Investigation of the stability of PEG stearate-coated Chitosan nanoparticles loaded with levothyroxine

Document Type : Original Research Paper


Department of Chemistry, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran



We report the formation and characterization of PEG stearate (PEG)-coated
Chitosan (CS) nanoparticles. Chitosan nanoparticles were synthesized using
tripolyphosphate (TPP) via the ionic crosslinking method. Preparation of PEG
Stearate-grafted Chitosan is essential to improve the biocompatibility and water
solubility of Chitosan. The size and morphologies of Chitosan nanoparticles
were measured with transmission electron microscopy and scanning electron
microscopy. Sizes of Chitosan nanoparticles were in the range of 150-200
nm. The particle size and zeta potential of PEG Stearate-coated Chitosan
had been measured at 187.5 nm by Photon Correlation Spectroscopy (PCS).
Drug entrapment efficiency (EE) was obtained to be 99%. The purpose of the
present work was to develop a new nanoparticle system, consisting of polymeric
nanoparticles coated with PEG Stearate. The modification procedure led to a
reduction in the zeta potential values, varying from +43.3 mV for the uncoated
particles to +20 mV for that of PEG Stearate-coated Chitosan. PEG Stearate
coated nanoparticles were more stable due to their polymer coating layer which
prevented aggregation of Chitosan nanoparticles. Consequently, it is possible that
the PEG Stearate surrounds the particles reducing the attachment of enzymes
and further degradation of the polymeric cores. Properties nanoparticles were
affected by the preparation variables and the coating layer. Chitosan nanoparticles
showed a smooth surface and globular shape. In this study, we explored the
release behavior of levothyroxine was affected by the coating layer. Coating
surface leads to a decrease in the burst release effect compared to uncoated
nanoparticle due to gradual release of adsorbed levothyroxine from PEG coated
Chitosan nanoparticles.