Magnetic Relaxation Switch Immunosensors Detect Enantiomeric Impurities

Tsourkas, Andrew; Hofstetter, Oliver; Hofstetter, Heike; Weissleder, Ralph; Josephson, Lee

doi:10.1002/anie.200352998

Cited by 117 publications

(82 citation statements)

References 47 publications

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“…67,105,107,144,164 During this cooperative process, the superparamagnetic iron oxide core of individual nanoparticles become more efficient at dephasing the spins of surrounding water protons, i.e., at enhancing spin-spin relaxation times (T2). Recently, this mechanism has been exploited as a tool for detecting biomolecules in homogeneous assays and has demonstrated detection limits as low as 500 attomoles.…”

Section: Magnetic Relaxation Switchingmentioning

confidence: 99%

“…144 Evidence that considerable differences may be present in the pharmacological activity of certain enantiomers has led to an urgent demand for a system that can detect enantiomeric impurities with high sensitivity, quick execution, and high-throughput capability. To help meet this demand, an MRS-based model system was established where SPIO were first labeled with the enantiomer D-Phe, (SPIO-D-Phe) considered to be the impurity in this case.…”

Section: Enantiomer Detectionmentioning

confidence: 99%

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Superparamagnetic Iron Oxide Nanoparticle Probes for Molecular Imaging

et al. 2006

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Abstract-The field of molecular imaging has recently seen rapid advances in the development of novel contrast agents and the implementation of insightful approaches to monitor biological processes non-invasively. In particular, superparamagnetic iron oxide nanoparticles (SPIO) have demonstrated their utility as an important tool for enhancing magnetic resonance contrast, allowing researchers to monitor not only anatomical changes, but physiological and molecular changes as well. Applications have ranged from detecting inflammatory diseases via the accumulation of non-targeted SPIO in infiltrating macrophages to the specific identification of cell surface markers expressed on tumors. In this article, we attempt to illustrate the broad utility of SPIO in molecular imaging, including some of the recent developments, such as the transformation of SPIO into an activatable probe termed the magnetic relaxation switch.

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Section: Magnetic Relaxation Switchingmentioning

confidence: 99%

Section: Enantiomer Detectionmentioning

confidence: 99%

Superparamagnetic Iron Oxide Nanoparticle Probes for Molecular Imaging

et al. 2006

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“…1,2 With new developments of more specialized and efficient contrast agents, MRI has evolved into a versatile technique with multiple functions. For instance, SPION-based contrast agents that generate a target-dependent MRI signal have been used for molecular or cellular detection.…”

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confidence: 99%

Clusters of Superparamagnetic Iron Oxide Nanoparticles Encapsulated in a Hydrogel: A Particle Architecture Generating a Synergistic Enhancement of the T₂ Relaxation

et al. 2011

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Clusters of iron oxide nanoparticles encapsulated in a pH-responsive hydrogel are synthesized and studied for their ability to alter the T 2 -relaxivity of protons. Encapsulation of the clusters with the hydrophilic coating is shown to enhance the transverse relaxation rate by up to 85% compared to clusters with no coating. With the use of pH-sensitive hydrogel, difficulties inherent in comparing particle samples are eliminated and a clear increase in relaxivity as the coating swells is demonstrated. Agreement with Monte Carlo simulations indicates that the lower diffusivity of water inside the coating and near the particle surface leads to the enhancement. This demonstration of a surface-active particle structure opens new possibilities in using similar structures for nanoparticle-based diagnostics using magnetic resonance imaging.

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“…Upon addition of mixtures of the phenylalanine enantiomers to the CLIO-D-Phe/anti-D-AA self assembled structures, the presence of D-Phe impurities resulted in the dispersion of the nanoparticles by competing with the CLIO-D-Phe conjugates for antibody binding sites. The immunosensor allowed to detect 0.1 µM D-Phe in the presence of 10 mM L-Phe, which is an equivalent to 99,998% enantiomer excess (Fig 7.) (Tsourkas et al, 2004). For the less sensitive determination of enantiomeric impurities a simple and inexpensive membrane-based optical immunosensor was invented.…”

Section: Other Type Of Detectionmentioning

confidence: 99%