Fluorescent Detection of Cu(Ⅱ) by Chitosan-based AIE Bioconjugate

Detection of Cu(Ⅱ) is very important in disease diagnose, biological system detection and environmental monitoring. Previously, we found that the product TPE-CS prepared by attaching the chromophores of tetraphenylethylene(TPE) to the chitosan(CS) chains showed excellent fluorescent properties. In this study, we tried to use TPE-CS for detecting Cu(Ⅱ) because of the stable complexation of CS with heavy metals and the luminosity mechanism of the Restriction of Intramolecular Rotations(RIR) for aggregation-induced emission(AIE)-active materials. The fluorescence intensity changed when TPE-CS was contacted with different metal ions, to be specific, no change for Na~+, slightly increase for Hg~(2+), Pb~(2+), Zn~(2+), Cd~(2+), Fe~(2+), Fe~(3+) due to the RIR caused by the complexation between CS and metal ions. However, for Cu~(2+), an obvious fluorescence decrease was observed because of the Photoinduced-Electron-Transfer(PET). Moreover, we found that the quenched FL intensity of TPE-CS was proportional to the concentration of Cu(Ⅱ) in the range of 5 μmol/L to 100 μmol/L, which provided a new way to quantitatively detect Cu(Ⅱ) . Besides, TPE-CS has excellent water-solubility as well as absorbability(the percentage of removal, R = 84%), which is an excellent detection probe and remover for Cu(Ⅱ) .

Fluorescent detection of Cu(II) by chitosan-based AIE bioconjugate

Detection of Cu(II) is very important in disease diagnose, biological system detection and environmental monitoring. Previously, we found that the product TPE-CS prepared by attaching the chromophores of tetraphenylethylene (TPE) to the chitosan (CS) chains showed excellent fluorescent properties. In this study, we tried to use TPE-CS for detecting Cu(II) because of the stable complexation of CS with heavy metals and the luminosity mechanism of the Restriction of Intramolecular Rotations (RIR) for aggregation-induced emission (AIE)-active materials. The fluorescence intensity changed when TPE-CS was contacted with different metal ions, to be specific, no change for Na⁺, slightly increase for Hg²⁺, Pb²⁺, Zn²⁺, Cd²⁺, Fe²⁺, Fe³⁺ due to the RIR caused by the complexation between CS and metal ions. However, for Cu²⁺, an obvious fluorescence decrease was observed because of the Photoinduced-Electron-Transfer (PET). Moreover, we found that the quenched FL intensity of TPE-CS was proportional to the concentration of Cu(II) in the range of 5 μmol/L to 100 μmol/L, which provided a new way to quantitatively detect Cu(II). Besides, TPE-CS has excellent water-solubility as well as absorbability (the percentage of removal, R = 84%), which is an excellent detection probe and remover for Cu(II).