Nanocarriers responding to light have great potential for pinpoint therapy, and recent studies have revealed promising in vivo activity. However, light-selective gene transfer still remains challenging in the systemic application. Here we report systemic light-responsive nanocarriers for gene delivery developed through the sequential self-assembly of ABC-type triblock copolymer/DNA/dendrimeric photosensitizer, forming polyplex micelles with three-layered functional nanocompartments. The DNA-packaged core is covered by the photosensitizer-incorporated intermediate layer, which is encompassed by an outer shielding shell. This three-layered structure permits multistep photosensitizer and DNA delivery into a solid tumour by a systemic route: the shielding layer minimizes unfavourable interactions with blood components, and the photosensitizer is delivered to endo-/lysosomal membranes to facilitate light-selective cytoplasmic translocation of the micelles, accomplishing DNA delivery into the nucleus to exert gene expression. The polyplex micelles display 4100-fold photoenhanced gene expression in cultured cells and exhibit light-induced in vivo gene transfer in solid tumours following systemic administration.

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Nanoparticle therapeutics are promising platforms for cancer therapy. However, it remains a formidable challenge to assess their distribution and clinical efficacy for therapeutic applications. Here, by using multifunctional polymeric micellar nanocarriers incorporating clinically approved gadolinium (Gd)-based magnetic resonance imaging contrast agents and platinum (Pt) anticancer drugs through reversible metal chelation of Pt, simultaneous imaging and therapy of an orthotopic animal model of intractable human pancreatic tumor was successfully performed without any serious toxicity. The strong tumor contrast enhancement achieved by the micelles correlated with the 24 times increase of r 1 of the Gd chelates, the highest for the formulations using clinically approved Gd chelates reported to date. From the microsynchrotron radiation X-ray fluorescence spectrometry scanning of the lesions, we confirmed that both the Gd chelates and Pt drugs delivered by the micelles selectively colocalized in the tumor interior. Our study provides new insights for the design of theranostic micelles with high contrast enhancement and site-specific clinical potential. Cancer Res; 70(18); 7031-41. ©2010 AACR.