Quantum dots (QDs) are composed of semiconducting material with high surface to volume ratios. QDs emit fluorescence based on the size of the valence band and conduction band of the material. Different types of QDs are available based on structure and composition. Core type QD is composed of a single material, whereas core—shell type is composed of two materials, a small region of one material embedded in another with a wider band gap. Alloy QDs allow tuning of multiple components. QDs are brighter, can emit the whole spectrum, and the degradation is very minimal compared with the traditional organic dyes used for biomedical analysis . Studies have shown that successful gene delivery can be developed for the treatment of lung cancer with carbon QD as theranostic nanocarriers  (Fig. 14.6). QDs have been explored and
Figure 14.6 Monitoring luciferase inhibition in vivo with bioluminescent imaging. Representative images show the reduction in lung tumor size following intratracheal instillation of fc-rPEI-Cdots nanoagents in luciferase-expressing H460 lung carcinoma. Panels (A—C) depict bioluminescent images of the lungs before and after treatment. (B) 7 days, (C) 10 days after two times inhaled administration. After aerosol delivery, the fc-rPEI-Cdots/pooled siRNA nanoagents (D) can accumulated at lung region when compared to PBS (E).
demonstrated with multidisciplinary applications. For example, graphene quantum dot (GQD) contains one or more lateral dimensional sheets of carbon nanomaterials. GQD is suitable as drug carrier, biosensors, and for cell imaging because of their photostability, low toxicity, and biocompatibility [26—29]. Similarly, fluorescence has been utilized in sensing temperature of human-derived neuronal cell lines, SH-SY5Y, because of nonhomogenous heat production in neurites relative to normal cells .