Hypericin photodynamic activity in DPPC liposomes - part II: stability and application in melanoma B16-F10 cancer cells.

Hypericin (Hyp) is considered a promising photosensitizer for Photodynamic Therapy (PDT), due to its high hydrophobicity, affinity for cell membranes, low toxicity and high photooxidation activity. In this study, Hyp photophysical properties and photodynamic activity against melanoma B16-F10 cells were optimized using DPPC liposomes (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) as a drug delivery system. This nanoparticle is used as a cell membrane biomimetic model and solubilizes hydrophobic drugs. Hyp oxygen singlet lifetime (τ) in DPPC was approximately two-fold larger than that in P-123 micelles (Pluronic™ surfactants), reflecting a more hydrophobic environment provided by the DPPC liposome. On the other hand, singlet oxygen quantum yield values (ΦΔ1O2) in DPPC and P-123 were similar; Hyp molecules were preserved as monomers. The Hyp/DPPC liposome aqueous dispersion was stable during fluorescence emission and the liposome diameter remained stable for at least five days at 30 °C. However, the liposomes collapsed after the lyophilization/rehydration process, which was resolved by adding the lyoprotectant Trehalose to the liposome dispersion before lyophilization. Cell viability of the Hyp/DPPC formulation was assessed against healthy HaCat cells and high-metastatic melanoma B16-F10 cells. Hyp incorporated into the DPPC carrier presented a higher selectivity index than the Hyp sample previously solubilized in ethanol under the illumination effect. Moreover, the IC50 was lower for Hyp in DPPC than for Hyp pre-solubilized in ethanol. These results indicate the potential of the formulation of Hyp/DPPC for future biomedical applications in PDT treatment.

Advanced theranostic nanoplatforms for hypericin delivery in the cancer treatment.

Biomodified coated-lipid vesicles were obtained using the DPPC lipid (L) and F127 copolymer linked covalently with spermine (SN), biotin (BT), and folic acid (FA), resulting in LF127-SN, LF127-BT, and LF127-FA nanoplatforms. The photosensitizer hypericin (HY) was incorporated into the nanosystem by a thin-film method and characterized by dynamic light scattering, zeta potential, encapsulation efficiency, and transmission electronic microscopy. The results provided a good level of stability for all nanoplatforms for at least 5 days as an aqueous dispersion. The in vitro serum stability showed that the HY-loaded LF127-SN has a lower tendency to form complexes with BSA protein than with its analogs. LF127-SN was the most stable HY formulation, followed by LF127-BT and LF127-FA, confirmed by the association constant (Kd) values: 600 µmol L-1, 1100 µmol L-1, 515 µmol L-1, and 378 µmol L-1 for LF127, LF127 FA, LF127-BT, and LF127-SN, respectively. The photodynamic potential of HY was accessed by cytotoxicity assays using Caco-2, B16-F10, L-929, and HaCat cells. HY-loaded LF127-SN revealed a significant increase in the selectivity compared to other nanoplatforms. HY-loaded in LF127-BT and LF127-SN showed distinct uptake and biodistribution after 2 h of intravenous application. All biomodified coated-lipids showed satisfactory metabolism within 72 h after application, without significant accumulation or residue in any vital organ. These results suggest that incorporating HY-loaded in these nanosystems may be a promising strategy for future applications, even with a small amount of binders to the coating copolymer (0.02% w/v). Furthermore, these results indicate that the LF127-SN showed remarkable superiority compared to other evaluated systems, being the most distinct for future photodynamic therapy and theranostic applications.

Design and Optimization of Stimuli-responsive Emulsion-filled Gel for Topical Delivery of Copaiba Oil-resin.

This study presents a phytotherapeutic emulsion-filled gel design composed of Pluronic® F127, Carbopol® C934P, and high level of copaiba oil-resin (PHY-ECO). Mathematical modeling and response surface methodology (RSM) were employed to access the optimal ratio between the oil and the polymer gel-matrix constituents. The chemometric approach showed robust mechanical and thermoresponsive properties for emulsion gel. The model predicts viscosity parameters at 35.0°C (skin temperature) from PHY-ECOs. Optimized PHY-ECOs were described by 18-20% (w/w) F127, 0.25% (w/w) C934P, and 15% (w/w) copaiba oil-resin, and showed interfacial layers properties that led to high physicochemical stability. Besides, it had thermal stimuli-responsive that led large viscosity range before and after skin administration, observed by oscillatory rheology. These behaviors give the optimized smart PHY-ECO high design potential to be used as a pharmaceutical platform for CO delivery, focusing on the anti-inflammatory therapy and skin wound care.

Melanoma-targeted photodynamic therapy based on hypericin-loaded multifunctional P123-spermine/folate micelles.

Multifunctional P123 micelle linked covalently with spermine (SM) and folic acid (FA) was developed as a drug delivery system of hypericin (HYP). The chemical structures of the modified copolymers were confirmed by spectroscopy and spectrophotometric techniques (UV-vis, FTIR, and 1H NMR). The copolymeric micelles loading HYP were prepared by solid dispersion and characterized by UV-vis, fluorescence, dynamic light scattering (DLS), ζ potential, and transmission electron microscopy (TEM). The results provided a good level of stability for HYP-loaded P123-SM, P123-FA, and P123-SM/P123-FA in the aqueous medium. The morphology analysis showed that all copolymeric micelles are spherical. Well-defined regions of different contrast allow us to infer that SM and FA were localized on the surface of micelles, and the HYP molecules are located in the core region of micelles. The uptake potential of multifunctional P123 micelle was accessed by exposing the micellar systems loading HYP to two cell lines, B16-F10 and HaCaT. HYP-loaded P123 micelles reveal a low selectivity for melanoma cells, showing significant photodamage for HaCat cells. However, the exposition of B16-F10 cells to Hyp-loaded SM- and FA-functionalized P123 micelles under light irradiation revealed the lowest CC50 values. The interpretation of these results suggested that the combination of SM and FA on P123 micelles is the main factor in enhancing the HYP uptake by melanoma cells, consequently leading to its photoinactivation.