%0 Journal Article
%T Application of Quantum Dots in Biological Imaging
%A Shan Jin
%A Yanxi Hu
%A Zhanjun Gu
%A Lei Liu
%A Hai-Chen Wu
%J Journal of Nanomaterials
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/834139
%X Quantum dots (QDs) are a group of semiconducting nanomaterials with unique optical and electronic properties. They have distinct advantages over traditional fluorescent organic dyes in chemical and biological studies in terms of tunable emission spectra, signal brightness, photostability, and so forth. Currently, the major type of QDs is the heavy metal-containing II-IV, IV-VI, or III-V QDs. Silicon QDs and conjugated polymer dots have also been developed in order to lower the potential toxicity of the fluorescent probes for biological applications. Aqueous solubility is the common problem for all types of QDs when they are employed in the biological researches, such as in vitro and in vivo imaging. To circumvent this problem, ligand exchange and polymer coating are proven to be effective, besides synthesizing QDs in aqueous solutions directly. However, toxicity is another big concern especially for in vivo studies. Ligand protection and core/shell structure can partly solve this problem. With the rapid development of QDs research, new elements and new morphologies have been introduced to this area to fabricate more safe and efficient QDs for biological applications. 1. Introduction Semiconductor nanocrystals, or so-called quantum dots (QDs), show unique optical and electronic properties, including size-tunable light emission, simultaneous excitation of multiple fluorescence colors, high signal brightness, long-term photostability, and multiplex capabilities [1每4]. Such QDs have significant advantages in chemical and biological researches in contrast to traditional fluorescent organic dyes and green fluorescent proteins on account of their photobleaching, low signal intensity, and spectral overlapping [5每7]. These properties of QDs have attracted great interest in biology and medicine in recent years. At present QDs are considered to be potential candidates as luminescent probes and labels in biological applications, ranging from molecular histopathology, disease diagnosis, to biological imaging [8每10]. Numerous studies have reported the use of QDs for in vitro or in vivo imaging of sentinel lymph nodes [11每17], tumor-specific receptors [18每20], malignant tumor detectors [21], and tumor immune responses [22]. However, the major concerns about potential toxicity of II-IV QDs (such as CdTe and CdSe) have cast doubts on their practical use in biology and medicine. Indeed, several studies have reported that size, charge, coating ligands, and oxidative, photolytic, and mechanical stability, each can contribute to the cytotoxicity of cadmium-containing QDs.
%U http://www.hindawi.com/journals/jnm/2011/834139/