Photo-oxidative action in MCF-7 cancer cells induced by hydrophobic cyanines loaded in biodegradable microemulsion-templated nanocapsules

Searching for photodynamic therapy-effective nanocarriers which enable a photosensitizer to be selectively delivered to tumor cells with enhanced bioavailability and diminished dark cytotoxicity is of current interest. We have employed a polymer-based nanoparticle approach to encapsulate the cyanine-type photosensitizer IR-780 in poly(n-butyl cyanoacrylate) (PBCA) nanocapsules. The latter were fabricated by interfacial polymerization in oil-in-water (o/w) microemulsions formed by dicephalic and gemini saccharide-derived surfactants. Nanocarriers were characterized by SEM, AFM and DLS. The efficiency of PBCA nanocapsules as a potential system of photosensitizer delivery to human breast cancer cells was established by dark and photocytotoxicity as the function of the cellular mitochondria. The photodynamic effect of cyanine IR-780 was determined by investigation of oxidative stress markers. The nanocapsules were the main focus of our studies to examine their cellular uptake and dark and photocytotoxicity as the function of the cellular mitochondria as well as oxidative stress markers (i.e., lipid peroxidation and protein damage) in MCF-7/WT cancer cells. The effects of encapsulated IR-780 were compared with those of native photosensitizer. The penetration of the nanocapsules into cancer cells was visualized by CLSM and their uptake was estimated by FACS analysis. Cyanine IR-780 delivered in PBCA nanocapsules to MCF-7/WT cells retains its sensitivity upon photoirradiation and it is regularly distributed in the cell cytoplasm. The intensity of the photosensitizer-generated oxidative stress depends on IR-780 release from the effective uptake of polymeric nanocapsules and seems to remain dependent upon the surfactant structure in o/w microemulsion-based templates applied to nanocapsule fabrication.