title: Supramolecular structure of 5-aminosalycilic acid/halloysite composites.
abstract: This paper assesses the supramolecular structure of nanocomposites prepared by including the anti-inflammatory drug 5-aminosalycilic acid in halloysite nanotubes. Halloysite tubes have sub-micron individual lengths with outer diameters ∼0.1 µm, as observed by FESEM. The mercury intrusion plots showed bimodal profiles with pore dimensions ∼10 and 0.06 µm. X-ray diffraction and thermogravimetric results revealed changes in the hydration form of the clay after the interaction. The groups associated to the interaction were studied by FTIR. The location of the drug in the composites was determined after uranium staining of its amino groups by X-EDS microanalysis coupled with HREM. The drug was located both inside and on the surface of the halloysite nanotubes. These results confirm the occurrence of two concomitant interaction mechanisms: rapid adsorption of 5-ASA at the external halloysite surface followed by slow adsorption of the drug inside the tubes.
authors.affiliation: Faculty of Pharmacy, Department of Pharmacy and Pharmaceutical Technology, University of Granada, Granada, Spain.
authors.forename: Maria-Teresa
authors.initials: MT
authors.lastname: Viseras
authors.forename: Carola
authors.initials: C
authors.lastname: Aguzzi
authors.forename: Pilar
authors.initials: P
authors.lastname: Cerezo
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cultrone
authors.forename: Cesar
authors.initials: C
authors.lastname: Viseras
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D000077215:Clay; D019804:Mesalamine / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D000538:Aluminum Silicates; D000894:Anti-Inflammatory Agents, Non-Steroidal; D019804:Mesalamine; D000077215:Clay