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.