Molecular interactions and solubilization of structurally related meso-porphyrin photosensitizers by amphiphilic block copolymers (Pluronics)

Abstract

The influence of four Pluronics block copolymers (i.e. F68, P123, F127, and L44) on the aggregation and solubilization of five structurally related meso-tetraphenyl porphyrin photosensitizers (PS) as model compounds for use in Photodynamic Therapy of cancer (PDT) was evaluated. Interactions between the PSs and Pluronics were studied at micromolar concentration by means of UV-Vis absorption spectrometry and by kinematic viscosity (υ) and osmolarity measurements at millimolar concentrations. Pluronic micelles were characterized by size and zeta potential (ζ) measurements. The morphology of selected PS-Pluronic assemblies was studied by atomic force microscopy (AFM). While hydrophobic 5,10,15,20-Tetrakis(4-hydroxyphenyl) porphine (THPP) seemed to be solubilized in the Pluronic micellar cores, amphiphilic di(monoethanolammonium) meso-tetraphenyl porphine disulphonate (TPPS2a) was likely bound to the micellar palisade layer. Hydrophilic PSs like 5,10,15,20-Tetrakis (4-trimethylaniliniumphenyl) porphine (TAPP) seemed to form complexes with Pluronic unimers and to be distributed among the micellar coronas. TPPS2a aggregated into a network which could be broken at Pluronic concentration ≫ cmc, but would reconstitute in the presence of tonicity adjusting agents, e.g. sodium chloride (NaCl) or glucose.

• Cancer
• nanoparticles
• photodynamic therapy
• photosensitizer
• pluronic

Declaration of interest

This work was kindly supported by the Norwegian Research Council. Authors would like to thank Tore Geir Iversen, PhD (Department of Biochemistry, Norwegian Radium Hospital) for providing a Zetasizer instrument. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Supplementary material available online

Supplementary Figures S1–S5 and Table S1