AFM investigation as a key analysis to determine the drug location in electrospun drug delivery systems

The current study analyzes the possibility of determining the drug location in electrospun polymeric matrices and forecasting the release kinetics of drug delivery systems. Electrospun membranes made of Polycaprolactone (PCL) loaded with Dacarbazine (the drug of choice for the treatment of melanoma) and with AuM1 (a promising synthetic Au-based complex recently proposed for antitumoral treatments) were successfully prepared. Atomic Force Microscopy (AFM) analysis was performed on various membranes, highlighting the relevance of investigating the 3-dimensional topology of the membranes for understanding the release kinetic. The produced mats are similar for all membranes, but significant differences in the microscopic roughness wall between the systems loaded with AuM1 and Dacarbazine were observed. For AuM1, which has a low affinity with the PCL matrix, the complex aggregates on the nanofibers' external walls, consequently increasing the roughness and causing a high burst in the first hours of release. On the other hand, Dacarbazine is successfully included in the bulk core of the PCL nanofibers. Thus, the release kinetics is diffusive and well described by the Fick model.