Near infrared-absorbing self-encapsulated phthalocyanine-cored polycaprolactone star polymeric nanoparticles

An octahydroxylated photosensitizing Zn phthalocyanine has been used as an initiator in ring-opening polymerization of epsilon-caprolactone. Three different phthalocyanine-core star polymers have been obtained, with each arm functionalized with either 20, 30, or 40 units. To benefit from the absorption of these polymers in the first near-infrared (NIR) phototherapeutic window, the phthalocyanine cores have been self-encapsulated into their polycaprolactone arms to yield biocompatible star polymeric nanoparticles exhibiting a remarkable absorption centered at 782 nm and an excellent logarithmic extinction coefficient value in water.