Electrochemical growth of two-dimensional MoS2 nanosheets for development of femtomolar Hg(II) ion label-free biosensor

[Display omitted] •Controlled growth of 2D-MoS2 thin films achieved from carboxylated MoS2.•Amino tagged poly(Thymine) shows potential affinity for Hg(II) ions.•T-Hg(II)-T hybridised MoS2 offers strong coordination for Hg(II) sensor.•10 fM of Hg(II) concentration could be detected in aqueous medium. 2D-Molybdenum disulfide (MoS2) is a transition metal dichalcogenide with unique conducting and optoelectronic properties. This paper proposes a novel facile method to grow 2D (MoS2) thin films by carboxylation of (MoS2) nanoflakes using electrochemical deposition technique. The growth of the films was confirmed by atomic force microscopy. Further, an electrochemical Hg(II) ion biosensor was developed using as-grown (MoS2) nanosheets functionalized with single-stranded deoxyribonucleic acid (ssDNA). The label-free electrochemical biosensor offered an excellent detection limit in the range of 10 fM to 10 nM of mercury concentrations. The selectivity measurements and environmental sample studies further revealed their superior applicability in environmental monitoring purposes.