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131.
Purpose The aim of this paper is to demonstrate that multiple crystal forms can be generated on patterned self-assembled monolayers
(SAMs) substrates in single experiments in a given solvent system.
Methods Functionalized metallic islands are fabricated and utilized as individual templates for crystal formation. Taking advantage
of the different wetting properties that patterned surfaces offered, arrays of small solution droplets on the nano- and pico-
liter scale were produced on the substrates. Different droplet dimensions were deposited on the substrate. As the solvent
evaporates from the droplets, crystals were formed within the constrained volume. Crystal habits were examined with optical
microscopy while the solid form was identified with Raman microscopy.
Results With mefenamic acid (MA) and sulfathiazole as model pharmaceutical compounds, two and four different polymorphs, respectively,
were observed under identical conditions. Moreover, it is established that the polymorphic distribution is highly dependent
on the solvent evaporation rate and the solution concentration. These results imply that multiple crystal forms competitively
nucleate in solution, and the probability of each form nucleating is strongly dependent on the supersaturation of the solution.
Additionally, solvent was observed to play a role in controlling the solid state outcome.
Conclusions Multiple crystal forms can concomitantly nucleate on patterned substrates. This technique can particularly be attractive to
screen for polymorphs as elusive, metastable solid forms are favored with the creation of high supersaturation and can be
stabilized due to the minimal volumes generated. 相似文献
132.
Purpose Characterization of hydroxypropyl-β-cyclodextrin/progesterone (HPBCD/P) complex solid particles obtained from an aqueous solution,
by three different technological processes, with the aim of preparing ready-to-dissolve powders for injectable as well as
solid oral formulations in progestinic therapy.
Methods HPBCD/P complex in the 2:1 molar ratio was prepared in aqueous solution and obtained as dry solid particles by freeze-drying,
by spray-drying and by fluid-bed evaporation of the solvent. The particles were characterized by μ-FT-IR, μ-Raman and X-ray
spectroscopy, by thermal analysis (differential scanning calorimetry-DSC and thermogravimetry-TGA), by Karl Fischer (KF) titration,
by image and fractal analysis and by BET specific surface area analysis. The structure of the complex was also defined by
comparison of FT-IR and Raman spectra of progesterone with those of pregnenolone and testosterone, structurally related. Dissolution
tests were also performed.
Results Powders of the complex obtained by the three different methods are different in size and shape. Particles obtained by freeze-drying
are flat and angular, irregularly shaped without any relation to known geometrical solid figures. Particles obtained by spray-drying
are spherically shaped and display a very small size (5-10 μm), with evident deformations and depression of the external surface,
due to the rapid evaporation of the solvent. Particles obtained by fluid bed technique have intermediate sizes, display a
tri-dimensional structure and irregular surface, with small and rounded protuberances. Fractal dimension of the particle contour
was found close to one unit for the microspheres obtained by spray-drying. FT-IR and Raman spectra confirm the occurrence
of the complexation by the shift of representative bands of the two carbonyl groups in positions 3 and 20 of the complexed
progesterone. X-ray diffractograms indicate the amorphous nature of all the types of particles, also suggested by the absence
of any melting peak of the drug in DSC thermograms. The samples contain different amounts of humidity: particles obtained
by fluid-bed method demonstrated non-porous in BET analysis. Dissolution of different types of particles is complete after
3 min and only negligible differences could be appreciated among the three powders.
Conclusions – μ-FT-IR, μ-Raman and X-ray spectroscopy, and the dissolution test did not reveal defined differences among the three different
types of particles, confirming occurrence of the complex in the solid state. The spherical shape, the very small size and
the low value of the contour fractal dimension allows better technological performance of the particles obtained by spray-drying:
this drying process appears the most promising one to prepare dry particles of the HPBCD/P complex, in view of its formulation
in the fast preparation of extemporaneous injectable solutions and solid oral formulations intended for sublingual delivery. 相似文献
133.
