Water-proton-spin–lattice-relaxation dispersion of paramagnetic protein solutions

Diakova, Galina; Goddard, Yanina A.; Korb, Jean-Pierre; Bryant, Robert G.

doi:10.1016/j.jmr.2010.11.001

Cited by 15 publications

(14 citation statements)

References 32 publications

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“…Several sources for the large high-field r 1 are possible: (i) unbound paramagnetic centers in solution (eliminated by chemical analysis), (ii) dipolar coupling of non-metal-protein-bound water molecules to the paramagnetic centers (19), and (iii) translational diffusion of water close to the paramagnetic centers in the protein interface region. Water molecules rigidly bound to the protein may contribute to relaxation by dipolar coupling to the metal centers; however, the contribution will disperse with the rotational correlation time of the protein.…”

Section: Resultsmentioning

confidence: 99%

“…If there are many sites and a distribution of local correlation times, the magnetic field dependence may be weak and the high-field r 1 significant. Diffusive motion of water adjacent to the paramagnetic centers also contributes to the high-field relaxivity; however, the contribution is expected to be small for an unmodified protein surface because the correlation times are in the range of tens of picoseconds (19,21). However, modification with PEG may slow this motion and amplify the contribution.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Protein MRI contrast agent with unprecedented metal selectivity and sensitivity for liver cancer imaging

Xue

Yang²,

Qiao

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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119

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With available MRI techniques, primary and metastatic liver cancers that are associated with high mortality rates and poor treatment responses are only diagnosed at late stages, due to the lack of highly sensitive contrast agents without Gd 3+ toxicity. We have developed a protein contrast agent (ProCA32) that exhibits high stability for Gd 3+ and a 10 11 -fold greater selectivity for Gd 3+ over Zn 2+ compared with existing contrast agents. ProCA32, modified from parvalbumin, possesses high relaxivities (r 1 /r 2 : 66.8 mmol −1 ·s −1 / 89.2 mmol −1 ·s −1 per particle). Using T 1 -and T 2 -weighted, as well as T 2 /T 1 ratio imaging, we have achieved, for the first time (to our knowledge), robust MRI detection of early liver metastases as small as ∼0.24 mm in diameter, much smaller than the current detection limit of 10-20 mm. Furthermore, ProCA32 exhibits appropriate in vivo preference for liver sinusoidal spaces and pharmacokinetics for high-quality imaging. ProCA32 will be invaluable for noninvasive early detection of primary and metastatic liver cancers as well as for monitoring treatment and guiding therapeutic interventions, including drug delivery.MRI | uveal melanoma | metastasis | contrast agents | T 2 /T 1 ratio imaging T umor metastasis is the main cause of nearly all human cancerrelated deaths. Liver is a common site for metastases of a variety of cancers, including melanoma, breast, pancreatic, and colon cancers (1, 2). For example, uveal melanoma, the most common primary intraocular tumor, has a 40% risk of metastasizing to the liver within 10 y of diagnosis of the primary tumor. Hepatic metastases, which occur in 95% of patients with uveal melanoma metastasis, result in death in almost all cases. This high death rate is related to the recognition of liver metastasis at a late clinical stage (at stage II or later in the TNM system) in which the metastatic uveal melanoma is resistant to currently available systemic chemotherapies (3, 4). The liver may also give rise to primary tumors such as hepatocellular carcinoma (HCC), which is the most common primary malignancy worldwide (5). However, currently there is no reliable way to detect primary liver cancer and hepatic metastases at early stages with high sensitivity and specificity.MRI is a widely used clinical imaging modality that provides exquisite soft-tissue contrast without using ionizing radiation (6, 7). More than 35% of MRI scans use MRI contrast agents, particularly paramagnetic gadolinium (Gd 3+ )-based contrast agents, which shorten T 1 and lead to an increase in MRI intensity (8). All clinically approved Gd 3+ -containing contrast agents are based on small chelators with relaxivity (r 1 and r 2 ) values around 4-6 mM −1 ·s −1 . Their low relaxivities severely limit the sensitivity of current MR imaging methods with respect to detection of lesions and treatment planning and monitoring. Repeat MRI scans are frequently requested for patients with ambiguous small lesions and are used as a routine follow-up modality for highrisk patients, but t...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Protein MRI contrast agent with unprecedented metal selectivity and sensitivity for liver cancer imaging

