The characterisation of three substituted zinc phthalocyanines of differing charge for use in photodynamic therapy. A comparative study of their aggregation and photosensitising ability in relation to mTHPC and polyhaematoporphyrin

A combination of techniques to evaluate photodynamic efficiency of photosensitizers

“…In order to estimate the hydrophobicity of the photosensitizers, the partition coefficient between 1-octanol and phosphate buffer at pH = 7.4 was determined by the well spread shake-flask method [19][20][21], using 2 mL of 1-octanol and 2 mL of photosensitizer solution (10 μg/mL) in buffer in a multiple extraction procedure using a vortex shaker (2 min). The phase separation was succeeded in about 15 min (centrifugation at 2000 rpm).…”

“…The aliquots were collected at desired times of irradiation, centrifuged at 2000 rpm during 1 min, and the absorbances at 577 nm of oxyhemoglobin of the supernatants diluted in buffered saline were measured [19]. The samples secure disposals were assured by treatment for 30 min with sodium hypochlorite 3% and sterilization in autoclave at 120…”

Photophysical studies of zinc phthalocyanine and chloroaluminum phthalocyanine incorporated into liposomes in the presence of additives

“…The deviation from linear Beer-Lambert behavior for these drugs in solution caused by dimer formation is normally more pronounced in water than in organic solvents. Dimers are reported to be inactive or much more inefficient than monomers as photosensitizers (10). Unfortunately, phthalocyanines have been reported to display a strong tendency to form dimers in water as a result of the large hydrophobic skeleton avoiding contact with the aqueous medium (11), leading to the dimerization process and affecting their photophysical and photosensitizing properties and photodynamic action (12).…”

Photochemical Transformations Involving Porphyrins and Phthalocyanines

“…Phthalocyanine derivatives exhibit some photophysical advantages compared to porphyrins: increased Q-band absorption coefficient, red-shifted absorption bands resulting in deeper light tissue penetration (Ochsner 1996), high triplet quantum yields, long triplet lifetimes and high singlet oxygen and fluorescence yields (Rosenthal 1991). For specific substituents pattern this can result in improved photodynamic activities compared to commercial photosensitizers (Ochsner 1996, Ball et al 1998). A few current examples are shown below and include unsymmetrically substituted derivatives 57 (Kudrevich et al 1997), the cationic derivative 58 (Fernández et al 1997), the neutral derivative 59 (Ball et al 1998) and the classic anionic derivative 60 (Griffiths et al 1994(Griffiths et al , 1997.…”

“…For specific substituents pattern this can result in improved photodynamic activities compared to commercial photosensitizers (Ochsner 1996, Ball et al 1998). A few current examples are shown below and include unsymmetrically substituted derivatives 57 (Kudrevich et al 1997), the cationic derivative 58 (Fernández et al 1997), the neutral derivative 59 (Ball et al 1998) and the classic anionic derivative 60 (Griffiths et al 1994(Griffiths et al , 1997. "(Tetrabenzoporphyrinato)zinc(II)", an intermediate structure between that of porphyrins and phthalocyanines, has also been investigated in this respect.…”