Tumor Microenvironment Responsive "Head-to-Foot" Self-Assembly Nanoplatform for Positron Emission Tomography Imaging in Living Subjects.

Sensitivity and specificity of molecular probes are two important factors in determining the accuracy of cancer diagnosis or the efficacy of cancer treatment. However, the development of probes with high sensitivity and strong specificity still poses many challenges. Herein, we report an 18F-labeled smart tracer ([18F]1) targeting cancer-associated biotin receptor (BR) and self-assembling into nanoparticles in response to intracellular glutathione. The tracer [18F]1 selectively targeted BR-positive cancer cells A549 and Hela and formed nanoparticles through self-assembly with an average diameter of 138.2 ± 16.3 nm. The character of self-assembly into nanoparticles enhanced the uptake and extended the retention of probe [18F]1 in the target tissue and hence improved the quality of positron emission tomography (PET) images. Thus, [18F]1 is a promising PET tracer for accurately detecting BR-positive cancers. Moreover, the tumor microenvironment responsive "head-to-foot" self-assembly nanoplatform is particularly attractive for development of other smart molecular probes.