Preparation of Peptide-Functionalized Gold Nanoparticles Using One Pot EDC/Sulfo-NHS Coupling
ABSTRACT Although carbodiimides and succinimides are broadly employed for the formation of amide bonds (i.e., in amino acid coupling), their use in the coupling of peptides to water-soluble carboxylic-terminated colloidal gold nanoparticles remains challenging. In this article, we present an optimization study for the successful coupling of the KPQPRPLS peptide to spherical and rodlike colloidal gold nanoparticles. We show that the concentration, reaction time, and chemical environment are all critical to achieving the formation of robust, peptide-coated colloidal nanoparticles. Agarose gel electrophoresis was used for the characterization of conjugates.
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ABSTRACT: The large size of many near-infrared (NIR) fluorescent nanoparticles prevents rapid extravasation from blood vessels and subsequent diffusion to tumors. This confines in vivo uptake to the peritumoral space and results in high liver retention. In this study, we developed a viscosity modulated approach to synthesize ultrasmall silver sulfide quantum dots (QDs) with distinct tunable light emission from 500 to 1200 nm and a QD core diameter between 1.5 and 9 nm. Conjugation of a tumor-avid cyclic pentapeptide (Arg-Gly-Asp-DPhe-Lys) resulted in monodisperse, water-soluble QDs (hydrodynamic diameter < 10 nm) without loss of the peptide's high binding affinity to tumor-associated integrins (KI = 1.8 nM/peptide). Fluorescence and electron microscopy showed that selective integrin-mediated internalization was observed only in cancer cells treated with the peptide-labeled QDs, demonstrating that the unlabeled hydrophilic nanoparticles exhibit characteristics of negatively charged fluorescent dye molecules, which typically do not internalize in cells. The biodistribution profiles of intravenously administered QDs in different mouse models of cancer reveal an exceptionally high tumor-to-liver uptake ratio, suggesting that the small sized QDs evaded conventional opsonization and subsequent high uptake in the liver and spleen. The seamless tunability of the QDs over a wide spectral range with only a small increase in size, as well as the ease of labeling the bright and noncytotoxic QDs with biomolecules, provides a platform for multiplexing information, tracking the trafficking of single molecules in cells, and selectively targeting disease biomarkers in living organisms without premature QD opsonization in circulating blood.ACS Nano 01/2015; 9(1). DOI:10.1021/nn5071183 · 12.03 Impact Factor
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ABSTRACT: A new method combining an interfacial strain-promoted azide-alkyne cycloaddition and post assembly deprotection (SPAAC-PAD) has been developed for the well-defined functionalization of small, water-soluble gold nanoparticles with oligopeptides.RSC Advances 09/2014; 4(81). DOI:10.1039/C4RA07574A · 3.71 Impact Factor
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ABSTRACT: Photodynamic therapy (PDT) involves generation of Reactive Oxygen Species (ROS) by the irradiation of a photosensitizer. Controlled and targeted release of ROS by photosensitizer is crucial in PDT. For the purpose of achieving controlled generation of ROS, a ZnSe/ZnS quantum dots (QDs) donor and protoporphyrin IX (Pp IX) acceptor based fluorescence resonance energy transfer (FRET) probe is reported here. The QDs and Pp IX are assembled either by direct conjugation or through DNA hybridization. Complimentary DNA strands are individually conjugated to the QDs and Pp IX by amide coupling. Due to the overlap of the emission spectrum of QDs and the absorption spectrum of Pp IX, efficient transfer of energy from QD-DNA conjugate to Pp IX-DNA conjugate was observed. The FRET efficiency was quantitatively evaluated by steady- state and time- resolved spectroscopy and compared between QD-Pp IX direct conjugate and QD-DNA-Pp IX assembly at various donor to acceptor ratio. Since a single QD can harbor multiple number of Pp IX-DNA counterpart through DNA hybridization, FRET efficiency was found to increase with the increase in the number of Pp IX acceptors. ROS generation from Pp IX was studied for the highest efficient FRET pair and was found to be affected by the irradiation time of the QD donor.Physical Chemistry Chemical Physics 01/2015; DOI:10.1039/C4CP05306K · 4.20 Impact Factor