Preparation of metal phthalocyanine (MPc)-polymer complexes: the possible anti-cancer properties of FePc-polymer complexes.

We have succeeded in preparing various water-soluble metal phthalocyanine (MPc)-polymer complexes, wherein the metal moiety is lithium, iron, cobalt, copper, zinc, or tin, and the polymer is one of the following water-soluble polymers: polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP), or polyvinyl alcohol (PVA). Among all MPc-polymer complexes, the iron phthalocyanine (FePc)-PVP complex in water showed the largest and sharpest absorption peak at ∼700 nm in UV-Vis absorption spectrum, which indicates that FePc-polymer complexes in water are easily prepared and the degree of stacking of FePc in the complexes, very small, such as that of a monomer or a similar structure. Conversely, the polymer chains including those of PEG, PVP, and dextran have high biological affinity as well as flexibility. Speculatively, the FePc-polymer (e.g., PEG, PVP, and dextran) complexes adsorbed onto the surface of a cancer cell might break it via the irradiation of near-infrared light having a wavelength of ∼700 nm. Furthermore, chlorophyll a-polymer complexes, previously prepared by our group, might similarly break a cancer cell because these complexes showed a large and sharp absorption peak at ∼700 nm in UV-Vis spectrum.