Fluorescent labeling of cells and biomolecules with nanocrystal quantum dots

ABSTRACT Fluorescent nanoparticles, such as nanocrystal quantum dots (QDs), novel nanometer-size probes and have the potentialto be used as easy imaging tool for molecular biology and bioimaging including medical applications, since somenanocrystals emit higher and far longer fluorescence than conventional organic probes. QDs are now becoming widelyused in biotechnology and medical applications. QDs have several advantages over organic fluorophores with regard tohigh luminescence, stability against photobleaching, and a range of fluorescence wavelengths from blue to infrareddepending on the particle size. In this review, we reported labeling of some kinds of immune cells and biomoleculeswith several QDs coated with hydrophilic carboxyl/amine groups, and reported that we could image the circulation ofmouse lymphocytes in vivo by QDs. In addition, we also reported here about the cytotoxicity of these nanocrystals. Keywords: bioimaging, cell trafficking, cytotoxicity, fluorescent probes, nanocrystal.1.1 Labeling of Immune Cells by QDs Here we demonstrated that we imaged the movements of mouse lymphocytes and macrophages by QDs. The QDswere actively taken into the target cells by endocytotic pathways. The fluorescence of QDs on T cells held in theendosomes could be studied for more than a week and remained as stable luminescence against cell activation induced