Laser-Induced CO2 Generation from Gold Nanorod-Containing Poly(propylene carbonate)-Based Block Polymer Micelles for Ultrasound Contrast Enhancement

Poly(propylene carbonate) (PPC) decomposes at high temperature to release CO2. This CO2-generation temperature of PPC can be reduced down to less than 80 °C with the aid of a photoacid generator (PAG). In the present work, we demonstrate that using an additional helper component, surface plasmonic gold nanorods (GNRs), the PPC degradation reaction can also be initiated by infrared (IR) irradiation. For this purpose, a PPC-containing nanoparticle formulation was developed in which PPC-based amphiphilic block copolymers (BCPs), poly(poly(ethylene glycol) methacrylate-b-propylene carbonate-b-poly(ethylene glycol) methacrylate) (PPEGMA-PPC-PPEGMA), were self-assembled with GNRs and PAG molecules via solvent exchange. Under IR irradiation, GNRs produce heat that can cause PPC to decompose into CO2, and PAG (after UV pretreatment) catalyzes this PPC degradation process. Two PPEGMA-PPC-PPEGMA materials were used for this study: PPEGMA7.3K-PPC5.6K-PPEGMA7.3K (“G7C6G7”) and PPEGMA2.1K-PPC5.6K-PPEGMA2.1K (“G2C6G2”)...