Koleva BB Kolev TM Spiteller M 《Journal of pharmaceutical and biomedical analysis》2008,48(1):201-204
Quantitative IR- and Raman spectroscopic determinations of four cephalosporin antibiotics in six solid binary mixtures have been conducted. This is a new approach for spectroscopic determination of these antibiotics, since the corresponding quantitative analysis in solution only has been reported so far. The correlation coefficient r(2) was found to be in the confidence intervals within 99.32-99.88% and 99.90-95.54% for the systems under study by using the absorption ratios of the characteristic bands at 800cm(-1) and 721cm(-1) present in the IR- and Raman spectra of the antibiotic compounds cephalexin, cephalotin, cephaloglycin and cephamandole, respectively. Solid-state linear dichroic infrared (IR-LD) spectral analysis of the solid mixtures was carried out in order to obtain experimental IR-spectroscopic assignment of the compounds studied. Independent high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis was performed for the validation of the vibrational spectroscopic data. The application of this instrumental analytical tool for the analysis of 10 tablets of the commercial products Cefamandole and Cefalotin (Actavis) was also studied. 相似文献
134.
Trefi S Routaboul C Hamieh S Gilard V Malet-Martino M Martino R 《Journal of pharmaceutical and biomedical analysis》2008,47(1):103-113
Counterfeit and/or imitation medicines are becoming a major health problem not only in developing countries but also in wealthier countries. The need of new and easy analytical methods for quality control of drugs is essential. We describe the use of Raman spectroscopy, 1H nuclear magnetic resonance (NMR) and 2D diffusion-ordered spectroscopy (DOSY) NMR to analyse genuine Cialis and seven illegally manufactured formulations of this drug purchased via the internet. Seven out of the eight commercial formulations of tadalafil contain the active ingredient, measured by high performance liquid chromatography (HPLC), within 100+/-5% of stated concentration. Vardenafil and homosildenafil instead of tadalafil were found in the Chinese imitation. 2D DOSY NMR spectra clearly showed similarities and differences in the composition of the pharmaceutical formulations of tadalafil, thus giving a precise and global "signature" of the manufacturer. Our data show that the quality of the Cialis imitations manufactured in India and Syria is correct, whereas the Chinese formulation is adulterated with active pharmaceutical ingredients. 相似文献
135.
Raman detected differential scanning calorimetry of polymorphic transformations in acetaminophen 总被引:1,自引:0,他引:1
Kauffman JF Batykefer LM Tuschel DD 《Journal of pharmaceutical and biomedical analysis》2008,48(5):1310-1315
Acetaminophen is known to crystallize in three polymorphic forms. Thermally induced transformations between the crystalline forms and the super-cooled liquid have been observed by differential scanning calorimetry (DSC), but the assignment of calorimetric transitions to specific polymorphic transformations remains challenging, because the transition temperatures for several transformations are close to one another, and the characteristics of the observed transitions depend on experimental variables that are often poorly controlled. This paper demonstrates the simultaneous application of DSC and Raman microscopy for the observation of thermally driven transitions between polymorphs of pharmaceutical materials. Raman detected differential scanning calorimetry (RD-DSC) has been used to monitor the DSC thermograms of super-cooled liquid acetaminophen and confirms the assignment of two exothermic transitions to specific polymorphic transformations. Principal component analysis of the Raman spectra have been used to determine the number of independent components that participate in the phase transformations, and multivariate regression has been used to determine transition temperatures from the spectral data. The influence of the laser excitation source on measured DSC thermograms has also been investigated, and it has been demonstrated that a baseline shift occurs in RD-DSC when a polymorphic transformation occurs between crystalline and amorphous forms. RD-DSC has been used to examine the influence of sample aging and sample pan configuration on the observed polymorphic transformations, and both of these variables were found to influence the thermal behavior of the sample. The results demonstrate the advantage of simultaneous Raman spectroscopy and differential scanning calorimetry for the unambiguous assignment of thermally driven polymorphic transformations. 相似文献
136.
摘 要 目的:建立一种利用拉曼技术快速测定注射用更昔洛韦的方法。方法: 运用拉曼光谱技术对注射用更昔洛韦进行含量测定,并与HPLC法进行比较。拉曼光谱条件:采用光纤自动测量模式,探头焦距为5 mm,激发光源为785 nm,分辨率为4 cm-1,测试时间为100 s,激光输出功率为400 mW,扫描范围为3 000~200 cm-1,检测器工作温度为-50℃。结果: 更昔洛韦在2.5~50.0 mg·mL-1浓度范围内与1 475 cm-1峰位的峰面积呈良好的线性关系(r=0.998 0),平均回收率为99.47%(RSD=1.02%,n=9)。结论:拉曼光谱法快捷、简便,可用于注射用更昔洛韦含量的快速测定。 相似文献
137.
