In-situ and ultrasensitive detection of mercury (II) ions (Hg2+) using the localized surface plasmon resonance (LSPR) nanosensor and the microfluidic chip

Mercury is one of the most dangerous heavy metals due to its extreme toxicity to both humans and the biosphere. In this work, an in-situ and ultrasensitive method for the detection of mercury (II) ions (Hg 2+ ) using the dark-field microspectroscopy-based localized surface plasmon resonance (LSPR) nanosensor is demonstrated. In our homemade high-throughput microfluidic chip, the fixed nanorods and the free small gold nanospheres combine to form the core-satellite structures with the help of T- Hg 2+ -T chemical coordination. Such a process results in a spectral red shift due to plasmonic coupling, which allows us to reach a picomolar detection limit and a linear response range from 10 pM to 10 µM. In addition, our LSPR nanosensor has excellent selectivity and no interference for the detection of Hg 2+ , which was evaluated by monitoring responses to different heavy metal ions (Pb 2+ , Cd 2+ , Cr 2+ , Ni 2+ , and Cu 2+ ) and their mixed samples. Our sensor platform's effectiveness offers a practical method for detecting traces of Hg 2+ in real-life water samples.