A hypericin
(HYP) delivery system was developed on the basis of
P84 copolymeric micelles linked covalently with N-(3-aminopropyl)-2-pyrrolidone (APP). The higher monomeric amounts
of HYP when loaded in different proportions of P84 and P84-APP micelles
were predicted by using a chemometric experimental design. Dynamic
light scattering (DLS), ζ potential, loading efficiency, and
transmission electron microscopy (TEM) were performed for characterizations
of the copolymeric micelles. The particle size and low negative ζ
potential showed that APP conjugation provides high levels of stability
in the aqueous medium of P84 micelles. 1H1H-NOESY
spectroscopy and theoretical calculations were applied to provide
accurate insight on the preferential interaction sites of HYP-loaded
P84 and P84-APP copolymeric micelles. The findings showed that HYP
molecules were preferentially located in the core of both P84 and
P84-APP micellar nanostructures. Self-assembled HYP molecules (in
a more stable “head-to-tail” conformation) were observed
when loaded into P84 micelles. In accordance with the chemometric
experimental design the optimal ratio of P84/P84-APP (1:1) showed
that the most pronounced HYP phototoxicity effect against B16-F10
melanoma cells recorded survival index that reached 18% at 10.0 μmol
L–1. The findings pointed out that the high phototoxicity
observed is related to the capacity of APP molecules in enhancing
the HYP uptake by melanoma cells.
Biotin, spermine, and folic acid were covalently linked to the F127 copolymer to obtain a new drug delivery system designed for HY-loaded PDT treatment against B16F10 cells. Chemical structures and binders quantification were performed by spectroscopy and spectrophotometric techniques (1NMR, HABA/Avidin reagent, fluorescamine assay). Critical micelle concentration, critical micelle temperature, size, polydispersity, and zeta potential indicate the hydrophobicity of the binders can influence the physicochemical parameters. Spermine-modified micelles showed fewer changes in their physical and chemical parameters than the F127 micelles without modification. Furthermore, zeta potential measurements suggest an increase in the physical stability of these carrier systems. The phototherapeutic potential was demonstrated using hypericin-loaded formulation against B16F10 cells, which shows that the combination of the binders on F127 copolymer micelles enhances the photosensitizer uptake and potentializes the photodynamic activity.
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