Highly fluorescent hematoporphyrin modified graphene oxide for selective detection of copper ions in aqueous...

Here, a highly sensitive and selective copper ion (Cu²⁺) fluorescence sensor is reported. The Hematoporphyrin functionalized Graphene Oxide (HP-GO) fluorescence sensor were synthesized via esterification reaction between Graphene Oxide and Hematoporphyrin (HP). The HP-GO sensor was fully characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electrom Microscopy (SEM), UV-Vis spectroscopy, Transmission Electron Microscopy (TEM), Fluor meter spectroscopy, X-Ray photoelectron spectroscopy(XPS), and Raman spectroscopy measurements. The HP-GO sensor advertised two linear regions over the range of 0-1.18 × 10³ nM and 3.93 × 10³ to 47.27 nM of copper (II) with detection limit of 54 nM in the aqueous solution. The selectivity of HP-GO for Cu²⁺ is much higher than that of other metal ions due to the presence of aza macrocyclic ring on the surface of HP-GO which has a high binding affinity with Cu²⁺. Additionally, the HP-GO shows wide pH viable range (pH 6-10). The effect of other metal ions on the fluorescence intensity of the HP-GO was also studied and other metal ions show a low interference response in the detection of Cu²⁺. HP-GO sensor manifests advantages of high reproducibility (The quenched fluorescence of HP/GO-Cu can be recovered by EDTA), attractive long term fluorescence stability (>21 days) in water, also remarkable selectivity regarding number of metal ions (Na⁺, K⁺, Ca²⁺, Fe³⁺, Fe²⁺, Al³⁺, Pb²⁺, Mn²⁺, Mg²⁺, Co²⁺, Ni²⁺, Cr⁶⁺, Cd²⁺, Hg²⁺, and Zn²⁺), low toxicity and can detect Cu²⁺ in real water samples which acquire well for its promising in environmental applications.