Thermoresponsive polymers incorporated with photo-absorbing agents have been widely utilized for controlled drug delivery using light as an external stimulus. However, previously developed thermoresponsive drug carriers have disadvantages such as low biocompatibility and implantation failure. In the present study, gold nanorods (GNRs)-encapsulated poly(N-vinyl caprolactam) (PVCL) (GNR-PVCL) microparticles were synthesized by the stop-flow lithography (SFL) method. The SFL method enabled the fabrication of near-infrared (NIR) light-responsive GNR-PVCL microparticles of uniform size, which can allow localized injection. Doxorubicin (DOX) was encapsulated into GNR-PVCL microparticles to achieve NIR light-responsive anticancer therapy. DOX-loaded GNR-PVCL (DOX-GNR-PVCL) microparticles exhibited NIR light-triggered drug release due to the photothermal effect of GNRs, which increases the local temperature above the volume phase transition temperature of GNR-PVCL microparticles. In addition, DOX-GNR-PVCL exhibited controlled DOX release in response to the periodic irradiation of NIR light. Moreover, we demonstrated the efficient intracellular release of DOX upon NIR light exposure, and thus, NIR light-responsive anticancer activity. This study demonstrates that DOX-GNR-PVCL microparticles have significant potential as implantable drug carriers enabling NIR light-triggered drug release.
