The Surprisingly Positive Effect of Zinc-Phthalocyanines With High Photodynamic Therapy Efficacy of Melanoma Cancer

Abstract

Phthalocyanine (Pc) dyes are photoactive molecules that can absorb and emit light in the visible spectrum, especially in the red region of the spectrum, with great potential for biological scopes. For this target, it is important to guarantee a high Pc solubility, and the use of suitable pyridinium units on their structure can be a good strategy to use effective photosensitizers (PSs) for photodynamic therapy (PDT) against cancer cells. Zn(II) phthalocyanines (ZnPcs) conjugated with thiopyridinium units (1–3) were evaluated as PS drugs against B16F10 melanoma cells, and their photophysical, photochemical, and in vitro photobiological properties were determined. The photodynamic efficiency of the tetra- and octa-cationic ZnPcs 1–3 was studied and compared at 1, 2, 5, 10, and 20 µM. The different number of charge units, and the presence/absence of a-F atoms on the Pc structure, contributes for their PDT efficacy. The 3-(4′,5′-dimethylthiazol-2′-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays on B16F10 melanoma cells show a moderate to high capacity to be photoinactivated by ZnPcs 1–3 (ZnPc 1 > ZnPc 2 > ZnPc 3). The best PDT conditions were found at a Pc concentration of 20 μM, under red light (λ = 660 ± 20 nm) at an irradiance of 4.5 mW/cm2 for 667 s (light dose of 3 J/cm2). In these conditions, it is noteworthy that the cationic ZnPc 1 shows a promising photoinactivation ratio, reaching the detection limit of the MTT method. Moreover, these results are comparable to the better ones in the literature.

A Comparative Evaluation of the Photosensitizing Efficiency of Porphyrins, Chlorins and Isobacteriochlorins toward Melanoma Cancer Cells

“…The fluorescence lifetime was determined on a Fluorescence Correlation Spectroscopy/Fluorescence Lifetime Imaging coupled to a laser with 420 nm excitation wavelength. Direct measurement of singlet oxygen was performed by luminescence method from Equation (2), as described in the literature [ 60 ], using ZnPc as standard (λ exc = 660 nm, Φ Δ = 0.56 in DMF) [ 61 , 62 ]. Φ Δ = Φ st (I s /I st ) where Φ Δ is the singlet oxygen quantum yield of the sample; Φ st the singlet oxygen quantum yield of ZnPc ; I st is the phosphorescence intensity of 1 O 2 at 1270 nm for ZnPc ; and I s the phosphorescence intensity for the sample.…”

Sustainable Photooxidation using a Subpart-per-million Heavy-Metal-Free Red-Light Photocatalyst

“…Concerning the t -Bu-substituted ones, no substrate conversion was observed with NiPCy t Bu 4 or MgPCy t Bu 4 , while ZnPCy t Bu 4 provided slow conversion to reach only 19% in 90 min. This result was rather surprising as Zn-phthalocyanines are among the most widely used phthalocyanines for 1 O 2 generation. ,− In comparison, the metal-free H 2 PCy t Bu 4 gave a better conversion of 52% in a 90 min reaction time. We were delighted to find out that Si­(OH) 2 PCy t Bu 4 and Si­(Cl) 2 PCy t Bu 4 gave good conversions of 75 and 78%, respectively, and PtPCy t Bu 4 and PdPCy t Bu 4 were even more reactive with 88 and 100% conversions, respectively, within the same reaction time presumably as a result of a higher TOF in the latter cases due to heavy-atom enhanced singlet-to-triplet ISC.…”

Collagen Hydrolysate Effects on Photodynamic Efficiency of Gallium (III) Phthalocyanine on Pigmented Melanoma Cells

“…The studied GaPc was evaluated with a high photodynamic activity as compared to similar phthalocyanine complexes studied on pigmented melanoma cells [ 27 , 28 , 29 ]. A high photo-safety (low cytotoxicity) was determined for GaPc and for its conjugate on the tested model embryonal cell line BALB 3T3 for the concentrations which related to PDT usage ( Figure 3 a).…”

“…Other parameters calculated based on the photo- and dark cytotoxicity studies are following the Equations reported before [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Briefly, these are the phototherapeutic index (PI), cytotoxicity (CC50), photodynamic activity (PDA50), selectivity index (SI), and photo-irritation factor (PIF) calculated using the Formula (2): PIF = CC50 (−Irr)/CC50 (+Irr) where −Irr is the absence of light and +Irr is the presence of light.…”

“…The measurements of optical density were carried out on TECAN microplate reader at λ = 570 nm. The cellular toxicity was calculated by the Equation (1): Cytotoxicity (%) = (1 − (OD 570 (treated sample)/OD 570 (negative control)) × 100 (1) Other parameters calculated based on the photo-and dark cytotoxicity studies are following the Equations reported before [27][28][29][30][31][32][33][34]. Briefly, these are the phototherapeutic index (PI), cytotoxicity (CC50), photodynamic activity (PDA50), selectivity index (SI), and photo-irritation factor (PIF) calculated using the Formula (2): PIF = CC50 (−Irr)/CC50 (+Irr) (2) where −Irr is the absence of light and +Irr is the presence of light.…”