Characterization of a fluorescent hydrogel synthesized using chitosan, polyvinyl alcohol and 9-anthraldehyde for the selective detection and discrimination of trace Fe and Fe in water for live-cell imaging.

A three-dimensional fluorescent hydrogel based on chitosan, polyvinyl alcohol and 9-anthraldehyde (ChPA) has been successfully designed and synthesized for the selective detection and discrimination of Fe and Fe in aqueous environment. The unique characteristics of ChPA has been confirmed by the Fourier-transform infrared spectroscopy (FTIR), rheological measurement, scanning electron microscopy (SEM), thermogravimetry and differential thermogravimetry (TG-DTG), ultraviolet-visible spectroscopy (UV-vis), fluorescence studies, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX), x-ray diffraction (XRD) and dynamic light scattering (DLS). The emission intensity at 516 nm of the hydrogel has been enhanced remarkably with the addition of Fe due to the inhibition of the photoinduced electron transfer (PET) process. However, it gets strongly quenched in the case of Fe owing to chelation enhanced quenching (CHEQ). The probe (ChPA) causes no significant change in the fluorescence and becomes highly specific and sensitive towards Fe and Fe compared to other interfering heavy and transition metal ions (HTM). The detection limits of the sensor for the Fe and Fe are 0.124 nM and 0.138 nM, respectively. The probe is also promising as a selective sensor for the Fe and Fe in the fluorescence imaging of living cells. Thus, such a probe opens up new opportunities to improve the chitosan based fluorescent chemosensor having biocompatibility, biodegradability, sufficient thermal stability and stability in a wide pH range.