The Japanese quail chorioallantoic membrane as a model to study an amphiphilic gradient copoly(2-oxazoline)s- based drug delivery system for photodynamic diagnosis and therapy research.

Amphiphilic gradient copoly(2-oxazoline)s are widely researched in the field of drug delivery. They could be used as a transport system for hydrophobic drugs such as hypericin (HYP). We prepared six gradient copolymers (EtOx)-grad-(ROPhOx) by living cationic ring-opening polymerization of a hydrophilic comonomer 2-ethyl-2-oxazoline (EtOx) and a hydrophobic comonomer 2-(4-alkyloxyphenyl)-2-oxazoline (ROPhOx), with different composition ratio (88:12 and 85:15) and three different alkyl chain lengths of alkyl (R) substituents. As an experimental model, Japanese quail chorioallantoic membrane (CAM) was used. The effect of nanoparticles loaded with HYP was evaluated by the changes of fluorescence intensity during photodynamic diagnosis (PDD) monitored under 405 nm LED light before administration, and 0,1,3 and 24 h after topical administration. The effectiveness of photodynamic therapy (PDT) (405 nm, 285 mW/cm2) applied 1h after the administration of HYP-loaded nanoparticles was evaluated using vascular damage score and histological sections. Molecular analysis was done by measuring angiogenesis-related gene expression by qPCR. The application of nanoparticles unloaded or loaded with HYP proved to be biocompatible, non-toxic, and undamaging to the CAM tissue, while they successfully altered the HYP fluorescence. We observed a possible anti-angiogenic potential of prepared nanoparticles, which could present an advantage for PDT used for tumour treatment.