Mechanism of Polyvinylpyrrolidone-coated Norcantharidin Chitosan Nanoparticles

The present study aims to investigate the drug-loaded mechanism of ion–cross-linked nanoparticles (NPs) in the presence of polyvinylpyrrolidone K30 (PVP K30) and set up the optimal PVP-coated norcantharidin (NCTD) chitosan NPs method. We compared and assessed PVP-coated norcantharidin chitosan NP (PVP-NCTD-NP) with norcantharidin chitosan nanoparticles (NCTD-CS-NP) using Xray diffraction (XRD) and atomic force microscopy (AFM). The results show that both kinds of nanoparticles were spherical, with an average size ranging from 100 nm to 250 nm. However, the entrapment efficiency of the PVP-NCTD-NP (67.33% ± 1.41%) was higher than that of NCTD-CS-NP (52.61% ± 1.28%), probably because of the PVP-coating effect on the surface of the NPs. The cumulative release percentages of PVP-NCTD-NP in vitro within 2 h, 4 h, and 6 h were 74%, 89%, and 92%, respectively. Those of NCTD-CS-NP within 40 min and 190 min were 67% and 90%, respectively. Thus, the PVP-NCTD-NP with dual physical drug-loaded mechanisms (physical encapsulation and coating of PVP) possessed higher drug content and showed longer sustained release.