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1.
Chem Pharm Bull (Tokyo) ; 68(3): 251-257, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32115532

RESUMO

A concise spherical granulation method is required to prepare extemporaneously granules remanufactured from oral dosage forms for administration to individuals who cannot swallow tablets or capsules. In this study, we determined the feasibility of spherical granulation using a planetary centrifugal mixer. A model formulation, 20% ibuprofen (IBP) granules, was prepared using a lactose/cornstarch (7 : 3, w/w) mixture or D-mannitol as diluents, and changes in granule characteristics (mean diameter (d50), distribution range of granule size (span), and yield) were evaluated according to the amount of water added and the granulation time. The amount of water was assessed using the plastic limit value as measured using a digital force gauge. We successfully produced granules, and larger amounts of water and longer granulation times resulted in larger d50 values and smaller span values. The optimal granulation time was 45 s and the optimal water contents were 70 and 67.5% of the plastic limit value for the lactose/cornstarch mixture and D-mannitol, respectively. When compared to commercial 20% IBP granules, powder X-ray diffraction and differential scanning calorimetry analyses showed that the granulation process did not alter the crystallinity of the drug. Thus, this novel granulation method using a planetary centrifugal mixer may be a promising technique for compounding in pharmacies and in pharmaceutical manufacturing.


Assuntos
Centrifugação , Ibuprofeno/química , Lactose/química , Manitol/química , Amido/química , Varredura Diferencial de Calorimetria , Ibuprofeno/isolamento & purificação , Tamanho da Partícula , Difração de Pó , Propriedades de Superfície
2.
Anal Bioanal Chem ; 412(6): 1353-1363, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31900540

RESUMO

The study of biologically important Cu2+ and S2- ions has drawn great attention in the recent years since an abnormal level of these ions is an indication for health impairment. Therefore, a reliable strategy for effective fluorescence determination of Cu2+ and S2- ions was developed. Simply, the method based on economical plant-dependent thermolysis procedure for efficient green synthesis of water dispersible luminescent polyamine-based carbon dots (PA@C-dots) utilizes Vitis vinifera juice as precursor with a high quantum yield (32.1%) and good photo-stability. The fluorescent PA@C-dots were characterized by different spectroscopical, physical, and structural techniques. Furthermore, the synthesized PA@C-dots can be used as an efficient dual functional fluorescent probe for the sensitive and selective estimation of Cu2+ and S2- ions. The incorporation of Cu2+ ions and their adsorption on the surface of PA@C-dot skeleton leads to the respectable fluorescence quenching of C-dots (turn-off mode). The Cu2+-PA@C-dot was found to be sensitive to S2- ions. The addition of S2- recovers the fluorescence (turn-on mode) of Cu2+-PA@C-dots, thanks to its capacity for withdrawing Cu2+ from the shell of PA@C-dots. Fluorescence quenching in the range of 0.07-60 µM Cu2+ was obtained with LOD and LOQ of 0.02 and 0.066 µM, respectively. Sulfide detection provides linearity in the range of 0.8 to 95 µM with LOD and LOQ of 0.24 and 0.79 µM, respectively. The optimal excitation and emission wavelengths for all experiments are 435 nm and 498 nm, respectively. Experiment results elucidate that the proposed method is suitable for Cu2+and S2- ion detection in environmental water samples. Graphical abstract Green synthesis of polyamine-functionalized nanoprobe by thermolysis method from plant source as bifunctional sensing platform for determination of Cu2+ and S2- in environmental water samples.


