Identification of an amorphous-amorphous ...
Document type :
Article dans une revue scientifique: Article original
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Title :
Identification of an amorphous-amorphous two-step transformation in indomethacin embedded within mesoporous silica
Author(s) :
Malfait, Benjamin [Auteur]
Paccou, Laurent [Auteur]
Correia, Natalia [Auteur]
Guinet, Yannick [Auteur]
Hédoux, Alain [Auteur]
Paccou, Laurent [Auteur]
Correia, Natalia [Auteur]
Guinet, Yannick [Auteur]
Hédoux, Alain [Auteur]
Journal title :
Microporous and Mesoporous Materials
Volume number :
328
Pages :
111502
Publication date :
2021-10-16
English abstract : [en]
A very unusual amorphous-amorphous two-step transformation was observed in indomethacin confined within MCM-41 mesoporous silica, via isothermal and non-isothermal routes. Isothermally, at room temperature, the first step ...
Show more >A very unusual amorphous-amorphous two-step transformation was observed in indomethacin confined within MCM-41 mesoporous silica, via isothermal and non-isothermal routes. Isothermally, at room temperature, the first step corresponds to the 1-dimensional growth of γ-nanocrystals along the mesoporous channels from pre existing incipient nuclei. In the second step nanocrystals slowly transform into an undercooled liquid state structurally different from the original liquid and characterized by a higher molecular mobility. The instability of nanocrystals detected in the continuation of the isothermal growth was explained as resulting from a very high specific area of nanocrystals imposed by the geometrical confinement when the size of nanocrystals along the channels achieves a dimension much larger than the channel diameter. The mechanism of the slow dissolution of nanocrystals was identified as similar to a digestive ripening process, inverse to the Ostwald ripening, by which larger clusters dissolve to the detriment of smaller ones. This two-step transformation was also observed upon heating. In this case, the growth of nanocrystals is followed by a melting far below the melting point of γ-crystals, according to Gibbs-Thomson effects. This study shows that the original amorphous form of indomethacin transforms into a second amorphous form via the transient growth of nanocrystals which become unstable via two different mechanisms induced by the geometrical confinement.Show less >
Show more >A very unusual amorphous-amorphous two-step transformation was observed in indomethacin confined within MCM-41 mesoporous silica, via isothermal and non-isothermal routes. Isothermally, at room temperature, the first step corresponds to the 1-dimensional growth of γ-nanocrystals along the mesoporous channels from pre existing incipient nuclei. In the second step nanocrystals slowly transform into an undercooled liquid state structurally different from the original liquid and characterized by a higher molecular mobility. The instability of nanocrystals detected in the continuation of the isothermal growth was explained as resulting from a very high specific area of nanocrystals imposed by the geometrical confinement when the size of nanocrystals along the channels achieves a dimension much larger than the channel diameter. The mechanism of the slow dissolution of nanocrystals was identified as similar to a digestive ripening process, inverse to the Ostwald ripening, by which larger clusters dissolve to the detriment of smaller ones. This two-step transformation was also observed upon heating. In this case, the growth of nanocrystals is followed by a melting far below the melting point of γ-crystals, according to Gibbs-Thomson effects. This study shows that the original amorphous form of indomethacin transforms into a second amorphous form via the transient growth of nanocrystals which become unstable via two different mechanisms induced by the geometrical confinement.Show less >
Language :
Anglais
Peer reviewed article :
Oui
Audience :
Non spécifiée
Administrative institution(s) :
Université de Lille
CNRS
INRA
ENSCL
CNRS
INRA
ENSCL
Collections :
Research team(s) :
Matériaux Moléculaires et Thérapeutiques
Submission date :
2022-01-28T08:12:08Z