Hello Yudhajit,

From what I know, most of the nanoparticle based sensors are generally selective toward Hg(II). 

However, I came across a paper by G. V. Ramesh and T. P. Radhakrishnan, where they detect all oxidation states of Hg (+2, +1, 0) with a nanocomposite thin film sensor based on silver nanoparticles embedded in PVA.

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ACS Appl. Mater. Interfaces, 2011, 3 (4), pp 988–994

DOI: 10.1021/am200023w

Publication Date (Web): March 11, 2011

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I have attached the link to this article. I hope this helps!

Grant B

http://pubs.acs.org/doi/abs/10.1021/am200023w

 Also, here is a review of the various types of sensors used in mercury detection. Although the nanosensor in this review is selective toward Hg(II), the selectivity of the various sensor types are discussed which might aid in your research. I hope you find these useful.

Sensing Mercury for Biomedical and Environmental Monitoring

doi:10.3390/s90705446

https://www.mdpi.com/1424-8220/9/7/5446/pdf