Assuntos
Carbono/química , Cobre/análise , Química Verde , Poliaminas/química , Pontos Quânticos/química , Enxofre/análise , Limite de Detecção , Microscopia Eletrônica de Transmissão , Difração de Pó , Análise Espectral/métodos , Vitis/química
3.
Ultrason Sonochem ; 62: 104861, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31796325

RESUMO

Emodin is a bioactive compound with strong anti-inflammatory and antioxidant properties. Micellar casein is casein concentrates close to the native state of casein micelles. The interaction of emodin and micellar casein under heat treatment in the absence and presence of ultrasound was investigated, and the properties of microencapsulated emodin in micellar casein were compared. Fluorescence experiments proved that the major interaction between emodin and micellar casein was through hydrophobic forces under heat treatment in the absence and presence of ultrasound. However, ΔH, ΔS and ΔG of emodin-casein complexation without sonication were higher than those with sonication, in contradiction to binding constants. The particle sizes of emodin-casein complexes in the presence of ultrasound were smaller than those without sonication, while the specific surface area showed an opposite trend. As to encapsulation, emodin-casein capsules under heat-sonication treatment showed higher antioxidant properties than those of heat treatment alone under similar experimental conditions. Interestingly, micellar casein-emodin encapsulation in the presence of ultrasound showed a lower release rate of emodin in gastrointestinal conditions than that without ultrasound at the emdoin concentration of 10 µmol per gram casein. Ultrasound has been shown to be a potential processing technology for customizing the release kinetics of bioactive compounds.


Assuntos
Caseínas/química , Emodina/química , Temperatura Alta , Micelas , Ondas Ultrassônicas , Antioxidantes/farmacologia , Caseínas/farmacologia , Formas de Dosagem , Emodina/farmacologia , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Difração de Pó , Ligação Proteica , Análise Espectral/métodos , Termodinâmica
4.
AAPS PharmSciTech ; 21(2): 35, 2019 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-31879830

RESUMO

The present work embarks upon increasing the dissolution rate and the bioavailability of model anti-diabetic drug, gliquidone, a sulfonylurea class drug used for treating diabetes mellitus type 2. The gliquidone nanoparticles were prepared by using anti-solvent precipitation technique in which, gliquidone solution in acetone was added at a controlled rate to an aqueous solution containing polyvinylpyrrolidone K25 (PVP K25) as stabilizer. The effect of drug concentration (X1), polymer concentration (X2) and solvent to anti-solvent ratio (X3) on particle size and dissolution was studied using Box-Behnken design. The results revealed that by decreasing the drug concentration and by increasing the stabilizer concentration and solvent/anti-solvent ratio, reduction in the size of the particles was observed. The mentioned parameters were optimised and particle of size about 175 nm was achieved. The relative dissolution rate of prepared gliquidone nanoparticles in phosphate buffer pH 7.4 was ~ 4.7 times faster than original drug at t = 45 min. Further, the gliquidone nanoparticles were characterized by scanning electron microscope (SEM), Fourier transform-infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD). The particles revealed to be oval in shape with stabilizer molecules on surface and exhibited decreased crystalline nature when compared to free gliquidone. Finally, the in vivo studies using gliquidone nanoparticles revealed ~ 2.5-fold increase in Cmax when taken orally in the form of hard gelatin capsules in comparison to free gliquidone. Thus, overall investigation suggests that the developed strategy of gliquidone nanoparticles possess a keen potential for exhibiting anti-diabetic effect.


Assuntos
Hipoglicemiantes/química , Hipoglicemiantes/farmacocinética , Nanopartículas/química , Compostos de Sulfonilureia/química , Compostos de Sulfonilureia/farmacocinética , Animais , Disponibilidade Biológica , Varredura Diferencial de Calorimetria , Técnicas In Vitro , Masculino , Microscopia Eletrônica de Varredura , Difração de Pó , Coelhos , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier
5.
Nat Commun ; 10(1): 5002, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31676820

