The Application of Polarization Microscopy in Observing the Dissolution Processes of Electrospun Drug-Loaded Nanofibers

This paper demonstrates that polarization microscopy can be a very useful tool for observing the dissolution processes of electrospun drug-loaded nanofiber mats, and thus providing useful information for preparing drug-loaded nanofibers with high quality. With icariin as the model active pharmaceutical ingredient and PVP K30 and K60 as filament-forming matrix, three different types of drug-loaded nanofibers have been successfully prepared using electrospinning processes. The samples for observation were prepared by first collecting the nanofibers on a slide glass for about 10s and later a drop of water was put on them. The results demonstrated that (1) the polymer PVP K30 could "lead" the icariin to dissolve directly when a 10% (w/w) content was presented in the fibers; (2) while the icariin molecules would underwent a molecule-to-crystal process and then dissolved when a 30% (w/w) content was presented in the PVP K30 fibers; and (3) when weight PVP K60 was used, the icariin would dissolve with polymer molecules even with a higher content of icariin of 28.57%, but underwent a gelating process. Thus if nanofibers would be used for fast drug delivery systems, hydrophilic polymers with a relatively low molecular weight should be suitable and the drug content has an upper limitation. Our research offers a simple, easy but useful optical method to achieve useful information for preparing high quality drug-loaded nanofibers using electrospinning process.