We report a portable and highly sensitive Hg 2+ nanosensor, where the CuS nanozyme functions as an Hg 2+ recognition unit, a Hg 2+ enrichment/preconcentration carrier, and a signal amplifier/output unit. The as-designed enrichmentdetection integration strategy is customizable and endows the sensor with both a wide detection range from 50 ppt to 400 ppb and a high sensitivity with a minimum detectable Hg 2+ concentration of 50 ppt. In order to make the Hg 2+ nanosensor portable and cost-effective, a commercial RGB sensor is employed here in conjunction with the Hg 2+ -dependent colorimetric reaction. More importantly, the as-developed Hg 2+ nanosensor is feasible for analysis of real samples with satisfactory accuracy (deviation <10%) and reproducibility (recovery ∼82%). Thus, this portable Hg 2+ nanosensor appears to be a viable solution to meet the actual needs of on-site and real-time mercury contamination analysis and may also pave the way to colorimetric nanosensors for other metal ions.
In the current work,
Cu(I)1.28Cu(II)0.36Se nanoparticles were synthesized
via a simple procedure and were applied for the first time for recognition,
adsorption, enrichment, and detection of Hg(II) ions. The experimental
results show that 99.9% Hg(II) could be adsorbed by Cu(I)1.28Cu(II)0.36Se nanoparticles within just 30 s, and the Hg(II)
concentration could be lowered down to a super-low level of 0.01 ppb.
Cu(I)1.28Cu(II)0.36Se nanoparticles also demonstrate
high selectivity to Hg(II) and Ag(I) among nine representative metal
ions. The enrichment experiments show that Hg(II) of ultratrace concentration
could be enriched significantly by Cu(I)1.28Cu(II)0.36Se nanoparticles, and thus, the detection limit of Hg(II)
based on inductively coupled plasma emission spectroscopy–mass
spectrometry would be pushed down by 2 orders of magnitude. These
outstanding features of Cu(I)1.28Cu(II)0.36Se
nanoparticles could be well accounted for in terms of the solubility
product principle and the high affinity between selenium and mercury.
Cu(I)1.28Cu(II)0.36Se nanoparticles were also
found to have peroxidase-like activity, which could be inhibited by
Hg(II) but not by Ag(I). This unique characteristic coupled with the
solubility product principle successfully allows recognition and detection
of Hg(II) even in the presence of Ag(I), which has a similar pK
sp to Hg(II). As a result, the qualitative and
quantitative analyses of Hg(II) could be performed by the naked eye
and UV–visible spectroscopy, respectively. The current results
indicate that Cu(I)1.28Cu(II)0.36Se nanoparticles
not only have great potential in various aspects of dealing with Hg(II)
pollution but would also shed light on discovering new nanomaterials
to address other heavy metal ions.
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