Synthesis and characterizations of water dispersible hybrid nanoparticles based on SPIONs and conjugated polymers for dual imaging applications

This study focuses on the synthesis and characterizations of conjugated polymer coated super-paramagnetic iron oxide nanoparticles for their potential uses in vivo and in vitro imaging. Water dispersible, stable super-paramagnetic iron oxide (SPIO) hybridized conjugated polymer nanoparticles are synthesized with three different types of conjugated polymers emitting in the region of blue, green and red. SPION, which is a T2 contrast agent due to its magnetic susceptibility, is taken into consideration because of its unique uptake mechanism by the Kupffer cells in the liver, spleen or bone marrow.[1] The core iron oxide nanoparticles are coated to increase blood circulation time, reduce the agglomeration of them and improve pharmacokinetic effect.2 Conjugated polymers utilized in this work were modified with allyl pendant groups in order to obtain cross linkable moieties. Polymer chains were cross-linked via [2+2] cycloaddition of ethylene units under UV light to confer stability .Cross-linking would not only confer stability to these hybrid nanoparticles but it can also help preventing the early leakage of SPIONs from the polymer matrix in the biological media. For this purpose, three polymers used in this study, which were poly[(9,9-bis{3-dihexyl}flourenyl-2,7-diyl)-co-(9,9-bis{3-diallyl}fluorenyl-2,7-diyl)] (PB), Poly[(9,9-bis ({3-diallyl}flourenyl-2,7-diyl)-co-(benzothiodiazole)] (PG) and poly[3-{(allyloxy)ethyl} (thiophene 2,5-diyl)-co-(5,5’-{2,2’}-bithiophene)] (P2). Nanoparticles of these polymers with and without SPIONs were synthesized. Optical and morphological characterizations were investigated via DLS, SEM, TEM, UV-Vis and Fluorescence spectroscopy.