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Magneto/optical annexin V, a multimodal protein
Eyk A Schellenberger1, David Sosnovik, Ralph Weissleder
1Center for Molecular Imaging Research, Massachusetts General Hospital, Building 149, 13th Street, Charlestown, Massachusetts 02129, USA.
Bioconjugate Chemistry
|September 16, 2004
Summary
Researchers developed a new magneto/optical protein, Anx-CLIO-Cy5.5, for imaging and cell sorting. This multimodal protein retains high bioactivity, enabling specific detection of apoptotic cells using MRI or optical methods.
Area of Science:
- Bioconjugation Chemistry
- Molecular Imaging
- Cell Biology
Background:
- Multimodal proteins offer versatile applications in diagnostics and research.
- Challenges exist in labeling proteins with multiple reporters while maintaining bioactivity.
Purpose of the Study:
- To synthesize a magneto/optical annexin V conjugate (Anx-CLIO-Cy5.5).
- To preserve the bioactivity and specific cell-binding properties of annexin V.
- To create a probe detectable by both MRI and near-infrared fluorescence (NIRF) imaging.
Main Methods:
- Synthesized a fluorescent, sulfhydryl-reactive nanoparticle by reacting amino-CLIO with Cy5.5 and SPDP.
- Introduced a single sulfhydryl group onto annexin V using SATA, preserving its apoptotic cell binding.
- Conjugated the modified annexin V to the activated nanoparticle to create Anx-CLIO-Cy5.5.
Main Results:
- Anx-CLIO-Cy5.5 specifically bound to apoptotic Jurkat T cells with an EC(50) of 3.66 nM.
- The binding affinity was comparable to unmodified annexin V.
- The resulting conjugate is suitable for standard MR imaging and NIRF optical detection.
Conclusions:
- The developed conjugation strategy successfully preserves annexin V bioactivity.
- Anx-CLIO-Cy5.5 is a novel magneto/optical probe for detecting apoptotic cells.
- This probe facilitates multimodal imaging and cell sorting applications.