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Issue 6, 2011
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Cell-compatible, integrin-targeted cryptophane-129XeNMR biosensors

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Peptide-modified cryptophane enables sensitive detection ofproteinanalytes using hyperpolarized 129Xe NMR spectroscopy. Here we report improved targeting and delivery of cryptophane to cells expressing αvβ3 integrin receptor, which is overexpressed in many human cancers. Cryptophane was functionalized with cyclic RGDyKpeptide and Alexa Fluor 488dye, and cellular internalization was monitored by confocal laser scanning microscopy. Competitive blocking assays confirmed cryptophaneendocytosis through an αvβ3 integrin receptor-mediated pathway. The peptidecryptophane conjugate was determined to be nontoxic in normal human lung fibroblasts by MTT assay at the micromolar cryptophane concentrations typically used for hyperpolarized 129Xe NMR biosensing experiments. Flow cytometry revealed 4-fold higher cellular internalization in cancer cells overexpressing the integrin receptor compared to normal cells. Nanomolar inhibitory concentrations (IC50 = 20–30 nM) were measured for cryptophane biosensors against vitronectin binding to αvβ3 integrin and fibrinogen binding to αIIbβ3 integrin. Functionalization of the conjugate with two propionic acidgroups improved water solubility for hyperpolarized 129Xe NMR spectroscopic studies, which revealed a single resonance at 67 ppm for the 129Xe-cryptophane–cyclic RGDyK biosensor. Introduction of αIIbβ3 integrin receptor in detergent solution generated a new “ bound” 129Xe biosensor peak that was shifted 4 ppm downfield from the “free” 129Xe biosensor.

Graphical abstract: Cell-compatible, integrin-targeted cryptophane-129XeNMR biosensors

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Supplementary files

Article information

22 Jan 2011
10 Mar 2011
First published
23 Mar 2011

Chem. Sci., 2011,2, 1103-1110
Article type
Edge Article

Cell-compatible, integrin-targeted cryptophane-129XeNMR biosensors

G. K. Seward, Y. Bai, N. S. Khan and I. J. Dmochowski, Chem. Sci., 2011, 2, 1103
DOI: 10.1039/C1SC00041A

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