Xue

Yang²,

Qiao

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

119

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“…Thus, the origin of the high relaxation rates is the coupling of the water protons to the paramagnetic centers in or on the full-length SWCNTs and US-tubes (collectively referred to as nanotubes below). The observation that the low-and high-field regions are linear in the logarithm of the Larmor frequency is the signature of dimensionally-restricted diffusion of the observed water protons in the vicinity of paramagnetic centers [31][32][33][34] . If we use the definition of the 2D translational correlation time as τ m = δ 2 /(4D I ⊥ ), we can write Equation 5 in terms which are relevant to a solution where water molecules diffuse within a transient layer of some thickness at the surface,…”

Section: Resultsmentioning

confidence: 99%

The Gadonanotubes as High-Performance MRI Contrast Agents: The Unappreciated Role of the Carbon Nanotube Component at Low Magnetic Fields

Moghaddam¹,

Sethi²,

Shayeganfar³

et al. 2017

ECS J. Solid State Sci. Technol.

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The Gadonanotubes (GNTs) are the highest-performing T 1 -weighted MRI contrast agent material known with a relaxivity of ∼160 mM −1 s −1 per Gd 3+ ion at 1.5 T. In this work, the contribution of carbon-based free radicals at defect sites on the sidewalls of the ultra-short carbon nanotube (US-tube) component of the GNTs to the T 1 relaxation time has been investigated by Nuclear Magnetic Resonance Dispersion (NMRD) and Electron Paramagnetic Resonance (EPR) studies. The NMRD results indicate that carbon-based radicals of the US-tube structure substantially shorten water proton spin-lattice relaxation times at low frequencies (< 1 MHz) and that the high water proton relaxation rate for the GNTs at these fields does not result from the Gd 3+ ion alone. Furthermore, a computational study suggests that the defect sites of the US-tube structure increase nanotube strain and create new interband electronic states. While the presence of Gd 3+ ions at the defect sites for the GNTs do not induce new electronic states, they do introduce a shift in the Fermi level to higher energy (0.4 eV).

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“…One can also notice that the relatively high content of magnetic impurities still allows extracting of information on molecular dynamics at the interface using low‐field relaxometry. These results will have impact in the development of new relaxometry techniques to be used in investigation of porous media with magnetic impurities such as soils and protein solutions . They will also contribute to the understanding of molecular dynamics at the interface.…”

Section: Discussionmentioning

confidence: 93%

Frequency‐dependent NMR relaxation of liquids confined inside porous media containing an increased amount of magnetic impurities

Muncaci

Mattea

Stapf

et al. 2013

Magnetic Reson in Chemistry

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Frequency-dependent NMR relaxation studies have been carried out on water (polar) and cyclohexane (nonpolar) molecules confined inside porous ceramics containing variable amounts of iron oxide (III). The porous ceramics were prepared by compression of powders mixed with iron oxide followed by thermal treatment. The pore size distribution was estimated using a technique based on diffusion in internal fields that exposed a narrow distribution of macropore sizes with an average pore dimension independent of iron oxide content. The relaxation dispersion curves were obtained at room temperature using a fast field cycling NMR instrument. They display an increase of the relaxation rate proportional to the iron oxide concentration. This behavior is more prominent at low Larmor frequencies and is independent of the polar character of the confined molecules. The results reported here can be fitted well with a relaxation model considering exchange between molecules in the close vicinity of the paramagnetic centers located in the surface and bulk-like molecules inside the pores. This model allows the extraction of the transverse diffusional correlation time that can be related to the polar character of the confined molecules.

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Water-proton-spin–lattice-relaxation dispersion of paramagnetic protein solutions

Cited by 15 publications

References 32 publications

Protein MRI contrast agent with unprecedented metal selectivity and sensitivity for liver cancer imaging

Protein MRI contrast agent with unprecedented metal selectivity and sensitivity for liver cancer imaging

The Gadonanotubes as High-Performance MRI Contrast Agents: The Unappreciated Role of the Carbon Nanotube Component at Low Magnetic Fields

Frequency‐dependent NMR relaxation of liquids confined inside porous media containing an increased amount of magnetic impurities

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