Cyclodextrins as nanocarriers of hydrophobic silicon phthalocyanine dichloride for the enhancement of photodynamic therapy effect

In this study, silicon phthalocyanine dichloride (SiCl₂Pc) was successfully encapsulated in β-cyclodextrin (β-CD) and hydroxy-propyl-β-cyclodextrin (HP-β-CD) using the kneading method. Dynamic Light Scattering (DLS) demonstrated complexes of various hydrodynamic diameters with moderate stability in aqueous solutions. Their structural characterization by Infrared Spectroscopy (FT- IR) indicated that a part of phthalocyanine is located inside the cyclodextrin cavity. Both photophysical and photochemical studies showed that phthalocyanine's encapsulation in cyclodextrins increased its aqueous solubility. The photodynamic studies against A431 cancer cell line indicated that the complexes are more effective than pure SiCl₂Pc. Pure SiCl₂Pc's photodynamic effect is characterized as dose-dependent, whereas both complexes presented a biphasic dose-response photodynamic effect. For the highest energy dose of 3.24 J/cm², pure SiCl₂Pc induced mild cell toxicity. SiCl₂Pc-β-CD complex was the most promising photosensitizer, exhibiting the highest photodynamic effect when irradiated at 2.16 J/cm².