Investigation on the uptake and release ability of β-cyclodextrin functionalized Fe3O4 magnetic nanoparticles by methylene blue

beta-cyclodextrin functionalized magnetic nanoparticles (beta-CD-MNPs) having a core-shell structure were fabricated with a layer-by-layer method by combining 3-aminopropyl triethoxysilane coated magnetic Fe3O4 nanoparticles (AP-MNPs) with 6-O-toluenesulfonyl-P-cyclodextrin (6-TsO-beta-CD) at 70 degrees C. The characterization by transmission electron microscopy revealed beta-CD-MNPs having an average diameter of 12 +/- 2 nm and an average hydrodynamic diameter of 56.8 nm in aqueous solution by dynamic light scattering. The beta-CD grafting was confirmed by Fourier-Transformed Infrared spectroscopy, and the amount of beta-CD grafted on MNPs was determined as 60 mg/g by thermogravimetric analysis. The uptake and release ability of beta-CD-MNPs was investigated using methylene blue (MB) as a biological staining dye by spectrophotometric method. The results showed that the uptake and release were greatly influenced by the pH value of dye solution, with a maximum loading capacity of 78.4 mg/g under pH = 8 at 25 degrees C, and the release was easily achieved at 73% within the first hour at physiological condition. The adsorption isotherms were examined by Langmuir and Freundlich models, and the satisfactory fitting to the Langmuir model suggested the adsorption on beta-CD-MNPs as a mono-layer coverage. (C) 2015 Elsevier B.V. All rights reserved.