Authors:A. Perera Pintado, S. Mather, M. Stalteri, D. Allison, A. Prats Capote, A. Hernández Cairo, O. Reyes Acosta and M. Bequet Romero
The aim of this work was to characterize the in vitro behavior of N4- and N3S-RGDS-derivative peptides labeled with 99mTc. Peptides AGGG-Abu-GRGDSPK-NH2 (F22) and C(acm)-GGG-Abu-GRGDSPK-NH2 (SMA1) were synthesized by solid phase. The stability of 99mTc-labeled peptides was assessed in a 30-fold molar excess of cysteine and in plasma. The affinity for plasma proteins was
also evaluated. Labeling yield was >95% for both peptides. 99mTc-F22 was not stable in presence of cysteine, but 63% of 99mTc remained chelated to SMA1 up to 24 hours. Both peptides showed low affinity to plasma proteins. N3S-RGDS-derivative peptide
(SMA1) showed more stable coordination binding with 99mTc and a higher stability in plasma with regard to N4-RGDS-derivative peptide (F22).
Authors:Nevenka Rajic, Djordje Stojakovic, Sanja Jevtic, Natasa Logar, Gregor Mali and Venceslav Kaucic
An open-framework aluminophosphate analog of the fluorogallophosphate structure-type ULM-3 was obtained by hydrothermal crystallization
of an aqueous aluminum phosphate suspension in the presence of 3-methylpropylamine (MAPA) and hydrofluoric acid. The open-framework
fluorinated aluminophosphate structure was confirmed by Rietveld analysis and the 27Al, 31P, and 19F MAS NMR spectroscopy. The MAPA, located in the ten-membered ring channels, is doubly protonated to balance the negative
charge of the Al3P3O12F22– framework. Thermogravimetric analysis data have been used to study kinetics of the thermal decomposition of MAPA. The decomposition
was found to be a complex process, its activation energy varied from 177 to 259 kJ mol−1. The relatively high E values are explained by the fact that the MAPA cations are bound to the anionic framework both by electrostatic forces as
well as strong N-H…O hydrogen bonds. The strength of the interactions is indirectly confirmed by the in situ high temperature
X-ray diffraction analysis which shows that the MAPA decomposition leads to a phase transformation of the open-framework structure
to the dense trydimite phase.