Peripheral and Axial Substitution of Phthalocyanines with Solketal Groups:  Synthesis and In Vitro Evaluation for Photodynamic Therapy

Abstract

Phthalocyanines (Pcs) are a class of photosensitizers (PSs) with a strong tendency to aggregate in aqueous environment, which has a negative influence on their photosensitizing ability in photodynamic therapy. Pcs with either peripheral or axial solketal substituents, that is, ZnPc(sol) 8 and Si(sol) 2 Pc, respectively, were synthesized and their tendency to aggregate as well as their photodynamic properties in 14C and B16F10 cell lines were evaluated. The results were compared to more hydrophilic silicon Pcs, that is, Si(PEG750) 2 Pc and Pc4. The order of cellular uptake was Pc4 > ZnPc(sol) 8 > Si(PEG750) 2 Pc > Si(sol 2 )Pc. In contrast, Si(sol 2 )Pc showed the highest photocytotoxicity, while ZnPc(sol) 8 did not show any photocytotoxicity up to a concentration of 10 µM in both cell types. UV/vis spectroscopy showed that Si(sol) 2 Pc is less prone to aggregation than ZnPc(sol) 8 , which can explain the lack of photoactivity of the latter. Si(sol) 2 Pc was predominantly located in lipid droplets, whereas Si(PEG750) 2 Pc was homogeneously distributed in the cytosol, which is probably the main cause of their difference in photoactivity. The very high photodynamic efficacy of Si(sol) 2 Pc makes this PS an interesting candidate for future studies.

Syntheses and Photodynamic Activity of Pegylated Cationic Zn(II)-Phthalocyanines in HEp2 Cells

“…No aggregation of the Pcs was apparent up to 10 μM concentrations in DMF 42. All ZnPcs showed strong Q absorptions and emissions in the near-IR between 679-686 nm in DMF, with small Stokes' shifts between 2-4 nm, as is characteristic of this type of macrocycle 35,41-43. All the ZnPcs show a Soret absorption between 330 - 360 nm, a strong Q band between 677-683 nm and a vibrational band at around 620 nm, that strictly follow the Lambert-Beer law.…”

Hydrolysable core-crosslinked thermosensitive polymeric micelles: Synthesis, characterisation and in vivo studies

“…All animal studies were performed in compliance with guidelines set by national regulations and were approved by the local animal experiments ethical committee. The head and neck squamous-cell carcinoma line 14C was introduced in the flank of the mice by inoculation with 1 Â 10 6 14C-tumour cells suspended in 100 mL [52]. Palpable subcutaneous tumours had developed over a period of approximately 1 month.…”

The effects of substituents' positions and variety of axial groups on the photochemical properties of coumarin substituted indium(III) phthalocyanines

“…The protons for coumarin lactone ring at four positions were observed at 8.32 ppm for compound 6, 8.29 ppm for compound 7, 8.28 ppm for compound 8 and 8.29 ppm for compound 9 as singlet peaks. The presence of phthalocyanine aggregation at the concentrations used for the NMR measurements may lead to broadening of the aromatic signals when compared with that of corresponding phthalonitrile derivatives (4,5).…”

“…However, these compounds have strong tendency to aggregate in aqueous environment, which has a negative influence on their photosensitizing ability [5]. For example, aggregation can result in the fast decay of the excited states.…”