RESUMO

Metal-organic frameworks (MOFs) have recently garnered consideration as an attractive solid substrate because the highly tunable MOF framework can not only serve as an inert host but also enhance the selectivity, stability, and/or activity of the enzymes. Herein, we demonstrate the advantages of using a mechanochemical strategy to encapsulate enzymes into robust MOFs. A range of enzymes, namely ß-glucosidase, invertase, ß-galactosidase, and catalase, are encapsulated in ZIF-8, UiO-66-NH2, or Zn-MOF-74 via a ball milling process. The solid-state mechanochemical strategy is rapid and minimizes the use of organic solvents and strong acids during synthesis, allowing the encapsulation of enzymes into three prototypical robust MOFs while maintaining enzymatic biological activity. The activity of encapsulated enzyme is demonstrated and shows increased resistance to proteases, even under acidic conditions. This work represents a step toward the creation of a suite of biomolecule-in-MOF composites for application in a variety of industrial processes.


Assuntos
Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Estruturas Metalorgânicas/química , Metais/química , Biocatálise , Catalase/química , Catalase/metabolismo , Catalase/ultraestrutura , Eletroforese em Gel de Poliacrilamida , Estabilidade Enzimática , Enzimas Imobilizadas/ultraestrutura , Estruturas Metalorgânicas/síntese química , Microscopia Eletrônica de Varredura , Difração de Pó , beta-Frutofuranosidase/química , beta-Frutofuranosidase/metabolismo , beta-Frutofuranosidase/ultraestrutura , beta-Galactosidase/química , beta-Galactosidase/metabolismo , beta-Galactosidase/ultraestrutura , beta-Glucosidase/química , beta-Glucosidase/metabolismo , beta-Glucosidase/ultraestrutura
6.
Yakugaku Zasshi ; 139(11): 1471-1478, 2019.
Artigo em Japonês | MEDLINE | ID: mdl-31685744

RESUMO

Phellodendron bark ("Obaku") is an important crude drug used in Kampo-medicine. Recently, powder formulation of phellodendron bark was approved as an "efficacious treatment for bruise, sprain, and periodontal diseases", and it has been marketed as an OTC agent. To obtain this approval, the examination of quality control-related characteristics is necessary. Therefore, we established a quantitative method for jatrorrhizine, palmatine, and berberine determination. In this study, we compared the contents of the three constituents obtained from the extracts of Japanese and Chinese phellodendron bark and found remarkable difference.


Assuntos
Alcaloides/análise , Berberina/análise , Phellodendron/química , Casca de Planta/química , Alcaloides/isolamento & purificação , Berberina/análogos & derivados , Berberina/isolamento & purificação , Alcaloides de Berberina/análise , Alcaloides de Berberina/isolamento & purificação , China , Cromatografia Líquida de Alta Pressão/métodos , Estabilidade de Medicamentos , Japão , Difração de Pó , Controle de Qualidade
7.
Int J Pharm ; 572: 118776, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31678374

RESUMO

A comprehensive cocrystal study for the insoluble natural pharmaceutical compound xanthotoxin (XT) was conducted, in which xanthotoxin-para aminobenzoic acid (XT-PABA) and xanthotoxin-oxalic acid (XT-OA) cocrystals were obtained. The xanthotoxin cocrystals were characterized by powder X-ray diffraction, thermal analysis, and FT-IR spectra, and the crystal structures were determined by single-crystal X-ray diffraction. Crystal structures and thermal analysis showed that XT-OA was more stable than XT-PABA. Energy framework calculation indicated that H-bond and π···π interactions generated in XT-OA were stronger than that in XT-PABA and xanthotoxin. The powder dissolution experiments of xanthotoxin and its cocrystals suggested the XT-OA cocrystal might be applied as an alternative formulation of API, on account of its enhanced solubility and stability in the hydrochloric acid buffer solution (pH 1.2). The cocrystallization engineering can prolong the enhanced apparent solubility via modulating the stability.


