Portable Detection of Copper Ion Using Personal Glucose Meter

A simple and sensitive method for Cu2+ detection was developed using the Cu+-catalyzed alkyne–azide cycloaddition reaction, Fe3O4 magnetic nanoparticles (MNPs) as the reaction platform, and a portable blood glucose meter (PGM) as the detection method. Gold nanoparticles (AuNPs) were labeled with glucose oxidase (GOx) and alkyne-functionalized, terminally thiolated ssDNA (C2). In the presence of Cu2+ and ascorbate, the functionalized AuNPs were captured onto MNPs modified with azide-functionalized ssDNA (C1) via the Cu+-catalyzed alkyne–azide cycloaddition reaction. The GOx on the AuNPs’ surface oxidized glucose (Glu) into gluconic acid and H2O2, reducing the Glu content in the reaction solution, which was quantitatively detected by the PGM. Under optimal conditions, the PGM response of the system showed a good linear relationship with the logarithm of Cu2+ concentration in the range of 0.05 to 10.00 μmol/L, with a detection limit of 0.03 μmol/L (3σ). In actual tap water samples, the spiked recovery rate of Cu2+ was between 92.30% and 113.33%, and the relative standard deviation was between 0.14% and 0.34%, meeting the detection requirements for Cu2+ in real water samples.