Image-guided nanosystems for targeted delivery in cancer therapy.

Current challenges in early detection, limitations of conventional treatment options, and the constant evolution of cancer cells with metastatic and multi-drug resistant phenotypes require novel strategies to effectively combat this deadly disease. Nanomedical technologies are evolving at a rapid pace and are poised to play a vital role in diagnostic and therapeutic interventions - the so-called "theranostics" - with potential to advance personalized medicine. In this regard, nanoparticulate delivery systems can be designed with tumor seeking characteristics by utilizing the inherent abnormalities and leaky vasculature of solid tumors or custom engineered with targeting ligands for more specific tumor drug targeting. In this review we discuss some of the recent advances made in the development of multifunctional polymeric nanosystems with an emphasis on image-guided drug and gene delivery. Multifunctional nanosystems incorporate variety of payloads (anticancer drugs and genes), imaging agents (optical probes, radio-ligands, and contrast agents), and targeting ligands (antibodies and peptides) for multi-pronged cancer intervention with potential to report therapeutic outcomes. Through advances in combinatorial polymer synthesis and high-throughput testing methods, rapid progress in novel optical/radiolabeling strategies, and the technological breakthroughs in instrumentation, such as hybrid molecular and functional imaging systems, there is tremendous future potential in clinical utility of theranostic nanosystems.