Membrane transport enhancement of chlorin e6-polyvinylpyrrolidone and its photodynamic efficacy on the chick chorioallantoic model

We have determined the influences of polyvinylpyrrolidone (PVP) on the topical delivery of chlorin e6 (Ce6) in malignant bladder cells. The chick chorioallantoic membrane (CAM) was used to model the tumor spheroids that resemble small residual bladder tumors prior to vascularization. Macroscopic fluorescence imaging showed that Ce6-PVP-induced fluorescence had a higher sensitivity and specificity for delineating tumor from the adjacent normal CAM compared to Ce6 alone. Nonlinear regression analyses have shown that Ce6-PVP has a longer half-life in the tumor compared to Ce6. The uptake ratio of Ce6-PVP was found to have a 2-fold increase across the CAM when compared to that of Ce6, indicating that PVP was able to facilitate diffusion of Ce6 across the membrane. Confocal laser scanning microscopy further confirmed that Ce6-PVP has better penetration in the CAM as well as in the tumor cells compared to Ce6. The present work contributes to our understanding of the Ce6-PVP drug–polymer system by demonstrating for the first time that the presence of PVP facilitates the transport of Ce6 across the chorioallantoic membrane. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)