Highly selective chemo-sensor for repetitive detection of Fe3+ in pure water and bio-imaging

Octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) with amine containing poly acryl amide (OV-POSS co-poly (acryl amid)) gives a new fluorescent polymeric chemo-sensor with fully water solubility. It shows better selectivity for Fe3+ in water solution over a wide detection range (pH=6-10). The incorporation with Fe3+ to OV-POSS co-poly (acryl amid) results in significant emission peak at 500 nm with fluorescence enhancement in water solution over other metal ions. The bound ratio of OV-POSS co-poly (acryl amid)-Fe3+ complex was determined to be 1:2 according to the Job’s plot. The association constant (Ka) of Fe3+ bounding with chemo-sensor was 7.416×107. and the detection limit was 0.9×10-9 M. It was found that the system possess has low-cytotoxic, good permeability, high stability, compatibility. Therefore, it has been applied in bio-image successfully with bright blue fluorescent. In addition, visible color change to the naked-eye from colorless to bright yellow can be observed directly when Fe3+ was added into chemo-sensor OV-POSS co-poly (acryl amid) compared with other metal ions.