materiales , Metacrilatos/química , Ácidos Polimetacrílicos/química , Saliva/química , Ensayo de Materiales/métodos , Ácidos Polimetacrílicos/síntesis química , SolubilidadRESUMEN
Chitosan/poly(methacrylic acid) complexes, CS/PMAA, were prepared via dropwise addition of a solution of PMAA to a solution of chitosan in acetic acid 2 wt %. The increase in molecular weight of PMAA inhibited the formation of insoluble complexes, while the increase in ionic strength first favored the formation of the complex followed by inhibiting it at higher concentrations. These observations were related to a description of polyelectrolyte complexation that was strongly dependent on macromolecular dimensions, both in terms of molecular weight and of coil expansion/contraction driven by polyelectrolyte effect.
Asunto(s)
Quitosano/química , Ácidos Polimetacrílicos/química , Electrólitos , Estructura Molecular , Peso Molecular , Nefelometría y Turbidimetría , Concentración Osmolar , Ácidos Polimetacrílicos/síntesis química , Sensibilidad y Especificidad , Soluciones/química , Espectroscopía Infrarroja por Transformada de Fourier , ViscosidadRESUMEN
Polymer shrinkage during photopolymerization of dimethacrylate monomers, used for many years to produce materials for dental restoration, can induce either the formation of tooth-restoration gaps or the production of residual stress depending on the quality of adhesion between tooth and dental composites. In this work, the effect of the power density, used to photopolymerize three commercial dental composites (Fill Magic, Supra Fill, and Z100), on the kinetics of the reaction was investigated to determine processing conditions in which the generation of residual stress would be reduced by allowing polymer chains and macromers to flow before freezing during gelation of the polymer network. The kinetics of photopolymerization of the dental composites was monitored by real-time infrared (FTIR) spectroscopy. Polymer shrinkage and mechanical properties were also investigated by using, respectively, density and microhardness measurements. Results showed that the final conversion (after 200 s), volumetric shrinkage, and microhardness values were not affected by different power densities, mainly because the amount of energy used during photopolymerization was set constant by using different irradiation times. Lower power densities were able to reduce the maximum polymerization rate and delay the formation of a rigid network. Conversion before the formation of the rigid network was also enhanced by using a lower power density. Considering that too premature gelation can lead to residual stress during shrinkage, the results of this work indicated that the use of a lower power density can be effective in terms of delaying the onset of the formation of a rigid network, providing then conditions for macromolecules to flow and relieve stress during shrinkage.