Assuntos
Metoxaleno/química , Solubilidade/efeitos dos fármacos , Ácido 4-Aminobenzoico/química , Cristalização/métodos , Cristalografia por Raios X/métodos , Estabilidade de Medicamentos , Ligação de Hidrogênio , Ácido Oxálico/química , Difração de Pó/métodos , Pós/química , Difração de Raios X/métodos
8.
Skin Pharmacol Physiol ; 32(6): 318-327, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31614350

RESUMO

BACKGROUND AND AIM: Since the pharmacological effects of diclofenac (DF) are short-lived because of its short half-life, prolongation of the pharmacological effect in a topical formulation is needed for more appropriate clinical use. For the enhancement of dermal accumulation and prolongation of the pharmacological effect of drugs, the aim of this study was to develop a simple gel formulation containing an ion-pair complex of DF and phenylephrine (PHE), which induce constriction of the vascular smooth muscles. MATERIALS AND METHODS: The ion-pair complex was prepared by mixing sodium DF and an ethanolic solution of PHE. The formed complex was characterized by powder X-ray diffraction (PXRD) and Fourier-transform infrared (FT-IR) spectroscopy. The ion-pair complex for the gel formulation was prepared by mixing an equimolar concentration of 50% 1,3-butylene glycol and distilled aqueous solution of 2% xanthan gum, which was characterized by proton nuclear magnetic resonance (1H-NMR). Skin permeation and accumulation of DF and PHE were evaluated by in vitro and in vivo studies. RESULTS: From the results of PXRD and FT-IR, it was suggested that new crystalline peaks formed by the ion-pair complex and their complex interacted with the carboxyl group in DF and the amino group in PHE. In the gel formulation, the ion-pair complexes were detected by 1H-NMR. The ion-pair complex enhanced the accumulation of DF in the skin in the in vitro study. On the other hand, PHE accumulation in the dermis increased with the ion-pair complex, as exhibited by the in vivo study. CONCLUSION: A new gel formulation containing the ion-pair complex of DF and PHE was developed, which improved the accumulation of DF in skin.


Assuntos
Anti-Inflamatórios não Esteroides/administração & dosagem , Diclofenaco/administração & dosagem , Portadores de Fármacos/administração & dosagem , Fenilefrina/administração & dosagem , Vasoconstritores/administração & dosagem , Administração Cutânea , Animais , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/farmacocinética , Diclofenaco/química , Diclofenaco/farmacocinética , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Feminino , Géis , Técnicas In Vitro , Masculino , Fenilefrina/química , Fenilefrina/farmacocinética , Difração de Pó , Espectroscopia de Prótons por Ressonância Magnética , Ratos Wistar , Pele/metabolismo , Absorção Cutânea/efeitos dos fármacos , Espectroscopia de Infravermelho com Transformada de Fourier , Suínos , Porco Miniatura , Vasoconstritores/química , Vasoconstritores/farmacocinética , Difração de Raios X
9.
Int J Pharm ; 570: 118653, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31472218

RESUMO

Co-amorphous mixtures have been demonstrated to represent a promising approach for enhancing the dissolution of poorly water-soluble drugs. However, little is known of their permeability properties, especially through biological membranes, or about the relationship between their dissolution and permeability. In the present study, co-amorphous glibenclamide (GBC) mixtures with two amino acids, arginine (ARG) and serine (SER), in molar ratios of 1:1 were prepared by cryomilling. Their dissolution and permeability properties were studied in side-by-side diffusion chambers using cell layers containing Madine Darby kidney cells overexpressing P-glycoprotein (Pgp) transporters (MDCKII-MDR1), as Pgp may influence the absorption of GBC. Furthermore, two other compounds, the flavonoid quercetin (QRT) which is a Pgp inhibitor and the surfactant, sodium lauryl sulfate (SLS), were used as excipients to investigate if they improved either passive or active diffusion of GBC. In addition, amorphous QRT and a co-amorphous mixture of GBC and QRT (1:1) were characterized with respect to their solid-state properties and physical stability. It was demonstrated that co-amorphous GBC mixtures exhibited superior dissolution properties over the corresponding physical mixtures and amorphous GBC. Furthermore, the co-amorphous GBC-ARG-SLS mixture exhibited a 9-fold increase in permeating through the MDCKII-MDR1 cell layer as compared to the corresponding physical mixture. There was a correlation between the dissolution and permeability area under curve (AUC) values, evidence that the main mechanism behind the improved permeability of co-amorphous mixtures was their improved dissolution. The simultaneous dissolution/permeation testing with side-by-side diffusion chambers and MDCKII-MDR1 cells proved to be a feasible method for evaluating the dissolution/permeation interplay of amorphous compounds.


