The tumor penetration and accumulation of nanoparticle-based drug delivery systems are highly dependent on the particle size. Nanomedicines in the sub-100nm range have been suggested by previous studies to have superior antitumor efficacy on various solid tumors. SN-38 is a very important and highly potent drug for several cancers including colon cancer. However, due to the ultra-flat aromatic structure of SN-38, it is typically very difficult to produce sub-100nm, SN-38-encapsulated nanoparticles without modification of the chemical structure. Here, we report on the successful production of 20-30nm, SN-38-encapsulated photonic micelles for effectively trimodal cancer therapy. Taking advantages of the supramolecular "π-π" stacking and hydrophobicity interaction between SN-38, and a unique class of photonic nanoporphyrin micelles (NPM), the extremely hydrophobic SN-38 was successfully encapsulated into NPM with significantly increased water solubility (up to 500 times). At equivalent dose of drug, photosensitizer and light irradiation, combination therapy with SN-38-encapsulated nanoporphyrin micelles (SN-NPM) enhanced the in vitro antitumor activity by 78 and 350 times over single treatment with SN-38 and phototherapy alone, respectively. Due to the relatively small size, SN-NPM possessed superior long tumor retention time (>5days) and much higher accumulation in tumors than in normal organs, as shown by near-infrared fluorescence (NIRF) imaging. Furthermore, the trimodal therapy (photothermal-, photodynamic- and chemo-therapy) with SN-NPM demonstrated dramatically enhanced in vivo antitumor efficacy over single treatment on nude mice bearing HT-29 colon cancer xenograft. Therefore, these sub-100nm, SN-38-encapsulated photonic micelles show great promise for multimodal cancer therapy.

Nanoparticle-based theranostic agents have emerged as a new paradigm in nanomedicine field for integration of multimodal imaging and therapeutic functions within a single platform. However, the clinical translation of these agents is severely limited by the complexity of fabrication, long-term toxicity of the materials, and unfavorable biodistributions. Here we report an extremely simple and robust approach to develop highly versatile and biocompatible theranostic poly(vinyl alcohol)-porphyrin nanoparticles (PPNs). Through a "one-pot" fabrication process, including the chelation of metal ions and encapsulation of hydrophobic drugs, monodispersenanoparticle could be formed by self-assembly of a very simple and biocompatible building block (poly(vinyl alcohol)-porphyrin conjugate). Using this approach, we could conveniently produce multifunctional PPNs that integrate optical imaging, positron emission tomography (PET), photodynamic therapy (PDT), photothermal therapy (PTT) and drug delivery functions in one formulation. PPNs exhibited unique architecture-dependent fluorescence self-quenching, as well as photodynamic- and photothermal- properties. Near-infrared fluorescence could be amplified upon PPN dissociation, providing feasibility of low-background fluorescence imaging. Doxorubicin (DOX)-loaded PPNs achieved 53 times longer half-life in blood circulation than free DOX. Upon irradiation by near infrared light at a single excitation wavelength, PPNs could be activated to release reactive oxygen species, heat and drugs simultaneously at the tumor sites in mice bearing tumor xenograft, resulting in complete eradication of tumors. Due to their organic compositions, PPNs showed no obvious cytotoxicity in mice via intravenous administration during therapeutic studies. This highly versatile and multifunctional PPN theranostic nanoplatform showed great potential for the integration of multimodal imaging and therapeutic functions towards personalized nanomedicine against cancers.