Triple dyes-labeled polyelectrolyte microcapsules@gold nanoparticles for anthocyanins delivery as topical administration for tumor skin cells

Over the past decades a great incidence of melanoma was recorded, maybe also because the atmosphere loses more and more of its protective filter function and more solar UV radiation reaches the Earth's surface. Anthocyanins... [ view full abstract ]

Over the past decades a great incidence of melanoma was recorded, maybe also because the atmosphere loses more and more of its protective filter function and more solar UV radiation reaches the Earth's surface.

Anthocyanins are natural pigments with remarkable health benefits against cancer. Unfortunately, anthocyanins are very sensitive to environmental conditions, such as alkaline pH, light or oxigen and therefore are easily degraded. To increase their stability and obtain an efficient release, a novel multifunctional delivery system targeted towards tumor skin cells should be urgently designed.

Herein, triple dyes-labeled polyelectrolyte microcapsules were firstly obtained through layer by layer assembly technique with nearly sherical shape and a diameter of 1 ± 0.1 μm, as proved by dynamic light scattering results and transmission electron microscopy observation. Subsequently, gold nanoparticles (like spheres, bipyramids and rods) were employed to be encapsulated into shells of microcapsules for an efficient release of the loaded drug under laser radiation.

The encapsulation efficiency of anthocyanins was confirmed through the cromatography technique coupled with mass spectrometry (LC –ESI(+)-MS).

The as-designed microcapsules were then labeled with a pH insensitive fluorophore as rhodamine B isothiocyanate or two pH sensitive fluorophores as oregon green isothiocyanate and fluorescein isothiocyanate, to establish their specific localization inside the tumor skin cells.

Notably, our proposed delivery system for anthocyanins locally administration proved do not reduce cell viability, according to WST-1 viability assay performed. More importantly, the intracellular tracking of the triple dyes-labeled microcapsules was evaluated by fluorescence imaging microscopy (FLIM), an ideal non-invazive tool to probe their local internalization inside B16F10 melanoma cells.

Taken together, our results could contribute and enlarge the research knowledge in the pharmaceutical and healthcare industry, leading to a real breakthrough on the sustained and targeted locally delivery therapies.