A novel sensor for dopamine based on the turn-on fluorescence of Fe-MIL-88 metal-organic frameworks–hydrogen peroxide–o-phenylenediamine system

In this work, a novel sensor based on fluorescence enhancement of Fe-MIL-88- H2O2-o-phenylenediamine (OPD) system for the determination of dopamine (DA) was developed. Fe-MIL-88 with intrinsic peroxidase-like catalytic activity tended to oxidize the nonfluorescent OPD into the fluorescent 2,3-diaminophenazine (DAP) with the presence of H2O2. When DA was introduced, the autoxidation of DA to yield hydroxyl radical (·OH) was further enhanced by Fe(3+) site in Fe3-μ3-oxo clusters exiting in Fe-MIL-88 MOFs, meanwhile the generated Fe(2+) appeared to involve a Fenton type reaction in the presence of H2O2 to cause a continuous production of ·OH radicals which greatly enhanced the conversion efficiency of the OPD to fluorescent DAP. Thus, the turn-on fluorescence method for the DA detection was established. The linear range was from 50nm to 30μM with detection limit 46nm (3σ/s). Furthermore, the proposed method has been reliably applied to determine dopamine content in dopamine hydrochloride injection and human urine with satisfactory results, which suggests its great potential for assay DA in chemical and biological analytical applications.