Characteristics and properties of nanospheres co-loaded with lipophilic and hydrophilic drug models

The biphasic nature of polymeric nanospheres prepared by the double emulsion method was exploited to co-encapsulate lipophilic and hydrophilic molecules. All-trans retinoic acid (RA) was selected as a lipophilic drug model whereas calf thymus DNA was chosen as a water-soluble model. Simultaneous quantification of the loaded ingredients was achieved by a second derivative spectrophotometric technique. In addition, prepared batches were fully characterized by atomic force microscopy, porosity measurement, and thermal analysis. Finally, the angiosuppressive action of loaded RA was assessed in a tissue culture model. A blend of either polycaprolactone-multiblock copolymer or the microemulsion technique improved DNA-loading, whereas RA-loading was decreased. DSC data were helpful in explaining the initial phase of RA release from the nanospheres. Along with affinity for the polymeric matrix, the microporosity of nanospheres seemed to play an important role in the diffusion rate and release profiles of both loaded drug models in aqueous medium. The anti-angiogenic effect of microencapsulated RA was generally more pronounced than that of the free drug, and its inhibitory action was maintained for the 14-day study period. Moreover, a relationship was observed between the release profiles and anti-angiogenic properties of the batches tested.