Chemical modification of inorganic nanostructures for targeted and controlled drug delivery in cancer treatment

Chemically modified inorganic nanoparticles (NPs) hold great promise for biomedical applications. In this review, we examine the recent advances in nanotechnology for targeted drug delivery and controlled drug release. The development of an effective drug delivery system requires good understanding of the chemical and physical properties that affect the interaction of nanoparticles with the biological environment. A robust drug carrier should have an appropriate circulation time and should not exert any harmful effect on normal cells. The nanostructures involved must satisfy the requirements of no pre-release of drugs, stability and biocompatibility in vivo, targeted delivery to cancer cells/inflammation area, and on-demand release of drugs. Herein we summarize the surface modifications of nanostructures to achieve systematic targeting to intended sites and controlled release by different stimuli, including pH, redox, light, enzyme and so on. The use of DNA, proteins and other biomolecules opens a new gate to create smart nanocarriers for anti-cancer drugs.