N,06-partially acetylated chitosan nanoparticles hydrophobically-modified for controlled release of steroids and vitamin E
Pérez Quinones, J.; Gothelf, K. V.; Kjems.; Caballero, A. M. H.; Schmidt, C.; Covas, C. P.
Carbohyd. Polym. 2013, 91, 143-151, DOI: 10.1016/j.carbpol.2012.07.080
- Center of Natural Products, Faculty of Chemistry, University of Havana, Havana, CUBA
- Interdisciplinary Nanoscience Center (iNANO)/Department of Chemistry, Aarhus University, Aarhus, DANEMARK
- Interdisciplinary Nanoscience Center (iNANO)/Department of Molecular Biology, Aarhus University, Aarhus, DANEMARK
- Instituto de Estudios Biojuncionales/Dpto Química Física II, Facultad de Farmacia, Universidad Complutense de Madrid, ESPAGNE
- Department of Chemistry, University of Paderborn, Paderborn, ALLEMAGNE
- Center of Biomaterials, University of Havana, Havana, CUBA
Diosgenin, two synthetic analogs of brassinosteroids, testosterone and DL-α-tocopherol were covalently linked to synthetic water-soluble N,O6-partially acetylated chitosan, for their controlled release. Drug linking was confirmed by FTIR spectroscopy and proton NMR. Conjugates were also characterized by differential scanning calorimetry and wide-angle X-ray diffraction. These conjugates formed self-assembled nanoparticles in aqueous solution with particle sizes ranging from 197 to 358 nm and drug contents between 11.8 and 56.4% (w/w). Spherical 30-60 nm nanoparticles were observed by scanning electron microscopy and transmission electron microscopy upon drying. In vitro release studies performed at acid pH indicated a drug release dependence on substitution degree and particle sizes. Almost constant release rates were observed during the first 6-8 h. Brassinosteroids-modified nanoparticles showed good agrochemical activity in radish seeds bioassay at 10―1 to 10―4 mg mL―1. Tocopheryl-modified nanoparticles exhibited radical scavenging activity in DPPH test.