Study of the optical and dosimetric properties of the nano conjugate 99mTc-EDDA/HYNIC-GGC-Au Np-Bombesin by effect of nano particle size

The receptors over-expressed on the surface of cancer cells represent promising targets for breast cancer diagnosis or therapy. The gastrin-releasing peptide receptor (GRP-r) is a seven-transmembrane G-protein coupled receptor that is over-expressed on primary prostate and breast cancer and lymph node metastases. Bombesin (Bn) is a tetradeca peptide that binds with high affinity to GRP-r. The strong, specific Bn-GRP-r binding is the basis for labelling Bn with radionuclides (i.e. 99mTc, 111In, 18F) to obtain molecular images. The aim of this work was to develop 3 multifunctional systems of 99mTc-labeled gold nanoparticles (Au Np) (5, 10 and 20 nm) conjugated to Lys3-Bombesin for GRP-receptor targeting in breast cancer. The systems were characterized by Tem and UV-Vis, IR, Raman, Fluorescence and XP spectroscopy. The 99mTc-Au Np-Lys3-Bombesin multifunctional system (20 nm) shows in vitro and in vivo specific recognition for GRP-r and suitable properties to be used as a nuclear molecular imaging agent. Results also showed a specific Lys3-Bombesin binding to the gold surface and higher fluorescence intensity for the 20 nm system. The Nir bands observed in the 20 nm radio conjugate indicate potential for bio imaging as dual systems. (Author)