AFM study of hydrophilicity on acetaminophen crystals

Kalyana C. Pingali, Troy Shinbrot, Alberto Cuitino, Fernando J. Muzzio, Eric Garfunkel, Yevgeny Lifshitz, Adrian B. Mann

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5 Citations (Scopus)

Abstract

Pharmaceutical powder processing is notoriously subject to unpredictable jamming, sticking and charging disturbances. To unveil the material science underlying these effects, we use atomic force microscopy (AFM) on a common pharmaceutical, acetaminophen (APAP). Specifically, we study surface adhesion and morphology as a function of relative humidity (RH) for monoclinic acetaminophen, using both plain AFM tips and tips functionalized to be hydrophobic or hydrophilic. Results indicate that the (0 0 1) crystal face exhibits significantly higher adhesion (surface potential) than the other crystal faces. For all the faces clear peaks in adhesion occur at 50-60% RH when they are examined using hydrophilic tips. The surface morphology of some facets showed a strong dependence on RH while others showed little or no significant change. In particular, the morphology of the (1 -1 0) faces developed large terraces at high humidity, possibly due to deliquescence followed by recrystallization. These results confirm the hypothesis that different crystal facets exhibit distinct surface potentials and morphology that change with environmental exposure. The work suggests that future studies of powder behaviors would benefit from a more detailed modeling of crystal surface contact mechanics.

Original languageEnglish
Pages (from-to)184-190
Number of pages7
JournalInternational Journal of Pharmaceutics
Volume438
Issue number1-2
DOIs
Publication statusPublished - Nov 15 2012

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Keywords

  • AFM
  • Humidity
  • Hydrophilic
  • Hydrophobic
  • Organic crystals

ASJC Scopus subject areas

  • Pharmaceutical Science

Cite this

Pingali, K. C., Shinbrot, T., Cuitino, A., Muzzio, F. J., Garfunkel, E., Lifshitz, Y., & Mann, A. B. (2012). AFM study of hydrophilicity on acetaminophen crystals. International Journal of Pharmaceutics, 438(1-2), 184-190. https://doi.org/10.1016/j.ijpharm.2012.08.029