An atomic force microscopy approach for assessment of particle density applied to single spray-dried carbohydrate particles

To evaluate an atomic force microscopy (AFM) approach for effective density analysis of single spray dried carbohydrate particles in order to investigate the internal structure of the particles. In addition, the AFM method was compared to an established technique, that is gas pycnometry. Resonant fr...

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Bibliographic Details
Published in:Journal of pharmaceutical sciences 2007-04, Vol.96 (4), p.905-912
Main Authors: Elversson, Jessica, Andersson, Karin, Millqvist-Fureby, Anna
Format: Article
Language:English
Subjects:
Amorphous
atomic force microscopy (AFM)
Biological and medical sciences
Carbohydrates - chemistry
Chemistry
Crystallization
FARMACI
Gas pycnometry
General pharmacology
Kemi
Medical sciences
Microparticles
Microscopy, Atomic Force - methods
Morphology
NATURAL SCIENCES
NATURVETENSKAP
Particle density
Particle Size
Pharmaceutical technology. Pharmaceutical industry
Pharmacology. Drug treatments
PHARMACY
Spray drying
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Summary:To evaluate an atomic force microscopy (AFM) approach for effective density analysis of single spray dried carbohydrate particles in order to investigate the internal structure of the particles. In addition, the AFM method was compared to an established technique, that is gas pycnometry. Resonant frequency AFM analysis was employed for determination of the mass of individual particles of spray-dried lactose, mannitol, and a mixture of sucrose/dextran (4:1). The effective particle density was calculated using the diameter of the spherical particles obtained from light microscopy. The apparent particle density was further analyzed with gas pycnometry. It was observed by microscopy that particles appeared either “solid” or “hollow.” A solid appearance applied to an effective particle density close to the true density of the material, whereas a density around 1 g/cm3 corresponded to a hollow appearance. However, carbohydrates, which crystallized during spray drying, for example, mannitol appeared solid but the average effective particle density was 0.95 g/cm3, indicating a continuous but porous structure. AFM measurements of effective particle density corroborate the suggestion of differences in particle structure caused by the varying propensity of carbohydrates to crystallize during spray drying, resulting in mainly either amorphous hollow or crystalline porous particles.
ISSN:0022-3549
1520-6017
1520-6017
DOI:10.1002/jps.20795