Novel Self-Assembled Nanoparticles of Testosterone-Modified Glycol Chitosan and Fructose Chitosan for Controlled Release

Glycol chitosan (GC) and fructose chitosan (FC) were linked to testosterone hemisuccinate through water-soluble carbodiimide activation. The resulting conjugates formed self-assembled nanoparticles in aqueous solution with particle sizes of 245-332 nm as measured by dynamic light scattering and testosterone content of 3% and 8% (w/w) for GC and FC conjugates, respectively. The particles appeared as 45-90 nm almost spherical nanoparticles when studied by scanning and transmission electron microscopy upon drying. Particles were also characterized by differential scanning calorimetry and wide-angle X-ray diffraction. Drug linking to both types of chitosan derivatives was confirmed by FTIR spectroscopy and proton NMR. In vitro testosterone release studies performed in water at acid pH indicated that the drug release was dependent on the acidity of the solution, testosterone content and the chitosan matrix. Almost constant release rates were observed initially. These results indicate that the obtained nanoparticles could be good candidates for testosterone delivery to humans and animals.