Development of superior nanotheranostic agents with indocyanine green-conjugated poly(styrene-alt-maleic acid) nanoparticles for tumor imaging and phototherapy.

Developing safe, high-quality theranostic agents for cancer treatment is of great clinical value. In this work, for the first time, the clinical indocyanine green (ICG) is coupled with the biocompatible poly(styrene-alt-maleic anhydride) (PSMAn) to obtain the PSMAn-ICG polymer. The self-assembly of its hydrolyzed product in water results in ICG-conjugated poly(styrene-alt-maleic acid) nanoparticles (PSMA-ICG NPs). Intriguingly, the NPs have many advantages, including good solubility and stability in aqueous solutions, high photostability and decreased hemolytic damage to red blood cells, highlighting the importance of PSMA coupling. More interestingly, PSMA-ICG NPs significantly promote tumor targeting and enable long-term imaging of tumors. Furthermore, the administration of PSMA-ICG NPs in combination with near-infrared laser irradiation provides superior potency in the photothermal therapy of tumors. Furthermore, 9-amino-sialic acid (Sia)-coated PSMA-ICG NPs are fabricated, further enhancing tumor imaging and phototherapy. This is the first report of PSMA-NIR conjugates achieving tumor reduction in mice. Overall, this study provides novel phototheranostic agents with broad clinical transformation prospects.