Preparation and Characterization of Kynurenic Acid Occluded in Sol-Gel Silica and SBA-15 Silica as Release Reservoirs

Figure 7

Micrographs from TEM studies of the silica-based materials. Cylindrical tubes with hexagonal mouths were observed in SBA-15-KYNA samples (a–c), while aggregated nanoparticles and large spaces were present in SiO₂-KYNA samples.

(a)

(b)

(c)

(d)

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(f)