Illinois State University, Department of Chemistry, Normal, IL 61761
The photophysical properties of a series of three porphyrins – Monoacenaphthoporphyrin (ANP), Adj-Diacenaphthoporphyrin (ADP), and Opp-Diacenaphthoporphyrin (ODP) - have been studied to evaluate these photosensitizers for potential use as Photodynamic Therapy (PDT) drugs. This porphyrin series has highly red-shifted absorbance spectra, making them suitable photosensitizers. Singlet Oxygen yields for the series range from 0.38 to 0.88, which shows that the orientation of the fused naphthalene unit can be used to tune the photophysical properties over a wide range of values. These porphyrins have very low water solubility, however, and would require a transport system for use in PDT. Thus, we present equilibrium studies of the porphyrins’ incorporation into phosphatidylcholine-based liposomes. Association constants for this series are on the order of 103-104 M-1. Addition of cholesterol to the liposomes has little effect on the association constants. Fluorescence polarization data shows that the acenaphthoporphyrins are buried deep into the nonpolar liposome bilayer as expected. Confocal microscopy shows that these liposomes are successful in transporting the photosensitizers into the parasite Leishmania tarentola.
[Abstract (DOC)]