Figure 2.

A multifunctional nanocarrier-based drug delivery system containing targeting moieties (antibody, peptide, aptamer, etc.) and active components (drug, nucleic acid, protein, contrast agent, etc.). Drugs and imaging agents are loaded in the core structure (or membrane) of the multifunctional nanocarrier, whereas the targeting moieties such as antibody, peptide, aptamer, etc. and nucleic acids in most cases are conjugated on the surface of the nanostructure through various linkers, electrostatic interactions as well as covalent or noncovalent bond formation.