Thermoresponsive polyamic acid-conjugated gold nanocarrier for enhanced light-triggered 5-fluorouracil release

Abstract

In this study, a light-responsive 5-fluorouracil (5-FU) drug carrier system was developed by combining gold nanoparticles with thermosensitive hydrophilic polyamic acid. The hydrophilic polyamic acid was cyclized when the synthesized gold polymer (GP) nanocluster was exposed to heat, and gold acted as a photothermal transfer agent, converting light energy into heat energy. After polyamic acid modification, the size of the GP nanocluster increased to 100 nm. The increase in the size of the GP nanocluster might be due to multiple chemical bonds between gold and the thiol group present in polyamic acid. The size of the GP nanocluster decreased after exposure to a temperature of approximately 30 °C, which changed polyamic acid into cyclized polyimide and cleaved the gold–thiol bonds. The light-induced successful release of the anticancer drug 5-FU from the GP nanocluster was confirmed through UV-vis spectroscopy. In addition, no toxicity was observed in cells treated with the GP loaded with 5-FU (GP–FU) under dark conditions. This result indicates the biocompatibility of the GP cluster and thus demonstrates the safety of the carrier when the anticancer drug was loaded inside the cluster. HeLa cells irradiated with light apparently died, indicating that light successfully induced drug release. These findings suggest that the synthesized thermosensitive nanocluster can be used as a nanocarrier.