Cell Imaging
“Using quantum dots (QD) can be used as imaging markers inside living organisms. These quantum dots can be used as biological markers to find a disease as well as to carry a drug to the exact cell that needs it by immobilizing antibodies on the surface of the quantum dots. Quantum dots may be specific to a particular disease and may be tailored to bind only to infected cells. Detection may be carried out either by locating the QDs' particles or by detecting signals emanating from the QDs' particles. For example, luminescence of antibody-coated QDs bound to the cancerous tissue in a mouse helped locate the tumor. Until now the main biological tags that have been employed are organic fluorophores or radioactive labels. Radioactive labels are short lived and radioactive. Concerns about the use of radioactive materials in the body always arise. Organic fluorophores have wide emission spectra and the emission is not as bright as that of QDs. In comparison to conventional dye molecules, QDs have the advantages of having tunable fluorescence signatures, narrow emission spectra, brighter emissions, and good photostability.” (Shih et al, US Patent 7,824,653; 11/2/2010)
Recent Journal Articles
12/17/2010
Ultrabright and Bioorthogonal Labeling of Cellular Targets Using Semiconducting Polymer Dots and Click Chemistry
(pages 9436–9440)Angewandte Chemie International Edition 49 #49 (2010)
Wu et al of the University of Washington, Seattle was able to covalently link functional molecules to semiconducting polymer dots for bioorthogonal labeling of cellular targets. Targeting of the polymer dots to newly synthesized proteins and glycoproteins in mammalian cells by click chemistry is highly efficient and specific. (RDC 12/14/2010)
Targeting of Cancer Cells Using Quantum Dot–Polypeptide Hybrid Assemblies That Function as Molecular Imaging Agents and Carrier Systems
(4091–4097)Advanced Functional Materials 20 #23 (2010)
Atmaja et al of Stanford University, California formed the assemblies self-assembly of carboxyl-functionalized quantum dots and poly(diethylene glycol-L-lysine)-poly(L-lysine) diblock copolypeptide molecules, and they are modified with peptide ligands containing a cyclic arginine-glycine-aspartate [c(RGD)] motif that has affinity for αvβ3 and αvβ5 integrins overexpressed on the tumor vasculature. Binding to U87MG glioblastoma cells can be modulated and optimized by changing either the conditions under which the assemblies are formed or the relative lengths of the different blocks in the copolymers. (RDC 12/14/2010)
12/3/2010
Fluorogenic assay and live cell imaging of HIV-1 protease activity using acid-stable quantum dot–peptide complex
(9146-9148) Chemical Communications #48 (2010)
Choi et al developed a quantum dot-peptide complex for detecting HIV-1 protease activity was prepared by a simple one step electrostatic interaction. Fluorescence recovery of the pre-quenched quantum dot through fluorescence resonance energy transfer allowed for in vitro assay and live cell imaging of the protease activity in HIV-1 transfected cells, proving the potential for cell-based protease inhibitor screening. (RDC 12/2/2010)
11/26/2010
Synthesis and Characterization of Near-Infrared Cu−In−Se/ZnS Core/Shell Quantum Dots for In vivo Imaging
(6117–6124) Chemistry of Materials 22 #22 (2010)
Cassette et al developed a a simple one-pot synthetic route without injection to make fluorescent sphalerite Cu−In−Se core and Cu−In−Se/ZnS core/shell QDs. We show that the photoluminescence (PL) of the resulting core QDs can be tuned from 700 nm to 1 μm depending on the QD size (from 2 to 5 nm in diameter). The optical and structural properties of these QDs are consistent with charge recombination via donor−acceptor levels instead of direct excitonic recombination. Finally, we show that the growth of a ZnS shell around these QDs increases their PL quantum yield substantially (up to 40−50% at 800 nm) and allows preservation of their PL properties after solubilization into water and in vivo, as demonstrated by detection of the regional lymph node in a mouse. (RDC 11/23/2010)