Multifunctional nanoparticles with combined diagnostic and therapeutic functions show great promise in nanomedicine. Herein, we develop an organic photodynamic therapy (PDT) system based on polyethylene glycol (PEG)-coated nanomicelles conjugated with ∼20% chlorin e6 (PEG-Ce 6 nanomicelles), which functions as an optical imaging agent, as well as a PDT agent. The formed PEG-Ce 6 nanomicelles with the size of ∼20 nm were highly stable in various physiological solutions for a long time. Moreover, Ce 6 can also be a (64)Cu chelating agent for in vivo positron emission tomography (PET). By simply mixing, more than 90% of (64)Cu was chelator-free labeled on PEG-Ce 6 nanomicelles, and they also showed high stability in serum conditions. Both fluorescence imaging and PET imaging revealed that PEG-Ce 6 nanomicelles displayed high tumor uptake (13.7 ± 2.2%ID/g) after intravenous injection into tumor-bearing mice at the 48 h time point. In addition, PEG-Ce 6 nanomicelles exhibited excellent PDT properties upon laser irradiation, confirming the theranostic properties of PEG-Ce 6 nanomicelles for imaging and treatment of cancer. In addition, PDT was not shown to render any appreciable toxicity. This work presents a theranostic platform based on polymer nanomicelles with great potential in multimodality imaging-guided photodynamic cancer therapy.
Keywords: EPR effect; PEG-Ce 6 nanomicelles; PET imaging; fluorescence imaging; photodynamic therapy.