Assuntos
Glibureto/química , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/química , Animais , Arginina/química , Cães , Composição de Medicamentos/métodos , Flavonoides/química , Células Madin Darby de Rim Canino , Permeabilidade/efeitos dos fármacos , Difração de Pó/métodos , Quercetina/química , Serina/química , Solubilidade/efeitos dos fármacos
11.
Anal Chim Acta ; 1086: 122-132, 2019 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-31561787

RESUMO

Novel multifunctional core-shell nanoparticles (NPs) have attracted widespread attention due to their easy-to-modify surface properties and abundant functional groups. This study introduces a facile approach to synthesize Ag@ iron oxide (Fe3O4) @C NPs, and modify with amino-poly (ethylene glycol) (PEG)-carboxyl and folate (FA) on the exposed carbon surface to produce high contrast for excellent stability, good biocompatibility, cancer cell targeting, and synergistic treatment. The multi-armed PEG at the edge of Ag@Fe3O4@C NPs provides the materials an excellent capacity for doxorubicin (DOX) loading. The carbon layer could be used as a photothermal reagent due to its excellent near-infrared (NIR) absorbance capacity, and Fe3O4 was used as a reagent for magnetic resonance (MR) imaging. In vivo combination therapy with this agent was administered in a mouse tumor model, and a remarkable synergistic antitumor effect that is superior to that obtained by monotherapy was achieved. Concerning these features together, these unique multifunctional Ag@Fe3O4@C-PEG-FA/DOX NPs could be regarded as an attractive nanoplatforms for chemo-photothermal synergistic tumor therapy with dual-modal fluorescence and MR imaging-guided targeting.


Assuntos
Antibióticos Antineoplásicos/uso terapêutico , Doxorrubicina/uso terapêutico , Imagem Multimodal , Nanopartículas/química , Neoplasias do Colo do Útero/diagnóstico por imagem , Neoplasias do Colo do Útero/terapia , Animais , Carbono/química , Feminino , Compostos Férricos/química , Células HeLa , Humanos , Camundongos , Camundongos Nus , Microscopia Eletrônica de Transmissão , Neoplasias Experimentais/diagnóstico por imagem , Neoplasias Experimentais/terapia , Fototerapia , Difração de Pó , Prata/química , Raios X
12.
AAPS PharmSciTech ; 20(7): 289, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31414349

RESUMO

The aim of this study was to evaluate the use of a novel porous silica carrier, AEROPERL® 300 Pharma (AP), to improve the in vitro release and oral bioavailability of puerarin (PUE) in solid dispersions (SDs). PUE-AP SD formulations with different ratios of drug to silica (RDS) were prepared by the solvent method. The scanning electron microscopy (SEM) results indicated that the dispersion of PUE improved as the concentration of AP was increased. The differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results revealed that PUE mostly existed in an amorphous state in the SDs. The rate of drug dissolution from the SDs was significantly higher than that from the PUE powder (p < 0.05). The in vitro drug release percentage from the PUE-AP SDs increased as the RDS was reduced. The oral bioavailability of PUE from the SDs improved when using AP, as indicated by AUC(0-∞), which was 2.05 and 2.01 times greater than that of the PUE (API) and PVP K30 SDs, respectively (p < 0.05). The drug content, in vitro release profiles, and the amorphous state of PUE in the PUE-AP SDs showed no significant changes after being stored at room temperature for 6 months or under accelerated conditions (40 ± 2°C, 75 ± 5% relative humidity) for 3 months. AP has a high pore volume, large specific surface area, excellent flowability, and hydrophilic properties, making it capable of improving the dissolution and bioavailability of poorly water-soluble drugs.


