Silicon nanohybrid-based SERS chips armed with an internal standard for broad-range, sensitive and reproducible simultaneous quantification of lead(ii) and mercury(ii) in real systems

Abstract

Lead ions (Pb) and mercury ions (Hg), the two commonly coexisting heavy metal ions, pose severe risks to environment and human health. To date, no surface-enhanced Raman scattering (SERS) sensor has been reported for the simultaneous quantification of Pb and Hg in real systems. Herein, the first demonstration of SERS chips for simultaneous quantification of Pb and Hg in real systems is presented based on the combination of reproducible silicon nanohybrid substrates and a corrective internal standard (IS) sensing strategy. This chip was made of a silver nanoparticle-decorated silicon wafer via modification of the IS, i.e. 4-aminothiophenol, molecules. The as-prepared chip was further functionalized with Pb- and Hg- specific DNA strands capable of simultaneously detecting Pb and Hg. Quantitatively, upon correction by the IS Raman signals, the broad dynamic ranges from 100 pM to 10 μM for Pb and from 1 nM to 10 μM for Hg were achieved, with the detection limit down to 19.8 ppt for Pb and 168 ppt for Hg. For real applications, we further demonstrated that Pb and Hg spiked into industrial wastewater could be readily distinguished via the presented chip, and the relative standard deviation (RSD) value was less than ∼15%. More significantly, the resulting SERS chip can be well coupled with a hand-held Raman instrument and can then be used for the qualitative analysis of both Pb and Hg in real systems in a portable manner. Our results suggest that this high-quality SERS chip is a powerful tool for on-site detection of various heavy metal ions in real samples in the field of food safety and environment protection.

Optical Multiplexed Bioassays for Improved Biomedical Diagnostics

“…As aresult, the produced fluorescence fingerprint spectrum could successfully indicate the presence of the detected ions ( Figure 3b). [23] In addition, the DNA-modified SERS sensor can also be used for multiplexed detection of metal ions.S hi et al [24] demonstrated aS ERS chip that is capable of simultaneous detection of Pb 2+ and Hg 2+ through functionalized Pb 2+ -a nd Hg 2+ -specific DNAs trands in real systems.B yi ntroducing an internal standard to reduce the variances from instrumental and measurement conditions, both of the heavy metal ions can be quantified with alow limit of detection, suggesting ap owerful tool for on-site detection of heavy metal ions ( Figure 3c).…”

Application of molecular SERS nanosensors: where we stand and where we are headed towards?

“…For the simultaneous detection of lead (Pb 2+ ) and mercury (Hg 2+ ), Shi et al developed silicon SERS chips including an internal standard sensing strategy [ 28 ]. For the detection in industrial wastewater, a silicon wafer was coated with AgNPs as an internal standard and the NPs were modified with 4-aminothiophenol (4-ATP).…”

Optical Multiplexed Bioassays for Improved Biomedical Diagnostics

“…In addition, the DNA‐modified SERS sensor can also be used for multiplexed detection of metal ions. Shi et al . demonstrated a SERS chip that is capable of simultaneous detection of Pb 2+ and Hg 2+ through functionalized Pb 2+ ‐ and Hg 2+ ‐specific DNA strands in real systems.…”