کاربرد های نانو بیو ریز بلور های کوانتوم در سرطان: تصویر برداری و سنجش و هدف یابی Nanobio applications of quantum dots in cancer: imaging, sensing, and targeting

In this article, the syntheses and optical properties of core/shell quantum dot (CdSe/ZnS) and their applications are reviewed. Nevertheless, the main focus is to provide an overview on biological applications of quantum dots that contain imaging, targeting, and sensing. We discuss the different synthetic methods, optical properties (photoluminescence intensity, absorption, and fluorescence spectra), and their dependence on shape, size, and inner structure of quantum dots. Also, the different mechanisms of quantum dots bio-targeting (passive and active mechanisms) are discussed. The impact of quantum dots in bioimaging is reviewed regarding its photoluminescence intensity, absorption and emission spectrum, and photo-stability on high-quality and sensitivity imaging. Further, the difference between near infrared and visible emission quantum dots in deep tissue imaging will be reviewed and some of done works are considered and compared with each other. And finally, the biosensing potential/application of quantum dots in medical diagnosis is going to be highlighted. Keywords Quantum dot (QD) . Photoluminescence intensity (PL) . Nanoparticles (NP) .FWHM (full width half maximum) . TEM (transmission electron microscope) 1 Introduction In nanotechnology area, the “nano” appears to be a prefix for other sciences/technologies to highlight its integration with the merged field, in which the operation size range become an order of nanometer (1–۱۰۰ nm) at a molecular level. In fact, due to the big ratio of surface-to-volume and quantum confinement effects, the most of material properties (e.g., electronic, optical, chemical, mechanical, and magnetic) differ from bulk materials when their sizes reach to nanoscale (Biju et al. 2008; Warburton 2002; Sharma et al. 2009). Such an approach has significantly promoted their scientific use in different applications such as military and optical electronic device (Kershaw et al. 2000; Wang et al. 2008c) and biological implementations such as bioimaging and biosensing (Ravindran Girija Aswathy et al. 2010; Debbage and Jaschke 2008; Frasco and Chaniotakis 2009; Hempen and Karst 2006; Willard et al. 2006), as well as bio-targeting (Gao et al. 2005; WeiboCai et al. 2007). From bioimaging and biosensing viewpoints, a nano-scaled particle can be categorized as an organic dye fluorophores and inorganic (i.e., semiconductor quantum dot (QD) (Mazumder et al. 2009) and metallic nanoparticle (NP) (Klaine et al. 2008; Suchita Kalele et al. 2006). The organic dyes were used for biological applications even though their efficiency was not high enough, perhaps due to narrow absorption spectrum. In fact, for the excitation, a tunable and fine wavelength of source is essential. The wide emission spectrum can cause aggregation of nanoparticles and overlap among different spectra. Moreover, the lack of photo-stability, photo-bleaching, and the variation of properties with the alteration of environment are other drawbacks of organic dyes (Murcia et al. 2008; Yu et al. 2006; Gao et al. 2005). Most problems associated with the organic dye fluorophores have been resolved by the emergence of QDs or NPs. In this article, we focus on QD nanocrystal with the cadmium selenide (CdSe) core. The wide absorption spectrum, narrow emission, photo-stability, lack of photo-bleaching, and high-quantum efficiency have made these nanostructures very attractive imaging/sensing materials in comparison with the dye fluorophores.