Abstract
Silica nanoparticles of average diameter 53±3nm 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 ~1200 Eu3+ 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)4- 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 Eu3+-bound water exchange peak and broadening of the bulk water signal. This observation was traced to catalysis of proton exchange from the Eu3+-bound water molecule by excess positively charged amino groups on the surface of the nanoparticles.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 19-25 |
| Number of pages | 7 |
| Journal | Contrast Media and Molecular Imaging |
| Volume | 7 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2012 |
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Keywords
- MRI
- PARACEST agents
- Silica nanoparticles
- Water exchange
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
Cite this
Nanoparticle-based PARACEST agents : The quenching effect of silica nanoparticles on the CEST signal from surface-Conjugated chelates. / Evbuomwan, Osasere M.; Merritt, Matthew E.; Kiefer, Garry E.; Dean Sherry, A.
In: Contrast Media and Molecular Imaging, Vol. 7, No. 1, 01.2012, p. 19-25.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Nanoparticle-based PARACEST agents
T2 - The quenching effect of silica nanoparticles on the CEST signal from surface-Conjugated chelates
AU - Evbuomwan, Osasere M.
AU - Merritt, Matthew E.
AU - Kiefer, Garry E.
AU - Dean Sherry, A.
PY - 2012/1
Y1 - 2012/1
N2 - Silica nanoparticles of average diameter 53±3nm 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 ~1200 Eu3+ 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)4- 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 Eu3+-bound water exchange peak and broadening of the bulk water signal. This observation was traced to catalysis of proton exchange from the Eu3+-bound water molecule by excess positively charged amino groups on the surface of the nanoparticles.
AB - Silica nanoparticles of average diameter 53±3nm 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 ~1200 Eu3+ 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)4- 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 Eu3+-bound water exchange peak and broadening of the bulk water signal. This observation was traced to catalysis of proton exchange from the Eu3+-bound water molecule by excess positively charged amino groups on the surface of the nanoparticles.
KW - MRI
KW - PARACEST agents
KW - Silica nanoparticles
KW - Water exchange
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UR - http://www.scopus.com/inward/citedby.url?scp=84857169569&partnerID=8YFLogxK
U2 - 10.1002/cmmi.459
DO - 10.1002/cmmi.459
M3 - Article
C2 - 22344876
AN - SCOPUS:84857169569
VL - 7
SP - 19
EP - 25
JO - Contrast Media and Molecular Imaging
JF - Contrast Media and Molecular Imaging
SN - 1555-4309
IS - 1
ER -