Development of highly-sensitive detection system in 19F NMR for bioactive compounds based on the assembly of paramagnetic complexes with fluorinated cubic silsesquioxanes

Abstract

This manuscript reports the detection system with ¹⁹F NMR probes for bioactive amine compounds at sub-micro molar concentrations. Water-soluble fluorinated polyhedral oligomeric silsesquioxane (POSS) derivatives were prepared, and the paramagnetic Ni-porphyrin (NiPor) with the fluorinated POSS (F-POSS) was adsorbed in the buffer. By adding the series of amine derivatives to the homogeneous dispersion containing the POSS-NiPor complexes, the changes in the signal intensity were evaluated. It was clearly observed from homogeneous dispersions that the signal intensity of ¹⁹F NMR decreased especially in the presence of ethanediamine and hexylamine. From the dynamic light scattering measurements, it was revealed that the assembly of the F-POSS complexes was dramatically induced by the amine compounds when the signal intensity decreased. According to these data, it is proposed that the signal reduction of ¹⁹F NMR from the POSS-NiPor complexes could be induced via the strong paramagnetic relaxation enhancement from NiPor in the assembly. Finally, based on the signal reduction by the assembly, we can detect the amine derivatives under 1μM concentration which is similar sensitivity to the conventional fluorescence probes. Our system is valid to monitor the distribution of the bio-active molecules at cellular concentrations.

Keywords: (19)F NMR; Fluorinated compound; Molecular probe; Paramagnetic relaxation enhancement; Silsesquioxane.