Assuntos
Portadores de Fármacos , Isoflavonas/administração & dosagem , Dióxido de Silício/química , Animais , Disponibilidade Biológica , Varredura Diferencial de Calorimetria , Composição de Medicamentos/métodos , Interações Hidrofóbicas e Hidrofílicas , Isoflavonas/farmacocinética , Masculino , Microscopia Eletrônica de Varredura , Porosidade , Povidona/química , Difração de Pó , Ratos , Ratos Sprague-Dawley , Solubilidade
13.
Mikrochim Acta ; 186(9): 631, 2019 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-31422477

RESUMO

Multimodal nanoporous PtCu flowers (np-PtCu) were prepared via a two-step dealloying strategy under mild conditions. The np-PtCu alloy possesses an interconnected flower-like network skeleton with multiscale pore distribution. This material was placed on a glassy carbon electrode where it shows outstanding detection performance towards hydrogen peroxide and glucose in near-neutral pH solutions. It can be attributed to the specific structure in terms of interconnected nanoscaled ligaments, rich pore openings and a synergistic alloying effect. Figures of merit for detection H2O2 assay include (a) a working voltage of 0.7 V (vs. the reversible hydrogen electrode); (b) a wide linear response range (from 0.01 to 1.7 mM), and (c) a low detection limit (0.1 µM). The respective data for the glucose assay are (a) 0.4 V, (b) 0.01-2.0 mM, and (c) 0.1 µM. The method is not interfered in the presence of common concentrations of dopamine, acetaminophen and ascorbic acid. Graphical abstract Multimodal nanoporous (np) PtCu alloy was prepared via a two-step dealloying strategy under mild conditions. Np-PtCu exhibits superior electrocatalytic activity. The assay is highly sensitive, selective, and it allows for a long-term detection of H2O2 and glucose.


Assuntos
Ligas/química , Cobre/química , Glucose/análise , Peróxido de Hidrogênio/análise , Platina/química , Eletrodos , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Porosidade , Difração de Pó , Soluções , Propriedades de Superfície
14.
Chem Pharm Bull (Tokyo) ; 67(8): 816-823, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31366831

RESUMO

In this present study a new co-crystals of zoledronic acid with DL-tartaric acid and nicotinamide has been developed with improved solubility. Zoledronic acid is a class III drug with poor oral bioavailability due to its poor permeability and low aqueous solubility; hence an attempt has been made to improve its solubility by co-crystallization technology. Pharmaceutical cocrystals are multi-component crystals with a stoichiometric ratio of active pharmaceutical ingredients (APIs) and cocrystal coformers (CCFs) that are assembled by noncovalent interactions such as hydrogen bonds, π-π packing, and Vander Waals forces. In this study the coformers selected were DL-tartaric acid and nicotinamide based on ease of hydrogen bond formation. The co-crystal of zoledronic acid with DL-tartaric acid were prepared in three ratios (1 : 1, 1 : 2 and 2 : 1) by slow solvent evaporation method and with nicotinamide in 1 : 1 ratio by dry grinding method. The formation of co-crystal was confirmed by powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC) and Fourier transform (FT)IR. The dynamic solubility of co-crystals with DL-tartaric acid in the ratios 1 : 1, 1 : 2 and 2 : 1 increased by fold as compared to pure drug.


