Nanoparticles-mediated drug delivery approaches for cancer targeting: a review.

Cancer has become the leading cause of death among different populations of the world. The treatment is limited to chemotherapy, radiation, and surgery. Selective targeting to the tumor cells is possible by nanoparticles-based drug delivery system. It maximizes the drug concentration at the desired target and protects the surrounding healthy tissues at the same time. To improve the targeting potential of the anticancer drugs, nanoparticles were optimized for the size and surface characteristics to enhance their circulation time and targeting efficiency. Passive targeting involves surface modification with polyethylene glycol to avoid its elimination by natural body defense mechanism. Active targeting involves chemical interaction with certain antigen, receptors, and genes which are over expressed during progression of disease. In addition, the article highlights recent developments in "smart"-stimulus-responsive-drug carriers designed to enhance the localization and efficacy of therapeutic payloads as compared with free drug. Enhanced targeting potential, imaging, and controlled release of drugs or therapeutic molecules could be possible through multi-functional nanocarrier. Such multi-faceted, versatile nanocarriers and drug delivery systems promise a substantial increase in the efficacy of diagnostic and therapeutic applications in pharmaceutical sciences.