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99mTc-dextran-antibody conjugates. Labelling procedures
M Márquez1, J E Westlin, S Nilsson
1Department of Oncology, University Hospital, Uppsala, Sweden.
Acta Oncologica (Stockholm, Sweden)
|January 1, 1996
Summary
Technetium-99m (99mTc) dextran chelates were optimized for radiolabeling, achieving 70-75% efficiency. Tartaric acid improved reproducibility for 99mTc-dextran labeling of antibodies in imaging.
Area of Science:
- Nuclear medicine
- Radiopharmaceutical chemistry
Background:
- Technetium-99m (99mTc) is a radionuclide suitable for scintigraphic and tomographic imaging.
- Dextran can form stable chelates with 99mTc, enabling its use in radiolabeling.
Purpose of the Study:
- To investigate factors influencing the formation of 99mTc-dextran chelates.
- To optimize the radiolabeling process for potential use in antibody conjugates for medical imaging.
Main Methods:
- Studied two radiolabeling methods: direct dextran labeling and labeling via tartaric acid.
- Investigated effects of ligand concentration, tin(II) chloride (SnCl2) concentration, technetium activity, pH, and incubation time.
- Compared gel filtration (GFR) and thin-layer chromatography (TLC) for assessing labeling efficiency.
Main Results:
- Optimal labeling conditions (70-75% efficiency) were achieved with 10-500 microM ligand, 5-100 microM SnCl2, 10-500 MBq 99mTc, pH 7, and 10-15 min incubation.
- Using 100 microM tartaric acid as an intermediate chelator with SnCl2 in ethanol enhanced labeling reproducibility.
- Labeling efficiency was unaffected by oxygen presence or oxygen scavengers.
- TLC generally indicated higher labeling efficiencies than GFR.
Conclusions:
- Optimized conditions provide efficient 99mTc-dextran chelation.
- Tartaric acid improves the reliability of the radiolabeling process.
- The developed method is suitable for labeling monoclonal antibodies with 99mTc for imaging applications.