Aims of this study were to synthesize methoxy poly
(ethylene glycol)-b-poly (ε-caprolactone) diblock copolymers
(MPEG-b-PCL) and to prepare their surfactant-free nanospheres by
modified-spontaneous emulsification solvent diffusion method for controlled
release delivery of hydrophobic drug. Ibuprofen was used as a poorly-water
soluble model drug. Influences of PCL block length and drug loading content
on nanosphere characteristics and drug release behaviors were evaluated.
The prepared nanospheres with and without drug loading were found of spherical
shape and smooth surface with size less than 150 nm. FTIR spectroscopy
and differential scanning calorimetry studies showed the interactions
between ibuprofen and MPEG-b-PCL had occurred, suggesting the well
distribution of ibuprofen into nanosphere matrices. An increase in the
PCL block length led to a decrease in drug encapsulation efficiency. The
drug release profiles were biphasic with a fast burst release followed
by a slow one. The drug release rates from the MPEG-b-PCL nanospheres
strongly depended on the PCL block length and the drug loading content.