Martina Alunni Cardinali Assunta Morresi Daniele Fioretto Leonardo Vivarelli Dante Dallari Marco Govoni 《Materials》2021,14(22)
Human bone is a specialized tissue with unique material properties, providing mechanical support and resistance to the skeleton and simultaneously assuring capability of adaptation and remodelling. Knowing the properties of such a structure down to the micro-scale is of utmost importance, not only for the design of effective biomimetic materials but also to be able to detect pathological alterations in material properties, such as micro-fractures or abnormal tissue remodelling. The Brillouin and Raman micro-spectroscopic (BRmS) approach has the potential to become a first-choice technique, as it is capable of simultaneously investigating samples’ mechanical and structural properties in a non-destructive and label-free way. Here, we perform a mapping of cortical and trabecular bone sections of a femoral epiphysis, demonstrating the capability of the technique for discovering the morpho-mechanics of cells, the extracellular matrix, and marrow constituents. Moreover, the interpretation of Brillouin and Raman spectra merged with an approach of data mining is used to compare the mechanical alterations in specimens excised from distinct anatomical areas and subjected to different sample processing. The results disclose in both cases specific alterations in the morphology and/or in the tissue chemical make-up, which strongly affects bone mechanical properties, providing a method potentially extendable to other important biomedical issues. 相似文献
138.
Federico Simone Gobber Elisa Fracchia Roberto Spotorno Alessandro Fais Diego Manfredi 《Materials》2021,14(22)
Metal–metal composites are a class of composite materials studied for their high ductility and strength, but their potential applications are currently limited by the complex manufacturing processes involved. Electro-sinter-forging (ESF) is a single-pulse electro discharge sintering technique that proved its effectiveness in the rapid sintering of several metals, alloys, and composites. Previous studies proved the processability of Ti and AlSi10Mg by ESF to produce metal–metal composites and defined a correlation between microstructure and processing parameters. This paper presents the wear and corrosion characterizations of two metal–metal composites obtained via ESF with the following compositions: 20% Ti/80% AlSi10Mg and 20% AlSi10Mg/80% Ti. The two materials showed complementary resistance to wear and corrosion. A higher fraction of AlSi10Mg is responsible for forming a protective tribolayer in dry-sliding conditions, while a higher fraction of Titanium confers improved corrosion resistance due to its higher corrosion potential. 相似文献
139.
Fluoride-substituted apatites were synthesized by the standard sol-gel method and then calcined at three different temperatures: 800 °C, 1000 °C, and 1200 °C. Using a similar method, hydroxyapatite was synthesized and used as a reference material. The obtained powders were characterized by physicochemical methods: powder X-ray diffractometry, Raman spectroscopy, transmission electron microscopy, and solid-state nuclear magnetic resonance. All these methods allowed to identify additional α-TCP phase (tricalcium phosphate) in the HAP samples heated at 1000 °C and 1200 °C while fluoridated apatites turned out to be thermally stable. Moreover, Raman spectroscopy and NMR allowed to establish that the powders substituted with fluoride ions are not pure fluorapatite and contain OH- groups in the crystal structure. All the obtained materials had crystals with a shape similar to that of biological apatite. 相似文献
140.
Enrico Boccaleri Cristina Marzetti Giorgio Celoria Claudio Cassino Geo Paul Ivana Miletto Enrica Gianotti 《Materials》2021,14(20)
Pharmaceutical active compounds, including hundreds of different substances, are counted among the emerging contaminants in waterbodies, whose presence raises a growing concern for the ecosystem. Drugs are metabolized and excreted mainly through urine as an unchanged active ingredient or in the form of metabolites. These emerging contaminants are not effectively removed with the technologies currently in use, making them a relevant environmental problem. This study proposes the treatment of urine and water at the source that can allow an easier removal of dissolved drugs and metabolites. The treatment of synthetic urine, with dissolved ibuprofen as a model compound, by adsorption, using various classes of inorganic materials, such as clays, hierarchical zeolites and ordered mesoporous silica (MCM-41), is presented. A multi-technique approach involving X-ray powder diffraction, solid-state NMR, UV-Vis and Raman spectroscopies was employed to investigate the adsorption process in inorganic adsorbents. Moreover, the uptake, the ensuing competition, the efficiency and selectivity as well as the packing of the model compound in ordered mesoporous silica during the incipient wetness impregnation process were all thoroughly monitored by a novel approach, involving combined complementary time-resolved in situ 1H and 13C MAS NMR spectroscopy as well as X-ray powder diffraction. 相似文献