Bioconjugated Quantum Dots for In Vivo Molecular and Cellular Imaging

Departments of Biomedical Engineering and Chemistry, Emory University and Georgia Institute of Technology, Atlanta, GA 30322, USA.
Advanced Drug Delivery Reviews (Impact Factor: 15.04). 09/2008; 60(11):1226-40. DOI: 10.1016/j.addr.2008.03.015
Source: PubMed


Semiconductor quantum dots (QDs) are tiny light-emitting particles on the nanometer scale, and are emerging as a new class of fluorescent labels for biology and medicine. In comparison with organic dyes and fluorescent proteins, they have unique optical and electronic properties, with size-tunable light emission, superior signal brightness, resistance to photobleaching, and broad absorption spectra for simultaneous excitation of multiple fluorescence colors. QDs also provide a versatile nanoscale scaffold for designing multifunctional nanoparticles with both imaging and therapeutic functions. When linked with targeting ligands such as antibodies, peptides or small molecules, QDs can be used to target tumor biomarkers as well as tumor vasculatures with high affinity and specificity. Here we discuss the synthesis and development of state-of-the-art QD probes and their use for molecular and cellular imaging. We also examine key issues for in vivo imaging and therapy, such as nanoparticle biodistribution, pharmacokinetics, and toxicology.

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Available from: Shuming Nie, Nov 28, 2014
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    • "Recently, the use of quantum dots (QDs) as fluorescence probes instead of conventional organic fluorescent molecules or biological fluorescence molecules such as green fluorescent protein [2] [3] [4] [5] [6] [7] [8] [9] has been investigated. QDs are semiconductor nanocrystals, and their fluorescence properties are determined by the size of the nanocrystal [3] [10] [11]. In general, QDs range in size from 2 nm to 10 nm. "
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    ABSTRACT: To add novel functionality to quantum dots (QDs), we synthesized water-soluble and pH-responsive block-type polymers by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were composed of cytocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer segments, which contain a small fraction of active ester groups and can be used to conjugate biologically active compounds to the polymer, and pH-responsive poly(2-(N,N-diethylamino) ethyl methacrylate (DEAEMA)) segments. One terminal of the polymer chain had a hydrophobic alkyl group that originated from the RAFT initiator. This hydrophobic group can bind to the hydrophobic layer on the QD surface. A fluorescent dye was conjugated to the polymer chains via the active ester group. The block-type polymers have an amphiphilic nature in aqueous medium. The polymers were thus easily bound to the QD surface upon evaporation of the solvent from a solution containing the block-type polymer and QDs, yielding QD/fluorescence dye-conjugated polymer hybrid nanoparticles. Fluorescence resonance energy transfer (FRET) between the QDs (donors) and the fluorescent dye molecules (acceptors) was used to obtain information on the conformational dynamics of the immobilized polymers. Higher FRET efficiency of the QD/fluorescent dye-conjugated polymer hybrid nanoparticles was observed at pH 7.4 as compared to pH 5.0 due to a stretching-shrinking conformational motion of the poly(DEAEMA) segments in response to changes in pH. We concluded that the block-type MPC polymer-modified nanoparticles could be used to evaluate the pH of cells via FRET fluorescence based on the cytocompatibility of the MPC polymer. Copyright © 2015 Elsevier B.V. All rights reserved.
    Colloids and surfaces B: Biointerfaces 08/2015; 135. DOI:10.1016/j.colsurfb.2015.08.001 · 4.15 Impact Factor
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    • "). QDs are extensively used as in vivo imaging agents (Smith et al. 2008, Choi et al. 2010, Papagiannaros et al. 2010, Han et al. 2001). In the treatment of cancer, a particular antibody coupled to near-IR QDs with a polymer coating is a very popular QD agent for tumor-targeted imaging (Smith et al. 2008). Quantum dots have also been extensively used as in vitro imaging agents. "
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    ABSTRACT: Quantum dots (QDs) as colloidal nanocrystalline semiconductors have exceptional photophysical properties, due to their quantum confinement effects. Depending on their sizes and chemical compositions, QDs emit different wavelengths over a broad range of the light spectrum, from visible to infrared. QDs are typically extensively used for optical applications due to their high extinction coefficient. This article reviews biomedical applications of QDs, especially the application of QDs in cell targeting, delivery, diagnostics, cancer therapy, and imaging for cancer research.
    Artificial Cells 01/2015; DOI:10.3109/21691401.2014.998826 · 1.02 Impact Factor
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    • "Most of the experimentally studied and commercial QDs are synthesized via traditional organometallic methods, which contain highly toxic elements, such as cadmium, lead and mercury, and use organic solvents and ligands at high temperatures [19]. Therefore, concern has been raised over the use of QDs containing toxic heavy-metal cores in living cells, animals and humans because the long-term impact is unknown [20]. Surprisingly, despite exhibiting very interesting properties, the use of QDs in environmental applications has only recently attracted attention from scientists [16,17,21–25]. "
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    ABSTRACT: Quantum dots (QDs) are semiconductor nanoparticles that are emerging as a new class of fluorescent nanomaterials for environmental applications. Heterogeneous photocatalysis using QDs is an attractive technology for the advanced treatment of water contaminated with organic dyes. In this work, novel nano-photocatalysts based on ZnS QDs functionalized with chitosan were developed using a "green" colloidal chemical method in aqueous media at room temperature. These ZnS/chitosan nano-photocatalysts (ZnS-CHI) were extensively characterized, and the results demonstrated that chitosan was an effective capping ligand for the direct production of water-soluble ZnS QDs with an average nanocrystal size of 3.8 nm. Methylene blue and methyl orange dyes, which were used as model organic pollutants, were effectively oxidized by the photocatalytic activity of the ZnS/chitosan nanostructured systems under UV irradiation. In addition, the ZnS-CHI nano-conjugates exhibited blue photoluminescent behavior upon ultraviolet excitation. Therefore, a "green" facile chemical synthesis of fluorescent nano-photocatalytic materials was developed using an abundant biocompatible polysaccharide that exhibit potential for the photodegradation of hazardous organic pollutants present in wastewater and several other environmentally friendly applications.
    Applied Catalysis B Environmental 10/2014; s 158–159:269–279. DOI:10.1016/j.apcatb.2014.04.026 · 7.44 Impact Factor
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