ABSTRACT
This chapter introduces the synthesis and applications of several heterostructures grown through the epitaxial process, including core/shell quantum dots (QD), core/shell upconversion nanoparticles and gold-based heterostructures. The heterostructured nanoparticles can be generated either by non-epitaxial or epitaxial techniques. In the non-epitaxial approach, the heterostructures are prepared by polycrystalline or amorphous growth process without matching of the lattice, covalent conjugation of surface functional groups, or physical absorption. QDs are nanocrystals made of semiconductor materials with a few hundred or a few thousand atoms. Among core/shell QDs, CdSe/ZnS heterostructure is one of the most commonly studied nanosystems, which was first reported in 1996. Optical imaging possesses numerous advantages, such as high sensitivity, low cost and short acquisition time, QDs and other optical imaging probes face a significant challenge for in vivo applications due to their limited tissue penetration.