Assuntos
Desenho de Fármacos , Niacinamida/química , Tartaratos/química , Ácido Zoledrônico/química , Varredura Diferencial de Calorimetria , Cristalização , Estrutura Molecular , Difração de Pó , Solubilidade , Ácido Zoledrônico/síntese química
15.
Chem Commun (Camb) ; 55(70): 10444-10447, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31410430

RESUMO

A new series of 2D catalytic materials whose inorganic surfaces are fully covered with pre-designed "promoter" groups are reported. One of them showed excellent biomimetic catalytic activity and provided the lowest detection limit to glucose among the reported 2D materials and their composite materials.


Assuntos
Biomimética , Calcogênios/química , Metais/química , Catálise , Limite de Detecção , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica , Difração de Pó
16.
J Synchrotron Radiat ; 26(Pt 4): 1238-1244, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31274449

RESUMO

In situ research of materials under moderate pressures (hundreds of bar) is essential in many scientific fields. These range from gas sorption to chemical and biological processes. One industrially important discipline is the hydration of oil well cements. Existing capillary cells in this pressure range are static as they are easy to design and operate. This is convenient for the study of single-phase materials; however, powder diffraction quantitative analyses for multiphase systems cannot be performed accurately as a good powder average cannot be attained. Here, the design, construction and commissioning of a cost-effective spinning capillary cell for in situ powder X-ray diffraction is reported, for pressures currently up to 200 bar. The design addresses the importance of reducing the stress on the capillary by mechanically synchronizing the applied rotation power and alignment on both sides of the capillary while allowing the displacement of the supports needed to accommodate different capillaries sizes and to insert the sample within the tube. This cell can be utilized for multiple purposes allowing the introduction of gas or liquid from both ends of the capillary. The commissioning is reported for the hydration of a commercial oil well cement at 150 bar and 150°C. The quality of the resulting powder diffraction data has allowed in situ Rietveld quantitative phase analyses for a hydrating cement containing seven crystalline phases.


Assuntos
Difração de Pó/métodos , Pressão , Síncrotrons , Temperatura , Desenho de Equipamento
17.
Acta Crystallogr A Found Adv ; 75(Pt 4): 600-609, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31264644

RESUMO

Electron density determination based on structure factors obtained through powder X-ray diffraction has so far been limited to high-symmetry inorganic solids. This limit is challenged by determining high-quality structure factors for crystalline urea using a bespoke vacuum diffractometer with imaging plates. This allows the collection of data of sufficient quality to model the electron density of a molecular system using the multipole method. The structure factors, refined parameters as well as chemical bonding features are compared with results from the high-quality synchrotron single-crystal study by Birkedal et al. [Acta Cryst. (2004), A60, 371-381] demonstrating that powder X-ray diffraction potentially provides a viable alternative for electron density determination in simple molecular crystals where high-quality single crystals are not available.


Assuntos
Elétrons , Teoria Quântica , Ureia/química , Difração de Raios X/métodos , Modelos Moleculares , Estrutura Molecular , Difração de Pó
18.
Anal Bioanal Chem ; 411(21): 5593-5603, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31289896

RESUMO

A novel SBA-15-based fluorescent sensor, SBA-PI: mesoporous SBA-15 structure modified with iminostilbene groups, was designed, synthesized, and characterized by Fourier transform-infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), low-angle X-ray diffraction techniques (low-angle XRD), and N2 adsorption-desorption techniques. The SBA-PI as a sensor with a selective behavior for detection of Cu2+ comprises iminostilbene carbonyl as the fluorophore group. The SBA-PI sensor displays an excellent fluorescence response in aqueous solutions and the fluorescence intensity quenches remarkably upon addition of Cu2+. Other common interfering ions even at high concentration ratio showed either no or very small changes in the fluorescence intensity of SBA-PI in the absence of Cu2+. A limit of detection of 8.7 × 10-9 M for Cu2+ indicated that this fluorescence sensor has a high sensitivity and selectivity toward the target copper (II) ion. The fabricated Cu2+ sensor was successfully applied for the determination of the Cu2+ in human blood samples without any significant interference. With the selective analysis of Cu2+ ions down to 0.9 nM in blood, the sensor is a promising and a novel detection candidate for Cu2+ and can be applied in the clinical laboratory. A reversibility and accuracy in the fluorescence behavior of the sensor was found in the presence of I¯ that was described as a masking agent for Cu2+. Graphical abstract.


