We investigated and monitored in situ the wetting and dissolution properties of polymeric\nnanofibers and determined the solid-state of a drug during dissolution. Piroxicam (PRX) was used\nas a low-dose and poorly-soluble model drug, and hydroxypropyl methylcellulose (HPMC) and\npolydextrose (PD) were used as carrier polymers for electrospinning (ES). The initial-stage dissolution\nof the nanofibers was monitored in situ with three-dimensional white light microscopic interferometry\n(SWLI) and high-resolution optical microscopy. The physical solid-state characterization of nanofibers\nwas performed with Raman spectroscopy, X-ray powder diffraction (XRPD), and scanning electron\nmicroscopy (SEM). We showed that PRX recrystallizes in a microcrystalline form immediately after\nwetting of nanofibers, which could lead to enhanced dissolution of drug. Initiation of crystal\nformation was detected by SWLI, indicating: (1) that PRX was partially released from the nanofibers,\nand (2) that the solid-state form of PRX changed from amorphous to crystalline. The amount,\nshape, and size of the PRX crystals depended on the carrier polymer used in the nanofibers and\ndissolution media (pH). In conclusion, the present nanofibers loaded with PRX exhibit a quasi-dynamic\ndissolution via recrystallization. SWLI enables a rapid, non-contacting, and non-destructive method\nfor in situ monitoring the early-stage dissolution of nanofibers and regional mapping of crystalline\nchanges (re-crystallization) during wetting. Such analysis is crucial because the wetting and\ndissolution of nanofibers can greatly influence the performance of nanofibrous drug delivery systems\nin pharmaceutical and biomedical applications.\n\n\n.
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