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Nanoparticle-based PARACEST agents: the quenching effect of silica nanoparticles on the CEST signal from surface-conjugated chelates.

ABSTRACT: Silica nanoparticles of average diameter 53 ± 3?nm were prepared using standard water-in-oil microemulsion methods. After conversion of the surface Si-OH groups to amino groups for further conjugation, the PARACEST agent, EuDOTA-(gly)? (-) was coupled to the amines via one or more side-chain carboxyl groups in an attempt to trap water molecules in the inner-sphere of the complex. Fluorescence and ICP analyses showed that approximately 1200 Eu(3+) complexes were attached to each silica nanoparticle, leaving behind excess protonated amino groups. CEST spectra of the modified silica nanoparticles showed that attachment of the EuDOTA-(gly)? (-) to the surface of the nanoparticles did not result in a decrease in water exchange kinetics as anticipated, but rather resulted in a complete elimination of the normal Eu(3+) -bound water exchange peak and broadening of the bulk water signal. This observation was traced to catalysis of proton exchange from the Eu(3+) -bound water molecule by excess positively charged amino groups on the surface of the nanoparticles.

SUBMITTER: Evbuomwan OM

PROVIDER: S-EPMC3400155 | biostudies-literature | 2012 Jan-Feb

REPOSITORIES: biostudies-literature

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Nanoparticle-based PARACEST agents: the quenching effect of silica nanoparticles on the CEST signal from surface-conjugated chelates.

Evbuomwan Osasere M OM Merritt Matthew E ME Kiefer Garry E GE Dean Sherry A A

Contrast media & molecular imaging 20120101 1

Silica nanoparticles of average diameter 53 ± 3 nm were prepared using standard water-in-oil microemulsion methods. After conversion of the surface Si-OH groups to amino groups for further conjugation, the PARACEST agent, EuDOTA-(gly)₄ (-) was coupled to the amines via one or more side-chain carboxyl groups in an attempt to trap water molecules in the inner-sphere of the complex. Fluorescence and ICP analyses showed that approximately 1200 Eu(3+) complexes were attached to each silica nanopartic ...[more]

PMID: 22344876

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Dataset Information

Nanoparticle-based PARACEST agents: the quenching effect of silica nanoparticles on the CEST signal from surface-conjugated chelates.

Publications

Nanoparticle-based PARACEST agents: the quenching effect of silica nanoparticles on the CEST signal from surface-conjugated chelates.

Similar Datasets

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