Multifunctional Nano-Micelles Formed by Amphiphilic Gold-Polycaprolactone-Methoxy Poly(ethylene glycol) (Au-PCL-MPEG) Nanoparticles for Potential Drug Delivery Applications

Multifunctional nano-micelles formed by amphiphilic gold-polycaprolactone-methoxy poly(ethylene glycol) (Au-PCL-MPEG) nanoparticles were synthesized and evaluated for potential drug delivery applications. Amphiphilic Au-PCL-MPEG nanoparticles were synthesized by the ring-opening polymerization of epsilon-caprolactone (epsilon-CL) using pre-synthesized 11-mercaptoundecanol stabilized Au (Au-MUD) nanoparticles in the presence of stannous octoate as a catalyst followed by esterification with MPEG-COOH. The amphiphilic Au-PCL-MPEG nanoparticles and the resulting nano-micelles formed in an aqueous solution have been characterized by a number of techniques, including H-1-NMR spectroscopy, transmission electron microscopy (TEM), fluorescent spectroscopy, and UV-vis spectroscopy. The critical aggregation concentration (CAC) of the micelles was 4 mg/l. The average size of the Au-PCL-MPEG nano-micelles below and above the CAC was 22 and 48 nm, respectively, as determined by the TEM. The controlled release of a model hydrophobic drug, 5-flurouracil, encapsulated in the Au-PCL-MEPG nanomicelles that lasted for more than four days was observed. In addition, due to the presence of Au nano-core, these Au-PCL-MPEG nanoparticles can potentially serve as a contrast agent for imaging (e.g., computed tomography (CT) imaging) and/or a nanoheater (e.g., in response to near infrared light) for photothermal therapy for cancer treatments.