noun. A stable blue-green porphyrin-based organic dye, C₃₂H₁₈N₈, or any of several blue-green derivatives containing chelated metals, used in enamels, printing inks, linoleum, and plastics.

noun. Any of a family of macrocyclic compounds having a structure similar to that of porphyrin; they are blue/green pigments that are used in plastics and enamels

"Their small size enables them to easily enter cells, and the phthalocyanine is taken up along with them."