Dendritic Silica Nanospheres with Au–Pt Nanoparticles as Nanozymes for Label-Free Colorimetric Hg2+ Detection

Mercury ion (Hg2+) is toxic and can severely damage the environment and human health. Therefore, sensitive and selective Hg2+ detection methods are needed. Here, we synthesized dendritic silica nanospheres (DSN) with central-radial porous structures and immobilized Au and Pt nanoparticles into their pores. The synthesized DSN with Au and Pt nanoparticles (AuPt@DSN) exhibited superior peroxidase-like activity, stability, and dispersibility. We found that AuPt@DSN can specifically reduce Hg2+, leading to the decreased catalytic activity of the nanozymes. Under optimal testing conditions, the AuPt@DSN material was efficiently used for the visual detection of Hg2+. The detection limit was 8.58 pM with a linear range from 0.1 nM to 10 μM. Selectivity toward Hg2+ has also been demonstrated in aqueous solutions in the presence of other metal ions. This strategy is simple to utilize and has a low cost and rapid response. The practicability was further investigated by analyzing complex water samples, which suggests its potential for mercury evaluation in environmental samples.