Assuntos
Cobre/sangue , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Oligoelementos/sangue , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Difração de Pó , Espectrometria por Raios X , Termogravimetria
19.
Eur J Pharm Sci ; 137: 104983, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31271876

RESUMO

Supersaturating drug delivery systems (SDDS) have dominated the commercial and academic spheres owing to their potential in overcoming the solubility issue of poorly soluble drugs. Precipitation inhibitors are used as excipients in such formulations which has necessitated the development of supersaturation assays that evaluate their precipitation-inhibition efficacy. Such assays are able to give relative estimates of polymer efficacy ceteris paribus within a given set-up. However, the estimates of different laboratories cannot be compared with each other owing to high variability in procedure. Microarray plate method allows comprehensive replicates and decent statistics that make the method an edge over the other exploratory assays. In the current study, the precipitation-inhibition performance of three polymers on the precipitation of a model BCS class II drug was evaluated using the microarray plate method. Quantitative estimations were made through application of Poisson equation for nucleation rates and area under curve. Insights of the precipitation process at particle level were obtained through focused beam reflectance measurement (FBRM) technique coupled with end-process PVM imaging. Through real-time particle size analysis, FBRM technique demonstrated the potential for discerning the role of polymer as nucleation-inhibitor or crystal growth inhibitor. The events observed in the scaled-up FBRM analysis could be correlated with the events observed visually and spectrophotometrically. Powder X-ray diffraction and scanning electron microscopy were performed to capture the influence of polymers on the precipitates formed. This study was able to demonstrate the applicability of microarray plate method for quantitative estimations of precipitation kinetics that can be utilized for excipient screening for poorly soluble drugs having intra-luminal precipitation as a problem. FBRM analysis is highly valuable to gain mechanistic insights and put to rest the prevalent conjecture-based role attribution for polymers.


Assuntos
Celecoxib/química , Polímeros/química , Precipitação Química , Microscopia Eletrônica de Varredura , Difração de Pó , Solubilidade , Soluções , Tecnologia Farmacêutica , Viscosidade , Difração de Raios X
20.
Pharm Dev Technol ; 24(9): 1115-1124, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31282827

RESUMO

The objective of the present study was to enhance the dissolution rate of carvedilol (CA), a poorly water-soluble antihypertensive drug, using a co-grinding method in the presence of polyvinylpyrrolidone (PVP) and sodium lauryl sulfate (SLS). Various ratios of CA:PVP:SLS were ground by a planetary ball mill. They were studied in terms of dissolution, solubility, and particle size. The solid state and morphology of the intact drug and prepared samples were also characterized using differential scanning calorimetry (DSC), infrared spectroscopy (IR), X-ray diffraction (XRD), and scanning electron microscope (SEM). According to the results, co-grinding in the presence of PVP and SLS significantly increased CA dissolution rate. DE60 (dissolution efficiency) obtained for the best ternary ground mixture (89.31%) was 3.4 and 4.5 times higher than that of the related physical mixture (PM) and the intact drug, respectively. Further, the solubility of this formulation was about 10 times higher compared to that of the intact CA. A direct correlation was also observed between the chamber rotation speed of the planetary mill within the range of 100-400 rpm and CA dissolution rate. Finally, DSC, IR, and XRD analysis ruled out any polymorphic changes and chemical interactions during the grinding process.


Assuntos
Anti-Hipertensivos/química , Carvedilol/química , Excipientes/química , Povidona/química , Dodecilsulfato de Sódio/química , Composição de Medicamentos , Liberação Controlada de Fármacos , Tamanho da Partícula , Difração de Pó , Solubilidade , Difração de Raios X
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