RESUMO
This paper reports for the first time the incorporation of gallium into the structure of the mesoporous SBA-3 material in order to modify the intrinsic acidity of the material. The study indicates the effective incorporation of Ga into a network in tetrahedral form, with most in the interior of the lodging and a low proportion on the external surface. Gallium was introduced via post-synthesis using Ga-nitrate in appropriate conditions. The nanostructured material was characterized by ICP, x-ray diffraction, nuclear magnetic resonance-MAS, x-ray photoelectron spectra, FTIR, SEM, transmission electron microscopy and UV-vis. Pyridine was used as a probe molecule for the determination of its acidity following the amount and type of acidic sites by FTIR. In addition, aniline adsorption/desorption studies and subsequent in situ polymerization, polyaniline (PANI)/Ga-SBA-3, were carried out with the aim of producing a nanocomposite with conductive properties. The original material had good structural regularity and acidity of Brønsted and Lewis; the PANI/Ga-SBA-3 composite also showed a conductivity of 2.5 × 10-3 S cm-1, higher than that of its homologs Al-SBA-3 and Al-MCM- 41.
RESUMO
The ordered mesoporous silica SBA-15 has been applied in studies of ketorolac tromethamine adsorption and release. The SBA-15 materials with hexagonal and regular structure were obtained using a triblock copolymer Pluronic P123 as a template and TEOS as a silica source. Ketorolac tromethamine was adsorbed into SBA-15 silica nanochannels using ethanol as solvent. The physicochemical and textural properties of SBA-15 and ketorolac tromethamine/SBA-15 were characterized by X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, fourier transform infrared spectroscopy and BET surface studies. Drug release was evaluated by soaking the loaded silica mesoporous material into a solution of HCl (0.1 N) at initial time (0-2 h) and buffer pH 7 at high times at 37 °C under continuous stirring. Oral commercial Keto tablets (Dolten®) and Keto solution (Keto power) were study for the contrast. Release studies were performed in order to evaluate the required therapeutic efficacy. SBA-15 provides significant improvement in the controlled release of ketorolac tromethamine. Release profile of KETO from SBA-15/KETO and control releases.
Assuntos
Sistemas de Liberação de Medicamentos , Cetorolaco de Trometamina/química , Dióxido de Silício/química , Administração Oral , Adsorção , Portadores de Fármacos , Trato Gastrointestinal/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Cetorolaco de Trometamina/farmacocinética , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Modelos Teóricos , Dióxido de Silício/farmacocinética , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Temperatura , Termogravimetria , Difração de Raios XRESUMO
Composite material formed from a mesoporous aluminosilicate, Na-AlMCM-41, with conducting polyaniline (PANI) has been synthesized by an in situ polymerization technique. Studies of aniline adsorption over mesoporous Na-AlMCM-41 synthesized in our laboratory allowed us to find the modes in which aniline interacts with the active sites of Na-AlMCM-41. In order to obtain the best reaction conditions to polymerize aniline onto Na-AlMCM-41, aniline was first polymerized to produce pure PANI. Hence, the oxidative in situ polymerization was carried out by two procedures, differing in the polymerization time and in static or stirring conditions. Studies of infrared spectroscopy and UV-vis spectroscopy indicated that higher polymerization time and static conditions allowed us to obtain mainly polyaniline in emeraldine form on the host. The N(2) isotherm of the polyaniline/Na-AlMCM-41 composite (PANI/MCM) indicated that the shape was similar to that of MCM, but the shift to saturation transition to lower partial pressure shows that the channels are occupied by PANI and they are now narrowed. The thermal properties of PANI, Na-AlMCM-41, and composite were investigated by TGA analyses and we found that the polymer shows higher thermal stability when it is forming the composite. Scanning electron microscopy indicated that PANI is not on the outer surface of the host. Conductivity studies show that PANI/Na-AlMCM-41 exhibits semiconductor behavior at room temperature and its conductivity was 7.0 x 10(-5) S/cm, smaller than that of pure polyaniline. PANI/Na-AlMCM-41 conductivity shows an increase as temperature increases. Magnetic measurements at room temperature confirmed that the composite has paramagnetic behavior; at lower temperatures the composite became diamagnetic.
Assuntos
Silicatos de Alumínio/química , Compostos de Anilina/química , Sódio/química , Adsorção , Tamanho da Partícula , Porosidade , Semicondutores , Sensibilidade e Especificidade , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Propriedades de Superfície , TemperaturaRESUMO
The adsorption of aniline on Na-AlMCM-41 synthesized by us has been characterized by infrared spectroscopy, temperature programmed desorption (TPD), and differential thermal analysis methods. Aniline would be mostly bound to the mesostructure through weak pi interactions. On the mesostructure containing adsorbed water, the co-adsorption of aniline could occur by weak hydrogen bonding through surface water molecules. For water, two possible modes of adsorption have been identified. Different associations between aniline and hydrated and nonhydrated mesostructures have been evaluated in order to favor the posterior in situ polymerization of adsorbed aniline.