Controlled release of hydrophobic drugs from poly(ethylene glycol) covered gold nanocages

by Chen, Jingyi; Jenkins, Samir V.; Srivatsan, Avinash; Reynolds, Kimberly Y.; Pandey, Ravindra K.

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Two strategies, exterior and interior loading, are demonstrated to entrap and controllably deliver hydrophobic drugs based on a poly(ethylene glycol) (PEG) monolayer covered gold nanocage (AuNC) platform. A protein-rich in vivo environment was imitated to study the release kinetics during delivery. To facilitate monitoring, a hydrophobic photosensitizer, 3-(1'-hexyloxyethyl)-3-devinylpyropheophorbide-a, was used for this study. For exterior loading, the release rate was found to increase with PEG terminus in the order of pos. charged (cationic terminus) > neutral (methoxy terminus) > neg. charged (anionic terminus). Using a surface crosslinking approach, the release was largely inhibited. External stimuli (e.g. light irradn.) led to a burst release due to the photothermal effect of the AuNCs. In the case of interior loading, no release was obsd. The study is extended to in vivo for image-guide enhanced photodynamic therapy. The short-term toxicity of the nanoparticles is also examd.