Portable Glucose Meter for Detection of Mercury (II) Ion

Based on the specific recognition of T-Hg2+-T mismatched for mercury ions (Hg2+), a simple and sensitive method for detecting Hg2+ was developed by using Fe3O4 nano-magnetic beads (MB) as reaction platform and portable blood glucose meter (PGM) as detection means-Gold nanoparticles (AuNPs) were prepared by sodium citrate reduction-The surface of AuNPs was modified with sulfhydryl terminal-rich thymine (T) oligonucleotide probe (S1) and glucose oxidase (GOx). In the presence of Hg2+, functionalized AuNPs were captured by capture-probe (S2)-modified MB due to T-Hg2+-T coordination. The labeled GOx oxidized glucose (Glu) to gluconic acid and H2O2. Thus, the concentration of Glu in the reaction solution was reduced and could be detected quantitatively by PGM. The optimal conditions of the assay were as follows: the volume ratio of S2 and GOx was 1:3, the reaction time of Hg2+ was 2 h, and the hydrolysis time of Glu was 1 h. Under optimized conditions, the PGM response of the system had a good linear relationship with the logarithm of Hg2+ concentration. The linear range was 0.05 - 8.00 nmol/L, and the detection limit was 0.02 nmol/L (3 sigma). The recovery of Hg2+ in actual water samples was 97.8% - 113.7%, and the relative standard deviation was 0.2% - 1.4%, which met the detection requirements of Hg2+ in actual water samples.