Colorimetric Method for the Detection of Mercury Ions Based on Gold Nanoparticles and Mercaptophenyl Boronic Acid

In the present study, we found that phenylboronic acid derivatives including benzene-1,4-diboronic acid (BDBA) and mercaptophenyl boronic acid (MPBA) can induce the aggregation of citrate-capped gold nanoparticles (Au NPs). However, the speed of Au NP aggregation induced by MPBA was much faster than that of BDBA. The reaction between MPBA and Hg²⁺ ions resulted in the formation of MPBA-Hg²⁺-MPBA, which was similar to BDBA having two free boronic acid groups. Based on the above phenomenon, a sensitive and selective colorimetric method for the detection of mercury ions (Hg²⁺) in aqueous solution was developed. The linear range for the detection of Hg²⁺ ions was from 0.08 to 1.25 μmol dm^-3 with a detection limit of 37 nmol dm^-3. The strategy offered excellent selectivity toward Hg²⁺ against other metal ions. Meanwhile, this simple and cost-effective sensor was applied to determine the Hg²⁺ in the lake water samples with satisfactory recoveries (91.3 - 100.7%).