Rapid capture and visual detection of copper ions in aqueous solutions and biofluids using a novel cellulose-Schiff base
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In this work, a novel colorimetric sensor was prepared via a cellulose-polyethylenimine-based Schiff base (cellulose-Schiff base) for capturing and detecting copper ions (Cu2+) in aquatic environments and life systems. The cellulose-Schiff base displayed continuous color changes from inherent pale yellow to deep green due to the formation of a cellulose-Schiff base-Cu2+ charge transfer complex within 30 s, indicating excellent “naked-eye” detection capability for Cu2+ ions in aqueous solution. The limit of detection (LOD) was 1.054 ppm, lower than the U.S. EPA guidelines for drinking water of 1.3 ppm. Moreover, the cellulose-Schiff base colorimetric sensor was successfully used to capture and detect exogenous Cu2+ ions in biofluids (simulated urine and bovine serum). The proposed sensing mechanism of the cellulose-Schiff base for Cu2+ ions is that N atoms (C=N and N–H) in the sensor capture and concentrate Cu2+ ions to form sensor-Cu2+ complexes, then intramolecular charge transfer occurs as a consequence. In addition, test strips based on cellulose-Schiff base were developed, and provide a convenient, cheap, sensitive, and reliable monitoring platform for on-site semi-quantitative analysis of Cu2+ ions in real samples.
KeywordsSchiff base Capture Visual detection Biofluids Chelation Copper ions
The work was financially supported by the Public Technology Research Plan of Zhejiang Province (LGF18E030003, LY15E030003), National Natural Science Foundation of China (51672251), and 521 Talent Project of Zhejiang Sci-Tech University.