Laser-Triggered Hybridize Magnetic Iron Oxide/Semiconductor Nanocrystals for Cancer Therapy

Semiconductor nanocrystals with small sizes close to or no more than their exciton Bohr radius are named quantum dots (QDs). These QDs include metal-based QDs, such as cadmium (Cd)-based QDs and metal-free QDs, including graphene QDs, carbon QDs, polymer QDs, silicon QDs, and black phosphors QDs. These nanocrystals have unique optical properties, which can be used for bioimaging and therapy. For example, the optical absorption and fluorescent emission spectra of metal-based QDs can shift to near-infrared wavelength regions even to the second biological window (~1000–1700 nm). This characteristic can be exploited for deep-tissue fluorescent imaging and tumor treatment through photothermal and photodynamic therapy (PTT and PDT). Upon laser irradiation with a suitable wavelength, these metal-based QDs may release metal ions, directly damaging biomacromolecules such as proteins and DNA or indirectly damaging biomacromolecules through biochemical reactions such as Fenton-like reaction. Therefore, magnetic iron oxide nanoparticles combined with semiconductor QDs may provide a strong magnetic-targeted theranostic tool for multimodal imaging and therapy. This chapter focuses on the discussion of magnetic nanocomposites consisting of metal-based semiconductor nanocrystals and magnetic iron oxide nanoparticles for enhanced optical absorption intensity and tumor phototherapy.