Protoporphyrin IX (PpIX) loaded PLGA nanoparticles for topical Photodynamic Therapy of melanoma cells.

INTRODUCTION: Nanoparticles (Np) can increase drug efficacy and overcome problems associated with solubility and aggregation in a solution of PpIX. PURPOSE: Evaluate if Np interferes in the photophysical and photobiological capacity of the PpIX comparing with free PpIX intended for topical PDT of melanoma. METHODS: In vitro photophysical evaluation of Np-PpIX was carried out through singlet oxygen (1O2) quantum yield. In vitro cytotoxicity and phototoxicity assays have used murine melanoma cell culture. RESULTS: The quantum yield of singlet oxygen has shown that Np did not influence the formation capacity of this reactive species. In the dark, all PpIX-Nps concentrations were less cytotoxic compared to free drugs. At a higher light dose (1500 mJ.cm2) 3.91 µg / mL PpIX had similar % viable cells for free and Np (∼34 %) meaning Nps did not interfere in the photodynamic effect of PpIX. However, at 7.91 µg / mL the phototoxicity increased for both (5.8 % viable cells for free versus 21.7 % for Nps). Despite the higher phototoxicity of free PpIX at this concentration, greater cytotoxicity in the dark was obtained (∼49 % viable cells for free versus ∼90.6 % Np) which means Nps protect the tumor tissue from the photodynamic action of PpIX. CONCLUSIONS: Np is a potential delivery system for melanoma skin cancer, since it maintained the photophysical properties of PpIX and excellent in vitro phototoxicity effect against melanoma cells, reducing cell viability ∼80 % (7.91 µg / mL PpIX in Nps) and provides safe PDT (due to lower cytotoxicity in the dark).

PLGA nanoparticles as delivery systems for protoporphyrin IX in topical PDT: cutaneous penetration of photosensitizer observed by fluorescence microscopy.

Poly(D,L lactic-co-glycolic acid) (PLGA) based nanoparticles (NPs) are proposed for topical delivery of Protoporphyrin IX (PpIX) in Photodynamic Therapy of skin cancers. PpIX loaded into PLGA NPs showed nanometric average diameter (-280 nm), spherical forms and pH - 5.7, conditions suitable for topical application. In vitro release of PpIX from NPs was sustained up to 24 hr with a burst release effect of about 37.0% at 2 hr. Penetration and distribution of PpIX in hairless mice skin was determined by fluorescence microscopy 8 or 24 hrs after application of PpIX-NPs in the animals. At 24 hours, areas located in deeper regions of the skin were found to have greater fluorescence intensity. The finding indicates a localized effect of PpIX-NPs in the epidermis plus dermis--a site of action for topical PDT--and suggests a potential use of PpIX-NPs in PDT associated to skin cancer treatments.