Dextran–rare earth ion interactions. II. Solid‐state characteristics

Abstract

ABSTRACT:The solid-state characteristics of dextran complexes precipitated from aqueous solutions with three different light-lanthanoid cations (La 3ϩ , Ce 3ϩ , and Nd 3ϩ ) were investigated by spectroscopic and thermal methods. Spectroscopic characterization was realized by the comparative interpretation of the FTIR spectra, and the complexes were found to involve both ligating water and dextran through its O(2) and O(3) atoms. Remarkable spectral changes were noted, particularly with La 3ϩ , which parallels the previous solution studies. The order of La 3ϩ Ͼ Ce 3ϩ Ͼ Nd 3ϩ was determined to display the tendency of the Ln 3ϩ ion in favor of dextran throughout the competition between water and dextran. The thermal stabilities of the complexes were examined by thermogravimetry (TG), differential TG, and DSC methods. The decomposition steps and temperatures were assigned with respect to the lanthanoid ions used. The TG and DSC results indicated that the complexes are less stable thermally than dextran itself with increasing thermal stabilities in the order of La 3ϩ Ͻ Ce 3ϩ Ͻ Nd 3ϩ in their anhydrous states.

Eudragit-coated dextran microspheres of 5-fluorouracil for site-specific delivery to colon

“…A sharp endotherm was observed for 5-FU at 280 C, corresponding to its melting transition temperature (Figure 4a). In case of dextran, broad endothermic peak observed between 25 and 120 C is due to the evaporation of residual water and peak was observed at 230 C, corresponding to its glass transition temperature (Figure 4b) (Zumreoglu-Karan et al, 2002). However, the melting endotherm also appeared in the DSC thermogram of uncoated dextran microspheres although less intense (Figure 4c).…”

Multi-Bit Biomemristic Behavior for Neutral Polysaccharide Dextran Blended with Chitosan

“…It could be seen that chitosan, dextran, and their nanocomposites experienced three thermal degradation processes during the 40–600 °C heating treatment. The first decomposition in all the TGA thermograms from 40 °C to 170 °C was attributed to the water weight loss due to the polymer possesses’ hydroscopic nature [ 28 ]. The second decomposition for chitosan started at 287 °C and ended at 371 °C, while the dextran started to decompose at 300 °C and stopped decomposing at 348 °C.…”

Fluorescent silk fibroin nanoparticles prepared using a reverse microemulsion

“…Therefore, the methanol treatment removed the surfactants used as templates and simultaneously induced the formation of β-sheet structures in the silk fibroin nanoparticles. 27 Given that the silk fibroin nanoparticles are nano-scale sized and can be used to encapsulate rhodamine B, they have potentially widespread applicability in molecular imaging and bioassays.…”