Polymeric nanocapsules and nanospheres for encapsulation and long sustained release of hydrophobic cyanine-type photosensitizer

Owing to the nanoprecipitation methodology IR-780 loaded PLA and PCL nanospheres and nanocapsules (stabilized by Cremophor EL and containing, in the case of nanocapsules, coconut oil as the liquid core) were fabricated and their colloidal stability, encapsulated cargo release and photoactivity were assessed. DLS measurements and AFM confirmed, respectively, the obtained nanoparticles diameter below 150 nm as well as their morphology and shape. Doppler electrophoresis provided the ζ-potential of the studied nanoobjects while UV–vis spectroscopy made it possible to determine the encapsulation efficiency (about 90%) of IR-780 and to establish its release characteristics. Nanofiltration and freeze drying approaches prior to storage in the dark provided the best conditions’ parameters for the near monodispersed nanocarriers of cyanine. In order to evaluate the photoactivity of IR-780, both as native and encapsulated in the obtained nanocarriers, photobleaching and ROS detection (by means of spectrophotometrical measurements) were successfully performed. The applied methodologies made it possible to obtain successfully stable and long sustained IR-780 loaded monodispersed oil-cored nanocapsules and nanospheres both under physiological conditions, and after freeze drying procedure.